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Production and characterization of recycled polycarbonate based composite material containing recycled glass fibers
Accepted Manuscript Title: Production and Characterization of Recycled Polycarbonate Based Composite Material Containing Recycled Glass Fibers Authors: Ping Zhu, Xiankai Liu, Yangjun Wang, Chuanjin Guan, Yazheng Yang, Jiahao Zhu, Xuheng Li, Guangren Qian, Ray L. Frost PII: DOI: Reference:
S2213-3437(17)30301-9 http://dx.doi.org/doi:10.1016/j.jece.2017.06.050 JECE 1712
To appear in: Received date: Revised date: Accepted date:
14-2-2017 23-6-2017 25-6-2017
Please cite this article as: Ping Zhu, Xiankai Liu, Yangjun Wang, Chuanjin Guan, Yazheng Yang, Jiahao Zhu, Xuheng Li, Guangren Qian, Ray L.Frost, Production and Characterization of Recycled Polycarbonate Based Composite Material Containing Recycled Glass Fibers, Journal of Environmental Chemical Engineeringhttp://dx.doi.org/10.1016/j.jece.2017.06.050 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Production and Characterization of Recycled Polycarbonate Based Composite Material Containing Recycled Glass Fibers Ping Zhu a, Xiankai Liua, Yangjun Wanga, Chuanjin Guanb, Yazheng Yanga, Jiahao Zhua, Xuheng Lia, Guangren Qiana, Ray L. Frost c* a
School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, People’s
Republic of China b
School of Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209, People’s Republic of China
c
School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of
Technology, GPO Box 2434, Brisbane Queensland 4001,Australia
*Corresponding author. Email address: [email protected] Ph: +61 7 3138 2407 Fax: +61 7 3138 1804
Highlight 1. Recycled glass fibers and polycarbonates were reused to prepare a composite. 2. The tensile and flexural strength of the composite increased by 73.52% and 30.43%. 3. The properties of the composite were quite close to those of the pure product. 4. The reinforcing mechanism of recycled glass fibers to polycarbonates was analyzed. Abstract: Nowadays, a large quantity of waste printed circuit boards (WPCBs) and waste compact discs (CDs) have been produced, which may cause secondary
pollution and are a waste of resources. In this study, recycled glass fibers (RGF) from non-metals of WPCBs and recycled polycarbonate (RPC) from waste CDs were reused simultaneously to produce composites. A fourier transform infrared (FT-IR) was used to evaluate the functional groups in the modified RGF, the mechanical properties of composites was tested by an universal testing machine and scanning electron microscope (SEM) was used to determine the morphology and surface fractures of the composites. The result indicated that the RGF modified by a silane coupling agent-KH-550 improved the dispersion and compatibility of RGF particles in RPC matrix. The property of composite decreased significantly with resins decomposed during high temperature injection molding when nonmetals were as a filler to prepare a composite. Therefore, RGF in nonmetals was selected as a reinforcing filler of composites. The properties and the fracture surface morphology of the RGF/RPC composite were investigated. The results indicated that the appropriate addition of RGF in the composites can significantly improve the mechanical properties. The maximum tensile and flexural strength of the composites could reach up to 84.68 MPa and 118.3 MPa, which significantly increased by 73.52% and 30.43% respectively than those of RPC when RGF content was 40% with the particle size of 0.15-0.30 mm. The properties were quite close to those of composite which was prepared with pure GF and PC. Keywords: Waste Printed Circuit Boards; Waste Compact Discs; Recycled Polycarbonate; Recycled Glass Fibers; Composite Materials 1. Introduction Recycling synthetic materials or using industrial by-products can be a sustainable strategy to reduce the use of virgin material and the disposal in landfill. As a consequence several researches were carried out to find innovative and sustainable uses for this category of materials. Life Cycle Assessment (LCA) is a methodology to evaluate the impacts of products and services on the environment and on human health during their entire life. LCA is much dependent on the primary sources of the energy of a particular place and conversion efficiency of materials production
processes [1,2]. Vidal et al. [3] carried out a comprehensive LCA of asphalt pavements. The result indicates that climate change, fossil depletion and total cumulative energy demand were decreased by 13~14% by adding 15% reclaimed asphalt pavement. F. Intini et al. [4] characterized the material made of recycled polyethylene terephthalate (PET) by a lower global warming potential (GWP) value and compared to the one of the kenaf-based material. Printed circuit boards (PCBs) are necessary components in electronic products, which are a layered structure and contains nearly 28% metals, such as Cu, Al, Sn, etc. and nearly 70% non-metal materials [5,6]. Glass fiber (GF) and thermosetting resin are the main components of non-metal materials in the PCBs [7]. With the growing volume of waste printed circuit boards (WPCBs) generated annually, the traditional WPCBs treatment (landfill disposal or incineration) must be replaced by recycling technology not only because of the negative environmental impacts of toxic waste, but also due to its potential profitable prospects of recovered metals [8,9]. A significant amount of endeavor on chemical recycling technology of the WPCBs has been reported, such as pyrolysis [10, 11], gasification [12] and supercritical extraction [13]. The most common recycling technology in the WPCBs treatment factory was a physical method. The WPCBs were crushed into small particles, and then the metals were separated from non-metals by air classification [14] or electrostatic separation [15]. As a result, a large quantity of non-metals were generated every year. Glass fibers have excellent physical and chemical properties, such as high mechanical strength, high temperature stability and corrosion resistance. Therefore, the non-metals which contained glass fibers were often used as reinforcing fillers in composites. Currently，this research mainly focuses on non-metal reinforcing pure polymer composites and the influence of non-metal content or particle size on composite properties. The addition of non-metals could obviously improve the mechanical properties of a plastic matrix, such as polypropylene [16,17], polyvinylchloride [18] and phenolic resin [19]. And non-metals which contained glass fibers also could be as reinforcing material in concrete and cement composites [20].
Further, the recycled glass fibers (RGF) which were obtained by pyrolysis of WPCBs was used to produce polypropylene (PP) composites and the resin component was supposed as impurities [21]. Indeed, the usage of pure commercial plastics as matrix must result in high cost and recycled plastics could be a good alternative. Therefore, recycled acrylonitrile butadiene styrene (ABS) and high-density polyethylene (HDPE) were applied to manufacture reproduction composites [22, 23]. And lots of recycled thermoplastics were reinforced by glass fibers to prepare commercial products [24]. Compact discs (CDs) can store information in digital format. They have a sandwich type structure, with a set of superimposed layers of lacquer, metal reflective layer, and polycarbonate substrate [25]. Waste CDs, which are manufactured with high quality PC (above 95 wt.%), may represent an important and relatively cheap material source. In order to recycle CDs and get recycled PC, different technologies have been used to separate PC from the other CD layers, such as abrasive fluidized bed machining, barrel finishing, dry-ice blasting, and brushing in a solvent bath [26]. To date, there are no studies that have investigated the properties of composites which made from recycled glass fibers (RGF) from nonmetals of WPCBs and recycled polycarbonate (RPC) from waste CDs have been forthcoming. In this paper, RGF from non-metals was used as reinforcing filler to produce PC composites. The influence of resin in non-metals, particle sizes and contents of RGF on composites properties were investigated by testing mechanical and morphological properties. The aim of the research is to develop a new technique for recycling RGF from non-metals in WPCBs and RPC from Waste CDs, and preventing the environmental pollution. 2. Materials and methods 2.1. Materials The non-metallic particles from WPCBs and Waste CDs were obtained from a local solid-waste treatment factory (as shown in Fig. 1). It can be seen from Table 1
that the non-metallic particles consisted of 50.4% glass fibers and 49.6% thermoset resins. Its main chemical elements as assessed by X-ray fluorescence (XRF-1800, Shimadzu Limited, Kyoto, Japan) are shown in Table 2. C, O, Si, Br were derived from glass fibers and brominated epoxy resin, as well as a small amount of metal elements such as copper, which were residues from a mechanical physical crushing and sorting process. Meanwhile the main chemical elements of Waste CDs as assessed by X-ray fluorescence (XRF-1800, Shimadzu Limited, Kyoto, Japan) are shown in Table 3. C and O were mainly from the polycarbonate plate, Al was from aluminum metal reflective layer. Pure PC and GF were supplied by CHI MEI Corporation and Hangzhou Corker composite material Company Limited (China). Silane coupling agent KH-550(γAminopropyl-triethoxysilane) and other reagents were supplied by Sinopharm Chemical Reagent Co., Ltd (China). 2.2. Preparations and treatment of Materials 2.2.1 Treatment of RGF The non-metallic particles were treated in a 2mol/L dilute nitric acid at 85oC until residual metal powders have been dissolved completely. Then, the solution was filtered, the non-metallic particles were washed up to neutral and dried at 80oC for 12h. If the non-metallic particles were calcined in a muffle furnace at 600oC for 2h, brominated epoxy resin would be removed and RGF was obtained (as shown in Fig. 2). In order to investigate the influences of particle sizes on composite properties, the RGF was screened to four size ranges which were ＜0.075mm, 0.075-0.1mm, 0.10.15mm and 0.15-0.3mm and were compounded in the RPC composites, respectively. Particle size was dependent on the process of physical crushing in the factory. Fig. 3 shows the particle size distributions of RGF. It can be seen that the most common sizes of RGF was between 0.075 and 0.15 mm, which amounted to 69.81 wt%.
In order to improve the dispersion and compatibility of RGF particles in RPC matrix and the mechanical properties of composites, the RGF particles were modified. Firstly, a methanol solution was prepared by 8:2 (volume ratio) methanol and water. Then, silane coupling agent KH-550 was mixed with the methanol solution at 4:6 volume ratio to prepare KH-550 solution. Finally, 1.0 wt% content of the KH-550 solution was added into RGF to silanize for 20 min with a high speed mixer. 2.2.2 Preparation of RPC The RPC were obtained from waste CDs. Main components of metal reflective layer in this type CDs was aluminum (Al). 1mol/L NaOH was used to remove lacquer and reflective layer. RPC which accounted up to above 95wt% of the total CDs mass was produced. After rinsing with distilled water and drying for 6 h, the RPC was crushed into 1~5mm2 to be as a matrix material in the experiments (shown in Fig.4). 2.2.3 Preparation of RGF/RPC composites The different sizes of RGF particles and RPC were selected to produce composites with the RGF content of 10%, 20%, 30% and 40%. After dried at 800C for 6 h, modified RGF and RPC had been mixed by a high speed mixer (Zhangjiagang Qiangda Plastic Machinery Co., Ltd, China) at 400C for fifteen minutes. Then, the mixtures were extruded into bars with a twin- screw extruder (TDS20B, Nanjing Useon Extrusion Machinery Co., Ltd, China) and were sheared into some particles by a granulator (shown in Fig. 5(a)). The particles were dried for 6h at 900C and injected into some standard samples with an injection molding machine (MA900/260, Haitian Plastics Machinery Co., Ltd, China)( shown in Fig. 5(b)). The extrusion process and injection conditions of the composite samples are shown in Table 4. And Fig. 6 shows the process of the preparation of the RGF/RPC composites. Furthermore, non-metals which contained RGF and 5%, 10%, 15% waste epoxy resins respectively were used to reinforce RPC in order to research the influence of resins on composite properties. Pure GF and pure PC were also used as raw materials
to manufacture composites to test the properties for the comparison with waste materials. 2.3. Characterization 2.3.1 Determination of functional groups The Fourier transform infrared (FT-IR) analyses (IFS 55, Bruker Company, Fällanden, Zurich, Switzerland) were conducted under the conditions of resolution of 4 cm−1, scan time of 32s, and scan range of 4000–400 cm−1 to analyze the samples of RGF and functional groups after treatment. 2.3.2 Determination of mechanical strength The mechanical properties of composites such as tensile strength, flexural strength and izod impact strength of notched specimens were tested by an universal testing machine (Proline z020tn, Germany Zwick Co., Ltd, Germany) according to ISO5272:1993, ISO178:2001 and ISO180:2001. The heat deflection temperature (HDT) was measured by a thermal deformation temperature meter (SWB-300C/D, Shanghai SRD Scientific Instrument Co., Ltd, China) according to ISO 75-2:2004 at a heating rate of 1200C/h and a load of 1.81N/mm2. 2.3.3 Determination of morphology and surface fracture Tungsten filament scanning electron microscope (HITACHI SU-1500) of the surface fracture was used to observe the dispersion and compatibility of the RGF into the composite. The surfaces of specimens were polished and coated with a thin layer of gold before tested. The surface structures were observed to analyze the influence of RGF sizes or contents of RGF to RGF/RPC properties. 2.4 The quality control of the RGF/RPC composites RGF as a reinforced filler was added into RPC to synthesize the composites. The effects of RGF sizes and contents on the composite quality were researched. Tensile strength, flexural strength, izod impact strength and heat deflection temperature of the
composites were used to evaluate good or bad of composite quality. Four specimens for each type of composite were tested and the mean values were reported. 3. Results and discussion 3.1. Changes of functional groups after RGF modified KH-550 is an aminosilane-coupling reagent and can serve as a bridge to connect GF filler and organic matrix due to its molecular structure [27]. As shown in Table 5, the properties of composites with modified RGF significantly enhanced in flexural and tensile strength compared with unmodified RGF. Thus, KH-550 was a better modifier to improve the properties of composites by strengthening the binding force. The FTIR spectra of nonmetals and RGF using IFS 55 examination are shown in Fig.7, a number of absorption bands can be observed in non-metals due to the complex ingredients. But after calcination, a large number of absorption bands disappeared in RGF, such as the stretching vibrations peaks of N-H at 3329 cm-1 or bending vibration peaks of C-H at 1450 cm-1 [28], which indicated the heat treatment removes all the organic components in the non-metals. New absorption peak was found in modified RGF, the peak at 2924 cm-1, 2857 cm-1 and were assigned to the SiO-CH3 from KH-550 and the peak at 1595 cm-1 corresponds to -HN2. Si-O-Si observed at 1092 cm-1 was from condensation reaction of KH-550. These functional groups demonstrate that KH-550 was strongly bound with RGF. The effect of KH550 on enhancing the binding force can be observed in micrographs. Fig. 8(a) shows the SEM micrograph of fracture of RGF/RPC composites without modification of RGF. The RGF surface was smooth and no matrix adhered to it. Furthermore, there was obviously the gap in tensile fracture-surface which implied that binding strength was very low between RGF and matrix. With modified RGF, a large more matrix was adhered to the surface of RGF (shown in Fig. 8(b)). This indicated chemical bonding force was produced. It was consistent with the FTIR analysis. The mechanical property is enhanced largely in this situation. So the modified RGF was used in the all following research.
3.2. Mechanical strength of nonmetal/RPC and RGF/RPC composites Nonmetals served as a filler which contained modified RGF and resins. 20% non-metals were filled into 80% RPC for producing composites and investigating the influence of different mass fractions of resins in nonmetals on properties. Fig. 9 shows the mechanical properties of nonmetal/RGF composites by an universal testing machine. Apparently, mechanical properties dropped a lot and the poorer properties with more resins. It is explained that resins were decomposed in 2600C in the twinscrew extruder [29]. For one reason was that the by-product of the decomposition such as carbon black could be supposed to be an impurity in the composite, the other was that pyrolytic reaction may produce gases in the process of molding injection to lead a lot of bubbles in the composites [30]. It indicated that the resins would decrease the mechanical properties of composites. However, the RGF is an excellent inorganic non-metallic material including heat resistance (more than 3000C) which was not decomposed in 2600C in the twin-screw extruder, and high mechanical strength. The surface of the RGF without modification has many hydroxyl bonds (RGF-OH), which caused bad interfacial adhesion between the RGF and RPC because RGF-OH was hydrophilic and the RPC was hydrophobic. After modification, RGF-OH was removed, which made the RGF converted from hydrophilicity into hydrophobicity. It can be seen from Table 5 and Fig.8 that the properties of composites with modified RGF significantly enhanced. Therefore, the RGF was used as a filler other than nonmetals in the following research. RGF as a reinforced filler was added into RPC to synthesize the composites. The effects and reinforcing mechanism of RGF on composites were investigated by using an universal testing machine. Fig. 10 shows the properties of composites with various contents of RGF (0-40 wt%) and the particle sizes of RGF were divided into four species (＜0.075, 0.075-0.1, 0.1-0.15, 0.15-0.3). It can be observed from Fig.10 (a, b) that the tensile and flexural modulus of composite improved with increasing RGF content. In addition, tensile strength of composite increased with less than 10% RGF, then, tended to be gentle and slightly decreased in 10%~40% RGF content with the
size of <0.075~0.15mm in Fig. 10(a). While flexural strength increased gently in 0~30% RGF content, then, decreased in 30%~40% RGF content with the size of <0.075~0.15mm in Fig. 10(b). This is the reason that the RGF orientation is chiefly parallel to the injection melt flow direction, which makes RGF serve as different functions [31]. In tensile testing, the direction of the force was parallel to the orientation of the RGFs, for tensile strength depended on the RGF tensile strength and the interfacial adhesion between RGFs and matrix. When RGF content increased, RGF tensile strength and the interfacial adhesion increased, which made composite tensile strength increase [32]. But when RGF reached a certain composition (>10%), its influence reached a limiting value in a particle size range and the composite tensile strength didn’t increase anymore. In flexural testing, the direction of the force was perpendicular to the orientation of the RGFs, the RGF was subjected to shear stress under the three-point bending load [33], which caused that flexural strength of composite can’t be enhanced but even weakened in more than 30% RGF content when RGF sizes were shorter than 0.15mm. But it can be also found that tensile strength and flexural strength of composite both increased with the increase of RGF contents in 0.15-0.3mm size. It can be explained that when RGF size was small (<0.15mm), the effect of RGF content on the strength was limited. When RGF size increased to a certain extent (>0.15mm), the effect produced a qualitative change. For tensile strength of composite, enough long RGF made RGF tensile strength and the interfacial adhesion between RGFs and matrix broke the limiting value, which led to the great increase of tensile strength of composite with the increase in RGF content [34]. For flexural strength, enough large RGF size can enhance the flexural strength of matrix, which led to flexural strength of composite increased with the increase of RGF content. Fig. 10(c) shows the impact strength of composites. It can be seen that the impact strength decreased with the increase of RGF content. It is not only because RPC was sensitive to notched impact, but also the addition of RGF destroyed the uniformity and consistency of the matrix [35]. Fig. 10(d) shows the heat deflection temperature of the composites. The increase of HDT was attributed to RGFs because
its component is silica，which has better thermal property than RPC. Long RGFs can scatter heat evenly and were not easier to aggregate than short RGFs. This is the reason that RGFs in the 0.15-0.3mm size had a high HDT in the composite. 3.3. Morphology and surface fractures of RGF/RPC composites The effect of RGF can also be indicated by fracture surfaces of composites through tensile failure by using SEM observation. When the composite was imposed to external force, the force would trigger an initial micro crack. When the crack was transferred to the RGF and matrix interface, RGF could share the force of the matrix. With the force increasing, the interface would be separated, and the RGF of high elastic modulus and low elongation broke, which caused the composites tensile failure to produce fracture. Fig. 11 shows morphology of the fracture surface of composites with different RGF content and particle sizes. It can be observed from Fig. 11(a) that the fracture surfaces of pure RPC without RGF were smooth. It indicated that the force acting on the RPC was focused, which makes the crack propagate rapidly and led to a brittle fracture. But it can be seen from Fig. 11(b, c) that the fracture surfaces with RGF were uneven and hollow. It has been reported that the force of matrix was transferred to RGF. RGF acted as a framework and the force can dispersed evenly through it, which led to RGF microcrack and surrender. When the force reached a certain degree, RGF would be pulled out and broke to cause hollows and cause bumps in the fracture surface. The process which stripped RGF from matrix and broke RGF would consume large amounts of energy, it made the increase of mechanical properties with the increase of the RGF content. However, when the RGF content increased to more than 30%, Fig. 11(d) clearly shows that RGF agglomerated, which would cause poor fluidity in injection process and weak the adhesion or compatibility between fiber and matrix [36]. It is for this reason that mechanical strength decreased when the content of RGF went beyond a certain range. Fig. 11(e, f) shows the fracture surface of the composites of different particle sizes. The shorter sized RGF appeared to distribute non-uniformly and resulted in aggregation. In contrast, the composites
with long RGF contained more rupture holes and tend to disperse stress between RGF or RGF and matrix. That made composites with long RGF had better property. 3.4. Comparison of recycled materials and pure materials Pure GF and pure PC were prepared in order to compare the reinforcing effects of recycled materials. Table 6 shows the mechanical properties of four kinds of composites in the same condition. It can be observed that the flexural and tensile strengths of four kinds of composites were much higher than that of RPC. Pure GF/PC composite has the best properties but the properties of the composites containing recycled materials were close to that of it. So the waste-based glass-fiberreinforced polycarbonate materials can be used in these aspects: 1) outdoor landscape materials, such as outdoor tables and chairs, garden armrest and decorative panels, open floors and waste boxes; 2) building materials, such as municipal engineering sewage pipes, sewers covers, moisture-proof partitions, fire boards, noise boards, staircase boards and handrails; 3) industrial and packaging materials, such as industrial pads, containers, packaging boards and cargo trays. Table 7 show the property comparisons of the composite and well lid and waterspout lid. It can be seen that the composite properties are much better than these of the building materials. In addition, it can be seen from the data of pure PC+ RGF and RPC+ pure GF that GF can have a greater impact on mechanical properties than PC. That was mainly because PC recycled from CDs was close to pure PC and the property is not damaged. On the contrary, after heat treatment, strength of the GFs was so weak that composite properties decreased [31]. 4. Conclusions and recommendations The RGF and RPC were successfully recycled from non-metal and CDs. The RGF was used as a filler and added to RPC matrix to improve mechanical properties. The effects of modification, particle sizes and RGF contents were investigated. The results indicated that the RGF modified with KH-550 can effectively improve property by enhancing the adhesion between RGF and PC matrix. In particular, the composites
show the higher performance by increasing particle sizes and RGF content. The maximum increment of tensile strength, flexural strength and distortion temperature of the composites were 73.51%, 30.46% and 11.4% when RGF content was 40% with the particle size of 0.15-0.3 mm. SEM analysis indicated that the force transmission of RGF could prevent and delay the crack extension in composites, and improve composite properties. Through the comparison and analysis of waste-based composites and pure materials, the performance of composite prepared by pure materials is better than that of waste-based. The overall performance order from high to low is pure PC + pure GF > pure PC + recycled GF > recycled PC + pure GF > recycled PC + recycled GF> RPC. But the performance of waste-based materials which are complies with the performance standards for the preparation of materials such as outdoor landscapes is close to pure material properties in the data. The result indicated that RGF can be utilized as a reinforcing filler into RPC matrix to manufacture waste-based composites. Acknowledgements The authors are grateful for support of Program of Innovative Research Team in University (IRT13078), the Funds of Jiahua Science and Technology Bureau (Grant No:2013-3-001) and the Funds of Jinhua Environmental Protection Bureau (Grant No:YG2014-FW673-ZFCG046)
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[31] Yang Y K, Yang R T, Tzeng C J. Optimization of mechanical characteristics of short glass fiber and polytetrafluoroethylene reinforced polycarbonate composites using the neural network approach [J]. Expert Systems with Applications, 2012, 39(3):3783-3792. [32] Zheng Y, Shen Z, Cai C, et al. The reuse of nonmetals recycled from waste printed circuit boards as reinforcing fillers in the polypropylene composites.[J]. Journal of Hazardous Materials, 2008, 163(2):600-606. [33] Liang H, Sun S, Long L, et al. Study on Polypropylene Matrix Composites Filled with Glass Fiber Recycled from Waste Printed Circuit Board[C]// International Conference on Computer Distributed Control and Intelligent Environmental Monitoring. IEEE Computer Society, 2011:1764-1768. [34] Giraldi A L F D M, Bartoli J R, Velasco J I, et al. Glass fibre recycled poly(ethylene terephthalate) composites: mechanical and thermal properties [J]. Polymer Testing, 2005, 24(4):507-512. [35] Gupta N, Brar B S, Woldesenbet E. Effect of filler addition on the compressive and impact properties of glass fibre reinforced epoxy [J]. Bulletin of Materials Science, 2001, 24(2):219-223. [36] Zheng Y, Shen Z, Ma S, et al. Influence of the recycled glass fibers from nonmetals of waste printed circuit boards on properties and reinforcing mechanism of polypropylene composites [J]. Journal of Applied Polymer Science, 2010, 118(5):2914-2920. Figure Caption
Figr‐1 Fig. 1. Raw materials of WPCBs and Waste CDs
80
4.0
a
＜0.075mm 0.075-0.1mm
3.5
0.1-0.15mm
Tensile strength(MPa)
70
0.15-0.3mm
3.0 60 50
2.5
40
2.0
30 1.5 20 1.0
10 0
0.5 0
10
20
30
40
Mass fraction（ %） Figr‐2
110
10
＜0.075mm
b
0.075-0.1mm
9
0.1-0.15mm 0.15-0.3mm
8
100 7 90 6 80 5 70 4 60 3 50 2 40 0
10
20
30
Mass fraction（ %）
40
Flexural modulus（ GPa）
Flexural strength（ MPa）
120
Tensile modulus(GPa)
90
7
c
＜0.075mm
0.075-0.1mm
Impact strength(MPa)
6
0.1-0.15mm 0.15-0.3mm
5
4
3
2
1 0
10
20
30
40
Mass fraction（ %）
140
d
＜0.075mm
0.075-0.1mm
135
0.1-0.15mm
HDT(
)
0.15-0.3mm
130
125
120
115 0
10
20
30
40
Mass fraction（ %） Fig. 10. Mechanical properties of RGF/RPC composites: (a) Tensile strength (—) and tensile modulus(---); (b) Flexural strength (—) and flexural modulus(---); (c) Impact strength; (d)Heat deflection temperature
Figr‐3
aFig. 11. Morphology of the fracturebsurface of composites: (a) pure RPC;c(b) 10% content RGF with 0.1-0.15 mm particle sizes; (c) 30% content RGF with 0.1-0.15 mm particle sizes; (d) 40% content RGF with 0.1-0.15 mm particle sizes;(e) 20% content RGF with ＜0075mm particle sizes; (f) 20% content RGF with 0.1-0.15 mm particle sizes;
Figr‐4
Fig. 2. the picture of RGF
Figr‐5
40
Proportion（ wt%）
35 30 25 20 15 10 5 0
＜0.075 0.075-0.1 0.1-0.15 0.15-0.3 Particle size of RGF(mm)
＞0.3
Fig. 3. Particle size distribution of RGF
Figr‐6
Fig. 4. the picture of RPC particle
a
b
Figr‐7
Fig. 5. The particles and splines of composites
Figr‐8
AirRGF/RPC separatingcomposites Waste PCBs Fig. 6. The process Coarse-crushing of the preparation for the
Nonmetals
(This research area)
Mechanica l Properties
Metals
Injected into molding
RGF Mixing and extruded
KH550 modified
+ RPC
Waste CDs
1595
2857
1092
Transmittance
Modified RGF
2924
Figr‐9
RGF
4000
3500
1450
3329
Nonmetals
3000
2500
2000 1500 Wavenumber(cm-1)
1000
Fig. 7. FTIR spectra of nonmetals, RGF and modified RGF
500
Figr‐10 Fig. 8. SEM micrograph of RGF/RPC composites: (a) unmodified RGF; (b) modified RGF
a
b
Matrix bonded to recycled glass fiber
1600 1400 60 1200 40
1000
20
800
0
600 0
5
10
Tensile modulus(MPa)
Tensile strength （ MPa ）
80
15
Mass fraction of resin in nonmetals（ %）
120
3800
100
3600
80
3400 3200
60
3000
40
2800 20
Flexural modulus（ MPa）
Flexural strength(MPa)
Figr‐11
2600 0 0
5
10
15
Mass fraction of resin in nonmetals（ %）
4
125
3
120
2
115
)
130
1
HDT(
Impact strength(MPa)
5
110 0
5
10
15
Mass fraction of resin in nonmetals（ %） Fig.9. Mechanical properties of RGF/RPC/resin composites with different mass fraction of resin
Table 1 The compositions of the non-metallic particles
Items
Glass fibers
Resins
W/%
50.4%
49.6%
Table 2 Chemical elementary analysis of the non-metallic particles from WPCBs
Elementary
C
O
Si
Br
Ca
Cu
Fe
Al
W/%
32.57
38.41
14.95
6.11
3.95
1.42
0.44
0.59
Table 3 Elemental analysis of Waste CDs
Elementary
C
O
Al
Si
Cu
Cl
Fe
Ca
Mg
W/%
40.87
52.01
2.07
0.22
0.20
0.20
0.39
1.11
1.94
Table 4 The conditions of Extrusion and injection molding process
Extrusion process conditions First district 240℃
Second district
Third district
Forth district
Fifth district
Nose
Feeding rate /HZ
Host rate /RPM
245℃
250℃
255℃
260℃
255℃
2.1
90
Injection molding process conditions First district
Second district
Third district
Forth district
Mouthpiece
Compress time /s
Mold temperature/ ℃
250℃
260℃
260℃
270℃
280℃
30
Room temperature
Table 5 Effect of KH550 on the properties of composites
Sample PC(CD) PC/RGF (unmodified) PC/RGF (KH550)
Flexural Strength(MP a)
Tensile strength(MP a)
Impact strength(KJ/m 2 )
Flexural modulus(GP a)
Tensile modulus(GP a)
HDT (℃)
90.7
48.8
45.1
2.11
1.11
121.1
91.4
54.6
45.4
2.80
1.35
127.6
94.3
58.1
44.5
2.98
1.21
126.7
Table 6 Mechanical properties of pure GF/PC composites Sample RPC Pure PC+Pure GF Pure PC+RGF RPC+ pure GF RPC+ RGF
Flexural Strength(MP a) 90.7
Tensile strength(MP a) 48.8
Impact strength(KJ/m 2 ) 45.2
Flexural modulus(GP a) 2.11
Tensile modulus(GP a) 1.17
121.5
96.2
60.67
59.3
2.71
1.21
127.2
93.7 95.9 94.27
58.6 59.72 58.13
47.3 52.6 44.5
2.73 2.95 2.98
1.28 1.25 1.21
126.9 126.4 126.7
HDT (℃)
Table 7 The property comparisons of the composite and some building materials* Flexural Strength（MPa）
Tensile strength（MPa）
Impact strength（KJ/m2）
waterspout lid
94.27 22
58.13 10
44.5 10
well lid
22
10
10
RPC+ RGF
* Waterspout lid data is from CJ/T 212-2005, well lid data is from GB/T23858-2009.
S2213-3437(17)30301-9 http://dx.doi.org/doi:10.1016/j.jece.2017.06.050 JECE 1712
To appear in: Received date: Revised date: Accepted date:
14-2-2017 23-6-2017 25-6-2017
Please cite this article as: Ping Zhu, Xiankai Liu, Yangjun Wang, Chuanjin Guan, Yazheng Yang, Jiahao Zhu, Xuheng Li, Guangren Qian, Ray L.Frost, Production and Characterization of Recycled Polycarbonate Based Composite Material Containing Recycled Glass Fibers, Journal of Environmental Chemical Engineeringhttp://dx.doi.org/10.1016/j.jece.2017.06.050 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Production and Characterization of Recycled Polycarbonate Based Composite Material Containing Recycled Glass Fibers Ping Zhu a, Xiankai Liua, Yangjun Wanga, Chuanjin Guanb, Yazheng Yanga, Jiahao Zhua, Xuheng Lia, Guangren Qiana, Ray L. Frost c* a
School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, People’s
Republic of China b
School of Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209, People’s Republic of China
c
School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of
Technology, GPO Box 2434, Brisbane Queensland 4001,Australia
*Corresponding author. Email address: [email protected] Ph: +61 7 3138 2407 Fax: +61 7 3138 1804
Highlight 1. Recycled glass fibers and polycarbonates were reused to prepare a composite. 2. The tensile and flexural strength of the composite increased by 73.52% and 30.43%. 3. The properties of the composite were quite close to those of the pure product. 4. The reinforcing mechanism of recycled glass fibers to polycarbonates was analyzed. Abstract: Nowadays, a large quantity of waste printed circuit boards (WPCBs) and waste compact discs (CDs) have been produced, which may cause secondary
pollution and are a waste of resources. In this study, recycled glass fibers (RGF) from non-metals of WPCBs and recycled polycarbonate (RPC) from waste CDs were reused simultaneously to produce composites. A fourier transform infrared (FT-IR) was used to evaluate the functional groups in the modified RGF, the mechanical properties of composites was tested by an universal testing machine and scanning electron microscope (SEM) was used to determine the morphology and surface fractures of the composites. The result indicated that the RGF modified by a silane coupling agent-KH-550 improved the dispersion and compatibility of RGF particles in RPC matrix. The property of composite decreased significantly with resins decomposed during high temperature injection molding when nonmetals were as a filler to prepare a composite. Therefore, RGF in nonmetals was selected as a reinforcing filler of composites. The properties and the fracture surface morphology of the RGF/RPC composite were investigated. The results indicated that the appropriate addition of RGF in the composites can significantly improve the mechanical properties. The maximum tensile and flexural strength of the composites could reach up to 84.68 MPa and 118.3 MPa, which significantly increased by 73.52% and 30.43% respectively than those of RPC when RGF content was 40% with the particle size of 0.15-0.30 mm. The properties were quite close to those of composite which was prepared with pure GF and PC. Keywords: Waste Printed Circuit Boards; Waste Compact Discs; Recycled Polycarbonate; Recycled Glass Fibers; Composite Materials 1. Introduction Recycling synthetic materials or using industrial by-products can be a sustainable strategy to reduce the use of virgin material and the disposal in landfill. As a consequence several researches were carried out to find innovative and sustainable uses for this category of materials. Life Cycle Assessment (LCA) is a methodology to evaluate the impacts of products and services on the environment and on human health during their entire life. LCA is much dependent on the primary sources of the energy of a particular place and conversion efficiency of materials production
processes [1,2]. Vidal et al. [3] carried out a comprehensive LCA of asphalt pavements. The result indicates that climate change, fossil depletion and total cumulative energy demand were decreased by 13~14% by adding 15% reclaimed asphalt pavement. F. Intini et al. [4] characterized the material made of recycled polyethylene terephthalate (PET) by a lower global warming potential (GWP) value and compared to the one of the kenaf-based material. Printed circuit boards (PCBs) are necessary components in electronic products, which are a layered structure and contains nearly 28% metals, such as Cu, Al, Sn, etc. and nearly 70% non-metal materials [5,6]. Glass fiber (GF) and thermosetting resin are the main components of non-metal materials in the PCBs [7]. With the growing volume of waste printed circuit boards (WPCBs) generated annually, the traditional WPCBs treatment (landfill disposal or incineration) must be replaced by recycling technology not only because of the negative environmental impacts of toxic waste, but also due to its potential profitable prospects of recovered metals [8,9]. A significant amount of endeavor on chemical recycling technology of the WPCBs has been reported, such as pyrolysis [10, 11], gasification [12] and supercritical extraction [13]. The most common recycling technology in the WPCBs treatment factory was a physical method. The WPCBs were crushed into small particles, and then the metals were separated from non-metals by air classification [14] or electrostatic separation [15]. As a result, a large quantity of non-metals were generated every year. Glass fibers have excellent physical and chemical properties, such as high mechanical strength, high temperature stability and corrosion resistance. Therefore, the non-metals which contained glass fibers were often used as reinforcing fillers in composites. Currently，this research mainly focuses on non-metal reinforcing pure polymer composites and the influence of non-metal content or particle size on composite properties. The addition of non-metals could obviously improve the mechanical properties of a plastic matrix, such as polypropylene [16,17], polyvinylchloride [18] and phenolic resin [19]. And non-metals which contained glass fibers also could be as reinforcing material in concrete and cement composites [20].
Further, the recycled glass fibers (RGF) which were obtained by pyrolysis of WPCBs was used to produce polypropylene (PP) composites and the resin component was supposed as impurities [21]. Indeed, the usage of pure commercial plastics as matrix must result in high cost and recycled plastics could be a good alternative. Therefore, recycled acrylonitrile butadiene styrene (ABS) and high-density polyethylene (HDPE) were applied to manufacture reproduction composites [22, 23]. And lots of recycled thermoplastics were reinforced by glass fibers to prepare commercial products [24]. Compact discs (CDs) can store information in digital format. They have a sandwich type structure, with a set of superimposed layers of lacquer, metal reflective layer, and polycarbonate substrate [25]. Waste CDs, which are manufactured with high quality PC (above 95 wt.%), may represent an important and relatively cheap material source. In order to recycle CDs and get recycled PC, different technologies have been used to separate PC from the other CD layers, such as abrasive fluidized bed machining, barrel finishing, dry-ice blasting, and brushing in a solvent bath [26]. To date, there are no studies that have investigated the properties of composites which made from recycled glass fibers (RGF) from nonmetals of WPCBs and recycled polycarbonate (RPC) from waste CDs have been forthcoming. In this paper, RGF from non-metals was used as reinforcing filler to produce PC composites. The influence of resin in non-metals, particle sizes and contents of RGF on composites properties were investigated by testing mechanical and morphological properties. The aim of the research is to develop a new technique for recycling RGF from non-metals in WPCBs and RPC from Waste CDs, and preventing the environmental pollution. 2. Materials and methods 2.1. Materials The non-metallic particles from WPCBs and Waste CDs were obtained from a local solid-waste treatment factory (as shown in Fig. 1). It can be seen from Table 1
that the non-metallic particles consisted of 50.4% glass fibers and 49.6% thermoset resins. Its main chemical elements as assessed by X-ray fluorescence (XRF-1800, Shimadzu Limited, Kyoto, Japan) are shown in Table 2. C, O, Si, Br were derived from glass fibers and brominated epoxy resin, as well as a small amount of metal elements such as copper, which were residues from a mechanical physical crushing and sorting process. Meanwhile the main chemical elements of Waste CDs as assessed by X-ray fluorescence (XRF-1800, Shimadzu Limited, Kyoto, Japan) are shown in Table 3. C and O were mainly from the polycarbonate plate, Al was from aluminum metal reflective layer. Pure PC and GF were supplied by CHI MEI Corporation and Hangzhou Corker composite material Company Limited (China). Silane coupling agent KH-550(γAminopropyl-triethoxysilane) and other reagents were supplied by Sinopharm Chemical Reagent Co., Ltd (China). 2.2. Preparations and treatment of Materials 2.2.1 Treatment of RGF The non-metallic particles were treated in a 2mol/L dilute nitric acid at 85oC until residual metal powders have been dissolved completely. Then, the solution was filtered, the non-metallic particles were washed up to neutral and dried at 80oC for 12h. If the non-metallic particles were calcined in a muffle furnace at 600oC for 2h, brominated epoxy resin would be removed and RGF was obtained (as shown in Fig. 2). In order to investigate the influences of particle sizes on composite properties, the RGF was screened to four size ranges which were ＜0.075mm, 0.075-0.1mm, 0.10.15mm and 0.15-0.3mm and were compounded in the RPC composites, respectively. Particle size was dependent on the process of physical crushing in the factory. Fig. 3 shows the particle size distributions of RGF. It can be seen that the most common sizes of RGF was between 0.075 and 0.15 mm, which amounted to 69.81 wt%.
In order to improve the dispersion and compatibility of RGF particles in RPC matrix and the mechanical properties of composites, the RGF particles were modified. Firstly, a methanol solution was prepared by 8:2 (volume ratio) methanol and water. Then, silane coupling agent KH-550 was mixed with the methanol solution at 4:6 volume ratio to prepare KH-550 solution. Finally, 1.0 wt% content of the KH-550 solution was added into RGF to silanize for 20 min with a high speed mixer. 2.2.2 Preparation of RPC The RPC were obtained from waste CDs. Main components of metal reflective layer in this type CDs was aluminum (Al). 1mol/L NaOH was used to remove lacquer and reflective layer. RPC which accounted up to above 95wt% of the total CDs mass was produced. After rinsing with distilled water and drying for 6 h, the RPC was crushed into 1~5mm2 to be as a matrix material in the experiments (shown in Fig.4). 2.2.3 Preparation of RGF/RPC composites The different sizes of RGF particles and RPC were selected to produce composites with the RGF content of 10%, 20%, 30% and 40%. After dried at 800C for 6 h, modified RGF and RPC had been mixed by a high speed mixer (Zhangjiagang Qiangda Plastic Machinery Co., Ltd, China) at 400C for fifteen minutes. Then, the mixtures were extruded into bars with a twin- screw extruder (TDS20B, Nanjing Useon Extrusion Machinery Co., Ltd, China) and were sheared into some particles by a granulator (shown in Fig. 5(a)). The particles were dried for 6h at 900C and injected into some standard samples with an injection molding machine (MA900/260, Haitian Plastics Machinery Co., Ltd, China)( shown in Fig. 5(b)). The extrusion process and injection conditions of the composite samples are shown in Table 4. And Fig. 6 shows the process of the preparation of the RGF/RPC composites. Furthermore, non-metals which contained RGF and 5%, 10%, 15% waste epoxy resins respectively were used to reinforce RPC in order to research the influence of resins on composite properties. Pure GF and pure PC were also used as raw materials
to manufacture composites to test the properties for the comparison with waste materials. 2.3. Characterization 2.3.1 Determination of functional groups The Fourier transform infrared (FT-IR) analyses (IFS 55, Bruker Company, Fällanden, Zurich, Switzerland) were conducted under the conditions of resolution of 4 cm−1, scan time of 32s, and scan range of 4000–400 cm−1 to analyze the samples of RGF and functional groups after treatment. 2.3.2 Determination of mechanical strength The mechanical properties of composites such as tensile strength, flexural strength and izod impact strength of notched specimens were tested by an universal testing machine (Proline z020tn, Germany Zwick Co., Ltd, Germany) according to ISO5272:1993, ISO178:2001 and ISO180:2001. The heat deflection temperature (HDT) was measured by a thermal deformation temperature meter (SWB-300C/D, Shanghai SRD Scientific Instrument Co., Ltd, China) according to ISO 75-2:2004 at a heating rate of 1200C/h and a load of 1.81N/mm2. 2.3.3 Determination of morphology and surface fracture Tungsten filament scanning electron microscope (HITACHI SU-1500) of the surface fracture was used to observe the dispersion and compatibility of the RGF into the composite. The surfaces of specimens were polished and coated with a thin layer of gold before tested. The surface structures were observed to analyze the influence of RGF sizes or contents of RGF to RGF/RPC properties. 2.4 The quality control of the RGF/RPC composites RGF as a reinforced filler was added into RPC to synthesize the composites. The effects of RGF sizes and contents on the composite quality were researched. Tensile strength, flexural strength, izod impact strength and heat deflection temperature of the
composites were used to evaluate good or bad of composite quality. Four specimens for each type of composite were tested and the mean values were reported. 3. Results and discussion 3.1. Changes of functional groups after RGF modified KH-550 is an aminosilane-coupling reagent and can serve as a bridge to connect GF filler and organic matrix due to its molecular structure [27]. As shown in Table 5, the properties of composites with modified RGF significantly enhanced in flexural and tensile strength compared with unmodified RGF. Thus, KH-550 was a better modifier to improve the properties of composites by strengthening the binding force. The FTIR spectra of nonmetals and RGF using IFS 55 examination are shown in Fig.7, a number of absorption bands can be observed in non-metals due to the complex ingredients. But after calcination, a large number of absorption bands disappeared in RGF, such as the stretching vibrations peaks of N-H at 3329 cm-1 or bending vibration peaks of C-H at 1450 cm-1 [28], which indicated the heat treatment removes all the organic components in the non-metals. New absorption peak was found in modified RGF, the peak at 2924 cm-1, 2857 cm-1 and were assigned to the SiO-CH3 from KH-550 and the peak at 1595 cm-1 corresponds to -HN2. Si-O-Si observed at 1092 cm-1 was from condensation reaction of KH-550. These functional groups demonstrate that KH-550 was strongly bound with RGF. The effect of KH550 on enhancing the binding force can be observed in micrographs. Fig. 8(a) shows the SEM micrograph of fracture of RGF/RPC composites without modification of RGF. The RGF surface was smooth and no matrix adhered to it. Furthermore, there was obviously the gap in tensile fracture-surface which implied that binding strength was very low between RGF and matrix. With modified RGF, a large more matrix was adhered to the surface of RGF (shown in Fig. 8(b)). This indicated chemical bonding force was produced. It was consistent with the FTIR analysis. The mechanical property is enhanced largely in this situation. So the modified RGF was used in the all following research.
3.2. Mechanical strength of nonmetal/RPC and RGF/RPC composites Nonmetals served as a filler which contained modified RGF and resins. 20% non-metals were filled into 80% RPC for producing composites and investigating the influence of different mass fractions of resins in nonmetals on properties. Fig. 9 shows the mechanical properties of nonmetal/RGF composites by an universal testing machine. Apparently, mechanical properties dropped a lot and the poorer properties with more resins. It is explained that resins were decomposed in 2600C in the twinscrew extruder [29]. For one reason was that the by-product of the decomposition such as carbon black could be supposed to be an impurity in the composite, the other was that pyrolytic reaction may produce gases in the process of molding injection to lead a lot of bubbles in the composites [30]. It indicated that the resins would decrease the mechanical properties of composites. However, the RGF is an excellent inorganic non-metallic material including heat resistance (more than 3000C) which was not decomposed in 2600C in the twin-screw extruder, and high mechanical strength. The surface of the RGF without modification has many hydroxyl bonds (RGF-OH), which caused bad interfacial adhesion between the RGF and RPC because RGF-OH was hydrophilic and the RPC was hydrophobic. After modification, RGF-OH was removed, which made the RGF converted from hydrophilicity into hydrophobicity. It can be seen from Table 5 and Fig.8 that the properties of composites with modified RGF significantly enhanced. Therefore, the RGF was used as a filler other than nonmetals in the following research. RGF as a reinforced filler was added into RPC to synthesize the composites. The effects and reinforcing mechanism of RGF on composites were investigated by using an universal testing machine. Fig. 10 shows the properties of composites with various contents of RGF (0-40 wt%) and the particle sizes of RGF were divided into four species (＜0.075, 0.075-0.1, 0.1-0.15, 0.15-0.3). It can be observed from Fig.10 (a, b) that the tensile and flexural modulus of composite improved with increasing RGF content. In addition, tensile strength of composite increased with less than 10% RGF, then, tended to be gentle and slightly decreased in 10%~40% RGF content with the
size of <0.075~0.15mm in Fig. 10(a). While flexural strength increased gently in 0~30% RGF content, then, decreased in 30%~40% RGF content with the size of <0.075~0.15mm in Fig. 10(b). This is the reason that the RGF orientation is chiefly parallel to the injection melt flow direction, which makes RGF serve as different functions [31]. In tensile testing, the direction of the force was parallel to the orientation of the RGFs, for tensile strength depended on the RGF tensile strength and the interfacial adhesion between RGFs and matrix. When RGF content increased, RGF tensile strength and the interfacial adhesion increased, which made composite tensile strength increase [32]. But when RGF reached a certain composition (>10%), its influence reached a limiting value in a particle size range and the composite tensile strength didn’t increase anymore. In flexural testing, the direction of the force was perpendicular to the orientation of the RGFs, the RGF was subjected to shear stress under the three-point bending load [33], which caused that flexural strength of composite can’t be enhanced but even weakened in more than 30% RGF content when RGF sizes were shorter than 0.15mm. But it can be also found that tensile strength and flexural strength of composite both increased with the increase of RGF contents in 0.15-0.3mm size. It can be explained that when RGF size was small (<0.15mm), the effect of RGF content on the strength was limited. When RGF size increased to a certain extent (>0.15mm), the effect produced a qualitative change. For tensile strength of composite, enough long RGF made RGF tensile strength and the interfacial adhesion between RGFs and matrix broke the limiting value, which led to the great increase of tensile strength of composite with the increase in RGF content [34]. For flexural strength, enough large RGF size can enhance the flexural strength of matrix, which led to flexural strength of composite increased with the increase of RGF content. Fig. 10(c) shows the impact strength of composites. It can be seen that the impact strength decreased with the increase of RGF content. It is not only because RPC was sensitive to notched impact, but also the addition of RGF destroyed the uniformity and consistency of the matrix [35]. Fig. 10(d) shows the heat deflection temperature of the composites. The increase of HDT was attributed to RGFs because
its component is silica，which has better thermal property than RPC. Long RGFs can scatter heat evenly and were not easier to aggregate than short RGFs. This is the reason that RGFs in the 0.15-0.3mm size had a high HDT in the composite. 3.3. Morphology and surface fractures of RGF/RPC composites The effect of RGF can also be indicated by fracture surfaces of composites through tensile failure by using SEM observation. When the composite was imposed to external force, the force would trigger an initial micro crack. When the crack was transferred to the RGF and matrix interface, RGF could share the force of the matrix. With the force increasing, the interface would be separated, and the RGF of high elastic modulus and low elongation broke, which caused the composites tensile failure to produce fracture. Fig. 11 shows morphology of the fracture surface of composites with different RGF content and particle sizes. It can be observed from Fig. 11(a) that the fracture surfaces of pure RPC without RGF were smooth. It indicated that the force acting on the RPC was focused, which makes the crack propagate rapidly and led to a brittle fracture. But it can be seen from Fig. 11(b, c) that the fracture surfaces with RGF were uneven and hollow. It has been reported that the force of matrix was transferred to RGF. RGF acted as a framework and the force can dispersed evenly through it, which led to RGF microcrack and surrender. When the force reached a certain degree, RGF would be pulled out and broke to cause hollows and cause bumps in the fracture surface. The process which stripped RGF from matrix and broke RGF would consume large amounts of energy, it made the increase of mechanical properties with the increase of the RGF content. However, when the RGF content increased to more than 30%, Fig. 11(d) clearly shows that RGF agglomerated, which would cause poor fluidity in injection process and weak the adhesion or compatibility between fiber and matrix [36]. It is for this reason that mechanical strength decreased when the content of RGF went beyond a certain range. Fig. 11(e, f) shows the fracture surface of the composites of different particle sizes. The shorter sized RGF appeared to distribute non-uniformly and resulted in aggregation. In contrast, the composites
with long RGF contained more rupture holes and tend to disperse stress between RGF or RGF and matrix. That made composites with long RGF had better property. 3.4. Comparison of recycled materials and pure materials Pure GF and pure PC were prepared in order to compare the reinforcing effects of recycled materials. Table 6 shows the mechanical properties of four kinds of composites in the same condition. It can be observed that the flexural and tensile strengths of four kinds of composites were much higher than that of RPC. Pure GF/PC composite has the best properties but the properties of the composites containing recycled materials were close to that of it. So the waste-based glass-fiberreinforced polycarbonate materials can be used in these aspects: 1) outdoor landscape materials, such as outdoor tables and chairs, garden armrest and decorative panels, open floors and waste boxes; 2) building materials, such as municipal engineering sewage pipes, sewers covers, moisture-proof partitions, fire boards, noise boards, staircase boards and handrails; 3) industrial and packaging materials, such as industrial pads, containers, packaging boards and cargo trays. Table 7 show the property comparisons of the composite and well lid and waterspout lid. It can be seen that the composite properties are much better than these of the building materials. In addition, it can be seen from the data of pure PC+ RGF and RPC+ pure GF that GF can have a greater impact on mechanical properties than PC. That was mainly because PC recycled from CDs was close to pure PC and the property is not damaged. On the contrary, after heat treatment, strength of the GFs was so weak that composite properties decreased [31]. 4. Conclusions and recommendations The RGF and RPC were successfully recycled from non-metal and CDs. The RGF was used as a filler and added to RPC matrix to improve mechanical properties. The effects of modification, particle sizes and RGF contents were investigated. The results indicated that the RGF modified with KH-550 can effectively improve property by enhancing the adhesion between RGF and PC matrix. In particular, the composites
show the higher performance by increasing particle sizes and RGF content. The maximum increment of tensile strength, flexural strength and distortion temperature of the composites were 73.51%, 30.46% and 11.4% when RGF content was 40% with the particle size of 0.15-0.3 mm. SEM analysis indicated that the force transmission of RGF could prevent and delay the crack extension in composites, and improve composite properties. Through the comparison and analysis of waste-based composites and pure materials, the performance of composite prepared by pure materials is better than that of waste-based. The overall performance order from high to low is pure PC + pure GF > pure PC + recycled GF > recycled PC + pure GF > recycled PC + recycled GF> RPC. But the performance of waste-based materials which are complies with the performance standards for the preparation of materials such as outdoor landscapes is close to pure material properties in the data. The result indicated that RGF can be utilized as a reinforcing filler into RPC matrix to manufacture waste-based composites. Acknowledgements The authors are grateful for support of Program of Innovative Research Team in University (IRT13078), the Funds of Jiahua Science and Technology Bureau (Grant No:2013-3-001) and the Funds of Jinhua Environmental Protection Bureau (Grant No:YG2014-FW673-ZFCG046)
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Figr‐1 Fig. 1. Raw materials of WPCBs and Waste CDs
80
4.0
a
＜0.075mm 0.075-0.1mm
3.5
0.1-0.15mm
Tensile strength(MPa)
70
0.15-0.3mm
3.0 60 50
2.5
40
2.0
30 1.5 20 1.0
10 0
0.5 0
10
20
30
40
Mass fraction（ %） Figr‐2
110
10
＜0.075mm
b
0.075-0.1mm
9
0.1-0.15mm 0.15-0.3mm
8
100 7 90 6 80 5 70 4 60 3 50 2 40 0
10
20
30
Mass fraction（ %）
40
Flexural modulus（ GPa）
Flexural strength（ MPa）
120
Tensile modulus(GPa)
90
7
c
＜0.075mm
0.075-0.1mm
Impact strength(MPa)
6
0.1-0.15mm 0.15-0.3mm
5
4
3
2
1 0
10
20
30
40
Mass fraction（ %）
140
d
＜0.075mm
0.075-0.1mm
135
0.1-0.15mm
HDT(
)
0.15-0.3mm
130
125
120
115 0
10
20
30
40
Mass fraction（ %） Fig. 10. Mechanical properties of RGF/RPC composites: (a) Tensile strength (—) and tensile modulus(---); (b) Flexural strength (—) and flexural modulus(---); (c) Impact strength; (d)Heat deflection temperature
Figr‐3
aFig. 11. Morphology of the fracturebsurface of composites: (a) pure RPC;c(b) 10% content RGF with 0.1-0.15 mm particle sizes; (c) 30% content RGF with 0.1-0.15 mm particle sizes; (d) 40% content RGF with 0.1-0.15 mm particle sizes;(e) 20% content RGF with ＜0075mm particle sizes; (f) 20% content RGF with 0.1-0.15 mm particle sizes;
Figr‐4
Fig. 2. the picture of RGF
Figr‐5
40
Proportion（ wt%）
35 30 25 20 15 10 5 0
＜0.075 0.075-0.1 0.1-0.15 0.15-0.3 Particle size of RGF(mm)
＞0.3
Fig. 3. Particle size distribution of RGF
Figr‐6
Fig. 4. the picture of RPC particle
a
b
Figr‐7
Fig. 5. The particles and splines of composites
Figr‐8
AirRGF/RPC separatingcomposites Waste PCBs Fig. 6. The process Coarse-crushing of the preparation for the
Nonmetals
(This research area)
Mechanica l Properties
Metals
Injected into molding
RGF Mixing and extruded
KH550 modified
+ RPC
Waste CDs
1595
2857
1092
Transmittance
Modified RGF
2924
Figr‐9
RGF
4000
3500
1450
3329
Nonmetals
3000
2500
2000 1500 Wavenumber(cm-1)
1000
Fig. 7. FTIR spectra of nonmetals, RGF and modified RGF
500
Figr‐10 Fig. 8. SEM micrograph of RGF/RPC composites: (a) unmodified RGF; (b) modified RGF
a
b
Matrix bonded to recycled glass fiber
1600 1400 60 1200 40
1000
20
800
0
600 0
5
10
Tensile modulus(MPa)
Tensile strength （ MPa ）
80
15
Mass fraction of resin in nonmetals（ %）
120
3800
100
3600
80
3400 3200
60
3000
40
2800 20
Flexural modulus（ MPa）
Flexural strength(MPa)
Figr‐11
2600 0 0
5
10
15
Mass fraction of resin in nonmetals（ %）
4
125
3
120
2
115
)
130
1
HDT(
Impact strength(MPa)
5
110 0
5
10
15
Mass fraction of resin in nonmetals（ %） Fig.9. Mechanical properties of RGF/RPC/resin composites with different mass fraction of resin
Table 1 The compositions of the non-metallic particles
Items
Glass fibers
Resins
W/%
50.4%
49.6%
Table 2 Chemical elementary analysis of the non-metallic particles from WPCBs
Elementary
C
O
Si
Br
Ca
Cu
Fe
Al
W/%
32.57
38.41
14.95
6.11
3.95
1.42
0.44
0.59
Table 3 Elemental analysis of Waste CDs
Elementary
C
O
Al
Si
Cu
Cl
Fe
Ca
Mg
W/%
40.87
52.01
2.07
0.22
0.20
0.20
0.39
1.11
1.94
Table 4 The conditions of Extrusion and injection molding process
Extrusion process conditions First district 240℃
Second district
Third district
Forth district
Fifth district
Nose
Feeding rate /HZ
Host rate /RPM
245℃
250℃
255℃
260℃
255℃
2.1
90
Injection molding process conditions First district
Second district
Third district
Forth district
Mouthpiece
Compress time /s
Mold temperature/ ℃
250℃
260℃
260℃
270℃
280℃
30
Room temperature
Table 5 Effect of KH550 on the properties of composites
Sample PC(CD) PC/RGF (unmodified) PC/RGF (KH550)
Flexural Strength(MP a)
Tensile strength(MP a)
Impact strength(KJ/m 2 )
Flexural modulus(GP a)
Tensile modulus(GP a)
HDT (℃)
90.7
48.8
45.1
2.11
1.11
121.1
91.4
54.6
45.4
2.80
1.35
127.6
94.3
58.1
44.5
2.98
1.21
126.7
Table 6 Mechanical properties of pure GF/PC composites Sample RPC Pure PC+Pure GF Pure PC+RGF RPC+ pure GF RPC+ RGF
Flexural Strength(MP a) 90.7
Tensile strength(MP a) 48.8
Impact strength(KJ/m 2 ) 45.2
Flexural modulus(GP a) 2.11
Tensile modulus(GP a) 1.17
121.5
96.2
60.67
59.3
2.71
1.21
127.2
93.7 95.9 94.27
58.6 59.72 58.13
47.3 52.6 44.5
2.73 2.95 2.98
1.28 1.25 1.21
126.9 126.4 126.7
HDT (℃)
Table 7 The property comparisons of the composite and some building materials* Flexural Strength（MPa）
Tensile strength（MPa）
Impact strength（KJ/m2）
waterspout lid
94.27 22
58.13 10
44.5 10
well lid
22
10
10
RPC+ RGF
* Waterspout lid data is from CJ/T 212-2005, well lid data is from GB/T23858-2009.