Applications of compatibilized polymer blends in automobile industry

CHAPTER 20

Applications of compatibilized polymer blends in automobile industry Sabana Ara Begum, Ajay Vasudeo Rane, Krishnan Kanny Composite Research Group, Department of Mechanical Engineering, Durban University of Technology, Durban, KwaZulu-Natal, South Africa

Abbreviations ABS ASA DSC EVA HDPE HDT HIPS LDPE LLDPE PA PANI PBT PC PE PEI PET PMMA POM PP PPE PPS PS PSF PTFE PU PVC SAN SMA TGA TPO TPU

Acrylonitrileebutadieneestyrene Acrylonitrileestyreneeacrylate Differential scanning calorimetry Ethyleneevinyl acetate High-density polyethylene Heat deflection temperature High-impact polystyrene Low-density polyethylene Linear low-density polyethylene Polyamide polyaniline Polybutylene terephthalate Polycarbonate Polyethylene Polyether imide Polyethylene terephthalate Polymethyl methacrylate Polyoxymethylene Polypropylene Polyphenyl ether Polyphenylene sulfide Polystyrene Polysulfone Polytertafluoroethylene Polyurethane Polyvinyl chloride Styreneeacrylonitrile Styreneemaleic anhydride Thermogravimetric analysis Thermoplastic olefin Thermoplastic urethane

Compatibilization of Polymer Blends ISBN 978-0-12-816006-0 https://doi.org/10.1016/B978-0-12-816006-0.00020-7

Copyright © 2020 Elsevier Inc. All rights reserved.

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20.1 Introduction A single commodity polymer cannot satisfyingly meet the increasing demanding applications, which requires improved or new combinations of properties. There has, therefore, been considerable scientific and industrial interest in modifying and mixing together these existing commodity polymers with a view to achieving properties currently exhibited only by more expensively engineered polymers or nonpolymeric materials. To fill the new requirements for material properties, polymer blends have provided a productive way. Polymer blends are a popular form of new thermoplastic engineering materials and constitute a rapidly progressing area. Their growth rate is very significant and exceeds more than 10% which is few times that of the plastics industry; on the whole, the most outstanding is performance engineering or specialty blends, and more than 600 new grades of these blends appear on the market annually. Polymer blending is a convenient route for the development of new polymeric materials, which combine the excellent properties of more than one existing polymer [1]. High temperature capability, good paintability, low temperature impact resistance, and excellent mechanical strength are the properties of the new material formed after blending. These properties are essential for automotive applications. At the beginning of 70s from the automotive field, which was passing through a transformation due to the initial oil crisis, new increasing opportunities arose for plastic materials meeting criteria of design concepts with particular regard to safety, weight, consumption, production cost, and maintenance cost [1]. The most important application area for polymer blends is in automotive industry. General application areas of polymer blends in automobile industry are exterior parts (body panels, seals, wheel covers, weather stripping, bumpers and fender, air dams, trims), interior parts (instrument panel, dashboard, door panels, steering wheels, seat and associated parts, instrument panel skin, decorative pieces), and underhood components (sensors, ignition compartments, fluid system, power distribution, resonators).

20.2 Properties of polymer blends Polymer blends constitute a very important class of materials where the components are either physically or chemically mixed with each other to achieve a certain set of functional properties. 2% of the total should be contributed by each component. Different types of blends can be formed

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by depending on the processing conditions and nature of components. Miscible blends are formed by interaction of the two polymers at the molecular level or the blend is homogeneous down to the molecular level. For such blends, free energy change during mixing is zero or negative. Blends having visible homogeneity with enhanced performance over constituent polymers are known as compatible blends. Compatibilization is the process to convert incompatible blends to compatible blends. Such blends prepared via compatibilization are known as alloys [2]. The physical means of compatibilization of phases in the blends are addition of compatibilizers, whereas chemical means include chemical reactions with the phases for chemical linking. Polymer blends have certain physical and chemical properties depending upon the configuration, order and combinations. By using an appropriate composition of polymer components, these properties can be controlled. The various economic and property advantages accomplished by blending are [2]: • The opportunity to develop or improve on properties to meet specific customer needs • Improved service temperature range • Increased toughening • Improved barrier property and flame retardancy • Improved mechanical and environmental stress cracking behavior • Permit the much more rapid development of modified polymerization step • Lightweighting • The ability to improve processability of materials which are otherwise limited in their ability to be transformed into finished products • Reduced material cost Some of the essential properties of compatibilized polymer blends are discussed below, which need to be considered for automotive applications.

20.2.1 Mechanical properties Mechanical properties of polymer blends, including strength and toughness, are described in terms of morphology, resulting texture, elementary deformation mechanisms, and cavitation. For any robust and tangible applications, the mechanical strength of polymer blends is the most important aspect. Mechanical property is considered as the response of a material when it is subjected under different mechanical loading conditions. For polymeric materials, it depends on time, otherwise for normal materials, it is the function of temperature. This is due to the viscoelastic behavior of polymers, or they

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show an intermediate position between viscous liquids and elastic solids in their response to mechanical loads. Stress is directly proportional to strain for an ideal elastic solid as per Hooke’s law. To enhance the mechanical properties, polymer blending is done. For determining the mechanical strength of compatibilized polymer blends, certain parameters are required such as tensile strength, impact strength, bulk modulus, Young’s modulus, ductility, hardness, plasticity, and yields strength. Generally, researcher uses different parameters and correlates them with the mechanical strength to evaluate their product [3]. From the study of Chung and Green, the synthesis of polymer blend films from the polymer tetramethyl bisphenol-A polycarbonate (TMPC) and polystyrene (PS), they determined the stiffness and elastic modulus of polymer blends. They concluded that the elastic properties and stiffness behavior change with the composition of components [4]. The mechanical properties can influence by several factors such as particle size, particle size distribution of the dispersed phase, and the degree of adhesion between two phases [5]. Aranburu et al. studied the change in the mechanical properties of the polymer before and after blending polypropylene (PP)/ polyamide 12 (PA 12); blends are synthesized by direct injection molding (DIM) and the changes are found in the crystalline morphology. The interaction between two polymers PP and PA 12 and nucleating effect of the PA 12 took place on the gradual cooling crystallization of PP; this results in the modification of crystalline morphology. There was a slight drop in crystallinity of PA 12, while the crystallinity of PP increases significantly. The increase in crystallinity is directly proportional to the enhancement in the mechanical properties. Young’s modulus of the compatibilized gPP/PA 12 to uncompatibilized blend is shown in Fig. 20.1. A positive deviation from linearity can be clearly seen. The Young’s modulus of the blends which behave synergistic throughout the composition range, due to the significant increase in crystallinity of the gPP phase which increases its continuity and its contribution to the modulus. Fig. 20.2 shows the yield strength of the compatibilized gPP/PA 12 blends which was rather linear. This is consistent with the local nature of the yielding process that occurs in the structurally lessresistant zone of the specimen. Ductility is a measure of compatibility. Fig. 20.3 shows the ductility of compatibilized blends to uncompatibilized blends. Fig. 20.3 indicates that the ductility increases due to the addition of compatibilizers, i.e., gPP leads a clear reduction in particle size due to the formation of PP-g-PA 12 copolymers at the interfaces. This together with the decrease in the dispersed phase is a clear indication of compatibilization [6].

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Figure 20.1 Young’s modulus of the uncompatibilized polypropylene (PP)/polyamide 12 (PA 12) (B) and compatibilized gPP/PA 12 (C) blends as a function of the PA 12 content.

Figure 20.2 Yield strength of the compatibilized gPP/PA12 (C) blends as a function of the PA 12 content.

Figure 20.3 Ductility of the uncompatibilized PP/PA12 (B) and compatibilized gPP/PA 12 (C) blends as a function of the PA 12 content.

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20.2.2 Thermal properties Thermal properties are relevant to the potential use of polymeric materials in many consumer-oriented applications. A detailed understanding of the thermal degradation of polymers is important in the design of materials with improved properties. Blending has been reported to have a great influence on the thermal stability of individual polymers. Compatibility in polymers determines the thermal stability. Dissimilar polymers decay over different temperature ranges yielding distinct fractions of volatiles and residues. For studying the thermal properties of the polymers, the most accepted method is thermogravimetry. Thermogravimetric curve shows drop in weight of the sample with respect to temperature. The thermogravimetric analysis (TGA) and the derivative thermogravimetric (DTG) curves give the information about the stages of breakdown, weight loss of the material in each stage, threshold temperature, polymerization reactions, the efficiencies of stabilizers and activators, thermal stability of final materials, and amount of degradation of the polymers [7]. The threshold temperature for breakdown determines the upper limit of the temperature of fabrications. For thermal industrial applications, thermal stability of polymer blends is an important factor. Less resistant to solar light and other temperaturechanging materials are the reasons for thermal aging of certain materials. These kinds of polymeric materials are not able to withstand heat even at very low temperature, so they get damaged quickly and liberate chemicals to the object in contact. Thermal expansion, heat deflection temperature, critical temperature, glass transition temperature, melting temperature, heat of fusion, heat of vaporization, flammability, thermal conductivity, and softness are various parameters that can be used to compare the thermal stabilities of various polymer blends. All these factors are equally important and can be correlated to each other. The thermal property of polyvinyl chloride (PVC)/ethyleneevinyl acetate (EVA), EVA/styreneeacrylonitrile (SAN), and PVC/SAN was reported by Lizymol and Thomas by using thermogravimetric methods. They concluded that the thermal stability of the polymer blends improved significantly [8]. Liu et al. studied the effect of compatibilizers on polycarbonate (PC) and acrylonitrileebutadienee styrene (ABS) blends. Two types of compatibilizers: methacrylatee butadieneestyrene (MBS) and styreneemaleic anhydride (SMA) were used to improve the compatibility between PC and ABS. TGA and DSC measurements were performed to have a detailed information on compatibility on PC/ABS blends. TGA confirmed that SMA and MBS had

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Figure 20.4 Melting thermograms of PA (A) and the binary and ternary mixtures (B). SEBS-g-MA, styreneeethyleneebutyleneestyrene-g-maleic anhydride.

slight effect on thermal stability of the PC/ABS blends. DSC confirms SMA has a better Compatibilizer in PC/ABS blends [9]. Carvalho and Sirqueira studied the mechanical, thermal, and rheological properties of polymer blends of polyamide 6 (PA 6) and styrenee ethyleneebutyleneestyrene (SEBS). Fig. 20.4 shows the thermogram obtained for the fusion of PA 6 and the PA/SEBS PA/SEBS-g-MA blends. In case of PA, two peaks are observed and they are assigned to different crystalline forms. The PA 6/SEBS thermogram showed two peaks but the compatibilized blend showed a tendency to form a peak, reflecting the effect of SEBSemaleic anhydride (MA) in reducing the interfacial tension. Fig. 20.5 shows the thermograms of PA 6/SEBS blends. The degradation of the uncompatibilized PA 6/SEBS blends occurred at lower temperature

Figure 20.5 TGA curves of PA/SEBS blends.

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than compatibilized blends. The compatibilized blend showed a single degradation step due to the anchoring effect between PA 6/SEBS phases, which results in increase in thermal stability [10].

20.2.3 Electrical properties The electrical and conducting properties of the polymer depend on the behavior of the overall structure of the polymer. For determining dielectric property, polarity of the polymers plays a vital role. Electrical properties also depend on crystallization, branching, frequency of applied voltage, and temperature. The important dielectrical property is dielectric constant, i.e., defined as the ability of the material to store electrical energy. Polymers are being used for applications like capacitors due to their good dielectric constant values. Most of the polymeric materials are insulators. By treatment with oxidizing or reducing agents, polymers with conjugated double bonds become electrically conducting. Examples of such polymers are polyacetal, polythiophene, polyaniline (PANI), and polypyrrole. By polymer blending, these properties can be changed. The modifications can be done by adding filler, i.e., making their blends with other polymers, though many other approaches can also be employed to get the desired product. Therefore, researchers are trying hard to build suitable polymer blends, which can be used as polymer blends in electrical industries. S. Ameen et al. studied the temperature dependence of direct current (DC) conductivity. They prepared the polymer blends with PANI/PVC; they concluded that the conductivity of the PANI/PVC blends increased regularly as the percentage amount of doped PANI increased in the polymer blend [11].

20.2.4 Optical and glass property Optical properties of polymers are important in a wide range of applications ranging from packaging where aesthetics of an underlying product must be maintained, to glazing products in construction and automobile industry. The interaction of radiations with the substance in the visible region is defined as the optical property. For determining optical property, molecular structure and crystallinity play a major role and they help to obtain varieties of information about the polymer blend. The optical behavior of the material is expressed by the molecular structure. Optical properties, which added versatility of polymers, are fundamentally dependant on directional distribution of light after impacting on the sample. The visual inspection by eye is the oldest and widely used method to determine optical behavior of

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the components. Apart from that two main techniques, UV and photoluminescence (PL) are used to study the interaction radiations with the substances. The optical properties of plastics are refractive index, luminous transmittance and haze, photoelastic properties, color, clarity and gloss. Polymethyl methacrylate (PMMA)/EVA blends show transparency at room temperature when the difference in refractive index between both phases is small. The light transmittance, however, decreases with increasing ambient temperature. This phenomenon is attributed to the difference in the volume expansion ratio, leading to the difference in refractive index, between PMMA and EVA [12].

20.3 Basic polymers used in automobile industry The demands on the modern automotive industry are ever challenging; motorists want high performance cars but at the same time they are looking for improved reliability and safety, greater comfort, fuel efficiency, style, and competitive increasingly about environmental impact. The plastic materials are rising to the challenge of these potentially conflicting demands. Plastics industry is very essential for the automotive industry. Plastics have actually been used in cars since the 1950s, but it is the latest innovations that are really changing the industry for the better. Engineered polymers and plastics are continuing to replace aluminum and other metals in automobiles, with the average car interior now being made up over 50% plastics. Over 1000 different car parts are now made of plastics, and these plastics can be molded together to replace the need for multiple parts, keeping manufacturing efficient and weight down. Automobile engineers are employed together closely to develop the other systems; blow molded and integrating injection molded parts offered a better product without expensive assembly work. In the structural design of the cars, the plastics are used (the most complicated design problem, the tank fuel system, has been solved by the plastics). The engineered polymer blends and plastics are used in wide range of applications in automobile industries. After ferrous metals and alloys, it is the second most common class of automotive material which represents 68% by weight. The other nonferrous metals are copper, zinc, aluminum, magnesium, and titanium, and their alloys are used in automobile industry [13]. In commercial vehicles, about 50% of all interior components, including safety subsystems, door and seat assembly contents, are plastics. There are several polymeric materials used in automotive industry. While all of the ones listed below may easily be used in a single

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vehicle, the three types of plastics make up approximately 66% of the total plastics used in automotive industry, i.e., PP (32%), polyurethane (PU, 17%), and PVC (16%). The reduction of fuel usage is dependent on the weight of the vehicle, i.e., every 10% reduction in vehicle weight results in a 5%e7% reduction in fuel usage. The creation of more fuel-efficient cars in the automobile industry is the economic and environmental concern. The advantages like less corrosive, i.e., it allows for longer vehicle life, flexibility in integrating components, safety comfort and economy, weight saving, parts consolidated, easy fabrication, recyclability, etc increase the use of polymeric material in automobile industry. The types of polymers used in the different component of a car are discussed in Table 20.1.

20.3.1 Polypropylene Polypropylene is a thermoplastic “addition polymer” made from the combination of propylene monomers by using ZieglereNatta catalysts. The monomer propylene is obtained as a product from gasoline refineries. The PP can be prepared in isotactic, syndiotactic, or atactic forms. The isotactic polymer melts at 208 C and is highly crystalline. Being highly crystalline, PP exhibits high stiffness, hardness, poor specific gravity, excellent tensile strength, and better chemical resistance and stain resistance. Its high strength-to-weight ratio makes it very useful in industries. The articles molded out of this polymer can be sterilized since it possesses a melting point higher than 100 C. It is insoluble in room temperature in many of the known solvents. The molecular weight, copolymers involved,

Table 20.1 Plastics used in a typical car. Components

Types of polymer used

Bumpers Seating Dashboard Fuel systems Body (incl. panels) Underhood components Interior trim Electrical components Exterior trim Lighting Upholstery Liquid reservoirs

PS, ABS, PC/PBT PU,PP, PVC, ABS, PA PP, ABS, SMA, PPE, PC HDPE, POM, PA, PP, PBT PP, PPE, UP PA, PP, PBT PP, ABS, PET, POM, PVC PP, PE, PBT, PA, PVC ABS, PA, PBT, POM, ASA, PP PC, PBT, ABS, PMMA, UP PVC, PU, PP, PE PP, PE, PA

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and methods of production are important factors for production of PP [14]. PP is extremely chemically resistant and almost completely impervious to water. Due to the good specific strength, PP has been very successfully applied to the forming of fibers; this makes PP the single largest polymer in use having density 0.905 g/cm3 [15]. However, PP on heating above its melting point can be dissolved in aromatic and chlorinated hydrocarbons. It is resistant to many chemicals such as acids, alkalis, oils, etc., but less resistant to oxidation compared to polyethylene. While its stability toward heat and light is lower than that of polyethylene, PP has excellent mechanical and dielectric properties. It is widely used in automotive industry; components made from PP are used in appliances such as automotive bumpers, chemical tanks, seat covers, cable insulations, battery cabinets, commercial bottles, petrol cans, storage tanks, indoor and outdoor carpets, and carpet fibers.

20.3.2 Polycarbonate Polycarbonates are the polyesters of phenols and carbonic acid. PC can be prepared by condensing diphenoxymethylene derivatives with diphenylcarbonate. PC melts around 265 C and has very high-impact strength. It is resistant to water and many other organic compounds, but alkalis will slowly hydrolyze it. It is a transparent plastic. PC is used in nonreinforced condition. It has a rare combination of mechanical properties like hardness, toughness, and stiffness. It shows good weathering, impact, optical, electrical, creep, thermal properties, and UV resistance with transparency levels almost good as acrylic. Many useful articles like safety goggles, safety shields, telephone parts, and machinery housing can be made from this polymeric material. In the automotive industry, injection molded PC can produce very smooth surfaces that make it well suited for sputter deposition or evaporation deposition of aluminum without the need for a base coat. Decorative bezels and optical reflectors are commonly made of PC. Due to its lightweight and high-impact resistance, PC is dominant material for making automotive headlamp lenses. It can be laminated to make bullet proof glass although bullet resistant is more accurate for the thinner windows, such as are used in bullet-resistant windows in automobiles. It is used in bumpers, headlamp lenses, head/rear light housings, security screens, helmets, etc [16].

20.3.3 Polyvinyl chloride Polyvinyl chloride is one of the cheapest and most widely used plastics globally. It is a thermoplastic having good resistance to alkalis, salts, and highly polar solvents, and it is flame retardant due to the presence of

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chlorine in the structure. The presence of chlorine makes it flame retardant. But PVC is not thermally stable at higher temperatures. Plasticizers are added to PVC for safe processing due to its thermal instability at high temperature [17]. In automobile industry, it is used for the fabrication of internal lining, protective covering of bottom flooring cars, and coating of electric cables in vehicles. It has excellent properties like good flexibility, flame retardancy, good thermal stability and high gloss and low lead content, diversity of manufacturing procedures, and easy to paste, print and weld [16]. It is used for the large scale production of cable insulations, equipment parts, pipes, laminated materials, and in fiber manufacture. The PVC polymer can be blow molded, calendared, injection molded, and compression molded to form a large varieties of products. Depending upon the amount and type of plasticizers used, the product formed from the PVC is either rigid or flexible. Its vinyl content that gives good tensile strength. It has good resistant to chemical and solvent attack. Colored or transparent material is also available. It is used in automobile instrument panels and sheathing of electrical cables.

20.3.4 Polyurethanes Polyurethane polymers are characterized by the presence of urethane linkage in their repeat unit. Depending on nature and length of isocyanate and hydroxyl molecule, thermosetting, thermoplastic, hard, soft, flexible, cellulartype PU is synthesized. The structure has some resemblance to polyamides, because both of them contain -CONH- groups. The principle linkage in PU however is -NHCOO-. The presence of additional oxygen in the chain increases its flexibility. For coating, elastomer and foam PU are used. PU exhibits good resistance to chemicals, good abrasion resistance but it has high hysteresis [16]. Due to the good combination of low heat transfer and good costeeffectiveness, PU foams are widely used in insulation materials. PUs are used in fabrication of high resilience foam seating and durable elastomer wheels and tires (such as escalator, shopping cart, elevator, roller coaster and skateboard wheels). In automotive industry, it is used in suspension bushings, body parts, hard plastic parts, and electrical potting compounds [16].

20.3.5 Polystyrene Polystyrene is a synthetic aromatic hydrocarbon polymer made from monomer styrene. Styrene is produced from ethylene and benzene. When ethylene passes into benzene in presence of an aluminum trichloride catalyst, ethylbenzene is produced, which on passing over a catalyst such as

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iron oxide or magnesium oxide at high temperature gets converted into styrene and hydrogen. Commercially available PS is atactic and is an amorphous, glassy polymer that is generally stiff and comparatively inexpensive. PS consists generally of linear molecules and is chemically inert. Acids, alkalis, oxidizing, or reducing agents have little effect on it. Unfilled PS has a glitter appearance and is often referred as general purpose PS (GPPS) or crystal PS, which is clear, hard, and rather brittle. By adding rubber or a butadiene copolymer which increases the toughness and impact strength of polymer, we can produce high-impact polystyrene (HIPS). PS is widely used in the manufacture of articles such as moulded containers, lids, jars, bottles, radio and television cabinets, toys, foamed plastics, and other household items. Copolymers of styrene with acrylonitrile, vinyl carbazole, or diphenyl acrylamide are few important ones. Introduction of a comonomer increases the heat and impact resistance of the polymer without sacrificing the useful properties of the styrene homopolymer. PS can be easily injection molded, compression molded, and extruded, and it has good flow properties at temperature safely below degradation ranges. For the production of foamed PS articles, significant amount of PS are fabricated in the form of heat expandable beads containing a suitable blowing agent [18]. It shows excellent chemical and electrical resistance. It can produce the car fittings equipment, equipment housing, buttons, and automotive display bases.

20.3.6 Polyethylene Polyethylene is a lightweight durable thermoplastic with variable crystalline structure and has extremely large range of applications depending on the particular type. It is one of the most widely produced plastic in the world. It is the member of polyolefin resins obtained by polymerization of ethylene gas. It is the largest scale commercial polymers. Depending on the production process, PP is available in a range of flexibilities and properties, with high-density material, and is the most rigid one. Due to the excellent insulation properties, good chemical resistance, low cost, good toughness and flexibility, good processability, reasonably low moisture permeability, and no odour or toxicity, it is widely used. There are different varieties of PE grades that are available in the market. Varieties of PE grades are used in automobile application which includes high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). LDPE and HDPE are branched and linear with density of 0.91 g/cm3 to 0.925 g/cm3, while HDPE ranges from 0.935 g/cm3 to

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0.96 g/cm3 and above [19].The applications of PE includes electrical insulation, car bodies (glass reinforced), and packaging, where strength and aesthetics are important.

20.3.7 Polyamide (Nylon, Nylon 6, 6) Polyamide or nylon is a semicrystalline polymer and has been commercialized since the mid of 1930.The material offers an excellent combination of mechanical, electrical, high resistance to abrasion, and low friction characteristics coupled with good resistance to heat and chemicals. It has high lubricity and moderate strength. It is tough and inexpensive but has poor dimensional stability due to water absorption. The key performance properties of PA include good rigidity and hardness, very high strength and toughness, good low temperature impact strength, high dynamic strength, high heat resistance (Nylon 6 short term to 200 C, long term from 80 to 150 C, Nylon 6, 6 short term to 250 C long term from 80 to 150 C), excellent processing properties, and tensile modulus 450 to 15,000 MPa for Nylon 6 and 900 to 15,000 MPa for Nylon 6, 6. Polyamides are prepared by the melt polycondensation between dicarboxylic acids and diamines. There are different types of PA having different properties and different applications are available in the market. The aliphatic PA is known as nylon. There are different types of nylons usually indicated by number system. This number of carbon atoms present in the monomer molecules. In automotive industry, nylons are used for various applications. For tire manufacturing, fabrics made from nylon chords are used. Nylons are widely used in automotive industry for the fabrication of components like peripherals, throttle body housing, and cylinder head covers, air intake manifolds, cooling systems, and engine parts are made of Nylons. Automotive air intake manifolds are made of PA 6. PA grades 6, 6 and 4, 6 are also used in manifolds, Nylon reduces the production cost by 30% and it reduces 50% weight of the component compared to metals. Nylon 6 allows better surface appearance, good strength, thinner walled designs, and wider processing window (good flow and low injection pressure), so it is used in engine covers, rocker valve covers, and exterior automobile parts that include door and tailgate handles, exterior mirror, wheel covers, and trim. Nylon 6, 6 is used in car power trims and headlamp bezels [20].

20.3.8 Acrylonitrileebutadieneestyrene Acrylonitrileebutadieneestyrene is a commercially important amorphous polymer, made by polymerizing styrene and acrylonitrile in presence of

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polybutadiene. The presence of styrene gives shiny appearance and good processability, and butadiene, a rubbery substance, provides resilience even at low temperature, good melting strength, and flexibility. It has good chemical resistance and highly polished surface [16]. For typical applications, ABS can be produced with desired properties by taking the appropriate amount of monomers. ABS is used in automotive body parts, helmets, dashboards, wheel covers, etc. Its general applications are in medical equipment, helmets, pipes and fittings, body of appliances like vacuum cleaners, sports equipments, safety helmets, luggage, furniture, tubes, caps, telephone sets, and cameras. For the washing machine and refrigerator housing, ABS grades with high gloss are used. Some grades are used for automotive interior and housings of domestic appliances. It is used for the production of various automotive components such as exterior components, door trim, loud speaker grilles, door handles, instrument panels, consoles, and electrical components like navigation system housings [21].

20.3.9 Polyoxymethylene It is also known as polyformaldehyde or polyacetal. This engineering thermoplastic has high stiffness, low friction, and excellent dimensional stability, so it is used in the production of precision parts. It is commonly used as a direct replacement for metals due to its stiffness, dimensional stability, and corrosion resistance. Polyoxymethylene (POM) is one of the major engineering thermoplastics that are characterized by a set of excellent properties. The key properties that makes POM a widely used material includes resistance toward chemicals, high crystalline content, and excellent short-term mechanical properties such as tensile strength, toughness, rigidity, low linear coefficient of thermal expansion and low tendency to creep, and fatigue. The crystallinity is important for POM, and it brings a high modulus as well as good dimensional stability. POM maintains good mechanical and electrical properties at 140 C (for a short term) and 90 C (for long term) [22], all of which it is widely used for producing selflubricating mechanical parts in automotive electronics and precision machine industries [14]. It is also used in manufacturing of engineering components such as bearings, gears, automotive interior and exterior trims, fuel tanks, window guides, zips, lighters, speaker grills, aerosol valves, and furniture components [23].

20.3.10 Polymethyl methacrylate It is a colorless transparent plastic with an excellent outdoor life period and good strength [24]. It is amorphous by nature, owing to the presence of

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bulky side groups in the molecules; PMMA is a tough, durable, and lightweight thermoplastic. The density of acrylic ranges between 1.17 and 1.20 g/cm3, which is half less than that of glass. It exhibits low moisture and water absorbing capacity, due to which products have good dimensional stability. It is resistant to many chemicals but soluble in organic solvents such as ketones, chlorinated hydrocarbons, and esters. It can be thermally depolymerized to yield back the entire quantity of monomers. Optical clarity is the main feature of this plastic. For high optical clarity and surface finish with a huge color range, PMMA is used in wide varieties of applications. PMMA is used to make attractive signboards and durable lenses, windows, motorcycle windshields, interior and exterior panels, fenders, etc. Also colored acrylic sheets are used in car indicator light covers, interior light covers, etc. It is also used for windows of a ship (salt resistance) and aviation process. PMMA also opens new design possibilities for car manufacturers, thanks to its pleasant acoustic properties, outstanding formability, and excellent surface hardness [24].

20.3.11 Polybutylene terephthalate Polybutylene terephthalate (PBT) is a semicystalline saturated polyester, which is made by polycondensation of terephthalic acid or dimethyl terephthalate with 1-, 4-butanediol in presence of a catalyst. There are different grades and types of PBT resins and compounds available. The most widely used are unreinforced reinforced injection molding grades, followed by extrusion and coating grades. Injection molding grades are available in wide range of strength and degree of toughness. The polymer displays excellent mechanical and electrical properties, such as high strength, stiffness, high heat resistance up to 140 C long terms, low temperature performance down to 40 C and long flow in thin section, and flame resistance [2]. It shows good durability under thermal stress and harsh chemical environment particularly in automotive underhood applications. PBT is used in automobile industry for manufacturing of electronic housing of automotive and power tool casing. In exterior automobile components, it is used in bumper fascias, mudguard, body plates, radiator grilles, door handles, mirror housings, wiper arms, sun roof parts, locking system housing, carburettor components, etc [13].

20.3.12 Polyethylene terephthalate Polyethylene terephthalate (PET) is a general purpose thermoplastic polyester. Polyester resins have excellent properties such as mechanical,

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thermal, and chemical, as well as good dimensional stability. In natural state, PET is a highly flexible, semicrystalline, and colourless material. Depending upon the processing parameters, it can be semirigid to rigid. It shows excellent electrical insulating properties, good dimensional stability, high strength, and very strong and lightweight and hence so easy and efficient to transport. PET shows different range of use temperature from 60 C to 130 C. PET has a higher heat deflection temperature (HDT) as compared to PBT. It has good fracture resistance as it does not break on fracture. It has low gas permeability, in particularly with carbon dioxide. PET is suitable for transparent applications, when quenching during processing [13]. It can be used in glass replacement in some applications PET is widely used in many applications in the automotive industry like engine cover, wiper arm and gear housings, head lamp retainer, and connector housings.

20.4 Polymer blends used in automobile industry In the recent decades, an ever growing demand for improved properties such as stiffness, ductility, thermal stability, flame resistance, impact resistance, etc had paved the development of blending of polymer mixtures. The total market volume for polymer blends is currently estimated to be more than million metric tons a year [25]. The most important application area of polymer blends is in automotive industry. A divergence should be drawn between body parts and cars interior applications. The specific demands have been met for the volume production; most thermoplastic parts for vehicle exteriors have been developed. These include excellent notched and unnotched impact resistance even at low temperatures, sufficient dimensional stability under heat, rigidity, fuel resistance, and easy processability. These excellent characteristics for bodywork applications are met to a high degree of thermoplastic blends of PC/thermoplastic polyester/ impact modifiers, modified PBT, PP/EPDM, and by modified polyamides. PU and unsaturated polyester are also used for the automobile components. In automobile industry, many different polymer systems are used in similar or sometimes in virtually identical exterior applications, where functional demands are largely the same across the board. The cause is that there are criteria governing the choice of material other than the function of the particular part and the resulting basic requirements regarding toughness, stiffness, heat resistance, fuel resistance, and weatherability. At present, the only plastics body part for volume-produced vehicles that may be left unpainted or also painted either off-line or on-line is the bumper. A

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wide variety of polymer blends can be used for production of bumpers. PC/PBT/modifiers and PBT/modifier polymer blends are used for selfsupporting bumper designs, and PP/EPDM and PA/modifier blends are used for bumper covers and supported bumpers. The automotive exterior parts such as spoilers, body side moldings, door sill panels, wheel covers, and rear view mirror housings made of thermoplastic blends are either integrated unpainted into the bodywork or painted off-line. Other applications are also being developed; one comparatively new application is wings or front fenders moulded in PC/ABS blends and painted off-line. ABS, PC/ ABS, and PPO/PS blends are used sometimes in various forms in automotive interior body parts. In these applications, certain characteristic properties of products which may not seem very significant at first sight can strongly influence the choice of material, example is the parameters governing the outward appearance, including the color, of an injection moulded parts. The parameters are degree of gloss, molding accuracy and light stability of the thermoplastic as well as the intensity and metamerism of the colorants. Various safety requirements, such as compliance with the head or knee impact test, and heat resistance demands lead to the use of various different blends within the passenger’s field of vision. The car manufacturer’s ideal is to ensure a perfect match in terms of color and surface finish, regardless of light conditions, between adjacent parts made of different thermoplastic blends, and this should persist throughout the cars service life. This need was easier to fulfill 10 or more years ago, when nearly all automotive interior parts were black. Nowadays, color fashions are constantly changing, demanding greater efforts in this direction on the part of raw material manufacturers and processors alike. Typical applications for thermoplastics blends in the passenger compartment are instrument panels, glove compartment flaps, consoles, and steering column shrouds. These may be made of PC/ABS, PPO/PS, or ABS blends depending on requirements. As far automotive applications are concerned, exterior parts have considerably greater potential for the future in terms of new and expanding applications. The possibilities for using thermoplastics in car interiors have been more or less exhausted, where as blends are only just beginning to establish themselves in body parts; many potential applications remain open [26]. The thermoplastic polyolefins (TPOs) have been widely used for automobile parts appliances and other improved mechanical properties compared with processability and improved mechanical properties compared with PP homopolymer. It is used in bumper guards, wheel liners, step pads, air dams, air bag covers, skin for instrument panels, side cladding, consoles, and door

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panels [27]. The impact properties of these blends are considerably improved by the presence of dispersed rubber particles in the PP matrix [28]. Several studies show that similar blends produced by a sequential process, with the formation of some crystalline polyethylene, present specific characteristics particle morphology; the polyethylene seems to form a core surrounded by the rubber, which forms a shell in contact with the PP matrix. The miscible polymer blend of PS and poly (2, 6-dimethyl phenylene oxide) (PPO) has been commercial from General Electric in the late 1960 under the trade name Noryl. Miscibility of this blend has been widely studied [29]. Commercially, impact PS is utilized for these blends. PPO offers improved heat distortion temperature, and PS yields improved processability and lower cost. Applications for these blends include appliance housings, business machine housings, automotive dashboards, pump components, and television components. The first application was that of bumpers traditionally made of chromium-plated metals, which often are too stiff and heavy and were produced by an expensive and polluting process. The use of plastic material/ polymer blend in place of metals solved the largest part of these problems; elastomer-modified polypropylene (EMPP) appears capable of solving all these problems. The use of glass-reinforced PP in automotive industry mainly includes parts of heating systems, air filter bodies, fans and electroventilator supports, radiator components, protection carters, and parts of lighting system. PA/ABS blends are mostly used in automobile industries, as the advantages of blending PA with ABS are essential to improve toughness, lower moisture sensitivity, shrinkage, and warpage of the polyamide phase. Low cost of the blend is due to the ABS compared to PA. Due to ABS, the blends have good impact strength at low temperature [30]. PC/ acrylonitrileestyreneeacrylate (ASA) blends are used for exterior components in automobile industry due to the good chemical, mechanical, and thermal properties [31]. The properties, applications, and types of polymer blends used in automobile industry are shown in Table 20.2.

20.5 Typical applications in automotive industry The modern automobile has seen a remarkable change in the types of materials employed in its fabrication. The applicability of plastics in automobile industry is enhanced by polymer blending. Polymer blending has many advantages over conventional material. Polymer blending gives improved fuel economy in automobile, this is due to the reduction of the vehicle weight; this is only possible by the plastics instead of metals. Material

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Compatibilization of Polymer Blends

Table 20.2 Types, properties and specific applications of polymer blends in automobile industry. Polymer blends Properties Applications

PBT/ elastomer PET/ elastomer PET/PSF

PET/PBT

PPE/HIPS or PPE/PS

PPE/PA

PC/ABS

PC/PBT

PC/PET

Good chemical resistance Notch izod impact strength Good thermal stability Good impact strength Stiffness Processability High temperature performance Good dimensional stability Resistant toward chemicals Chemical resistance Excellent surface aesthetics Impact and electrical properties Good dimensional stability High resistance to moisture Low temperature impact strength Low creep Improved processing Excellent impact strength Good chemical resistance High-impact resistance High modulus High deflection temperature under load (DTUL)

Toughness Good tensile strength Flame resistance Color stability Good surface appearance Good heat resistance moldability Dimensional stability Low temperature impact Chemical resistance

Automotive body parts, steering wheel Underhood components, body parts Electrical connectors

Electrical and electronic connectors

Automotive instrument panels, interior trim

Automotive wheel covers Injection molded automotive body panels Trim components Thermoformed truck body panels Wheel covers Underhood electrical connectors Mirror housings Exterior automotive trim Instrument panel Interior parts

Automotive bumpers

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Table 20.2 Types, properties and specific applications of polymer blends in automobile industry.dcont'd Polymer blends

PC/SMA

PC/TPU

PC/Acrylic

Properties

Applications

Low temperature performance Transparent Good abrasion resistance Impact resistance

Automotive bumpers Exterior trim

Heat resistance High stiffness Good impact resistance Excellent mechanical properties Good chemical resistance Improved toughness

Automotive application

PA/ABS

High temperature warp resistance Good processability Superior appearance Chemical resistance

PA/PE

Chemical resistance Impact properties High durability and wear resistance Good tensile properties Heat resistance High flow properties Low flash during injection molding High heat resistance

PPS/PTFE

PPS/PEI

Exterior motor vehicle

Protective gear Casings and housings for power tools Automotive body panels Underhood connectors Fuel tanks Bearings Bushings Cams Fuel tanks Valves and bushings

Electrical and electronic connectors

substitution, design optimization, and parts consolidation are the reason for the lightweighting of the components. The general applications of polymer blends in automotive industry mainly divided into three parts; • Exterior • Interior • Underhood A list of different components in each section is given in Fig. 20.6.

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Compatibilization of Polymer Blends

Figure 20.6 Categorization of automobile components made from polymer blends.

20.5.1 Exterior components External body structure, bumpers, wheels, mirrors housings lenses, and sunroofs are under the exterior components of a car. For the external structure, it is necessary to have good optical properties, high strength, and high crash resistance. The exterior components also expected to be lightweight. Lightweighting is an important factor for fuel consumption. The advantages of polymer blends over conventional materials for exterior applications in automobile industry are lightweighting, part consolidation, low cost, design flexibility, improved impact resistance, and good surface aesthetics. All these properties help in developing the use of plastics and blends in different exterior parts, and their respective blends are mentioned in Table 20.3.

Table 20.3 Exterior automotive application for polymer blends [32]. Part

Materials

Rear bumper cover Bumpers Bumper beams Trim Mirror housing Side moldings Rear spoiler Head lamp bezels Wheel covers Grille

PC/PBT PBT/PC, PP/EPDM PBT/PC PC/ABS, PC/ASA, PA/PPE, PS/PPE PPE/PA, PPE/HIPS, PC/ABS PS/PPE PPE/PA PPE/PA, PPE/HIPS PC/ABS, PPE/PA PC/ASA,PPE/HIPS

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20.5.1.1 Bumpers A bumper is a structure attached to or integrated with the front and rear ends of a motor vehicle, to absorb impact in a minor collision, ideally minimizing costs. The function of the bumper is to prevent or minimize damage to the car body caused by low speed collision. It acts as a shield, as it helps to protect car parts critical for safety reasons (headlights, tailings, etc.) and the parts that are too costly to repair on being damaged (e.g., hoods, fenders, exhaust and cooling systems, etc.). Brush guards and push bars were added to the bumpers of automobiles; this provides the additional protection to the vehicle. While bumpers were originally made of heavy steel, in later years they have been constructed of rubber, plastic, or painted light metal, leaving them susceptible to damage from even minimal contact. Sufficient resilience and deformability in a bumper system restricts the damage to the bumper itself. The bumpers are also expected to meet additional requirements currently, such as contributing to lightweighting of vehicles to improve fuel economy and reduce environmental pollution, as well as contributing to vehicle aesthetics and being recyclable. The bumper system mainly consists of three parts. The fascia which is made from plastics controls air flow and ensure aesthetics. The energy absorbing material, usually plastics due to their stress absorbing property, is used to absorb shock along with a reinforcement beam, typically made of steel, aluminium or fiber reinforced composite, which protects the car body by absorbing the crash energy. Various polymer blends have been used in different bumper components. PP, polyurethane (PU), and PC are mostly used for the bumper fascias, due to good strength, low density, stiffness, and properties that ensure they stick to the bumper body [33,34]. For mechanical energy absorbers, PP, PU, and LDPE materials are used and these materials reinforced with other materials to improve shock-absorbing ability, strength, and stiffness. Blends of PPE and PA 6,6 are used for the fabrication of automobile bumpers. PU/PC blends are used for soft bumpers due to the high-impact strength, flexibility, and good paintability. PP copolymers and TPO blends are used for the bumper cover for high volume cars in Europe [35]. Remain the major materials of use, mainly as foams, though TPOs have also gained prominence in recent times. Often, these are reinforced with other materials to improve their strength and toughness, thereby improving their shock-absorption ability.

586

Compatibilization of Polymer Blends

20.5.1.2 Head/rear light housings Headlights are lights, which installed in the front portion of a car to enable the car’s driver to see all kinds of moving objects in darkness. To know about the presence and action of the car, taillights are installed in the back portion of the car. Both head and rear lights are important at bad weather condition and at night. Head/rear lights housings are meant to ensure a clear and visible light beam; it protects the lighting arrangements from extreme environmental conditions like dust, dirt, moisture etc. Headlight housings are needed to be heat resistant because high amount of heat is generated by headlight systems [36]. The headlight housing needs to have the following properties like high scratch resistance, high strength and toughness, easy processability, and good optical properties and be transparent. In addition to all these requirements, headlights and headlight assemblies are expected to adhere to the standards set under the Federal Motor Vehicle Safety Standard 108 (FMVSS 108) [37]. The difference between head and rear light housings is that, for headlight housing it is essential to have a plastic with high heat resistance and low coefficient of thermal expansion [38]. But in case of rear lighting systems, housings are not required to possess a high resistance to heat; so ABS, ASA, and PP (pure or blend) can be used. Due to the transparency of PMMA and PC, they are considered for headlight housings materials. PPE/HIPS and PA/ABS blends are used for headlight housings due to the excellent properties. For automotive lens most of the automobile companies are using ABS/PC blends for reflectors and PMMA/PC blends for automotive blends. 20.5.1.3 Wheel covers The function of the wheel cover is to protect the wheel nuts and bolts from corrosion and from falling off in case they are loosened. It gives a decorative appearance to the wheel. Due to the advantageous properties of plastics like resistance to extreme environmental conditions (salt, chemicals, heat, or cold), lightweight, good dimensional stability, easy paintability, high corrosion resistance, it becomes the principal material for wheel covers. PC/ABS blends are used for wheel covers due to the high-impact resistance, high heat resistance (withstand temperature 105 C), and low cost. ABS, ASA, TPO, and PA 6 are widely used for covers in both pure and blended form, due to the durability, high strength, and excellent resistance toward breaking scratch and chipping [39].

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20.5.1.4 Other exterior automotive components The other exterior automotive body parts are body-in-white (BIW); it is the name given to a car body’s sheet when all its components barring moving parts (e.g., hoods, fenders, etc), trims (e.g., glass, seats, etc) or chassis subassemblies, cowl vent grilles, spoilers, vertical body panelsdpictures of which are presented in Fig. 20.7. The following exterior components must have high tensile strength and high stiffness bending. BIW is expected to possess a number of significant properties. It should provide good quality safety both to the car body and to its occupants against crashes of all kinds like front, rear, side, or even rollover, and it should meet the Federal Motor Vehicle Safety Standard No. 208. It should also be able to protect occupants from noise, vibration, and harshness by absorbing or reducing these conditions. Also, it should be easy to weld and form, as well as be highly paintable and easy to design [40]. The use of lightweight material in BIW improves the fuel economy, so lightweighting is the important factor for BIW. PC/ASA and PC/ABS blends find use in the exterior automotive parts like wheel covers, vertical body panels, spoilers, cowl vent grilles, etc.

20.5.2 Interior components The main interior components of an automobile are the seats, door trim, roof trim, and floor covering. Fogging and acoustic properties are the important factors for interior components. Table 20.4 shows the interior

Figure 20.7 Exterior components in a car.

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Compatibilization of Polymer Blends

Table 20.4 Interior automotive applications for polymer blends [32]. Parts Polymer blends

Trim Instrument panel or dashboard Door assemblies Instrument panel skin Seat belts

PMMA/PVC, ABS/PC HIPS/PPO, PPE/PS, PC/ABS, PMMA/ PVC PVC/PE PVC/ABS PU/ABS

automotive applications of polymer blends; some of pictures are shown in Fig. 20.8. 20.5.2.1 Door panels Door panels work as combination between the interior of the car and the inner workings of the door and between vehicle occupants and the door. The door panels are expected to meet a variety of design specifications regarding safety, aesthetics, and functionality. In addition, they are expected to continue the material theme of the dashboard and pillars while concealing intricate electrical and mechanical components for operating locks, windows, and other features. The door panel has evolved from a simple two-part system of latch and simple winding mechanism to a more sophisticated enclosure. Doors currently have an inner full width panel consisting of electronic windows, central locking system, and speakers. The door panels typically consist of a foamed core covered with either textiles or plastics. PVC and PU foamed core are used in door panels. Subsequently, there was a shift toward thin wall moldings of ABS or PP backed by textiles in order to manufacture a contour-backed panel with recesses. This is primarily because integrated injection molded door panel assemblies reduce the need for other energy-absorbing materials, resulting in cost reduction

Figure 20.8 Interior components in a car.

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for manufacturers due to simplification of door construction. ABS/PP blends are highly acceptable for automotive interior application with high mechanical strength and chemical resistance. 20.5.2.2 Instrument panel or dashboard The instrument panel or dashboard consists of number of components such as fuel gauge, speedometer, tachometer, odometer, climate control system, and safety features such as air bag housings. Instrument panel (IP) is unique in the car, because it can heat by sun up to the temperature 120 C, and it has high load of attached components and extreme impact requirements. A PC/ ABS blend used in IP shows better performance than ABS and it is found more durable than PC, also has the critical ability of IP to withstand the forces of airbag arrangement without breaking or damage to other components. For IP, PC/ABS and PPE/PS blends are used due to high heat capability and impact resistance. IPs can be categorized as hard-touch or soft-touch panels. Hard-touch panels are used in high volume cars as a base for manufacturing integrated IPs and/or cockpit modules, such that they can support airbags and provide basic functionality. In contrast, softtouch panels consist of a base-level structural component with an integrated crossbeam and impact absorbing foams or crash pads [41]. For IP and related trim parts, such as glove box doors and bolsters, specially engineered polyolefins materials are being used. The TPO offers the structural stiffness and heat resistance that are essential and demanded for these applications. 20.5.2.3 Seats and associated parts Car seats comprise of different parts like armrest, backrest or seat back, headrest, seat base, and seat track; the seat belt and airbags are for safety purposes. In the Keiper Recaro A8 sports car (1991), some experimental approaches have been made by using various plastics like impact-modified glass fiber reinforced PA 6 in front seat back frames. In Chevrolet Corvette (1997), structural reaction injection molded seat back frames are used [36]. PC/ABS blends are used in rear seat backs [35]. The seat covers needs to be resistant toward numbers of factors like variable temperature, abrasion resistant, UV radiation, and humidity [42]. The PVC is replaced by woven nylon and polyester fabric by the 1960s. 90% of the cars seat fabric is made of polyesters and are typically used as trilaminates, with the face and lining fabric having a thick layer of foam, usually of polyurethane (PU), in between [38]. PU is used as foam for its energy-absorbing properties and flexibility.

590

Compatibilization of Polymer Blends

Table 20.5 Underhood applications for polymer blends [32]. Parts Polymer blends

Sensors Resonators Ignition components Fluid handling Power distribution Connectors

PBT/PC, PPE/HIPS PBT/PC, PPE/PA PBT/PC, PPE/HIPS PPE/PA, PET/PC PBT/PC, PA/PPE, PPS/PEI PBT/PC, PA/PPE, PPS/PEI

20.5.3 Under hood application When selecting materials for underhood applications, some important factors like good processability, good heat aging, low specific gravity, extremely high heat loads, in addition to severe UV and dimensional stability consideration, chemical resistance, and high modulus at elevated temperature are considered. Some of the polymer blends which are applicable in underhood parts are shown in Table 20.5 and Fig. 20.9 represents underhood area. Ignition compartments require good electrical properties, i.e., high dielectric strength and good adhesion to epoxy potting compounds. PBT/PC and PPE/HIPS blends are used for ignition compartments. Resonators and air ducts require excellent melt strength, good surface appearance, lightweight, and excellent noise reduction. PPE/PA and PBT/PC fulfill the above properties so these blends are used in resonators and air ducts. The fluid in an underhood application is corrosive but that does not prevent the use of polymer blends in these applications. PPE/PA and PET/PC blends are used in pump impellers and components which have direct contact with fluid. The engine compartment of an automobile is one of the most demanding environments for plastics. The ability to withstand extremes in heat, corrosive fluids, vibration, and mechanical loads is the requirements for the material.

Figure 20.9 Underhood components in a car.

Applications of compatibilized polymer blends in automobile industry

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The electrical and electronic connector is one of the increasing areas for polymer blends in underhood applications. Low melt viscosity at injection molding temperatures to fill the complex tooling is the requirement for such applications. For this application, the polymer blends may be required to improve dimensional stability and modus. PBT/PC, PA/PPE, and PPS/ polyether imide (PEI) blends are suitable for underhood applications [32].

20.6 Conclusion Polymer blends which are compatibilized possess good interfacial strength owing to which they possess excellent structural properties for exterior, interior, and underhood applications. Polymeric materials have become reliable and are in demand in automotive industry. Polymeric automotive parts are light in weight which reduces the overall weight of the final vehicle and hence increases fuel economy.

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