Waterborne polyurethane nanocomposite reinforced with amine intercalated α-zirconium phosphate - Study of thermal and mechanical properties

Journal Pre-proof Waterborne polyurethane nanocomposite reinforced with amine intercalated αzirconium phosphate - study of thermal and mechanical properties

Manoj B. Kale, Nidhin Divakaran, Suhail Mubarak, Duraisami Dhamodharan, T. Senthil, Lixin Wu PII:

S0032-3861(19)31015-8

DOI:

https://doi.org/10.1016/j.polymer.2019.122008

Reference:

JPOL 122008

To appear in:

Polymer

Received Date:

02 September 2019

Accepted Date:

14 November 2019

Please cite this article as: Manoj B. Kale, Nidhin Divakaran, Suhail Mubarak, Duraisami Dhamodharan, T. Senthil, Lixin Wu, Waterborne polyurethane nanocomposite reinforced with amine intercalated α-zirconium phosphate - study of thermal and mechanical properties, Polymer (2019), https://doi.org/10.1016/j.polymer.2019.122008

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Waterborne polyurethane nanocomposite reinforced with amine intercalated α-zirconium phosphate - study of thermomechanical properties Manoj B. Kale a,b, Nidhin Divakaran a,b, Suhail Mubarak a,b, Duraisami Dhamodharan a,b, T. Senthil c, , Lixin Wu a

a CAS

Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Key

Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People’s Republic of China b University

cAdvanced

of Chinese Academy of Sciences, Beijing 100049, China Research School for Technology and Product Simulation, Central Institute of

Plastics Engineering and Technology, Chennai, 600032, India

*

Corresponding author

Email address: [email protected] (Lixin Wu)

WPU/fZrP thin film

10 5 0

0

200 400 600 800 1000 Elongation (%)

0.30 (a)

0.2969 0.2519

0.25 0.20

0.2094 0.2178 0.1777

0.15 0.10 0.05

WPU

rP -1

PU /fZ

-0 .5

/fZ rP PU

W

W

-0 .1

-1

/fZ rP

PU

/Z rP

PU

0.00

W

Amine intercalated α-ZrP (fZrP) WPU In situ polymerization

15

PU

Amine

20

W

Amine

WPU WPU/ZrP-1 WPU/fZrP-0.1 WPU/fZrP-0.5 WPU/fZrP-1

25

W

13.3 nm

Ethylenediamine

Tensile Strength (MPa)

α-ZrP

Thermal conductivity (W/m*K)

0.76 nm

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WPU/ZrP- WPU/fZrP- WPU/fZrP- WPU/fZrP1 0.1 0.5 1

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Waterborne polyurethane nanocomposite reinforced with amine intercalated α-zirconium phosphate - study of thermal and mechanical properties Manoj B. Kale a,b, Nidhin Divakaran a,b, Suhail Mubarak a,b, Duraisami Dhamodharan a,b, T. Senthil c, Lixin Wu a, *

a

CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Key

Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People’s Republic of China b University

cAdvanced

of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China

Research School for Technology and Product Simulation, Central Institute of Plastics

Engineering and Technology, Chennai, 600032, India

*

Corresponding author

Email address: [email protected] (Lixin Wu)

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Abstract The in situ polymerization scheme was chose to introduce the amine intercalated α-zirconium phosphate (fZrP) in the waterborne polyurethane (WPU). The α-ZrP (ZrP) was prepared by refluxing zirconyl chloride octahydrate and then amine intercalated using ethylenediamine. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and thermo gravimetric analysis. The fZrP was introduced in the WPU with the known filler content of 0.1, 0.5 and 1 wt%, respectively. The prepared WPU/fZrP nanocomposites films have shown better mechanical, thermal and water resistance properties compared to the neat WPU and unmodified ZrP nanocomposites. The tensile strength of WPU filled with 1 wt% fZrP was increased by 57.09 % against the WPU filled with 1 wt% unmodified ZrP. The thermal properties of the WPU showed increasing performance with the increasing fZrP content. The incorporation of fZrP in the WPU increased the thermal conductivity from 0.1777 W/m.K for virgin WPU and 0.2969 W/m.K for WPU/fZrP (1 wt%). The water resistance performance of the WPU was also improved with the increasing filler content. The results portray that the α-ZrP nanoplates can be an additive material to improve the thermo-mechanical performance of polymers.

Keywords: WPU; α-zirconium phosphate; mechanical properties; thermal properties; water resistance

1. Introduction Waterborne polyurethane (WPU) is an environmentally friendly material that has been dominantly used in adhesives and coatings [1-3]. WPU is elastic in nature, ecofriendly, and flameproof but it has some limitations such as low thermal stability, minimal mechanical properties [4,5]. There are

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lots of efforts taken to enhance the properties of WPU by using organic polymers and/or nanomaterials such as epoxy, silica, silver nanoparticles, zinc oxide, magnetic nanoparticles, carbon nanotubes [6-11]. Also, the two-dimensional materials like graphene, Mxenes and layered double hydroxides (LDH) have been explored by researchers to study and improve the various properties of WPU [12-15]. ZrP nanosheets can also be proved as promising materials to improve the properties of polymers because of its surface properties. The synthesis of crystalline α-Zirconium hydrogen phosphate (αZrP) was first reported by Clearfield by refluxing the mixture of ZrP and phosphoric acid [16]. The crystalline α-ZrP, (Zr (HPO4)2 ·H2O) now on denoted as ZrP, has always been considered as the reference for studying because of highly pure crystal structure, controllable morphology, and better ion exchange capability [17,18]. The single crystal X-ray diffraction study of the ZrP illustrates that the Zr atoms are attached to one another by phosphate groups and resides in one plane, on either side of the layer. The three oxygen atoms among the oxygen atoms in the phosphate groups are bonded to various Zr atoms while the lingering hydroxyl groups directs away from the layers [19]. The water molecules stuck in the zeolite cavity are created by layers arrangement. These cavities in ZrP are useful to intercalate the interlayers with various functional groups and small molecules. The functional groups intercalated ZrP are useful in number of applications, such as drug delivery, catalysis, flame retardancy and lubricant [20-23]. There is growing interest in designing specific task oriented ZrP composites, where there will be use of advantageous properties of ZrP and surface modifying groups [24,25]. The design of novel hybrid composites of ZrP, comprising of inorganic background intercalated or functionalized by organic materials could be used in variety of applications [26]. Yuan Hu et al. synthesized the cardanolderived ZrP (CZrP) and epoxy nanocomposite and studied the flame retardant properties of the

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nanocomposites [27]. The interlayer spacing in CZrP was five times more than the unmodified ZrP and the peak heat release rate, total heat release, and total smoke production were reduced by the 42%, 21%, 26%, respectively. In this work, we have synthesized the ZrP and WPU nanocomposites by in situ polymerization. In the literature, there has been enough work reported regarding the preparation and study of epoxy and other polymers nanocomposites using solution mixing and/or melt mixing method [27]. But there is no reported work stating the in situ preparation and detailed study of amine intercalated ZrP and WPU nanocomposites up to our knowledge. Herein, we have synthesized the ZrP by etching the zirconyl chloride and then amine intercalated by ethylenediamine. The amine intercalated ZrP and WPU nanocomposites were prepared by in situ polymerization. The Figure 1 shows the schematic of the synthesis procedure of WPU nanocomposite. The amine intercalation in ZrP nanoplatelets may facilitate the even dispersion in WPU matrix and may positively affect the properties of polymer. As the amine intercalation creates the more space between layers which may facilitate the high degree of ZrP nanoplates exfoliation in WPU and may further improve the properties of waterborne polyurethane. The WPU and ZrP nanocomposites films were further explored to study the surface, mechanical, thermal, water resistance properties. This work will pave a way in the application of ZrP in the synthesis of multifunctional thin film polymer nanocomposites which can be applicable in the areas require high thermal stability, better mechanical properties with good water resistance properties.

ZrOCl2 ·8H2O

100 °C 48 h H3PO4 (6M)

Ethylenediamine

13.3 nm

0.76 nm

Reflux

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Amine

Amine

Amine intercalated α-ZrP (fZrP)

α-ZrP PCL IPDI DMPA HD

N2 80 oC

WPU/fZrP thin films

In-situ WPU/fZrP preparation

Figure 1. Schematic procedure of synthesis of α-ZrP, amine intercalation in α-ZrP and in situ WPU nanocomposites preparation.

2 Materials and Methods 2.1 Materials Zirconyl chloride octahydrate (ZrOCl2 ·8H2O), phosphoric acid (H3PO4), ethylenediamine, polycaprolactone diol (PCL, ~2000 mn), isophorone diisocyanate (IPDI), dibutyltin dilaureate (DBT), dimethyl propionic acid (DMPA), triethylamine (TEA) and acetone were purchased from Aladdin Reagents co. limited, Peoples Republic of China. The PCL was kept at 80 °C in vacuum oven for seven days to remove the surface absorbed moisture. The TEA was kept in molecular sieves for 24 hours prior to use to remove any water content. All the other reagents were used with no further purification. The di ionized (DI) water was used wherever required.

2.2 Synthesis 2.2.1 Synthesis and amine intercalation of α-ZrP

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The α-ZrP were prepared by the reflux method as reported by [28] with some modification. 10 g of ZrOCl2 ·8H2O was dissolved in 200 ml 6M H3PO4 and refluxed at 100 ºC for 48 h. The milky white solution was washed and centrifuged three times with distilled water and dried at 65 ºC for 24 h. The α-ZrP nanosheets intercalation of ethylenediamine was carried out using as per the procedure by Tindwa et al and H. Xiao et al. [29,30] with slight modification. 2 g of α-ZrP was dissolved in 200 ml of distilled water. A stoichiometric proportion of ethylenediamine introduced in the α-ZrP solution and subsequently sonicated for 30 min followed by stirring for 48 hrs. The amine intercalated α-ZrP was washed using distilled water and dried at 65 ºC for 24 h. The α-ZrP and amine intercalated α-ZrP are denoted as ZrP and fZrP hereafter for convenience purpose, respectively.

2.2.2 In situ exfoliation of α-ZrP in waterborne polyurethane The WPU/ZrP nanocomposite were synthesized in three necked, 500 ml round-bottom flask arranged with mechanical stirrer, condenser and in nitrogen atmosphere in an oil bath. First, appropriate amount of ZrP was suspended in acetone and sonicated for 30 min. Then PCL was added into ZrP suspension and mixed properly. Subsequently, an isocyanate IPDI and DBT were added into the above solution and allowed to react at 80 ºC for 2 hours. The IPDI and DBT acted to create a -NCO terminated prepolymer and as a catalyst, respectively. After -NCO termination reaction, the DMPA was added for further chain extension reaction at 80 ºC for 4 h. the additional chain extender HD was added and reacted for 2 h at 80 ºC. After the desired polymerization achieved, the oil bath temperature was cooled down to room temperature and TEA was fed and to the reaction chamber to terminate the chain extension. Then the desired aqueous dispersion obtained by slowly adding distilled water under vigorous stirring. Finally, the WPU of 30 wt %

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solid content was obtained. Similarly, the WPU and fZrP (WPU/fZrP-k) nanocomposites with (k =) 0.1, 0.5, and 1 wt % content was prepared. The pristine WPU was also prepared using similar technique as above.

2.3 Material characterization methods The X-ray diffraction (XRD) study was carried on a Rigaku Miniflex600 (Japan) with Cu- Kα radiation (λ=0.15418 nm, 40 kV, 15 mA) between 2θ = 5°-40° at a scan rate of 8° min−1. The XRD study of WPU thin films was carried out between 2θ= 5°-50° at the scan rate of 5° min−1. The Elementar vario Micro elemental analyzer, Germany was used for C H N elemental analysis. The surface morphology study of ZrP and fractured surface analysis of WPU films were studied on HITACHI, SU8010/EDX, Japan (image resolution of 1.5 nm at 15 kV energy). JEM-2010 (JEOL, Japan) at a 200 kV use for transmission electron microscopy (TEM) studies. The elemental composition studied on X-ray photoelectron spectroscopy (XPS) (Thermo Scientific ESCALAB 250Xi+ spectrometer, USA). The thermogravimetric analysis (TGA) were performed on TA Instruments STA449C, USA (temperature range = 35-800 °C, N2 flow rate = 100 mL min−1 and heating rate = 10 °C min−1). TA DMA Q800 instrument used for the dynamic mechanical testing (TA Instruments, USA). The mechanical tensile testing of thin films was performed on SANS powertest, MTS SYSTEMS (China) Co. Ltd at the elongation speed of 50 mm min-1 (ASTM standard D412-16). Thermal conductivity studies were performed on the Xiatech instrument (TC3000E), China at 298 °K in a thin film mode. The final tensile test measurement values are the averages of 5 samples. The water resistance capacity of polymer nanocomposites thin films was tested using the water swelling degree percentage calculations. The

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films were kept in 15 % ethanol contained water for 36 hours and then the swelling degree of samples was measured using following equation (1) Swelling degree 

M  M 100% M

(1)

The M  and M  are weight of wet film at equilibrium swelling and weight of dry film respectively.

3 Results and discussions 3.1 Amine intercalation mechanism and XRD analysis The α-ZrP is the semi-planar structure containing zirconium (IV) atoms attached on the either side of the plane. The crosslinked structured is derived from the phosphate group oxygen atoms connected to the various zirconium. The interlayer distance of ZrP is 0.76nm, in which the 0.66 nm is the layer thickness and 0.1 nm is the interspaced water molecules [31]. The interlayers are weakly attached by the Van der Waals forces [32]. The phosphate group contains the OH groups (P-OH) and are directed towards the interspace. These P-OH groups in the interlayer of the α-ZrP gives semi-strong Bronsted acidity and creates the space for intercalation chemistry [33,34]. The small molecule amines can be easily intercalated using an acid-base reaction, replacing proton from P-OH to the nitrogen atom [35]. The Figure 2 depicts the XRD spectra to verify the extent of introduction of amine in ZrP layers using ethylenediamine. The as synthesized ZrP shows the reflection peak at 2θ=11.7 (0 0 2) with measured interlayer spacing of 7.6 Å. The XRD of amine intercalated fZrP shows the mixture of different phases with slightly varying interlayer distance. The strong reflection peak appears at 2θ=7.83° with interlayer spacing of 13.3 A° with some other peaks at 2θ= 7.79°, 7.65°. The mixed

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phases fZrP are appeared due to the variation in amine alignment in the interlayer spacing [36]. Furthermore, the fading of the XRD peaks of ZrP and advent of the strong peaks of fZrP indicates the complete intercalation of ethylenediamine in ZrP layers. The previous studies reported the formation of various phases due to the ethylenediamine introduction [36]. The 7 meq/g loading of ethylenediamine comprise of the two phases with interlaying spacing of 10.3 Å and 11.1 Å. At the maximum loading increased to 8 meq/g the phase at 10.3 Å was converted to the phase having layer distance of approximately 11.1 Å. The XRD pattern also depend on amine intake as well as the presence of water in the material [30]. The slight increase in the interlayer spacing of XRD patterns in our samples is might be because of the water content in the material.

fZrP ZrP

Intensity (a.u.)

1.33 nm

0.76 nm

5

10 15 20 25 30 35 40 2 ()

Figure 2. Shows the XRD spectrum of ZrP and fZrP. As can be seen in Figure, due to the intercalation of amine group in ZrP the interlayer distance increased from 0.76 nm to 1.33 nm.

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3.2 Surface morphology studies

(b)

(a)

100 nm

(c)

(d)

100 nm

100 nm

(e)

Element Weight % Atomic % CK 16.21 31.98 OK

26.06

38.59

PK

28.58

21.86

ZrL

29.15

7.51

(f)

Element Weight % Atomic % CK 18.48 27.23 NK 10.34 13.07 OK 46.13 51.03 PK 10.09 5.77 ZrL 14.96 2.90

Figure 3. FESEM images of (a) ZrP, (c) fZrP; TEM images of (b) ZrP, (d) fZrP; EDS elemental analysis of (e) ZrP (f) fZrP. In the Figure f, the presence of 13.07% of nitrogen implies the successful amine intercalation in ZrP nanoplates.

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The Figure 3a and 3c show the FESEM images of as synthesized ZrP and fZrP. The FESEM and TEM images shows the randomly oriented ZrP and fZrP nanosheets. The TEM images of pristine ZrP and fZrP in Figure 3e and 3d show that there is no change in shape and size observed after amine intercalation reaction. The EDS elemental analysis results are shown in Figure 3e and 3f for ZrP and FZrP nanosheets. The 13.07 % of nitrogen content in fZrP shows the successful intercalation of amine.

3.3 Thermogravimetric analysis

Figure 4. Shows the thermogravimetric analysis of ZrP and fZrP. The weight loss at round 350400 ºC is due to the combustion of amine intercalated at the ZrP layers.

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TGA was performed to study the thermal decomposition of virgin ZrP and fZrP. The samples were preheated at 80 °C for some time in vacuum to remove the surface absorbed moister and then kept for thermal analysis, the results are shown in Figure 3. For ZrP, the maximum of 9.67% weight loss occurred in the two temperature ranges at around 100-400 °C and 420-620 °C. The first step weight loss was owed to the hydration of water captivated on ZrP surface and water trapped between the ZrP sheets. The second step weight loss, at around 600 °C, might have occurred due to the water condensation, converting the monohydrogen phosphate to the zirconium pyrophosphate [37]. Zr(HPO4 )2 ·H2 O + Heat (100 °C to 400 °C)

-H2 O (g)

Zr(HPO4 )2 (s) + Heat (~ 600 °C)

-H2 O (g)

ZrP2 O7 (s)

For the fZrP, the weight loss was about 20% at 800 °C, which is more than twice the weight loss of pristine ZrP. The weight loss occurs at the early stage up to 400 °C was due to evaporation of the surface absorbed water and trapped water in the interlayers. Also, the weight loss in the range of 200-400 °C might have occurred due to the intercalated amine groups. Finally, above 600 °C, the water condensation of monohydrogen phosphate to pyrophosphate took place. From the C H N analysis and TGA data, the chemical formula of fZrP appears to be ZrP (ethylenediamine)0.85 (HPO4)2 0.58H2O.

3.4 XPS We performed XPS analysis for the detailed amine intercalation studies as shown in Figure 5. The Figure 5a shows the detailed survey spectrum of ZrP and fZrP. The fZrP clearly shows the amine peak at around 400 eV, which indicates the successful amine intercalation in ZrP. The Figure 5b, 5c, 5d show the high resolution XPS of Zr3d for ZrP, Zr3d for fZrP and N1s for fZrP, respectively.

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Figure 5b and 5c show the Zr 3d3/2 and Zr 3d5/2 peaks are separated by about ∼2.3 eV for ZrP and fZrP. It can be clearly seen in the Zr 3d spectra that there is a blue shift for fZrP by about 1.3

Figure 5. Show the XPS analysis of (a) survey spectrum of ZrP and fZrP, (b) Zr3d spectra of ZrP, (c) Zr3d spectra of fZrp, (d) N1s spectra for fZrP. The presence of peak at around 398 eV in survey spectra of fZrP attributes to the successful amine intercalation.

eV. The shift to the lower binding energy in Zr 3d peak of fZrP might have occurred due to intercalation of amine in ZrP and replacing a proton in P-OH by amine group. The N1s spectra in the Figure 5d represents the two oxidation states of nitrogen. The lower binding energy at about 399.3 eV indicates the aromatic groups of ethylenediamine molecules [38]. The higher binding

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energy (401 eV) come into picture if the N--H interaction takes place [38]. We propose that the higher binding energy in N1s spectra might be due to proton replacement in P-OH by amine in ZrP interlayers. 3.5 WPU nanocomposite thin film characterization studies 3.5.1 XRD

Intensity (a.u.)

WPU/fZrP-1 WPU/fZrP-0.5 WPU/fZrP-0.1 WPU/ZrP-1 WPU 10 15 20 25 30 35 40 45 50 2 Theta (deg) Figure 6. Shows the XRD of WPU, WPU/ZrP-1 and WPU/fZrP-k. The slight decrease in the intensity peaks with the filler content is might be due to the improved soft segment crystallization of WPU matrix. In the Figure 6, the XRD spectra of nanocomposites has two sharp peaks at around 2θ= 21.5° and 23.75°, depicting the high degree of crystallinity in the soft segment and hard segment for the WPU and ZrP nanocomposites [39,40]. Further, there wasn’t any change in the XRD patterns for

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WPU/ZrP and amine intercalated WPU/fZrP-k nanocomposites. The slight decrease in the intensity of diffraction peaks with filler content implies that the ZrP nanoplates reacted with the hard segments of polymer which results in better phase separation and in turn improved the soft segment crystallinity [41]. The absence of diffraction peaks of ZrP and fZrP indicates that the nanoplates were uniformly dispersed in the WPU matrix. The XRD results show the semi crystalline nature of WPU composites.

3.5.2 Mechanical testing

Figure 7. Shows the mechanical properties of (a) WPU, WPU/ZrP-1 and WPU/fZrP-k, (b) change in strength and elongation of WPU with filler content. The tensile strength increases while elongation decreases with increase in filler content. The Figure 7 shows the tensile stress-strain studies of WPU/ZrP-k thin films. The pristine WPU possesses the low tensile strength of about 15.25 MPa, because of its amorphous nature and has a highest elongation at break of about 884.5 %. The addition of 1 wt% unmodified ZrP in WPU exhibits the less tensile strength than pristine WPU, which might be due to the aggregation of ZrP

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sheets in WPU matrix. The minimal exfoliation of unmodified ZrP could have led to the aggregation in WPU matrix. The aggregated patterns of ZrP sheets can be observed in fractured surface FESEM analysis of WPU/ZrP-1 composite (Figure 8). The incorporation of the amine introduced ZrP in WPU matrix has shown the increasing tensile stress pattern with the increasing wt% as can be seen Figure 7b. There is a 15.25 %, 29.25 % and 57.09 % increment for the addition of 0.1, 0.5 and 1 wt%, respectively, for fZrP in WPU. The strong interfacial interaction between the fillers and polymer medium might have decreased the molecular motion of polymer which lead to increase in the tensile properties [42]. The low molecular motion caused by the rigid fZrP sheets resulted in declined elongation at break which was proved by the curbed damping nature in the nanocomposite (Figure 7a) [43]. This study on the incorporation of pristine and amine introduced ZrP platelets clarifies the idea on how the two-dimensional nanofillers changes the physical and mechanical properties of WPU.

3.5.3 Fractured surface analysis To verify the exfoliation effect of ZrP and fZrP on the WPU, the fractured surface FESEM analysis was performed on the tensile strength tested samples. The Figure 8a shows the surface of pristine WPU with some wrinkles on it. the FESEM of 1 wt% ZrP in WPU, the ZrP nanoplates can be seen comping out of fractured area, indicated by yellow arrows in Figure 8c. The aggregation of ZrP sheets could be caused by the partial exfoliation in WPU matrix, which resulted in the least interphase interaction and affected the tensile properties. As in the case of fZrP and WPU composite (Figure 8e), there isn’t any clearly visible ZrP nanosheets coming out of fractured surface which could be indication of complete exfoliation of ZrP in polymer matrix. The increase in the tensile properties are also indicative that there is better phase interaction as a result of

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complete exfoliation. The Figure 8b, 8d and 8f show the corresponding EDS analysis of fractured surfaces of WPU, WPU/ZrP-1, WPU/fZrP-1. The WPU filled with ZrP and fZrP shows the minimal weight percent content of Zr and P as there was only 1 wt% of filler present in polymer matrix.

(a)

(b)

(c)

(d)

(e)

(f)

Figure 8. the FESEM and EDS images of (a,b) WPU, (c,d) WPU/ZrP-1, (e,f) WPU/fZrP-1.

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3.5.4 Thermal properties The TGA was used to study the thermal behavior of WPU, WPU/ZrP-1 and WPU/fZrP-k under nitrogen atmosphere, shown in Figure 9a. The 5%, 10% and 20% weight loss temperatures (T5%, T10%, T20%) are presented in Table 1. The T5% for WPU is 261 °C that is slightly higher than that of all the other nanocomposites because at the initial stage, the higher weight loss in nanocomposites might be due the decomposition of oxygen captured by ZrP plates in WPU. The T10% and T20% show increment of about 16.9 °C, 40.60 °C for WPU/ZrP-1 and 26 °C, 41.72 °C for WPU/fZrP-1 respectively, compared to that of pristine WPU. It is obvious that the well dispersed ZrP acted as a physical barrier to reduce the flow of unstable polymer products and improve the thermal stability of WPU. Also, the excellent interfacial interaction between filler and polymer matrix lead to the reduced thermal decomposition. Further, we can see the slightly enhanced thermal stability for WPU/fZrP-1 compared to the WPU/ZrP which can only be ascribed to the better dispersion fZrP nanoplates in WPU matrix. The residual char yield for WPU and ZrP composites increased with the increasing filler amount which is indicative that the fZrP could have enhanced the thermal stability of polymers.

Table 1. Thermogravimetric analysis of WPU, WPU/ZrP and WPU/fZrP-k films T5% (°C)

T10% (°C)

T20% (°C)

Residue char at 800 °C (wt%)

WPU

261

281

296.277

0.121

WPU/ZrP-1

249.23

297.90

336.88

2.027

WPU/fZrP-0.1

258.92

288.13

307.60

0.421

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WPU/fZrP-0.5 WPU/fZrP-1

259.97

297.89

321.0

1.529

260

307

338

2.522

Figure 9. (a) the thermogravimetric analysis and (b) Storage modulus (c) loss modulus and (d) damping factor (tanδ) of WPU, WPU/ZrP and WPU/fZrP-k, respectively. The weight loss has decreased with the increase in the wt% fZrP nanosheets.

The storage modulus variations of WPU, WPU/ZrP-1 and WPU/fZrP-k nanocomposites with respect to temperature are represented in Figure 9b. At minimum temperatures less than about 40 °C, the molecular motions of pristine WPU are limited to vibrations and short-range rotations. At

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a temperature above -40 °C, with the rise of temperature the storage modulus lessened and the glass to rubber transition observed. In the rubbery stage, the elastic behaviour of WPU could be the reason for the enduring molecular chain drift and eventually, the reason for the decline in storage modulus with the surge in temperature. In the WPU and fZrP nanocomposites, two phases observed in the temperature ranges as below -40 °C, between -40 °C to 50 °C. The gradual storage modulus loss with increasing temperature up to -40 °C is due to the glassy phase. In the temperature range of -40 °C to 50 °C, the semi-crystalline and rubbery phase of polymer coexist. In this range, the fall in storage modulus is because of the melting of amorphous and crystalline phases of WPU. Finally, at the temperature 50 °C, the storage modulus decreases suddenly due to the irreparable melting of final crystalline phase of WPU. The storage modulus results also depicts the semicrystalline nature of WPU and fZrP nanocomposites which was also confirmed by the XRD analysis. Furthermore, the WPU/fZrP-1 shows the highest dynamic storage modulus, demonstrating the increased interaction degree resulting from the strong interfacial interactions, uniform dispersion and large number of interaction points [44]. The loss modulus gives the energy dissipated by the polymer under external stress. The Figure 9c show the loss modulus vs. temperature curves for WPU, WPU/ZrP-1 and WPU/fZrP-k. The loss modulus has increased with the increasing filler loading indicating the rise in damping behaviour of the nanocomposites [45]. The nanocomposites show the β transition approximately in the temperature range between -40 to -10 °C. the β transition shifts towards higher temperature with the increasing filler content implying the enhanced interphase region and arrested mobility [46]. The increasing trend in the loss modulus values is well in agreement with storage modulus values. The figure 9d shows the damping factor (tanδ) vs temperature curves of WPU nanocomposites. it is evident from the figure that the tanδ decreased with the increase in the fZrP

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content in the temperature range between -40 °C to +50 °C. The decrease in tanδ can be due to the restriction of WPU molecules by the fZrP nanoplates. The pristine WPU shows the high tanδ value approximately between -25 °C to +10 °C. The continuous fall in the tanδ values with the increase in filler content implies that the higher filler content increases the polymer matrix stiffness and eventually reduces the matrix volume in the nanocomposites to transfer the vibrational energy [45, 47]. The reduction in the tanδ values also implies the increment in the interfacial adhesion due to. The relaxation observed at the around 10 °C for pristine WPU which is vanished with the introduction of the ZrP nanoplates indicates that the ZrP fillers broadened the tanδ peaks. The tanδ for the WPU/fZrP-1 has the lowest value indicating the strong interfacial interaction which is

0.30 (a)

0.2969 0.2519

0.25 0.20

(b) Amorphous

Crystalline

0.2094 0.2178 0.1777

0.15

Heat

0.10 0.05 rP -1

PU /fZ

-0 .5

/fZ rP PU

W

W

-0 .1

-1

/fZ rP

PU W

W

PU

/Z rP

PU

0.00 W

Thermal conductivity (W/m*K)

consistent with the outcomes of the storage modulus.

fZrP filler

Figure 10. (a) Thermal conductivity of WPU, WPU/ZrP-1 and WPU/fZrP-k, (b) hypothetical thermal conductivity mechanism in WPU after addition of filler.

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The thermal conductivity of the material is the result of vibrational phonons and thermal movement of electrons [48]. There is lot to explore in the area of thermal conductivity caused by lattice vibrational phonons in polymer nanocomposites. The exfoliation of thermally conductive ZrP can be an effective method to boost the thermal conductivity of polymer as we can see in Figure 10. There is slight increase in thermal conductivity of the WPU with the wt% increase in the fZrP in WPU. The dispersion of nanomaterials play an important role in enhancing overall thermal conductivity of polymer matrix. As we can predict from Figure 10a that the thermal conductivity of WPU/ZrP-1 is less compared to the WPU/ZrP-1 recorded at 298 K. It is evident from the fractured surface morphology studies (Figure 8c) of WPU/ZrP-1 composite that the ZrP has some agglomeration in WPU which might be the reason for lowered thermal conductivity. The Figure 10b shows the simplified hypothetical heat transfer mechanism of the modified WPU. The phonon free mean path value of the unmodified WPU is very low (few angstroms) due to the random phonon vibrations resulting from various defects which in turn makes it difficult for heat to transfer through polymer matrix. The addition of filler in WPU matrix might have created the semi crystalline phase as hypothetically depicted in Figure 10b, which caused the lattice phonon vibrations and enhances the thermal conductivity of WPU [49]. The fZrP exfoliation in the polymer matrix can enhance the interfacial heat transfer between ZrP nanoplates and WPU matrix by reducing the interfacial phonon scattering, which improves the thermal conductivity of nanocomposites [44,50]. Also, the fZrP fillers in the polymer might have created the interconnected channels, promoting the phonon transfer between filler and polymer by reducing the acoustic impedance mismatch at the interface between filler and polymer which resulted in the thermal conductivity enhancement [51]. This indicates that the thermal conductivity of polymer

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may be dependent on some of the factors such as filler content, exfoliation probability, and crystallization behavior.

3.5.5 Shape stability and water resistance The water resistance performance of the films was observed by immersing WPU, WPU/ZrP-1 and WPU/fZrP-k nanocomposites in water and ethanol mixture for 36 hours and by measuring water swelling degrees of films at a regular time interval. The Figure 11a shows the swelling degree of WPU, WPU/ZrP-1 and WPU/fZrP-k nanocomposites as a function of immersion time. The swelling degree of entire nanocomposites amplified with the immersion time. The swelling degree in water for the all the sample films follows the order, WPU/fZrP-1 < WPU/ZrP-1 < WPU/fZrP0.5 < WPU/fZrP-0.1 < WPU. The highest degree of swelling in WPU/fZrP-1 could be due to the high degree of exfoliation ZrP nanoplates in WPU matrix. The strong interfacial interaction between polymer chains and ZrP nanoplates acts as the barrier between the water molecule polymer chains. The created barrier between water molecules and polymer chains avoid the water absorption in polymer and increases the water resistance of composites films. The above results show that the fZrP has improved the water resistance properties of WPU films to some extent. The shape stability of WPU nanocomposites were examined by stirring the films at 50 rpm in water for 24 hours. The Figure 11b shows the photographs of WPU, WPU/ZrP-1 and WPU/fZrP-k films immersed in water at 0 hours and at 24 hours. As seen in the photographs, the films seem stable and has no visible damage which states that the films are stable. The shape stability in the films can be owed to the hydrophobic alkyl chains and ZrP surface interactions and strong interfacial interaction between WPU chains and ZrP nanoplates.

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(b)

Swelling degree (%)

25

WPU

(a)

20

Before stirring WPU/ZrP- WPU/fZrP- WPU/fZrP- WPU/fZrP1 0.1 0.5 1

15 WPU WPU/ZrP-1 WPU/fZrP-0.1 WPU/fZrP-0.5 WPU/fZrP-1

10 5 0 0

8

16 24 Time (hr)

After stirring (24 hr) WPU

WPU/ZrP- WPU/fZrP- WPU/fZrP- WPU/fZrP1 0.1 0.5 1

32

Figure 11. (a) Water swelling test for WPU, WPU/ZrP-1 and WPU/fZrP-k, (b) Stability test photos of WPU, WPU/ZrP-1 and WPU/fZrP-k before and after 24 hr stirring. The thin films were still stable and without damage as seen in photograph in Figure 11b.

4 Conclusions In this work, we have studied the effect of amine intercalation in α-ZrP on the morphological, mechanical, thermal, and water resistance properties of WPU. For this purpose, the WPU nanocomposites prepared via in situ polymerization with the 0.1 wt %, 0.5 wt % and 1 wt % content of fZrP. The result analysis showed that WPU nanocomposites were affected by the amine intercalation chemistry in ZrP as well as the amount of filler content. The ethylenediamine intercalation had increased the interlayer distance from 0.76 nm for ZrP to 1.33 nm for fZrP. The morphological studies using FESEM and TEM also evidenced the successful amine intercalation. The elemental composition studies using XPS analysis has also witnessed the successful introduction of amine groups in the ZrP interlayers. Further, the in situ addition of fZrP in the WPU amplified the mechanical, thermal and water resistance properties of polymer matrix. The

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maximum increment in the tensile strength was observed in 1 wt% of WPU/fZrP, about 57.09% more than the pristine WPU. The tensile strength of WPU/ZrP (1 wt %) was decreased compared to the neat WPU. This implies that the amine introduction facilitated the exfoliation of ZrP nanoplates in the polymer matrix. In contrast, the unmodified ZrP tends to aggregate without proper dispersion in polymer matrix which was also seen in the FESEM fractured surface analysis of nanocomposites. The DMA results showed the increase in the storage modulus of WPU with the increase in the quantity of fZrP and implying the semi crystalline nature of WPU/fZrP-k nanocomposites. It is assumed that the projected nanocomposites of ZrP nanoplates and WPU can be a basic step towards prevalent application of ZrP and other polymer nanocomposites in the areas requiring robust thin films with good thermomechanical and water resistance properties.

Acknowledgements: The first author would like to thank to the University of Chinese Academy of Sciences (UCAS) for providing the International Student PhD scholarship. The Regional Key Program of Science and Technology Service Network Initiative from Chinese Academy of Sciences, grant number 2019T3013, the Fund of National Engineering and Research Center for Commercial Aircraft Manufacturing, grant number 2019T3016 and the STS Project of FujianCAS, grant number 2019T3018.

Conflict of interest The authors declare no conflict of interest.

References

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1. H. Fu, Y. Wang, W. Chen, W. Zhou, J. Xiao, A novel silanized CoFe2O4/fluorinated waterborne polyurethanepressure sensitive adhesive, Applied Surface Science 351 (2015) 1204–1212. 2. L. Lei, L. Zhong, X. Lin, Y. Li, Z. Xia, Synthesis and characterization of waterborne polyurethane dispersions with different chain extenders for potential application in waterborne ink. Chemical Engineering Journal 253 (2014) 518–525. 3. C.A. Heck, João Henrique Z. dos Santos, C.R. Wolf, Waterborne polyurethane: the effect of the addition or in situ formation of silica on mechanical properties and adhesion. International Journal of Adhesion & Adhesives 58 (2015) 13–20. 4. B.K. Kim, J.W. Seo, H.M. Jeong, Morphology and properties of waterborne polyurethane/clay nanocomposites, European Polymer Journal 39 (2003) 85–91. 5. H. Zhou, H. Wang, X. Tian, K. Zheng, Cheng, Q. Effect of 3-aminopropyltriethoxysilane on polycarbonate based waterborne polyurethane transparent coatings. Prog. Org. Coat. 77, (2014) 1073–1078. 6. G.M. Wu, Z.W. Kong, J. Chen, S.P. Huo, G.F. Liu, Preparation and properties of waterborne polyurethane/epoxy resin composite coating from anionic terpene-based polyol dispersion. Pro.Org. Coat. 77 (2014) 315–321. 7. L. Zhang, H. Zhang, J. Guo, Synthesis and properties of UV-curable polyester-based waterborne polyurethane/functionalized silica composite sand morphology of their nanostructured films, Ind. Eng. Chem. Res. 51 (2012) 8434–8441. 8. X. Zhang, M. Zhu, W. Wang, D. Yu, Silver/waterborne polyurethane-acrylate’s antibacterial coating on cotton fabric based on click reaction via ultraviolet radiation. Progress in Organic Coatings 120 (2018) 10–18.

Journal Pre-proof

9. L. Xiong, W. Zhang, Q. Shi, A. Mai, Waterborne polyurethane/NiAl‐LDH/ZnO composites with high antibacterial activity. Polym. Adv. Technol. 26 (2015) 495–501. 10. L.M. dos Santos, R. Ligabue, A. Dumas, et al. Waterborne polyurethane/Fe3O4-synthetic talc composites: synthesis, characterization, and magnetic properties. Polym. Bull. 75 (2018) 1915–1930. 11. F. Wang, L. Feng, M. Lu, Mechanical Properties of Multi-Walled Carbon Nanotube/Waterborne Polyurethane Conductive Coatings Prepared by Electrostatic Spraying. Polymers 11 (2019) 714. 12. F. Zhang, W. Liu, S. Wang, C. Jiang, Y. Xie, M. Yang, et al. A novel and feasible approach for polymer amine modified graphene oxide to improve water resistance, thermal, and mechanical ability of waterborne polyurethane. Applied Surface Science, 491 (2019) 301– 312. 13. M.B. Kale, Z. Luo, X. Zhang, D. Dhamodharan, N. Divakaran, S. Mubarak, et al. Waterborne

polyurethane/graphene

oxide-silica

nanocomposites

with

improved

mechanical and thermal properties for leather coatings using screen printing. Polymer 170 (2019) 43–53. 14. W. Zhi, S. Xiang, R. Bian, R. Lin, K. Wu, T. Wang, et al. Study of MXene-filled polyurethane nanocomposites prepared via an emulsion method. Composites Science and Technology, 168 (2018) 404–411. 15. H. Hu, Y. Yuan, W. Shi, Preparation of waterborne hyperbranched polyurethane acrylate/LDH nanocomposite. Progress in Organic Coatings, 75 (2012) 474–479. 16. A. Clearfield, J. Stynes, The preparation of crystalline zirconium phosphate and some observations on its ion exchange behaviour. J. Inorg. Nucl. Chem. 26 (1964) 117–129.

Journal Pre-proof

17. A. Clearfield, Inorganic-ion exchangers with layered structures. Annu Rev Mater Sci. 14 (1984) 205–229. 18. R.M. Tindwa, D.K. Ellis, G.Z. Peng, A. Clearfield, Intercalation of n-Alkylamines by aZirconium Phosphate. J. Chem. SOC. Faraday Trans. 81 (1985) 545–552. 19. J.M. Troup, A. Clearfield, Mechanism of ion exchange in zirconium phosphates. 20. Refinement of the crystal structure of .alpha.-zirconium phosphate. Inorg. Chem. 16 (1977) 3311–3314. 20. F. Wang, Z. Yuan, B. Liu, S. Chen, Z. Zhang, Catalytic oxidation of biomass derived 5hydroxymethylfurfural (HMF) over RuIII-incorporated zirconium phosphate catalyst. J. Ind. Eng. Chem. 38 (2016) 181–185. 21. L. Xu, C. Lei, R. Xu, X. Zhang, F. Zhang, Synergistic effect on flame retardancy and thermal behavior of polycarbonate filled with α-zirconium phosphate@gelsilica. J. Appl. Polym. Sci. 19 (2017) 134. 22. X. Cai, G.J. Dai, S.Z. Tan, Y. Ouyang, Y.S. Ouyang, Q.S. Shi, Synergistic antibacterial zinc ions and cerium ions loaded α-zirconium phosphate. Mater. Lett. 67 (2012) 199–201. 23. X. He, H. Xiao, H. Choi, A. Díaz, B. Mosby, A. Clearfield, et al. α-Zirconium phosphate nanoplatelets as lubricant additives. Colloids Surf. A Physicochem. Eng. Asp. 452 (2014) 32–38. 24. H. Xiao, S. Liu, Zirconium phosphate (ZrP)-based functional materials: Synthesis, properties and applications. Materials and Design, 155 (2018) 19–35. 25. R. Vivani, G. Alberti, F. Costantino, M. Nocchetti, New advances in zirconium phosphate and phosphonate chemistry: structural archetypes. Microporous Mesoporous Mater. 107 (2008) 58–70.

Journal Pre-proof

26. B.M. Mosby, A. Díaz, V. Bakhmutov, A. Clearfield, Surface Functionalization of Zirconium Phosphate Nanoplatelets for the Design of Polymer Fillers. ACS Appl. Mater. Interfaces, 6 (2014) 585–592. 27. X. L. Fu, X. Wang, W. Xing, P, Zhang, L, Song, Y. Hu, Two-dimensional cardanol-derived zirconium phosphate hybrid as flame retardant and smoke suppressant for epoxy resin. Polymer Degradation and Stability, 151 (2018) 172–180. 28. H.J. Sue, K.T. Gam, Epoxy Nanocomposites Based on the Synthetic r-Zirconium Phosphate Layer Structure. Chem. Mater. 16 (2004) 242–249. 29. W.J. Boo, L. Sun, H.J. Sue, A. Clearfield, Preparation of alpha-zirconium phosphate nanoplatetlets with wide variation in aspect ratio. New Journal of Chemistry 31 (2007) 39– 43. 30. H. Xiao, W. Dai, Y. Kan, A. Clearfield, H. Liang, Amine intercalated α-zirconium phosphates as lubricant additives. Applied Surface Science 329 (2015) 384–389. 31. H. Xiao, S. Liu, Zirconium phosphate (ZrP)-based functional materials: Synthesis, properties and applications. Materials and Design 155 (2018) 19–35. 32. J. Albertsson, A. Oskarsson, R. Tellgren, J. Thomas, Inorganic ion exchangers. 10. Aneutron powder diffraction study of the hydrogen bond geometry in α-zirconium bis(monohydrogen orthophosphate) monohydrate. A model for the ion exchange. J. Phys. Chem. 81 (1977) 1574–1578. 33. L. Sun, W.J. Boo, R.L. Browning, H.J. Sue, A. Clearfield, Effect of crystallinity on the intercalation of monoamine in α-zirconium phosphate layer structure. Chem. Mater. 17 (2005) 5606–5609.

Journal Pre-proof

34. A.R. Hajipour, H. Karimi, Synthesis and characterization of hexagonal zirconium phosphate nanoparticles. Mater. Lett. 116 (2014) 356–358. 35. L. Sun, W.J. Boo, H.J. Sue, A. Clearfield, Preparation of α-zirconium phosphate nanoplatelets with wide variations in aspect ratios. New J. Chem. 31 (2007) 39–43. 36. A. Clearfield, R.M. Tindwa, On the mechanism of ion exchange in zirconium phosphates XXI intercalation of amines by alpha zirconium phosphate. Journal of Inorganic and Nuclear Chemistry 41 (1979) 871–878. 37. L. Xu, C. Lei, R. Xu, X. Zhang, F. Zhang, Hybridization of a-zirconium phosphate with hexachlorocyclotriphosphazene and its application in the flame retardant poly(vinyl alcohol) composites. Polymer Degradation and Stability 133 (2016) 378–388. 38. Fulvio Parmigiani, Laura E. Depero, Diffraction and XPS Studies of Cu Complexes of Intercalated Compounds of a-Zirconium Phosphate. II: XPS Electronic Structures. Structural Chemistry, 5 (1994) 2. 39. H. Fu, Y. Wang, W. Chen, Y. Xiao, Reinforcement of waterborne polyurethane with chitosan-modified halloysite nanotubes. Applied Surface Science 346 (2015) 372–378. 40. A.H. Matthew, B. Wang, James M. Sands; John J. La Scala, Frederick L. Beyer, Y.L. Christopher, Morphology control of segmented polyurethanes by crystallization of hard and soft segments. Polymer 51 (2010) 2191–2198. 41. Y.R. Lee, Anjanapura V. Raghu; H.M Jeong, B.K. Kim, Properties of Waterborne Polyurethane/Functionalized Graphene Sheet Nanocomposites Prepared by an in situ Method. Macromol. Chem. Phys. 210 (2009) 1247–1254.

Journal Pre-proof

42. Z. Wu, H. Wang, X. Tian, M. Xue, X. Ding, X. Ye, et

al.

Surface

and

mechanical

properties of hydrophobic silica contained hybrid films of waterborne polyurethane and fluorinated polymethacrylate. Polymer, 55 (2014), 187–194. 43. H.J. Sue, K.T. Gam, Epoxy Nanocomposites Based on the Synthetic r-Zirconium Phosphate Layer Structure. Chem. Mater. 16 (2004) 242–249. 44. Y. Zhang, Soo-Jin Park, Imidazolium-optimized conductive interfaces in multilayer graphene nanoplatelet/epoxy composites for thermal management applications and electroactive devices. Polymer 168 (2019) 53–60. 45. A. Tharayil, S. Banerjee, K.K. Kar, Dynamic mechanical properties of zinc oxide reinforced linear low density polyethylene composites, Mater. Res. Express 6 (2019) 055301. 46. Menard KP. Dynamic mechanical analysis : A practical introduction. (Florida: CRC press) ;2008. 47. S.R. Khimi, K.L. Pickering, Comparison of dynamic properties of magnetorheological elastomers with existing antivibration rubbers. Comp. Part B Eng 83 (2015) 175–183. 48. J. Li, M.L. Sham, J.K. Kim, G. Marom, Morphology and properties of UV/ozone treated graphite nanoplatelet/epoxy nanocomposites. Compos Sci Technol. 67 (2007) 296–305. 49. J.W. Chung, S.B. Son, S.W. Chun, T.J. Kang, S.Y. Kwak, Thermally stable exfoliated poly(ethylene terephthalate) (PET) nanocomposites as prepared by selective removal of organic modifiers of layered silicate. Polym. Degrad. Stab. 93 (2008) 252–259. 50. Y. Zhang, J.R. Choi, Soo-Jin Park, Enhancing the heat and load transfer efficiency by optimizing the interface of hexagonal boron nitride/elastomer nanocomposites for thermal management applications. Polymer 143 (2018) 1–9.

Journal Pre-proof

51. R. Aradhana, S. Mohanty, S.K. Nayak, Comparison of mechanical, electrical and thermal properties in graphene oxide and reduced graphene oxide filled epoxy nanocomposite adhesives. Polymer, 141 (2018) 109–123.

Journal Pre-proof

Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

There are no financial interest/personal relationship which may be considered as potential competing interest.

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Waterborne polyurethane nanocomposite reinforced with amine intercalated α-zirconium phosphate - study of thermal and mechanical properties Manoj B. Kale a,b, Nidhin Divakaran a,b, Suhail Mubarak a,b, Duraisami Dhamodharan a,b, T. Senthil c, Lixin Wu a, *

Highlights 1.

The WPU and amine intercalated α-ZrP (WPU/fZrP) nanocomposites were prepared by in situ polymerization.

2.

The WPU/fZrP exhibit excellent tensile and thermal properties compared to the pristine WPU and WPU/ZrP nanocomposites.

3.

The amine intercalated α-ZrP had shown better exfoliation in WPU matrix compared to the unmodified α-ZrP.

4.

The Thermal conductivity, water resistance and water stability of WPU/fZrP nanocomposites improved drastically.