Spinning and properties of poly(ethylene terephthalate)/organomontmorillonite nanocomposite fibers

By in situ polycondensation, a intercalated poly(ethylene terephthalate)/organomontmorillonite nanocomposite was prepared after montmorillonite (MMT) had been treated with a water‐soluble polymer. This nanocomposite was produced to fibers through melt spinning. The resulting nanocomposite fibers were characterized by X‐ray diffraction (XRD), differential scanning calorimeter (DSC), and transmission electron microscopy (TEM). The interlayer distance of MMT dispersed in the nanocomposite fibers was further enlarged because of strong shear stress during processing of melt spinning. This was confirmed by XRD test and TEM images. DSC test results showed that incorporation of MMT accelerated the crystallization of poly(ethylene terephthalate) (PET), but the crystallinity of the drawn fibers just had a little increasing compared with that of neat PET drawn fibers. Also compared with pure PET drawn fibers, tensile strength at 5% elongation and thermal stability of the nanocomposite fibers were improved. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1443–1447, 2005     

Microstructure and crystallization of melt‐mixed poly(ethylene terephthalate)/poly(ethylene isophthalate) blends

Physical blends of poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI), abbreviated PET/PEI (80/20) blends, and of PET and a random poly(ethylene terephthalate‐co‐isophthalate) copolymer containing 40% ethylene isophthalate (PET₆₀I₄₀), abbreviated PET/PET₆₀I₄₀ (50/50) blends, were melt‐mixed at 270°C for different reactive blending times to give a series of copolymers containing 20 mol % of ethylene isophthalic units with different degrees of randomness. ¹³C‐NMR spectroscopy precisely determined the microstructure of the blends. The thermal and mechanical properties of the blends were evaluated by DSC and tensile assays, and the obtained results were compared with those obtained for PET and a statistically random PETI copolymer with the same composition. The microstructure of the blends gradually changed from a physical blend into a block copolymer, and finally into a random copolymer with the advance of transreaction time. The melting temperature and enthalpy of the blends decreased with the progress of melt‐mixing. Isothermal crystallization studies carried out on molten samples revealed the same trend for the crystallization rate. The effect of reaction time on crystallizability was more pronounced in the case of the PET/PET₆₀I₄₀ (50/50) blends. The Young's modulus of the melt‐mixed blends was comparable to that of PET, whereas the maximum tensile stress decreased with respect to that of PET. All blend samples showed a noticeable brittleness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3076–3086, 2003     

Casting solvent effect on crystallization behavior and morphology of poly(ethylene oxide)/poly(methyl methacrylate)

Poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends were prepared by casting from either chloroform or benzene solvents. After casting from solvents, all samples used in this study were preheated to 100°C and held for 10 min. Then, the solvent effect on the crystallization behavior and thermodynamic properties were studied by differential scanning calorimeter (DSC). Also, the morphology of spherulite of casting film was studied by polarized optical microscope. From the DSC and polarizing optical microscopy (POM) results, it was found that PEO/PMMA was miscible in the molten state no matter which casting solvent was used. However, the crystallization of PEO in the chloroform‐cast blend was more easily suppressed than it was in the benzene‐cast blend. Relatively, the chloroform‐cast blend showed the greater melting‐point depressing of PEO crystals. Also, the spherulite of chloroform‐cast film showed a coarser birefringence. It was supposed that the chloroform‐cast blend had more homogeneous morphology. It is fair to say that polymer blends, cast from solvent, are not necessarily in equilibrium. However, the benzene‐cast blends still were not in equilibrium even after preheating at 100°C for 10 min. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1627–1636, 2000     

Impact modification of poly(trimethylene terephthalate)/polypropylene blend nanocomposites: Fabrication and characterization

A poly(trimethylene terephthalate) (PTT)/polypropylene (PP) blend and the nanocomposites were prepared with and without the addition of a compatibilizer precursor [maleic anhydride grafted polypropylene (MAPP)]. A reactive route was used for the compatibilization with the addition of MAPP during melt blending in a batch mixer. Organically modified nanoclays were used as nanoscale reinforcements to prepare the blend nanocomposites. Mechanical tests revealed optimum performance characteristics at a PTT/PP blend ratio of 80 : 20. Furthermore, incorporation of nanoclays up to 3 wt % showed a higher impact strength and higher tensile strength and modulus in the blend nanocomposites compared to the optimized blend. The nanocomposite formation was established through X‐ray diffraction and transmission electron microscopy (TEM). Thermal measurements were carried out with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC thermograms revealed an increase in the crystallization temperature in the presence of the nanoclays in the blend system containing Cloisite 30B. TGA thermograms also indicated that the thermal stability of blend increased with the incorporation of Cloisite 30B. Furthermore, dynamic mechanical analysis measurements showed that the Cloisite 30B nanocomposite had the maximum modulus compared to other nanocomposites. TEM micrographs confirmed an intercalated morphology in the blend nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by melt mixing. The miscibility, crystallization behavior, mechanical properties and hydrophilicity of the ternary blends have been investigated. The high compatibility of PVDF/PMMA/PVP ternary blends is induced by strong interactions between the carbonyl groups of the PMMA/PVP blend and the CF₂ or CH₂ group of PVDF. According to the Fourier transform infrared and wide‐angle X‐ray difffraction analyses, the introduction of PMMA does not change the crystalline state (i.e. α phase) of PVDF. By contrast, the addition of PVP in the blends favors the transformation of the crystalline state of PVDF from non‐polar α to polar β phase. Moreover, the crystallinity of the PVDF/PMMA/PVP ternary blends also decreases compared with neat PVDF. Through mechanical analysis, the elongation at break of the blends significantly increases to more than six times that of neat PVDF. This confirms that the addition of the PMMA/PVP blend enhances the toughness of PVDF. Besides, the hydrophilicity of PVDF is remarkably improved by blending with PMMA/PVP; in particular when the content of PVP reaches 30 wt%, the water contact angle displays its lowest value which decreased from 91.4° to 51.0°. Copyright © 2011 Society of Chemical Industry     

Effect of poly(ethylene glycol) on the solid‐state polymerization of poly(ethylene terephthalate)

Poly(ethylene glycol) (PEG) and end‐capped poly(ethylene glycol) (poly(ethylene glycol) dimethyl ether (PEGDME)) of number average molecular weight 1000 g mol^?1 was melt blended with poly(ethylene terephthalate) (PET) oligomer. NMR, DSC and WAXS techniques characterized the structure and morphology of the blends. Both these samples show reduction in T_g and similar crystallization behavior. Solid‐state polymerization (SSP) was performed on these blend samples using Sb₂O₃ as catalyst under reduced pressure at temperatures below the melting point of the samples. Inherent viscosity data indicate that for the blend sample with PEG there is enhancement of SSP rate, while for the sample with PEGDME the SSP rate is suppressed. NMR data showed that PEG is incorporated into the PET chain, while PEGDME does not react with PET. Copyright © 2005 Society of Chemical Industry     

Preparation,crystallization behavior,and dynamic mechanical property of nanocomposites based on poly(vinylidene fluoride) and exfoliated graphite nanoplate

Nanocomposites based on poly(vinylidene fluoride) (PVDF) and exfoliated graphite nanoplate (xGnP) were prepared by solution precipitation method. The resulting nanocomposites were investigated with respect to their structure and properties by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction, and dynamic mechanical analysis. Both SEM and TEM examinations confirmed the good dispersion of xGnP in the PVDF matrix. The nonisothermal crystallization behavior of the PVDF/xGnP nanocomposites was studied using DSC technique at various cooling rates. The results indicated that the xGnPs in nanometer size might act as nucleating agents and accelerated the overall nonisothermal crystallization process. Meanwhile, the incorporation of xGnP significantly improved the storage modulus of the PVDF/xGnP nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and properties of PET/PA6 copolymer/montmorillonite hybrid nanocomposite

From in situ polycondensation, a poly(ethylene terephthalate)/Polyamide 6 copolymer/montmorillonite nanocomposite was prepared, after the treatment of montmorillonite (MMT) with a water soluble polymer. The resulting nanocomposites were characterized by X‐ray diffraction (XRD), differential scanning calorimeter (DSC), nuclear magnetic resonance (NMR), dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The results of DSC, ¹H NMR, and DMA proved that the nanocomposite synthesized was PET/PA6 copolymer/MMT nanocomposite, not the PET/PA6 blend/MMT nanocomposite. The results of XRD and TEM proved that the dispersion of MMT was improved observably after the introduction of PA6 molecular chain into PET. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2512–2517, 2006     

Influence of tacticity of poly(methyl methacrylate) on the compatibility with poly(vinyl phenol)

Isotactic, atactic, and syndiotactic poly(methyl methacrylate) (PMMA) were mixed with poly(vinyl phenol) (PVPh) separately in tetrahydrofuran to make three polymer blend systems. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to study the miscibility of these blends. Isotactic PMMA was found to be more miscible with PVPh than atactic or syndiotactic PMMA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1773–1780, 1997     

Investigation on the crystallization behavior of poly(ether ether ketone)/poly(phenylene sulfide) blends

The morphology of nonisothermally crystallized poly(phenylene sulfide) (PPS) and its blend with poly (ether ether ketone) (PEEK) have been observed by polarized optical microscope (POM) equipped with a hot stage. The nonisothermal crystallization behavior of PPS and PEEK/PPS blend has also been investigated by differential scanning calorimetry (DSC). The maximum crystallization temperature for PEEK/PPS blend is about 15°C higher than that of neat PPS, and the crystallization rate, characterized by half crystallization time, of the PEEK/PPS blend is also higher than that of the neat PPS. These results indicate that the PEEK acts as an effective nucleation agent and greatly accelerates the crystallization rate of PPS. The Ozawa model was used to analyze the nonisothermal crystallization kinetics of PPS and its blends. The Avrami exponent values of neat PPS are higher than that of its blend, which shows that the presence of PEEK changed the nucleation type of PPS from homogeneous nucleation to heterogeneous nucleation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and properties of poly(ethylene terephthalate)/ATO nanocomposites

Antimony doped tin oxide (ATO) nanoparticles modified poly(ethylene terephthalate) (PET) composites used for manufacturing antistatic PET fiber were synthesized by in situ polymerization. The crystallization and multiple melting behavior of the nanocomposites were systemically investigated by means of Differential Scanning Calorimeter (DSC), Fourier Transform Infrared (FTIR), X‐ray Diffraction (XRD) techniques. The degree of crystallinity in nanocomposites increased with increasing ATO content. Smaller and more incomplete crystals are presented in the crystalline regions of the nanocomposites with increasing the content of ATO, which could be attributed to heterogeneous nucleation effects of ATO nanoparticles. Dynamic Mechanical Analysis (DMA) measurements showed that the storage moduli of the nanocomposites increased with increasing the content of ATO, due to formation of immobilized layer between polymer and filler. The interactions between ATO and PET molecules result in high tan δ for the PET/ATO nanocomposites. Percolation threshold of PET/ATO hybrid fibers prepared by the nanocomposites at room temperature was as low as 1.05 wt %, much lower than that of the composites filled with conventional conductive particles. Adding ATO nanoparticles obviously improves the conductivity of PET. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

PEN/PET共混物结晶行为研究

用差示扫描量热法(DSC)研究了不同共混比例PEN/PET共混物的熔体结晶行为,并进行了等温结晶动力学测定。结果表明:随着两种组分向中间比例(50/50)靠近,共混物的熔融温度越低,结晶速率也越慢。     

Partial delamination of the organo-montmorillonite with surfactant containing hydroxyl groups in maleated poly(propylene carbonate)

Maleated poly(propylene carbonate) (PPC-MA)/organo-montmorillonite (OMMT) nanocomposites were first prepared via melt end-capping poly(propylene carbonate) (PPC) with maleic anhydride (MA) and melt-mixing the PPC-MA with commercial OMMT without and with hydroxyl groups in surfactants: Cloisite 20A (C20A) and Cloisite 30B (C30B), respectively. Intercalated and partially delaminated morphologies were corroborated via X-ray diffraction (XRD) and transmission electron microscopy (TEM). Dynamic mechanical analysis (DMA) revealed that PPC-MA was evidently reinforced by the partially delaminated C30B platelets. From XRD patterns of statically annealed PPC-MA/C20A and PPC-MA/C30B mixtures and Fourier transform infrared (FTIR) results of equivalent nanocomposites, partial delamination of C30B in PPC-MA was confirmed to be relevant to diffusion of PPC-MA molecular chains in C30B galleries, grafting of PPC-MA to C30B platelet surfaces and further separation of C30B platelets.     

Crystallization and melting behavior of poly(p‐phenylene sulfide) in blends with poly(ether sulfone)

Crystallization and melting behaviors of poly(p‐phenylene sulfide) (PPS) in blends with poly(ether sulfone) (PES) prepared by melt‐mixing were investigated by differential scanning calorimetry (DSC). The blends showed two glass transition temperatures corresponding to PPS‐ and PES‐rich phases, which increased with increasing PES content, indicating that PPS and PES have some compatibility. The cold crystallization temperature of the blended PPS was a little higher than that of pure PPS. Also, the heats of crystallization and melting of the blended PPS decreased with increasing PES content, indicating that the degree of crystallinity decreased with an increase of PES content. The isothermal crystallization studies revealed that the crystallization of PPS is accelerated by blending PPS with 10 wt % PES and further addition results in the retardation. The Avrami exponent n was about 4 independent on blend composition. The activation energy of crystallization increased by blending with PES. The equilibrium melting point decreased linearly with increasing PES content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1686–1692, 1999     

Dispersion of nanoclays with poly(ethylene terephthalate) by melt blending and solid state polymerization

Melt intercalation of clay with poly(ethylene terephthalate; PET) was investigated in terms of PET chain mobilities, natures of clay modifiers, their affinities with PET, and nanocomposite solid state polymerization (SSP). Twin screw extrusion was used to melt blend PET resins with intrinsic viscosities of 0.48, 0.63, and 0.74 dL/g with organically modified Cloisite 10A, 15A, and 30B montmorillonite clays. Clay addition caused significant molecular weight reductions in the extruded PET nanocomposites. Rates of SSP decreased and crystallization rates increased in the presence of clay particles. Cloisite 15A blends showed no basal spacing changes, whereas the basal spacings of Cloisite 10A and Cloisite 30B nanocomposites increased after melt extrusion, indicating the presence of intercalated nanostructures. After SSP these nanocomposites also exhibited new lower angle X‐ray diffraction peaks, indicating further expansion of their basal spacings. Greatest changes were seen for nanocomposites prepared from the lowest molecular weight PET and Cloisite 30B, indicating its greater affinity with PET and that shorter more mobile PET chains were better able to enter its galleries and increase basal spacing. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of poly(ethylene terephthalate)/attapulgite nanocomposites

A kind of clay with fibrous morphology, attapulgite (AT), was used to prepare poly (ethylene terephthalate) (PET)/AT nanocomposites via in situ polymerization. Attapulgite was modified with Hexadecyltriphenylphosphonium bromide and silane coupling agent (3‐glycidoxypropltrimethoxysilane) to increase the dispersion of clay particles in polymer matrix and the interaction between clay particles and polymer matrix. FTIR and TGA test of the organic‐AT particles investigated the thermal stability and the loading quantity of organic reagents. XRD patterns and SEM micrographs showed that the organic modification was processed on the surface of rod‐like crystals and did not shift the crystal structure of silicate. For PET/AT nanocomposites, it was revealed in TEM that the fibrous clay can be well dispersed in polymer matrix with the rod‐like crystals in the range of nanometer scale. The diameter of rod‐like crystal is about 20 nm and the length is near to 500 nm. The addition of the clay particles can enhance the thermal stability and crystallization rate of PET. With the addition of AT in PET matrix, the flexural modulus of those composites was also increased markedly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1279–1286, 2007     

Preparation and characterization of poly(ethylene terephthalate) incorporated with secondary-modified montmorillonite

Hexadecyl triphenyl phosphonium bromide montmorillonite (PMMT) was first modified via secondary modification method, and then conjugated with toluene-2,4-diisocyanate (TDI). The as-prepared TDI-PMMT sample was used as a blend polymer in poly(ethylene terephthalate)/TDI-PMMT composite (PET/TDI-PMMT). The chemical properties of original PMMT, TDI-PMMT and PET/TDI-PMMT composite were investigated by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). Results showed that chemical bonds which were formed between TDI and montmorillonite surface provided massive active isocyanate groups in in situ polymerization for the montmorillonite and matrix materials. This structure could have improved the compatibility between PMMT and PET effectively, and allow good distribution of the montmorillonite in polymer matrix. The spacing of montmorillonite layer decreased from 3.72 to 3.28 nm owing to the encapsulation of TDI groups. The physical morphology of nanocomposites was observed through scanning electron microscopy (SEM), transmission electron microscopy (TEM) and XRD, and their thermal performance was evaluated by differential scanning calorimetry (DSC). XRD and SEM studies confirmed that compared to PMMT, the secondary-modified montmorillonite exhibited a better dispersion in PET matrix. TGA and DSC results showed that the thermal stability of PET/TDI-PMMT was superior to PET/PMMT. TEM images of PET/TDI-PMMT indicated that the TDI-PMMT exhibited good dispersion and the TDI-PMMT silicate layers were in better exfoliated state. The interface spacing of all samples was enlarged because of the heating reaction of oligomers. In the meanwhile, the mechanical properties such as tensile strength, flexural strength and flexural modulus of PET/TDI-PMMT were higher than those of PET/PMMT.     

Effects of mixing protocols on impact modified poly(lactic acid) layered silicate nanocomposites

Poly(lactic acid)/2 wt % organomodified montmorillonite (PLA/OMMT) was toughened by an ethylene‐methyl acrylate‐glycidyl methacrylate (E‐MA‐GMA) rubber. The ternary nanocomposites were prepared by melt compounding in a twin screw extruder using four different addition protocols of the components of the nanocomposite and varying the rubber content in the range of 5–20 wt %. It was found that both clay dispersion and morphology were influenced by the blending method as detected by X‐ray diffraction (XRD) and observed by TEM and scanning electron microscopy (SEM). The XRD results, which were also confirmed by TEM observations, demonstrated that the OMMT dispersed better in PLA than in E‐MA‐GMA. All formulations exhibited intercalated/partially exfoliated structure with the best clay dispersion achieved when the clay was first mixed with PLA before the rubber was added. According to SEM, the blends were immiscible and exhibited fine dispersion of the rubber in the PLA with differences in the mean particle sizes that depended on the addition order. Balanced stiffness‐toughness was observed at 10 wt % rubber content in the compounds without significant sacrifice of the strength. High impact toughness was attained when PLA was first mixed with the clay before the rubber was added, and the highest tensile toughness was obtained when PLA was first compounded with the rubber, and then clay was incorporated into the mixture. Thermal characterization by DSC confirmed the immiscibility of the blends, but in general, the thermal parameters and the degree of crystallinity of the PLA were not affected by the preparation procedure. Both the clay and the rubber decreased the crystallization temperature of the PLA by acting as nucleating agents. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41518.     

Preparation and crystallization of poly(ethylene terephthalate)/SiO2 nanocomposites by in‐situ polymerization

Poly(ethylene terephthalate) (PET)/SiO₂ nanocomposites were prepared by in situ polymerization. The dispersion and crystallization behaviors of PET/SiO₂ nanocomposites were characterized by means of transmission electron microscope (TEM), differential scanning calorimeter (DSC), and polarizing light microscope (PLM). TEM measurements show that SiO₂ nanoparticles were well dispersed in the PET matrix at a size of 10–20 nm. The results of DSC and PLM, such as melt‐crystalline temperature, half‐time of crystallization and crystallization kinetic constant, suggest that SiO₂ nanoparticles exhibited strong nucleating effects. It was found that SiO₂ nanoparticles could effectively promote the nucleation and crystallization of PET, which may be due to reducing the specific surface free energy for nuclei formation during crystallization and consequently increase the crystallization rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 655–662, 2006     

Proton exchange membranes based on poly(vinylidene fluoride) and sulfonated poly(ether ether ketone)

Blend membranes were obtained by solution casting from poly(vinylidene fluoride) (PVDF) and sulfonated poly(ether ether ketone) (SPEEK) in N,N-dimethylacetamide (DMAc). DSC and XRD were used to characterize the structure of the blend membranes. The effect of PVDF content on the membrane properties was investigated. The methanol permeability, water uptake and the swelling ratio of blend membranes decreased with the increase of PVDF content. Though the proton conductivity decreased upon the addition of PVDF, they were still comparable to that of Nafion^® 117 membrane. Higher selectivities were also found for most blend membranes in comparison with Nafion^® 117 membrane. The effect of methanol concentration on solution uptake, swelling ratio and methanol permeability of the blend membranes was also studied.