The aim of this study was to investigate the crystallization behavior and UV-protection property of polyethylene terephthalate (PET)-ZnO nanocomposits. PET-ZnO nanocomposites containing 0.5-3.0 wt % of ZnO were successfully synthesized by in situ polymerization. The Fourier transformed infrared (FTIR) spectroscopy indicated the silane coupling agent was anchored onto the surface of ZnO. Scanning electron microscope (SEM) images showed ZnO particles were dispersed homogeneously in PET matrix with amount of 0.5-1.0 wt %. Differential scanning calorimetry (DSC) results exhibited that the incorporation of ZnO into PET resulted in increase of the melting transition temperature (T m ) and crystallization temperature (T c ) of PET-ZnO nanocomposites. The crystallization behavior of PET and PET-ZnO nanocomposites was strongly affected by cooling rate. ZnO nanoparticles can act as an efficient nucleating agent to facilitate PET crystallization. UV-vis spectrophotometry showed that UV-ray transmittance of PET-ZnO nanocomposites decreased remarkably and reached the minimum value of 14.3% with 1.5 wt % of ZnO, compared with pure PET whose UV-ray transmittance was 84.5%. PET-ZnO nanocomposites exhibited better UV-protection property than pure PET, especially in the range of UVA.
The effects of copper and polytetrafluoroethylene (PTFE) on thermal conductivity and tribological behavior of polyoxymethylene (POM) composites were investigated by a hot disk thermal analyzer and an M-2000 friction and abrasion testing machine. The results indicated that the incorporation of 3 wt% copper particles into POM had little effect on the thermal conductivity of POM composites, but led to the decreased friction coefficient and wear rate of composites. As the copper content was increased, the thermal conductivity increased and reached 0.477 W m −1 K −1 for POM-25% Cu composite, an increase of 35.9% compared with that of unfilled POM, while the friction coefficient and wear rate of composites also increased. The incorporation of PTFE into POM-Cu composites had a negligible effect on the thermal conductivity of composites, but helped in the formation of a continuous and uniform transfer film and resulted in the reduction in the friction coefficient and wear rate of composites. The POM-15% Cu-10% PTFE composite, with a value of wear rate similar to unfilled POM possessed higher thermal conductivity and lower friction coefficient.
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 d 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.
In this work, perfluoroalkylmethacrylate ester (PFAMAE)grafted-linear low-density polyethylene (LLDPE) was synthesized by UV-induced surface graft polymerization. The effect of PFAMAE-grafted-LLDPE on the tribological behavior of LLDPE-filled polyoxymethylene (POM) composite was investigated using a friction and abrasion testing machine. The results showed that LLDPEg-PFAMAE was a more effective modifier in improving tribological property of LLDPE-filled POM composite than conventional maleic anhydride-grafted-polyethylene (PE-g-MAH). POM/LLDPE composite possessed much lower friction coefficient but higher wear rate than pristine POM. The incorporation of LLDPE-g-PFAMAE into POM/LLDPE further decreased the friction coefficient, which was 45% lower than that of POM. The wear rate of POM/LLDPE/LLDPE-g-PFAMAE composite was also reduced and was lower than that of pristine POM. The primary wear mechanisms of POM/ LLDPE composite with and without LLDPE-g-PFAMAE were adhesive and abrasive wear. POLYM. ENG. SCI., 51:925-930,
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