Poly(ether ester) / zinc oxide composites: Synthesis, process and characterization

The objective of this study is to prepare and characterize multiblock polyester elastomers and their composites. This study consists of three parts. In the first part of the study, the copolymers of poly(butylene terephthalate) ? poly(tetramethylene ether) glycol (PBT-PTMEG) were synthesized with varying hard/soft segment ratio.In the second part of the study, zinc oxide (ZnO) particles were synthesized by homogeneous precipitation method. The particles, which were approximately 300 nm in dimension, were modified with polyvinylpyrrolidone (PVP) to improve the compatibility between the polymer matrix and the filler. The doping of ZnO with aluminum (Al) decreased its electrical resistivity by 2 orders of magnitude.In the last part of the study, composites were prepared by introducing the fillers into the copolymers by using a melt compounder. The influence of ZnO type and concentration on the properties of the nanocomposites was studied. Microscopic scale investigations showed homogeneous dispersion of the fillers in the matrix. Although there was not a great difference in tensile strength and elastic modulus values of the composites and the neat matrix, there was a sharp decrease in elongation at break values with increasing filler content. It was found that addition of ZnO increased thermal stability, while it decreased coeffiecient of thermal expansion of the composites at low temperatures. The resistivity of composites remained constant until 15 wt % ZnO concentration and then started to decrease by 3-4 orders of magnitude. Whereas the dielectric constants increased with increasing filler concentration, they were not affected by the concentration at higher frequencies. The results showed that ZnO filled elastomers could be used as thermal interface materials and as antistatic materials.