Study Of Polymer Blends With Hyperbranched Polyester

As a new polymer material, hyperbranched polyesters are high branched and contain many cavitas and active terminal groups. Because of these peculiar structures, there are many different performances from the linear polymers, such as improved rheological behavior, low viscosity, well dissolubility and easy mambrance formation and so on. During recent 20 years, there are a lot of studies about hyperbranched polyesters (HBP) and many achievements have been made. However, they are mainly about synthesis and characterization of HBP. Studies about the related theories of HBP are gradually increased, but practical applications of HBP just underway and many performances of HBP still cannot be well explained.The main purpose of this paper is to do a contrast study involving crystallization kinetics, rheological behavior, tensile strength etc. Polymer blends prepared via different generation or content of HBP blended with polar polymer and nonpolar polymer respectively. From this study, on the one hand we can get better understanding of the effects of HBP as an additive, and on the other hand we can also to get better comprehension of the structure of HBP.The contents mainly contain several studies as follow:The stepwise growth polymerization was used to synthesize the HBP based upon 2-ethyl-2-(hydrxymethyl)-1,3-propanediol (trimethylol-propane ,TMP) and 2,2-dimethylolpropionic acid (bis-MPA). The acetic anhydride and phthalic anhydride were used to modify the terminal groups. From the thermal analysis, it was proved the physical performance of the HBP such as thermal decomposition temperature, glass transition temperature and crystallization was mainly influenced by the terminal groups of HBP unlike the case of the linear polymer, which is mainly influenced by molecular weight.The crystallization kinetics of PP and POM which were blended with 10% HBP of the second to the fifth generations were studied via employing differential scanning calorimetry (DSC). The results of the isothermal kinetics of the blends could be well described by Avrami equation and the results of nonisothermal kinetics of the blends could be well described by Avrami equation, Ozawa equation and Mo equation. The results of isothermal kinetics of the blends indicated that HBP mainly acted as a nucleation agent for PP and which mainly acted as a nucleus dilution agent for POM. The second generation of HBP (HBP2) had the weakest ability of nucleation for PP but the strongest ability of nucleus dilution. The ability of nucleation of HBP3, HBP4 and HBP5 for PP was close and the ability of nucleus dilution of HBP3 and HBP5 was close. And also the results showed HBP would be in favor of transferring of molecular chains of POM as the subcooling degree increased and which woud accelerate the crystallization rate of POM. After blended with HBP, the nonisothermal crystallization energy of PP was decreased and which of POM was increased.The study showed HBP was incompatibility with PP but compatibility with Nylon6 particularly via SEM. The rheological experiment indicated the Newton performance of Nylon 6 increased as the content of HBP increased while which of PP was invariable and for Nylon 6 system the effect of added HBP on the shear thinning was more apparent than the case of PP system. The results of tensile test showed the tensile strength of PP and Nylon 6 decreased as the additive content of HBPincresed.