Studies On The Exchange Reaction Between PBS And PA6IcoT And Its Products

In recent years, many researchers are focusing on the environmentally friendly materials, especially on the biodegradable polymers. Most of the biodegradable polymers are polyesters, which have poor thermal properties and mechanical properties. Therefore, their practical applications are limited. On the other hand, the polyamide chains contain amide bond (-CONH-). Because of the existence of hydrogen bonds between molecular chains, they have good thermal and mechanical properties. However, they are not biodegradable. To combine the advantage of two polymers, high molecular weight poly(ester amide)s are prepared by ester-amide exchange reaction between aliphatic polyester and semi-aromatic polyamide.Firstly, amorphous nylon PA6IcoT and poly(butylene succinate) (PBS) are blended in the horizontal reactor under melting conditions. The mechanism of exchange reaction and structure of copolymers are analyzed by solubility experiment, FT-IR and 13C-NMR. Scanning electron microscope (SEM) is used to analyze the influence of exchange reaction on phase morphology. The results show that ester-amide exchange reaction between PBS and PA6IcoT can occur with paratoluenesulfonic acid as the catalyst. With the increase of reaction extent, the randomness of copolymers is increased and the molecular weight distribution became wider. The copolymers can play the role of compatibilizer to improve the compatibility of blends. The dispersed particle size of disperse phase is significantly reduced with increasing reaction extent.Secondly, the crystallization behavior, crystalline morphology, and crystal structure of the blends are studied. It had been showed that the PA6IcoT in the blends hinders the crystallization of PBS, leading to higher activation energy, slow crystal growth rate and low crystallinity. This trend is enhanced by the increasing irregularity of macromolecular chain caused by the ester-amide exchange reaction. With the increase of reaction extent, spherulite size is gradually decreased and interface between spherulites become indistinctly. Although there is little difference in crystal structure, diffraction peaks appear drift. In the end, the relations between thermal property, mechanical property and degradation property and chemical structure and condensed state structure of blends are studied. The results show that the glass transition temperature of two polymers shifted gradually toward the middle due to exchange reaction. The incorporation of aromatic group into copolymer chain can suppress its thermal decomposition rate. The physical blend of PBS and nylon has worse mechanical properties than PBS due the compatibility between two polymers. On the other hand, the products of reactive blending have much better tensile strength and module, and impact strength than PBS. With the increase in exchange reaction, the rate of polymer degradation is increased due to lower crystallinity and higher randomness. Therefore, poly(ester amide)s with better enhanced thermal property mechanical property and biological degradability are produced.