Modification Of Aliphatic Polyester With Nano-silica And Polyamide Powder

Latterly, the aliphatic polyester has aroused widespread concern. Despite the aliphatic polyester has a lot of outstanding properties such as biodegradability, biocompatibility, so it has vast application prospect, but the large-scale utilization of their products are restricted because of the different imperfect properties. Therefore, it is necessary to modify them and we choose two types of nano-silica and three types of polyamide powder as modifying agents to modify PBS, PLA and PCL with different methods, the specific work is shown as follows:(1) PBS/nano-silica modified with epoxy group(RNS-E) nanocomposites were fabricated by in-situ polymerazation. Research suggests that chemical bond formed after the incorporation of RNS-E, which strengthen the interface interaction between filler and PBS but affects the process of polymerization reaction, leading to the low molecular weight at the same time. The temperature of crystallization rate of nanocomposites increased compared with plain PBS, when the content of RNS-E increased from 0 to 4 wt%, crystallization temperature increased from 74.0 oC to 83.6 oC, The Young's modulus and tensile strength of PBS/RNSE increased heavily, but elongation at break decreased.(2) PLLA/DNS nanocomposites were prepared with nano-silica modified with methyl group(DNS) and L-lactide(L-LA) by in-situ polymerization. Studies have indicated that DNS dispersed uniformly in the PLLA matrix, but DNS agglomeration appeared over a content of 1 wt%. Glass transition temperature(Tg) and the temperature of maximum crystallization rate(Tc) move to the low temperature region accompanied with the increase of DNS dosage during cold crystallization process, which is contrary to the variation trend of Tg and Tc during the melt crystallization process. The introduction of DNS promotes the crystallization of PLLA, improve the crystallinity of PLLA. With the increasing of DNS dosage the nucleation density gradually increased and the spherulite size decreased gradually. The incorporation of DNS improves the thermal stability of PLLA.(3) PBS/wool powder(WP) composites were prepared by solution blending, the addition of WP promotes the crystallization of PBS dramatically, also the isothermal crystallization kinetics and the non-isothermal crystallization kinetics of composites were studied. The incorporation of WP reduces the crystallization activation energy of PBS, and, at a unit time, a lower cooling rate should be employed to obtained a certain degree of crystallinity with the increase of WP during the process of non-isothermal crystallization. Simple analysis was carried out by comparing the influence of talcum powder(Talc), polyamide3(PA3) powder, polyamide6(PA6) powder on the crystallization of PBS, in relation to the heterogeneous nucleation mechanism of WP wok on PBS.(4) PCL/PA6 composites were prepared by means of solution blend, then the crystallization properties of composites were tested with DSC, and the outcome show that the effect of PA6 powder was obviously prominent in promoting the crystallization of PCL. The initial crystallization temperature and maximum crystallization temperature of the composites increased with the increase of the amount of PA6 powder. The incorporation of PA6 powder increase nucleation density and lead to the refinement of spherulite. The remarkable heterogeneous nucleation mechanism of PA6 powder exert on PCL was discussed by comparing the the difference of PA6 powder, PA3 powder and WP imposing on the crystallization behavior of PCL.