Copolyester / Montmorillonite Nano-composite Materials

Three nanocomposites(PET/PEG/MMT, PET/PEN/MMT and IPA modified PET/MMT) were acquired by using intercalating polymerization. The procedures of synthesis, the dispersion of MMT and the crystallization behavior of the nanocomposites were studied systematically.It has been found that the previous treatment of MMT with intercalant agents is the most important step for synthesizing nano-copolyesters. The preferred intercalant agents are organic molecules whose two ends are made of active groups. One end group is onium ion which has the capability of exchanging cations between layers of MMT, another is one of the groups which can react with copolyesters. MMT treated by such intercalants is dispersed in copolyesters at nano scale easily. The interaction between MMT and matrixes is also strengthened. In principle, nanocomposites can be obtained whenever MMT is added to polymerization system. But it has been found through experiments that MMT is dispersed uniformly in copolyesters only by strictly controlling its adding conditions.The results of WAXD and TEM showed that MMT layers were intercalated and delaminated by copolyesters, the diffraction peak of (001) was almost disappeared and the layers were dispersed less than 100nm at thick direction.The results of DSC and crystallization experiments showed that PEG or PTMG segments improved the flexibility of PET molecular chain, which could increase not only the nucleating rates but also the growing speed of crystal. So, the crystallization rate of PET/PEG/MMT was faster than PET/MMT. Among the nano-copolyesters, PEG-2000(mass fraction: 6%)had the best promoting effect on the crystallization rate of PET/MMT.The results of DSC and WAXD showed that copolymerizing PET/MMT with PEN increased the cold crystallization temperature and decreased themelting crystallization temperature of PET/MMT. It meant the crystallization rate of PET/PEN/MMT was slower than PET/MMT. The nucleating rate of PET/PEN/MMT was faster than PET/PEN while its growing speed of crystal was slower than PET/PEN and its crystallization degree was lower also.The results of DSC showed that PET/MMT modified by IPA increased the cold crystallization temperature and decreased the melt crystallization temperature of PET/MMT. It meant the crystallization rate of IPA modified PET/MMT was slower than PET/MMT.