The combination of two modification techniques developed for the ZSM-5 zeolite, i.e., desilication and incorporation of lanthanum under microwave irradiation, has produced a highly efficient catalyst, DeLaZSM-5, for catalytic degradation of low-density polyethylene (LDPE). Its performance on the degradation was studied at 390C and compared with the parent ZSM-5 and the modified intermediate products desilicated ZSM-5 (DeZSM-5) and LaZSM-5. Among the catalysts tested, DeLaZSM-5 showed the highest catalytic degradation rate. In addition, on DeLaZSM-5 the liquid yield was slightly increased and the isoparaffin index of the liquid was almost doubled, which indicated higher liquid quality compared with the parent ZSM-5 zeolite. The high catalytic activity of DeLaZSM-5 could be explained by its unique acidic properties with a sharp increase of the number and strength of weak acid sites and a decrease of strong acidsites.

A new biodegradable starch graft copolymer, starch-g-poly(1,4-dioxan-2- one), was synthesized through the ring-opening graft polymerization of 1,4-dioxan-2-one onto a starch backbone. The grafting reactions were conducted with various 1,4-dioxan-2-one/starch feed ratios to obtain starch-g-poly (1,4-dioxan-2-one) copolymers with various poly(1,4-dioxan-2-one) graft structures. The microstructure of starch-gpoly (1,4-dioxan-2-one) was characterized in detail with one- and two-dimensional NMR spectroscopy. The effect of the feed composition on the resulting microstructure of starch-g-poly(1,4-dioxan-2-one) was investigated.

A kind of synthesized thermotropic liquid crystal copolyester containing phosphorus (PLCP) with high flame retardancy (oxygen index, 70%) has been used to prepare in situ reinforced PET composites that have both good flame retardancy and better mechanical properties than pure PET. The melt dripping behavior of PET was also improved.

The thermal transition, crystallization and spherulitic morphology of starch-g-poly (1,4-dioxan-2-one) copolymers were studied by means of differential scanning calorimetry (DSC) and polarized optical micrographs (PM). It is found that the graft structures of copolymers have obvious effects on the thermal and crystallization behaviors. Because there were more defect sites in the crystalline phase originating from the short grafted chains of poly (1,4-dioxan-2-one)(PPDO), the crystal structure of the copolymers was much less perfect than that of PPDO. PM revealed that the spherulitic morphology of the graft copolymers depended on graft structures and crystallization temperatures. From the single polarized micrograph of the graft copolymers it was observed clearly that the starch segments acted as nucleation sites. The Avrami equation was used to analyze the overall isothermal crystallization of the graft copolymers. Avrami exponents were almost constant at crystallization temperatures Tc ranging from 45 to 60 8C. Both the PM observation and the DSC investigation (crystallization rate constant, K values) indicated that the graft copolymers crystallize faster than pure PPDO, especially at higher crystallization temperatures.