Crystallization Bchaviors And Morphology Of Biodegradable Polymer Blends And Composites

As the severe environmental problems caused by the wide use of the conventional plastics, it is very necessary to do research on biodegradable polymers. However, the application of biodegradable polymers has been badly limited due to many factors, such as narrower processing condition and poorer mechanical properties; thus, the modification is urgent and suitable.There are three methods to be used in the modification of the polymer: crystalline/amorphous blends, crystalline/crystalline blends and composites. The miscibility, crystallization behavior, spherulitic morphology, and crystal structure of the samples were investigated, with various techniques.Crystalline/amorphous polymer blendsPoly(vinyl phenol)(PVPh) and tannic acid (TA), amorphous content, were mixed with poly(butylene succinate-co-butylene carbonate)(PBSC) via solution and casting methods, respectively. With the assistance of differential scanning calorimeter (DSC), the complete miscibility of the polymer blends were indicated. Relative to neat PBSC, blending with amorphous contents suppress the crystallization rate and spherulitic growth rates of PBSC, while the crystallization mechanism and the crystal structure do not change. Moreover, in the PBSC/PVPh blends, the apparent increase in both long period and amorphous layer thickness values indicates that amorphous PVPh resides in the interlamellar region of PBSC spherulites in the blends.Crystalline/crystalline polymer blendsWith small difference in melting points, PESA/PEO and PESub/PEO blends were prepared via solution and casting method.In the PESA/PEO blends, three different crystalline morphologies are found. Moreover, it is the first time to observed interpenetrating spherulites over the entire blend compositions for the miscible crystalline/crystalline polymer blends.In the PESub/PEO blends, when the rich contents reach85%, the poor one may reside in interlamellar of spherulites.CompositesBiodegradable poly(L-lactide)(PLLA)/cyanuric acid(CA) and poly(ethylene succinate)(PES) composites were fabricated by solution and casting methods. The nonisothermal melt crystallization behavior, overall isothermal melt crystallization behavior, spherulitic morphology, and crystal structure of samples were investigated with various techniques.Relative to the neat polymers, the crystallization process has been accelerated obviously by the presence of small molecule particles, indicating that small molecule particles acts as an efficient nucleating agent for the crystallization of polymers. Moreover, CA is more efficient than Talc to enhance the nucleating of PES.