Miscibility And Crystallization Behaviors Of Poly(Butylene Suberate)-Based And Poly(Hexylene Oxalate)-Based Polymer Blends

In recent years, due to the environmental concerns and a shortage of petroleum resources, more and more biodegradable polymers especially the biodegradable aliphatic polyesters with environmentally friendly characteristics have been wildly researched. Unfortunately, the high prices as well as the poor mechanical properties limit their broader use. In order to expand their application fields, we should take some measures to modify their properties. It is well-known that polymer blending is one of the most convenient and economic methods. Therefore, in this work, we mainly prepared several kinds of biodegradable aliphatic polyester blends through the normal solution and casting method, and then fully studied their miscibility, crystallization behavior and so on. The main research results are as follows.(1) Crystalline/amorphous blendsWith the biodegradable aliphatic poly(butylene suberate) (PBSub) as the crystalline component, poly(vinyl phenol) (PVPh) and tannic acid (TA) as the amorphous component, we respectively prepared the PBSub/PVPh and PBSub/TA blends via the normal solution and casting method. Both the variation trends of the glass transition temperature (Tg) which could be well fitted by the Kwei equation and the depression of the equilibrium melting point indicated that both PBSub/PVPh and PBSub/TA blends were miscible. Our further investigation revealed that the addition of PVPh and TA would impede the crystallization behavior of PBSub, but would not change the crystallization mechanism and the crystal structure of PBSub. The degree of supercooling was the key factor to influence the crystalline morphology and the spherulite growth rate in the crystalline/amorphous blends.(2) Crystalline/crystalline blendsIn this work, we also prepared the poly(hexylene oxalate) (PHO)/ poly(ethylene oxide) (PEO) blends with chloroform as the mutual solvent, and mainly researched the miscibility, crystalline structures as well as the spherulitic morphologies of this system. Through the variation trend of Tgs of some samples and the homogeneous melt morphologies over the whole blend compositions, we could conclude that the blends were miscible. In the blends, both PHO and PEO components could form their own crystal structure, instead of forming the eutectic. Depending on the composition of these blends and the crystallization temperature (Tc), there were three kinds of spherulitic morphologies in these blend samples. What is more, when 70/30 PHO/PEO blend was crystallized at 40?46?, 50/50 to 30/70 blends at 40?50? and 15/85 PHO/PEO blend at 42? 50?, the crystallization rates of PHO and PEO were comparable, the two components could crystallize simultaneously, form their own crystal structure and exhibit different spherulitic morphologies. Eventually, the interpenetrating spherulites were formed.It is my sincere belief that the study is rather meaningful. On one hand, it can help us have a better understanding of the biodegradable aliphatic polyester materials. On the other hand, the research can provide some reference for the promotion of aliphatic polyesters blends in their practical applications.