不相容PHBV/PS、PHBV/PMMA结晶/非晶共混体系的结晶行为研究

在不同的共混比例、不同的结晶温度下对不相容PHBV/PS、PHBV/PMMA结晶/非晶共混体系的结晶行为做了系统的研究.研究发现当PHBV含量为75wt%时,共混体系仍然和纯PHBV一样生成环带球晶;而当PHBV含量为50wt%时,共混体系在略低于非晶组分玻璃化转变温度时呈现花瓣状的球晶形貌;当PHBV含量为25wt%时,PHBV/PS体系出现不规则的晶体形貌,而PHBV/PMMA体系在偏光显微镜下没有观察到晶体.在这种不相容共混体系中,非晶组分的分散状态以及共混比例对共混体系中PHBV环带球晶的形成起到决定性的作用,而非晶组分对PHBV球晶的片晶前端生长的影响是形成花瓣状球晶的主要原因.

CRYSTALLIZATION BEHAVIOR OF INCOMPATIBLE PHBV/PS AND PHBV/PMMA CRYSTALLINE/AMORPHOUS BLENDS

The crystallization behaviors of incompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)/PS,PHBV/PMMA crystalline/amorphous blends with different ratios and different crystallization temperatures were investigated,with particular emphasis on the effect of amorphous components,such as PS or PMMA,on the morphology of PHBV ring-banded spherulites.PHBV ring-banded spherulites with slightly fuzzy bands were obtained when the content of PHBV in blends was 75%,which was similar to pure PHBV.Petal shaped spherulites were obtained at the crystallization temperature slightly lower than Tg of amorphous components when the content of PHBV in blends was 50%.When the content of PHBV in blends was 25%,irregular crystal morphologies were obtained in PHBV/PS blends,whereas no crystal was observed under POM in PHBV/PMMA blends.In the incompatible blends,the dispersion state and blends ratio of amorphous content had the decisive effect on the formation of PHBV ring-banded spherulites:ring-banded spherulites developed only at low crystallization temperatures when amorphous component content was high,and ring-banded spherulites generated at a wide range of crystallization temperature when amorphous component content was low,whereas the effect of amorphous content on the growth of lamellae at the front of spherulites was the main cause of the formation of petal shaped spherulites.