Crystalline Morphologies Of Poly (ε-caprolactone) And Its Blends

Polymer crystallization is an important issue in polymer science. In this paper, the crystalline morphology of Poly(s-caprolactone)(PCL) and its blends were studied;PCL was used to study its crystalline morphology. First, the crystalline temperature and melt temperature of PCL were measured by DSC and the crystalline type was measured by XRD. Then, the effect of crystallization temperature, crystallization time and molecular weight of PCL was studied by polarized optical microscope (POM). It was found that the effect of temperature on the arystallization was every obvious. On low temperature, PCL can form the spherulites, on high temperature, PCL can form the ringed spherulites; But the change of crystallization time and molecular weight of PCL only change the dimension of crystal, which did not influence the crystalline morphology.Crystalline morphology of PCL in PCL/PVC, PCL/SAN, and PCL/PC blends were studied. The effect of blends, contents and temperature was studied by POM. It was found that with suitable interaction strength, the crystallizable component could have suitable crystallization rate and the non- crystallizable component could have suitable diffusion rate. While they are matched, the crystallizable component could form regular ringed spherulites.PCL and SiO2 organic-inorganic hybrid materials have been synthesized by sol-gel approach and the crystalline behavior of PCL in the silica networks has been investigated by DSC and WAXD. The degree of PCL crystallinity in the PCL/SiO2 hybrid networks reduces with the increase of SiO2 content. PCL is in an amorphous state when the concentration of PCL is lower than 40wt% in the hybrid materials. The melting points of PCL in the networks are lower than that of pure PCL, but they almost have the same value. WAXD results show that when the PCL weight percentage is higher than 40wt% in the hybrid samples, part of PCL can crysatllize and the PCL crystallites are almost in the same size. The crystalline PCL in the hybrid samples is relatively free from the composition of the materials, because the crystallization temperature and melting point of PCL of the samples are almost equal, and the crystalline PCL of different samples has the same crystalline structure, that means the crystalline part of PCL in the hybrid samples is unperturbed and the porous silica gel gives enough space for PCL to crystallize into the same crystalline structure and the same size crystallites.