PLLA and PHB blend film and cast film were studied by grazing incidence X-ray diffraction. In order to investigate the impact of the addition of PHB on the crystallinity of PLLA of the blend film

blend films of various mixture ratios

molecular weights of PLLA

and thicknesses were prepared. The results were compared with the cast film. It is found that the crystallinity of PLLA in the blend film is increasing sharply with the addition of PHB during thermosetting. The crystallization temperature is lowered dramatically and the melting temperature is raised simultaneously. However this phenomenon was not observed in the bulk

i.e. cast film. Comparing with the PLLA with higher molecular weight

the crystallinity of lower ones is increasing more significantly after blending with PHB.