The melts of poly(lactic acid) underwent two different treatments (naturally cooling (CN) and rapidly compressing respectively).For the first time

amorphous PLA samples have been successfully prepared by rapidly compressing (RC) process

and its isothermal cold crystallization behavior and the corresponding crystalline structure were studied by using differential scanning calorimetry (DSC)

Fourier transform infrared (FTIR)

and wide angle X-ray diffraction (WAXD).It was found that RC samples possessed a faster crystallization rate and higher final crystallinity than those of CN samples at all selected cold crystallization temperatures (110

115

125

130

135 and 140 ℃

respectively) according to the FTIR and WAXD data.However

there was almost no difference of the crystallize size between RC and CN samples.With the FTIR and WAXD results

it could be concluded that the crystal nucleation density was higher in RC samples.Besides

polarized FTIR results exhibited that there was no orientation of molecular chains in the raw RC samples

thus the impact of molecular orientation on crystallization behavior of RC samples could be excluded.As a result

the unique crystallization behavior of RC samples could be attributed to the higher crystal nucleation density

which was caused by local order domains formed during the rapid compression process

accelerating the crystallization rate and increasing the final crystallinity of RC samples.