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采用溶液法制备聚乳酸(PLA)薄膜,并利用偏光显微镜在线研究了不同温度及不同牵引速率下,单根蚕丝纤维(SF)诱导PLA柱晶的形成,并利用显微红外光谱表征柱晶结构.结果表明,当牵引速率大于或等于临界速率时,纤维表面有连续的柱晶生成,反之柱晶不连续;当牵引速率大于临界饱和速率时,柱晶的结晶度和取向度分别趋于稳定值;在等温条件下,随着牵引速率的增大,柱晶的成核诱导期缩短,晶体的成核密度增大,取向度增加;当牵引速率一定时,与130℃相比,温度为120℃时形成柱晶的成核诱导期较短,成核密度更大,结晶度更高,柱晶层的生长更快.
Polylactic acid (PLA) thin films were prepared by solution method. The formation of PLA columnar crystals induced by single silk fibers (SF) at different temperatures and different traction rates were investigated by using a polarizing microscope. The columnar crystal structure The results show that when the traction rate is greater than or equal to the critical rate, there is a continuous columnar crystal on the fiber surface, whereas the columnar crystal is discontinuous. When the traction rate is higher than the critical saturation rate, the crystallinity and orientation of the columnar crystal tend to be stable Under the condition of isothermal temperature, the nucleation induction period of the column crystal is shortened and the nucleation density of the crystal is increased and the degree of orientation is increased with the increase of the pulling rate. When the pulling rate is constant, the temperature is The formation of columnar crystals at 120 ℃ has a shorter nucleation induction period, a higher nucleation density and a higher degree of crystallinity, and the columnar layer grows faster.