缓冷条件对TLCP初生纤维分子链取向和力学性能的影响

Effect of heat retarding conditions on molecular chain orientation and mechanical properties of TLCP as-spun fibers

采用熔融纺丝法在不同缓冷条件下制备热致液晶聚芳酯(TLCP)初生纤维,研究不同缓冷条件下TLCP初生纤维的分子链取向及结晶度,以及缓冷条件对纤维力学性能的影响。结果表明:缓冷条件的变化对TLCP初生纤维的结晶度几乎没有影响,但对于其分子链取向的影响较为显著;当缓冷温度固定在280℃、缓冷高度由80 mm降为40 mm时,TLCP初生纤维的取向因子(f)由0.945增加至0.964,当缓冷高度固定为80 mm、缓冷温度由280℃变为无缓冷时,纤维的f由0.945提高至0.970;TLCP初生纤维的断裂强度随着缓冷温度的降低而增大,随着缓冷高度的增加而降低;当缓冷高度固定为80 mm、缓冷温度由280℃变为无缓冷时,TLCP初生纤维断裂强度由5.9 cN/dtex增加至8.7 cN/dtex,当缓冷温度固定为280℃、缓冷高度由40 mm增至80 mm时,纤维断裂强度由7.3 cN/dtex下降至5.9 cN/dtex。

Thermotropic liquid crystalline polyarylester(TLCP)as-spun fibers were prepared by melt spinning under different heat retarding conditions.The molecular chain orientation and crystallinity of TLCP as-spun fibers were studied under different heat retarding conditions,as was the effect of heat retarding conditions on mechanical properties.The results showed that the change in heat retarding conditions had almost no effect on the crystallinity of TLCP as-spun fibers,but had a significant impact on their molecular chain orientation;the orientation factor(f)of TLCP as-spun fibers increased from 0.945 to 0.964 when the heat retarding temperature was controlled at 280℃and the heat retarding height was reduced from 80 mm to 40 mm;f increased from 0.945 to 0.970 when the heat retarding height was set as 80 mm and the heat retarding temperature changed from 280℃to no heat retarding;the breaking strength of TLCP as-spun fibers increased with the decrease of heat retarding temperature and decreased with the increase of heat retarding height;the breaking strength of TLCP as-spun fibers increased from 5.9 cN/dtex to 8.7 cN/dtex when the heat retarding height was set as 80 mm and the heat retarding temperature changed from 280℃to no heat retarding;and the fiber breaking strength decreased from 7.3 cN/dtex to 5.9 cN/dtex when the heat retarding temperature was set as 280℃and the heat retarding height was increased from 40 mm to 80 mm.