The nonisothermal crystallization of poly(butylene dodecanedioate) was studied by differential scanning calorimetry,crystals of polyesters were observed through polarized optical microscope,and an Avrami method was us...The nonisothermal crystallization of poly(butylene dodecanedioate) was studied by differential scanning calorimetry,crystals of polyesters were observed through polarized optical microscope,and an Avrami method was used to analyze the kinetics of nonisothermal crystallization.The results showed that the crystallization temperature decreased slowly with an increase in the cooling rate.Furthermore,secondary nucleation was observed in the process of PBDD nonisothermal crystallization,and the Avrami exponential values n of PBDD indicated that the mechanism of crystallization was a tridimensional growth with heterogeneous and homogeneous nucleation.Meanwhile,the Avrami values n of P(BDD-co-BT)-20 is 1,which indicated that their mechanism of crystallization was a one-dimensional growth with heterogencous nucleation.Crystallization activation energies implied that it is easier to crystallize for copolyester.From the observed results of spherulites,it can be concluded that the size of spherulites decreases with increasing the content of terephthalic acid.展开更多
采用共酯化工艺,利用熔融缩聚法制备不同组成的聚丁二酸-己二酸丁二酯(PBSA)共聚酯和均聚物(聚丁二酸丁二醇酯PBS、聚己二酸丁二醇酯PBA)。利用核磁氢谱(1 H NMR)、差示扫描量热(DSC)和热失重(TGA)对合成的(共)聚酯进行了表征。结果表...采用共酯化工艺,利用熔融缩聚法制备不同组成的聚丁二酸-己二酸丁二酯(PBSA)共聚酯和均聚物(聚丁二酸丁二醇酯PBS、聚己二酸丁二醇酯PBA)。利用核磁氢谱(1 H NMR)、差示扫描量热(DSC)和热失重(TGA)对合成的(共)聚酯进行了表征。结果表明共聚酯摩尔组成与投料基本一致。所合成共聚酯都表现出优异的热稳定性,起始分解温度高于300℃,共聚酯的热降解行为主要受二酸组分影响。共聚酯的熔点、熔融结晶温度随AA含量变化呈现先下降后上升的规律,在AA摩尔含量为50%~70%时,存在两种晶体共结晶,因而出现了两个熔点。共聚酯的玻璃化转变温度符合Gorden-Taylor方程,方程参数k=2.4。共聚酯的力学性能同样受组成变化影响,随着AA含量的增加,拉伸强度、弹性模量先降低后上升,断裂伸长先上升后降低。展开更多
文摘The nonisothermal crystallization of poly(butylene dodecanedioate) was studied by differential scanning calorimetry,crystals of polyesters were observed through polarized optical microscope,and an Avrami method was used to analyze the kinetics of nonisothermal crystallization.The results showed that the crystallization temperature decreased slowly with an increase in the cooling rate.Furthermore,secondary nucleation was observed in the process of PBDD nonisothermal crystallization,and the Avrami exponential values n of PBDD indicated that the mechanism of crystallization was a tridimensional growth with heterogeneous and homogeneous nucleation.Meanwhile,the Avrami values n of P(BDD-co-BT)-20 is 1,which indicated that their mechanism of crystallization was a one-dimensional growth with heterogencous nucleation.Crystallization activation energies implied that it is easier to crystallize for copolyester.From the observed results of spherulites,it can be concluded that the size of spherulites decreases with increasing the content of terephthalic acid.
文摘采用共酯化工艺,利用熔融缩聚法制备不同组成的聚丁二酸-己二酸丁二酯(PBSA)共聚酯和均聚物(聚丁二酸丁二醇酯PBS、聚己二酸丁二醇酯PBA)。利用核磁氢谱(1 H NMR)、差示扫描量热(DSC)和热失重(TGA)对合成的(共)聚酯进行了表征。结果表明共聚酯摩尔组成与投料基本一致。所合成共聚酯都表现出优异的热稳定性,起始分解温度高于300℃,共聚酯的热降解行为主要受二酸组分影响。共聚酯的熔点、熔融结晶温度随AA含量变化呈现先下降后上升的规律,在AA摩尔含量为50%~70%时,存在两种晶体共结晶,因而出现了两个熔点。共聚酯的玻璃化转变温度符合Gorden-Taylor方程,方程参数k=2.4。共聚酯的力学性能同样受组成变化影响,随着AA含量的增加,拉伸强度、弹性模量先降低后上升,断裂伸长先上升后降低。
