Study On Blending Modification And Crystallization Properties Of Bio-based Polyamide 56

Polyamide fiber is the second largest synthetic fiber,the main varieties are polyamide 6（PA6）fiber and polyamide 66（PA66）fiber,accounts for about 98%of the polyamide fibre above,an annual output of polyamide fiber in our country in 2018 is 3.41 million tons,it is the largest in the world,bio-based polyamides 56（PA56）as a new type polyamide,has become the hotspot for study,one of the synthetic monomers of PA56,opentylenediamine,is derived from biomass,which can not only reduce the dependence on petroleum resources,but also reduce the emission of carbon dioxide.However,the crystallinity of PA56 is relatively low and the crystalline grain size is relatively large,which leads to the high boiling water shrinkage rate of its fiber and the poor dimension stability of its fabric.This topic,nano SiO₂、TiO₂、Al₂O₃、ZrO₂ and PA6,PA66 were carried out on the bio-based PA56 blending modification,preparing two series of modified PA56,comparing the changes of PA56 crystallization performance before and after modification,since the the nano SiO₂ and PA66had the better modification effects,they were choosen for bio-based PA56 blending modification and low speed spinning experiment,by comparing the fibre properties,such as the change of the boiling water shrinkage rate,5%PA66 is finally chosen for bio-based PA56 modification,and then carrying out high speed spinning experiment and studying the performance of the fabric,the conclusion is as follows:（1）The semi-crystallization time of bio-based PA56 modified with nano SiO₂ and PA66 was the shortest of the two series respectively,the crystallization rate was higher than pure PA56,the size of the spherulite was also reduced under the polarizing microscope,making PA56 spherulite more neat during crystallization,the consistency of crystallization was improved,in terms of crystallinity improvement,nano Al₂O₃ has the best effect,but the improvement effect on semi-crystallization time and spherulite size is poor.（2）Through the analyze of crystallinity,orientation degree of the fiber and the tensile properties,moisture regain with the draft ratio,analysis shows that at the same drafting times,the crystallinity and orientation of modified PA56 fiber were increased than that of PA56 fiber,the mechanical properties were improved to different degrees,and the moisture regain rate was decreased,the boiling water shrinkage of 5%PA66 modified fiber is the lowest.（3）The gloss of the fabric modified with 5%PA66 was slightly lower than pure PA56 fabric.,in terms of contact temperature and friction performance,the difference between the two fabrics is slight,but the difference is not obvious,in terms of the tensile,compression,bending and shear properties of the fabric,modified PA56 fabric has improved its tensile and shear properties,but decreased its compression and bending properties,mainly due to the introduction of PA66,which improves the crystallinity of PA56 and then improves the strength of the fiber,but reduces the softness,in terms of fabric shrinkage,the shrinkage of the fabric modified by 5%PA66 was reduced by about 20%,which greatly improved the dimensional stability of the fabric.