Study On Modification And Foaming Performance Of Thermoplastic Polyamide Elastomer

Polyamide elastomer(TPAE)is a new kind of soft hard period of alternating block of thermoplastic elastomer,can have good resilience,and mechanical properties,TPAE foaming material is qualitative light,wear resistance,impact resistance and other properties,can be used in aerospace,automotive,sports protection,furniture,and many other fields,has wide prospect of research.However,the foaming process of TPAE has some difficulties,such as narrow melting temperature zone,high price,low foaming rate and large shrinkage degree,which hinders its industrialization.In this paper,the properties of three new types of TPAE elastomers were analyzed comprehensively,and chain extension and plasticizing modification were carried out in view of the foaming difficulties such as low melt strength and large shrinkage,and the influence of modification methods on the material properties and foaming performance of TPAE was explored.(1)to three different hard segment content of TPAE elastomer materials and foaming performance evaluation,through testing the infrared spectrum analysis of the hydrogen bond and phase separation,identified three grades TPAE elastomer sort of hard segment content,by DSC and TGA analysis its crystallization properties and thermal stability,through the analysis of the dynamic frequency and temperature scanning its rheological behavior,The foaming properties were evaluated by solid phase and melt foaming processes.The results show that the TPAE elastomer with high hard segment content has high hydrogen bond density,excellent crystallization property,good thermal stability,high viscosity and modulus,high melting point temperature,high foaming temperature and narrow foaming temperature zone.(2)The chain expansion reaction was used to improve the melt strength of TPAE.KL-E4370 and TIC were used as chain extenders respectively.The reaction process and principle of the two chain extenders were analyzed by infrared spectroscopy.The effect of chain extension reaction on the crystallization property of TPAE was analyzed by DSC test,and the product after chain extension reaction was foamed by melt foaming process to analyze the change of its foaming property.The results showed that the chain expansion reaction with KL-E4370 formed branched structure at first,and the cross-linked structure was produced when the content of chain extender was above 1.25%.The chain expansion reaction with TIC mainly formed long chain structure.Compared with the chain growth reaction,the chain branching reaction had higher melt strength,better crystallization performance,higher foaming rate and better quality of bubble pores.(3)TPAE elastomer after chain extension reaction with KL-E4370 was added with carbamide.The crystallinity and crystallization rate of TPAE after chain extension agent and carbamide were analyzed by DSC test.The influence of carbamide on its molecular structure and rheological behavior was scanned by dynamic frequency.The effect of carbamide on the pore structure and shrinkage was analyzed through melt foaming.Results show that the rigid amide join can improve the starting of TPAE crystallization temperature and crystallization degree,and lubrication in TPAE melt,the movement of molecular chain reduce the resistance and reduce the chain entanglement between,thereby lowering the melt viscoelastic,join after hard amide,shrinkage rate of foam samples is reduced,the degree of contraction is slightly improved.