Study On Preparation And Foaming Of Polyamide Thermoplastic Elastomer

Polyamide thermoplastic elastomer(TPAE)is a high-performance elastomer formed by block polymerization of polyamide hard segments and polyether(or polyester)soft segments.The hard segment provides physical cross-linking points for TPAE,giving it excellent mechanical properties,and the other provides elasticity properties.By adjusting the ratio of polyamide and polyether segments in the polymerization process,it can also be made into elastomers that meet different use environments,which can be widely used in many fields such as automobiles,aerospace,sports equipment,cold chain transportation,medical equipment,electronics and electrical appliances.Among them,the TPAE micro-foam material made of supercritical physical foaming has excellent resilience,tear strength and high and low temperature resistance,and has appeared in the application market of high-end shoe materials at home and abroad.In this paper,a polyamide 1012 thermoplastic elastomer(TPAE1012)with a block copolymer structure was synthesized.The TPAE1012 was prepared using a two-step method.Firstly,a double carboxyl-terminated PA1012 prepolymer was synthesized via poly condensation reaction,and then three kinds of TPAE1012s with different hardness were synthesized by controlling the addition of the polytetrahydrofuran(PTMG2000)soft segment via esterification.Two tests of FTIR and 1H NMR,have verified the successful preparation of prepolymers and elastomers.DSC and TGA tests have verified the great thermal stability of TPAE1012.Mechanical performance tests have verified that TPAE1012 with more content of PTMG has better flexibility.Its elongation at break can reach up to 1200%.Based on the status quo of TPAE foaming,this paper studied the influencing factors of the foaming TPAE process by chemical foaming.The TPAE 1012 foam material with millimeter-level cells was prepared by the normal pressure foaming molding process,and the feasibility of normal pressure foaming was explored.On this basis,by introducing the traditional ethylene vinyl acetate copolymer(EVA)material with mature foaming process,it is used as the foaming matrix,and TPAE1012 is used as the modified material to prepare the TPAE-based composite material.Then EVA/TPAE1012 composite materials with good compatibility were prepared,and the EVA/TPAE1012 foams were prepared by chemical foaming method.The cell morphology,resilience,mechanical properties,etc.were tested to determine the feasibility of TPAE-based composite foaming.Then introduced the commercially available polyamide 12 elastomer(PEBAX2533)as a comparison with the self-made TPAE1012 to continue to prepare the EVA/PEBAX composite foam.The cell size of the foam is between 60?70 ?m,which is microporous and the resilience performance exceeds 50%.The elongation at break is increased by 28%?135%compared with traditional EVA foam.And when the addition amount of foaming agent is 1%,the low-foaming EVA/PEBAX foam's various properties such as resilience,mechanical strength and elongation at break are all better than traditional EVA foam.It is expected to replace EVA and TPU materials and become a new shoe midsole material.