Synthesis And Characterization Of Polyamide 6 By Block Copolymerization

Thermoplastic elastomers have rubber elasticity at room temperature and plasticized at high temperature,both plastic flowability,processability and rubber elasticity,which are widely used in medical,electronic accessories,construction,automotive,food packaging and many other fields.As a new kind of thermoplastic elastomer,polyamide thermoplastic elastomers belong to the segmented block polymer,are similar to polyurethane and polyether ester thermoplastic elastomers,which has a good application prospect.In this paper,polyamide 6 thermoplastic elastomer with segmented block copolymer structure was synthesized by two steps(two steps).In the first stage,the prepolymer polyamide 6 with double-capped carboxyl groups is synthesized first,and the second stage is then subjected to polyesterification reaction with polyethylene glycol(PEG)to produce polyamide 6 thermoplastic elastomer.The influence of the time and content of capping agent on the molecular weight of the prepolymer was studied.The synthesis conditions and parameters such as time,temperature,vacuum,catalyst were optimized.The structure and properties of prepolymer and polyamide 6thermoplastic elastomer were characterized by Fourier transform infrared spectroscopy(FTIR),1HNMR,TG,differential scanning calorimetry,X-ray diffraction and scanning electron microscopy.The results showed: 1,The optimal synthesis process of the prepolymer was as follows: the polymerization was carried out at 240 ? for 4 h,the end capping agent was added for 1 h,the vacuum was 1 h(vacuum was 0.05-0.07 MPa),the block copolymer was synthesized(Vacuum 0.05-0.07 MPa);2,Fourier transform infrared spectroscopy(FTIR)diagram of the methylene group of alcohols appeared in the reaction temperature of 250 ? reaction for 3 h,vacuum 1 h(1H-NMR).The results show that the synthesized products have the peak values of both polyamide 6 and polyethylene glycol,indicating that the block copolymers are successfully synthesized;3.Thermogravimetric analysis and differential scanning calorimetry(DSC)test showed that the copolymer had good thermal stability within 300 ? and goodelasticity at-50 ? to 192 ?,with a wide range of operating temperature;4,XRD results show that the addition of the soft segments leads to the transformation of?-form into ?-form;5,SEM showed that the soft segment made polyamide 6thermoplastic elastomer possess rubber elasticity,but there was some incompatibility between soft and hard segments.