Synthesis Of Thermoplastic Polyamide Elastomer PA1212-b-PTMG

As an excellent material,elastomer has been paid attention to because of its wide application range and excellent performance.With the development of the times,the elastomer has developed to the third generation.The third generation of thermoplastic elastomers is diverse,and polyamide elastomers are one of them with excellent processing properties.At present,the most widely used polyamide elastomer synthesis method is classified into a dibasic acid method,an isocyanate method,and an anionic polymerization method according to a synthesis mechanism;and a two-step method and a one-step method according to the reaction step.In this paper,PA1212 prepolymer was synthesized,then MDI and PTMG were used as reaction materials.The new PA1212-b-PTMG was synthesized by isocyanate method.Six PA1212-b-PTMG were synthesized by controlling the molecular weight of soft and hard segments.The PA1212 prepolymers with different molecular weights were synthesized by melt polymerization method.The molecular structure of the product was measured by infrared spectroscopy and ~1H-NMR spectroscopy.The synthesized product was confirmed to be1,6-hexanediamine-terminated PA1212 prepolymer.The molecular weight of the prepared PA1212 prepolymer was measured by acid-base titration and found to be comparable to the pre-calculation.The melting point and crystallization temperature of the prepared PA1212prepolymer were measured by differential scanning calorimetry.It was found that the melting points T_m of PA1000,PA1500 and PA2000 were 155?,167?and 171?,respectively,and the crystallization temperature T_c was 142?,154?,158?,respectively.The initial thermal decomposition temperature T_i,the maximum thermal decomposition rate temperature T_p,and the final thermal decomposition temperature T_f of the prepolymer were measured by measuring the TG-DTG curve of the PA1212 prepolymer.The melting point and crystallization temperature of the purchased PTMG were measured.It was found that the melting point T_m and the crystallization temperature T_c of the PTMG850 were 8?and-8?,respectively,and the melting point T_m and the crystallization temperature T_c of the PTMG2000 were 14?and-6?,respectively.The molecular structure of the product was confirmed by infrared spectroscopy and nuclear magnetic resonance spectroscopy,and the product was PA1212-b-PTMG.The melting point T_m and crystallization temperature T_c of the soft and hard segments of the six PA1212-b-PTMG were measured by differential scanning calorimetry.It was found that the melting point and crystallization temperature of the hard segment of the soft segment were affected by the molecular weight of the soft and hard segments.By measuring the TG-DTG curve of PA1212-b-PTMG,it was found that the initial thermal decomposition temperatures of the six PA1212-b-PTMGs were all higher than 300?,and all had good heat resistance.Adjusting the molar ratio of different MDI and PTMG to the reaction,it was found that with the increase of MDI input,the prepared PA1212-b-PTMG will crosslink and find that the molar ratio of PTMG to MDI is 1,the PA1212-b-PTMG is made.The relative viscosity is the largest.The crystallization behavior and phase structure of PA1212-b-PTMG were investigated by variable temperature polarized light microscopy,variable temperature infrared spectroscopy and variable temperature XRD.It was found that the soft segment PTMG spherulites of PA1212-b-PTMG of PA2000 and PTMG2000 disappeared completely at 37.5?.The hard segment PA1212 spherulites completely disappeared at 166?,and it was found that the prepared PA1212-b-PTMG had a two-phase separated structure.