Block Polymerization And Performance Of Biodegradable Thermoplastic Elastomers

Polybutylene succinate (PBS) is a white semi-crystalline polymer with good degradation properties.There are hydrodegradable ester groups in the main chain structure of PBS molecules,which are decomposed by water,air,microorganisms and other factors in the natural environment,and finally form CO2 and H2 O.This paper takes the synthesis of succinate and 1,4-butanediol polymer as a hard segment polyester prepolymer(HPE),a highly compliant aliphatic polyester soft segment polyester prepolymer(SPE)polymerized by a variety of aliphatic dibasic acids and dibasic alcohols,and a hexamethylene diisocyanate(HDI)as a chain expander,and a biodegradable thermoplastic elastomer(BTPE)was obtained through the chain expansion block reaction.The test results show that BTPE has excellent mechanical properties and degradability.The following are the specific research efforts:Preparation and performance of soft and hard segment polyester prepolymers.He was prepared by 1,4-butanediol and butanediol,and SPE was synthesized by succinic acid,adipic acid,sebacic acid,1,3-propanediol and 1,4-butanediol,and a series of HPE and SPE with different molecular weights were designed and prepared by adjusting the proportion of monomers.Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance hydrogen spectrometer(1H-NMR),polarization microscopy(POM),wide-angle X-ray diffractometer(WXRD)and other analytical results show that HPE is a hydroxyl-terminated polyester prepolymer with strong crystallization performance,suitable for the hard segment structure of BTPE,while SPE is a viscous flow state at room temperature,does not have any crystal properties,and is suitable for the soft segment structure of BTPE.Synthesis and performance study of BTPE.HPE and SPE were prepared by using hexamethylene diisocyanate(HDI)as the chain spreader and melt chain expansion method.The crystallization properties,mechanical properties,thermal properties and other factors of BTPE are discussed.The results show that the crystallization performance of BTPE is improved with the increase of HPE content or molecular weight,and its crystal morphology becomes clearer,but with the decrease of SPE molecular weight,the crystallization performance decreased first and then increased,the tensile strength was 1.4-45.9 MPa,the elongation at break was 115%-1559%,and the 100% elastic recovery rate was between 65.1%-95.7%.And AFM studied the microscopic morphology of BTPE and determined that BTPE is a "sea-island" two-phase structure.Biodegradable properties of BTPE.After degradation in 1 mg/m L of lipase for 8days,the mass loss rate of BTPE was between 35% and 89%,and its mass loss rate was inversely proportional to the crystallization performance of BTPE,and the degradation process would cause the degradation of the p H of the degradation environment to decrease;BTPE was the fastest under alkaline conditions;after 30 days of degradation in p H=6.86 phosphate buffer solution,the mass loss rate of BTPE was between 1.55% and 6.26%,and its degradation law was related to its water absorption The water absorption rate of BTPE is directly proportional to the dosage of chain extender and the content of HPE,and inversely proportional to the molecular weight of HPE,and with the decrease of SPE molecular weight,the water absorption of BTPE is increased after the first decrease.