Preparation And Properties Of Bisphenol-type Polyarylates

Among special engineering plastics,polyarylates are an important class of high-performance thermoplastics with good chemical resistance,mechanical properties and ultraviolet shielding,and are widely used in aerospace,information technology and electronics industries.Benefiting from the accelerated construction of 5G communications,the market demand for polyarylenes continues to grow.However,at present,China is highly dependent on imported polyarylate materials from Europe and the United States,and cannot mass-produce polyarylate materials,so the work related to the preparation of polyarylate needs to be paid attention to.In this paper,bisphenol-A polyarylates were prepared by interfacial polymerization and melt polymerization processes,and polymers with different molecular weights were synthesized by regulating the ratios of reaction components,and the relationship between the structure and properties of polyarylates was systematically studied.To address the problems of poor processing performance and low solubility of bisphenol-A polyarylates,we prepared bisphenol-A/bisphenol-B copolyesters by introducing asymmetric bisphenol-B structural units into the main chain of bisphenol-A polyarylates from the perspective of molecular design.Meanwhile,in order to meet the experimental goal of batch production of polyaryl esters in the laboratory,a melt polymerization process combined with industrial production was used,and the differences between the two paths of interfacial polymerization and melt polymerization for the synthesis of polyaryl esters were systematically compared,and data were accumulated for the next pilot test.The above work was accomplished by three main parts as follows.（1）Bisphenol-type polyarylates（bisphenol-A polyarylates and bisphenol-B polyarylates）were prepared by interfacial polymerization.The functional groups and chemical structures of the bisphenol-type polyarylates were characterized by FT-IR and NMR.The analysis by XRD test showed that the presented bisphenol-A type polyarylate（PAR）had continuous strong diffraction peaks at 12-25°,and the structure of PAR aggregated state was crystalline,and the results showed that the PAR molecular chain was rigid.the TGA and DSC test results showed that the initial thermal decomposition temperature of PAR was up to 471°C and the maximum T_gwas 210°C,which had good thermal properties.The dissolution test in organic solvents showed that PAR was only partially soluble in chloroform and dichloromethane,and the results showed that the dissolution performance was poor.can reach 458℃,and the maximum Tg is 202℃,which is not much different from the thermal performance parameters of PAR,and also has good thermal performance.The dissolution performance test shows that PBR can be dissolved in polar solvents and halogenated hydrocarbon solvents at room temperature,and the dissolution performance is good.According to the results of mechanical properties and UV-Vis test,the tensile strength of PBR film samples is 40.54-50.52 MPa,Young’s modulus is up to 1701.18 MPa,and the film transmittance is up to 99.73%,the performance parameters are obviously better than the commercial U-100,which shows that PBR has good mechanical properties and light transmittance.With the introduction of IPC,the same effects on properties were observed in PAR and PBR systems,i.e.,a decrease in molecular chain rigidity,an increase in solvent properties,an increase in mechanical properties and light transmission properties,and a decrease in thermal stability.Specifically,the dissolution of bisphenol type polyarylates in some organic solvents required heating conditions changed to soluble at room temperature,and the tensile strength of PBR increased by10 MPa,Young’s modulus increased by nearly 400 MPa,and the light transmission increased by about 10%,while the initial thermal decomposition temperature of PAR decreased by 180°C and that of PBR decreased by only 10°C.The difference in the initial thermal decomposition temperature of polyarylates is caused by the difference in the structure of bisphenol monomer.（2）Polyarylate copolymers（BPAR）containing bisphenol-A/bisphenol-B structures were designed and synthesized by an interfacial polymerization process.The molecular weights(M_n=7362-44413 g mol^-1,M_v=16250-59859 g mol^-1)and characteristic viscosities(ηinh=0.16-0.53 d L g^-1)of the series of copolyesters BPAR were obtained by GPC and Uhr’s viscosity tests,which satisfied the characteristics of polymers.The chemical structure of the copolyester was also characterized by NMR and FT-IR.XRD test results showed that the copolyester had no sharp diffraction peaks in the tested range,the structure of the physical phase was amorphous,the molecular chain rigidity was low,and the crystallinity was poor.According to the TGA and DSC tests,it was found that the initial thermal decomposition temperature and maximum thermal decomposition temperature of the copolyester showed a trend of increasing and then decreasing due to the introduction of bisphenol-B structure into the PAR main chain,reaching a maximum of 460.9 and 506.4℃respectively,but the overall decrease was small and controlled within 10℃,and the Tg of the copolyester decreased by nearly 35℃due to the influence of the reduced rigidity of the molecular chain.Compared with the industrialized commercial U-100,the mechanical properties of the co-polyester performed more excellent.Among them,the tensile strength of the film samples increased by 18 MPa and Young’s modulus increased by 340 MPa compared with U-100.And the transmittance of BPAR was good,and the transmittance of BPAR90 was close to or better than that of U-100,in which the transmittance of the film at 450 nm reached 98.41%.（3）Bisphenol-A polyarylates（OPAR）were prepared by melt polymerization.The experiments were carried out in two steps,firstly,the bisphenol-A was acetylated to obtain the bisphenol-A diethyl ester,and then the OPAR was prepared by high temperature melt ester exchange method.the successful preparation of the polyaryl esters was demonstrated by the structural characterization of OPAR by IR and NMR.the XRD test results showed that the OPAR had strong and sharp diffraction peaks in the tested range,indicating that the OPAR is highly crystalline with a crystalline molecular structure and high rigidity of molecular chain.According to the TGA and DSC tests,the initial thermal decomposition index of OPAR was up to 370.13℃and the T_gwas up to 165.03℃,which showed that OPAR has good heat resistance.With the introduction of the intermediate benzene substituted structure of OPAR system,the rigidity of the main chain of the polyarylate decreased,leading to the decrease of thermal stability,the initial thermal decomposition temperature dropped to 80°C and Tg dropped by 15°C.The structure of the physical phase changed from the crystalline state to the amorphous form,which was reflected in the improvement of the dissolution performance.Compared with the interfacial polymerization system,the melt polycondensation was limited by the objective experimental conditions,the overall polymerization degree was lower,the OPAR viscosity was in the range of0.06-0.11 d L g-1,the number average molecular weight was 2190,the heavy average molecular weight was 2581,and the molecular weight distribution index was 1.17.and the thermal performance was poorer,the difference in the initial thermal decomposition temperature was nearly 100°C.Through the above experimental work,we have mastered the method of interface polymerization and melt polymerization to prepare polyarylate,and through copolymerization modification design to optimize the molecular structure of polyarylate,improve the performance of polyarylate,combined with the practical application,further expand the application range of polyarylate.Figure[35]table[21]reference[97]...