Physical Foaming And Thermal Conductivity Regulation Of Polysuccinate Fatty Alcohol Ester Ionomer

High performance polymers have gradually replaced metal materials because of their advantages such as light weight and easy processing,but their low thermal conductivity limits their applications in the field of highly integrated electronics.The crystalline morphology and molecular chain structure of the polymer will significantly affect the thermal conductivity.Polymer with different macroscopic properties can be obtained by designing molecular chain structure and changing crystalline morphology.Phosphorus-containing ionic groups(PCIG)were introduced in Poly(butylene succinate)(PBS)and Poly(ethylene succinate)(PES)and Poly(decamethylene succinate)(PDS).By changing the parameters of ionic group content and the molding process,the PBS ionomer crystallization behavior and the mechanism of heat conduction performance were explored.And the effects of the molecular chain structure and condensed structure on the properties of ionomer heat transfer mechanism were obtained.In chapter three,phosphorus-containing PBS ionomer(PBSIs-K)was synthesized by condensation polymerization.The PBSIs-K foams were fabricated by sc-CO₂ via batch foaming method.The effects of PCIG on the crystallization,compression,thermal conductivity and thermal stability of PBSIs-K foams were investigated.Strikingly,owing to the physical cross linking by PCIG aggregation,the significant increases in the melt strength generated stronger surface tension and orientation force.Consequently,FPBSI7.5-K(7.5mol%PCIG content)achieved about 100%closed cell structure,and high orientation for cells.Compared with those of PBS foams,FPBSI7.5-K achieved 8-folds and 4-folds increases in thermal conductivity and compressive strength,and their values were 315 m W/(m·K)and 3.5 MPa,respectively.The mechanism for FPBSIs-K with significant improvements in thermal conductivity and compressive strength were proposed.Moreover,the incorporation of PCIG promoted FPBSIs-K to form a stable char layer and inhibit the release of combustible gaseous pyrolysis products.According to our previous research,PBSIs-K with larger spherulites displayed higher thermal conductivity.In chapter four,to prepare PBSIs-K with larger spherulites,a series of anisotropic PBSI1-K were prepared by compression molding.The relationships between the compression molding pressure and properties,including thermal conductivity,crystallization behavior and chain orientation degree of PBSI1-K films were investigated.Strikingly,PBSI1-K film fabricated at 2500 psi pressure,denoted as PBSI1-K-2500,achieved 4-folds increase in in-plane thermal conductivity when PBS was used as the contrast.The impressive improved thermal conductivity(542 m W/(m·K))in horizontal direction are ascribed to the fact that PBSI1-K-2500 obtained the large spherulite diameter(517 um)and high chain orientation degree(1.90).Furthermore,we introduced graphene into PBSI1-K and the thermal conductivity of GNS/PBSI1-K composites have also been discussed.In order to investigate the effects of different monomers on the crystallization behavior and thermal conductivity of the polysuccinate fatty alcohol ester ionomer.In chapter five,PES and PDS phosphorus-containing ionomer(PESIs-K and PDSIs-K)were synthesized by condensation polymerization.The effects of PCIG on the crystallinity,crystallization behavior and thermal conductivity of PESIs-K and PDSIs-K were investigated.The results demonstrated that the crystallinity of PESIs-K increased first and then decreased with the increase of PCIG concentration.PESI1-K displayed the highest crystallinity(41.8%)and the largest spherulite size.The crystallinity and spherulite size of PDSIs-K decreased with the increase of PCIG concentration.The crystallization mechanism of PES and PESIs-K was same,exhibiting non-thermally nucleated three-dimensional spherulites.The crystallization rate of PESIS-K increased first and then decreased with the increase of PCIG concentration.PESI1-K had the fastest crystallization rate.The semi-crystallization time of PESI1-K at 73?decreased from11.2 min(PES)to 5.3 min.PDS,PDSI0.5-K,PDSI1-K and PDSI2-K exhibited non-thermally nucleated three-dimensional spherulites,while PDSI3-K displayed three-dimensional spherulite growth of thermal nucleation.The crystallization ability of PDSIs-K decreased with the increase of PCIG concentration.The thermal conductivity results showed that the thermal conductivity of PESIs-K and PDSIs-K was related to the crystallization property.The large size of spherulites and high crystallinity contributed to the improvement of thermal conductivity.The thermal conductivity of PESI1-K increased from 176 mW/(m·K)(PES)to 214 mW/(m·K).