Study On Preparation And Properties Of PET Micro-fibrids Induced By Anti-solvent

In recent years,a great deal of wastes was produced with the increase of the use of disposable polyester bottles.The waste polyester is difficult to degrade rapidly and to pollute the environment easily.Therefore,the waste polyester recycled and high-value application has been gradually attracted people's attention.Meanwhile,the polyester fiber and the functional material are widely applied to the papermaking,textiles,filtration and energy efficient buildings,due to their good mechanical properties,heat resistance and chemical stability.However,there are few kinds and high production cost of polyester fibers in the market.In order to expand the application field of waste polyester,the goal of high-value application of waste polyester was achieved.In this study,PET micro-fibrids as bonding reinforcement materials with uniform size and good morphology were prepared by anti-solvent induced forming method.Moreover,a new type of PET-based composite phase change energy storage material was prepared by using PET polymer as the supporting material of fatty acid phase change material based on anti-solvent induction technology.In this paper,starting with the correlation of various influencing factors of fibrids forming process,the dissolution of PET polymer in solvent and the process of fibrids formation induced by anti-solvent were studied.On the basis of this,the effect of the concentration of PET solution,the shear rate and the ratio of anti-solvent on the morphology,size distribution and crystallization properties of the fibrids were investigated.The results showed that increasing the fluid shear rate and the content of glycerol in anti-solvent,decreasing the concentration of PET solution were favorable to obtain fine and uniform fibrids.However,micro-fibrids with high crystallinity can be obtained by increasing shear rate and decreasing the content of glycerol in anti-solvent.In order to investigate the effect of PET micro-fibrid on the structure and properties of PET paper,five kinds of PET micro-fibrid were obtained by screening,and then we discussed the morphological parameters,crystallization properties of the micro-fibrid,physical structure and mechanical strength of PET paper.The results showed that PET paper-based materials with excellent mechanical and electrical properties that were prepared by using R100PET fibrid.At present,the specific surface area of R100PET fibrid was 7.93 m²/g,and curl index was 16.7%,and the tensile index was 44.63 N·m/g,the elongation was7.96%,and dielectric strength was 6.34 kV/mm of PET paper.The results indicated that PET paper exhibited high mechanical strength and electrical properties,and R100PET fibrids could be used as a kind of composite reinforcing material with excellent properties.The surface morphology,specific surface area,crystallization properties and paper-forming properties of Lab-made PET fibrids and commercial PET pulp were discussed to investigate paper-forming properties of Lab-made PET fibrids.The experimental results showed that Lab-made PET fibrids were ribbon,fiber morphology soften,lightweight and thinner,larger specific surface area,compared with the commercially available PET pulp.The crystallinity of the fibrid was 36.10%,and the dispersion of fibrid suspension reached 97%,which were helpful to improve the evenness and mechanical strength of PET paper.Compared with the paper made from commercial PET pulp and PET chopped fiber,the tensile index,tear index and elongation of Lab-made PET fibrid and PET chopped fiber were increased by 6.3%,11.2%and 38.8%,respectively.The results showed that the Lab-made PET fibrids presented high composite reinforcement effect,which was beneficial to the formation of PET paper-based materials with higher mechanical properties.Finally,considering the versatility of PET micro-fibrids,PET-based composite phase change material?CA-LA-PA/PET/SiO₂ composite phase change fiber?was successfully prepared based on anti-solvent induction process,in which PET polymer was used as the supporting material,and CA-LA-PA ternary eutectics was introduced as a new phase change heat storage material.The effects of the content of CA-LA-PA on the morphology and thermal properties of the composite phase change fibers were studied systematically.The results showed that with the increase of the mass ratio of fatty acid ternary eutectic?CA-LA-PA?in the composite phase change fiber,the morphology of the fiber varied from fibrous to fiber bundle,and the melting enthalpy and crystallization enthalpy of the composite phase change fiber were increased gradually.When the mass ratio of CA-LA-PA/PET was 150/100,the maximum melting enthalpy of the composite phase change fiber was 69.20 kJ/kg,enthalpy of crystallization of the composite phase change fiber was 68.14 kJ/kg,which indicated that the PET-based composite phase change material displayed higher thermal storage properties and manifested potential application value in energy efficient buildings and thermo-regulating fibers.