| With the continuous improvement of human living standards,people in the daily consumption widely used various objects made of polyethylene(polyethylene terephthalate PET),these items became waste after being used and being discarded directly to the naturel environment,due to its physical and chemical properties of stability,extremely difficult to natural degradation,thus cause great pollution to the ecological environment.At the same time,with the rapid development of society,the demand for unsaturated polyester resin with good properties is increasing.Based on these two reasons,this paper chooses waste PET bottle flakes as raw materials and USES them to prepare modified unsaturated polyester materials after alcoholization.It is of great significance to solve these two problems simultaneously.In this paper,ethylene glycol was used as the alcoholysis agent in the catalyst of zinc acetate.The study showed that the best conditions for PET degradation were: the mass ratio of PET to ethylene glycol was 1:2,the amount of zinc acetate as catalyst was 3.0% of the mass of PET,the reaction temperature was 200 ?,and the reaction time was 2.5h.Under the experimental conditions,the maximum alcoholic rate of PET was about 84.5%.The results of infrared spectroscopy and high performance liquid chromatography showed that the main product of alcoholysis was the mixture of ethylene terephthalate glycol and its lower compounds.Using the PET alcoholysis product as a raw material,it was found that the amount of the initial alcohol used in the reaction and the two different mass ratio anhydrides had a significant influence on the properties of the synthesized unsaturated polyester resin by reacting with maleic anhydride.When PET was reacted with maleic anhydride in a mass ratio of 65:35,the resulting unsaturated polyester has a molecular weight Mn of from 2,100 to 2,500.The weight average molecular weight Mw was 5100-6000,the corresponding molecular weight distribution was 2.35,the flexural strength of the material was 103 MPa,the flexural modulus was 2970 MPa,the tensile strength was 55.3 MPa,the tensile modulus is 2.43 MPa,and the Barcol hardness was 37.The heat distortion temperature was 83?,the impact toughness was 5.46 KJ/m2,the elongation at breakwas 3.5%,and the comprehensive performance of the material was excellent.The use of fumed silica as a modifier to modify unsaturated polyesters has been found to increase the thixotropy,tensile strength,modulus of elasticity and impact strength of unsaturated resins as the amount of silica increases.When the amount of silica used was 2%,the tensile strength of the modified resin was improved by about 140% compared with the strength of the unmodified resin,the elastic modulus was increased by about 5.18 times,and the impact strength was improved by about 2.7 times.However,the elongation at break of the resin decreased.When the amount of silica used was 0.5%,the corresponding elongation at break of the resin decreased by about 14.5%,and the downward trend was more obvious,but with its further increase.The decrease in elongation at break of the resin tends to be slow.At the same time,the study also found that dispersion speed and dispersion time have a great influence on the thixotropic properties of unsaturated polyester. |
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