Study on the Degradation of Unsaturated Polyester Resin and Fiber Reinforced Polymer in Hot Compressed Water
|School||Harbin Institute of Technology|
|Course||Polymer Chemistry and Physics|
|Keywords||HCW Degradation UPR FRP Reaction kinetics|
Fiber reinforced plastics (FRP) are used extensively in high pressure pipelines or vessels and vehicles such as watercrafts and automobiles. However, the high output of FRP to meet the rising market demands has produced a great amount of UPR wastes, which would bring serious burden to the environment. Unsaturated polyester resins (UPR) are the thermoset resins of greatest consumption in production of FRP. Therefore, it is necessary to propose a recovery processing to dispose the FRP wastes and obtain the renewable resources.In this article, the degradation of UPR and FRP in hot compressed water (HCW) is discussed. This article comprises three parts: degradation in HCW, characteration of reaction products and analyse of reaction kinetics. The apparent degree of degradation and factual degree of degradation were the main parameters to assess degradation efficiency. Frontier Transform Infrared Spectroscopy (FTIR), Thermogravimetry (TG), Gas Chromatography-Mass Spectrum (GC-MS), Liquid Chromatography- Mass Spectrum (LC-MS) and High Performance Liquid Chromatography (HPLC) were employed to analyze water products and solid products. The kinetic models in literatures were employed in this article to describe the degradation rate of UPR in HCW.The reaction time and the reaction temperature had positive influence to the degradation of UPR and FRP in HCW. In the experiments of UPR decomposed in HCW, the optimum water volume is 30ml. While in the experiments of FRP decomposed in HCW, the optimum water volume is 40ml. When the FRP decomposed in HCW at 350℃, 40ml H2O for 60min, the apparent degree of degradation was 74.32% and the factual degree of degradation was 90.82%; the surface of recycled glass fiber was relatively pure, and the resin content that remains on the surface of recycled glass fiber was only 6.52%. The alkali NaOH was significant in enhancing the degradation of UPR and FRP in HCW, but at the same time it can damage the glass fiber to some extent.When the reaction temperature was lower than 280℃, the network structure of crosslinked unsaturated polyester resin did not have much distinct destruction with exception of broken ester bond of phthalate. Phthalic acid and acetic acid were found in water phase. When the reaction temperature was between 280℃and 310℃, the chemical bonds of succinic acid ester were broken and cyclized to anhydride. Phthalic acid and 2,3-bis(2-phenylpropyl) succinic acid were found in water phase. When the reaction temperature was between 310℃and 350℃, benzoic acid was found in water phase. When the temperature was higher than 350℃, the crosslinked network structure of crosslinked unsaturated polyester resin was completely destroyed. The solid products could dissolve in the ethyl acetate and water phase products were mainly benzoic acid.By studying the degradation of UPR in HCW between 280~310℃, the rate constants were 0.00932s-1, 0.01249s-1, 0.01549s-1 and 0.01720s-1, respectively. And the apparent activation energy of degradation reaction was worked out through Arrhenius equation. In the experiments, the value of activation energy was 55.21kJ/mol.