Investigation On The Degradation Behavior And The Method Of Rapid Detection The Degradation Performance Of PLA

Four kinds of Polylactic acid(PLA) provided by the 863 project team were degraded by traditional ways including soil degradation, simulated exposed in natural environment degradation and hydrolytic degradation to investigate the degradation behavior and degradation performance of PLA in this article. Additionlly, a method of hydrothermal degradation which could degrade and detection the degradation performance of PLA rapidly was presented in this paper. And the influence of degradation temperature and pH value of solution were studied. Meanwhile, weight loss of PLA and the degradation time were nonlinear fitting according to the theory of equation model to detect the reliability of degradation performance. The degradation behavior and degradation performance of PLA were analyzed by weight loss,infrared spectra(IR), X-ray diffraction pattern(XRD), gel permeation chromatography(GPC),scanning electron microscopy(SEM) and so on. The results showed that:(1) The weight loss of Revode 101, Revode 210, Revode 190 and Revode 290 degraded in soil after 3 months were 9.52%, 5.93%, 6.50% and 4.76%, respectively.The largest tensile force of the four kinds of PLA degraded in the ultraviolet aging oven reduced to 0 when degraded 15 days, 30 days, 20 and 30 days, respectively. The weight loss of the four kinds of PLA degraded in acidic, neutral and alkaline solution at room temperature after 12 weeks were less than 10%, and the PLA were degraded fastest in alkaline solution. The surface of PLA films became rough in the process of degradation which known by the analysis of surface morphology. Through the analysis, the crystallinity of PLA films risen gradually in the process of degradation.Through the analysis of the molecular structure, the molecular weight and the concentration of ester bond of PLA films reduced in the process of degradation. The results show that was that the degradation performance of four the PLA were Revode101 > Revode210 > Revode190 > Revode290, and the degradation speed was slow as the mass loss rate was below 10% even buried in soil 3months.(2) Hydrothermal degradation was used to quickly detect the degradation performance of PLA films and the the influence factors were studied. The results showed that the temperature was the main factor influencing the degradation of PLA by hydrothermal degradation, because with the increase of temperature, the influence of pH became weaker. The detection time reduced from 8 hours to 2 hours when the degradation temperature rose from 130? to 170?. The weight loss of Revode 101,Revode 210, Revode 190 and Revode 290 degraded 2 hours by hydrothermaldegradation at 170 ? were 69.86%, 35.6%, 50.2% and 69.86%, respectively. The result of degradation performance were not influenced by environmental temperature and pH value by hydrothermal degradation. Hydrothermal method compared with traditional degradation method, its degradation time reduced from 3 months to 2 hours,the degradation rate increased from less than 10% to the highest 70%, and the results was Revode101 > Revode210 > Revode190 > Revode290, which illustrated that hydrothermal method could accelerate the degradation of PLA.(3) The feasibility analysis of hydrothermal degradation were proved by nonlinear fitting the weight loss of PLA and the degradation time according to the theory of equation model. The results showed that the experimental data of hydrothermal degradation were in accordance with the theoretical model and the statistical parameter value R2 were close to 1. The hydrothermal degradation degradation kinetics constants of Revode 101, Revode 190, Revode 210, and Revode290 which calculated by the model were 8.217, 4.262, 4.853 and 3.471 respectively, which could illustrated that the degradation speed was Revode101 >Revode210 > Revode190 > Revode290. The results obtained from the model,traditional degradation methods, and hydrothermal degradation were consistent, thus,the method of hydrothermal degradation was feasible for detection the degradation performance of PLA.The method of hydrothermal degradation had advantages as short testing cycle,simple operation and low cost compared with the traditional degradation, so, it has application prospect. Therefore, this research results for rapid detect the degradation performance of PLA laid a foundation.