Study On Degradation Law Of LDPE/HA And LDPE/PP/HA Composites

Polyethylene(PE)usually has a molecular weight of more than 20,000,which is difficult to degrade,and its waste pollutes the environment.Humic acid(HA)is a polymer that can be photolyzed and degraded by microorganisms.Usually used as fertilizer(ammonium humate,potassium humate,sodium humate,etc.)to improve soil,polypropylene(PP)has excellent photodegradation performance.using PE,PP as matrix resin,HA as filler,it is unclear that the law of photolysis,microbial degradation to the three blend and whether three blend can help soil improvement.Therefore,LDPE/HA composites,LDPE/PP/HA composites and LDPE/AHA(ammonia humic acid)composites and LDPE/PP/AHA were studied by UV degradation experiments,water environmental impact experiments and microbial degradation experiments.The degradation of composite materials was studied and the following results were obtained:(1)High content of HA can improve the UV degradation performance of LDPE.After 2310 h of UV irradiation,the tensile strength of LDPE/HA composite strips with HA content of 65%,55% and 45%,respectively decreased by 16.9%,22.5% and 16.49%,and the elongation at break decreased by 45.83%,69.16% and 75.93%;The tensile strength and elongation at break of LDPE/HA composite splines with HA content of 35% and 25% showed oscillations during different irradiation times,indicating UV light of LDPE/HA composites at this HA content.There are multiple reactions during the degradation process,including cleavage of the LDPE molecular chain,cross-linking between the LDPE molecular chains,and cross-linking of the HA degradation products with the LDPE molecular chains.(2)Ammonia humic acid(AHA)can not promote the UV degradation of LDPE,and the UV aging life of the composite is prolonged.(3)When PP is added to LDPE/HA composite,the content of PP is 9%~13%,the composite exhibits good UV degradation performance,and the degradation effect is better than LDPE/HA composite;To the LDPE/AHA composite,When PP is added,the content of PP is 9% to 13%,and the composite exhibits good UV degradation performance,but mainly caused by degradation of PP.(4)In the water environment impact experiment,after the composite materials were placed in pure water and organic humic solution for 120 days,the composite materials of several formulations slightly lowered the pH of pure water and organic humic solution,and the migration of HA and AHA from the matrix resin.The extent of the reaction and the reactions that occur.The four composite materials slightly increase the acidity of the acidic soil,but do not cause soil compaction.(5)The pH of the saline solution showed an oscillating change during the 120 d period in the alkaline environment(salt solution).After 120 d,the pH of the saline solution was slightly increased,indicating that the four composites did not improve the saline soil.(6)In the microbial degradation experiment,when the HA content is 65%,it was found that Trichoderma viride,Pseudomonas fluorescens and Aspergillus fumigatus have a certain degradation effect on LDPE,In the microbial environment,both LDPE has degradation and cross-linking.HA ammoniation can increase the degradation of LDPE by Pseudomonas fluorescens and Aspergillus fumigatus;Trichoderma viride,Pseudomonas fluorescens and Aspergillus fumigatus may degrade propylene.(7)During the environment of Trichoderma viride 120 d,LDPE/PP/HA composites had the best degradation effect,and the tensile strength and elongation at break of the splines decreased respectively by 13.03% and 43.53%;The degradation of LDPE/PP/AHA composites was best in 120 days of Bacillus,and the tensile strength and elongation at break of it decreased respectively by 8.64% and 17.81%;during the Aspergillus fumigatus environment 120 d,the degradation effect of LDPE/PP/AHA composites was the best,its tensile strength and elongation at break decreased respectively by 14.38% and 14.16%.