Interfacial Strengthening And Performance Optimization Of Waste Newspaper Fiber/HDPE Composite

The waste newspaper fibers are similar in the structure and properties to nature fibers,which have the high specific strength and rigid.The newspaper fibers are the ideal material to reinforce polymers to replace inorganic reinforcement material.It has significant influence in environmental protection and effective utilization of resources.However,the preparation of the composite materials is difficulty and the properties are poor due to the formation of agglomerates between fibers,caused by hydrogen bonds with each other.Therefore,the key to applying waste newspaper fibers to wood-plastic composites is to reduce the surface polarity of paper fibers and solve the problem of fibers agglomeration.This study modifies the waste newspaper fibers with sodium hydroxide(NaOH)and trichloromethylsilane(MTCS),respectively,to reduce the surface polarity.First,the effects of pretreatment on the physical and chemical properties of waste newspaper fiber and the properties of waste newspaper fiber/high-density polyethylene(HDPE)composite were studied systematically.Then the optimization scheme of the properties of the waste newspaper fiber/HDPE composite was studied.The contents and results of this paper are as follows:(1)NaOH and MTCS are used to treat waste newspaper fibers,to solve the problem of fiber agglomeration.The detection devices,such as scanning electron microscope,fourier infrared spectrometer,surface contact angle meter and thermogravimetric analyzer were used to analyse the changes of physical and chemical properties of fiber before and after pretreatment.Results show that both the pretreatment of NaOH and MTCS can solve the problem of fiber agglomeration and improve the dispersion of paper fiber.However,the waterproof property of the fiber was decreased,and the thermal stability was also greatly reduced after the treatment with the NaOH.MTCS pretreatment can effectively reduce the surface polarity of the fiber and increase its hydrophobicity.However,the high concentration of MTCS would decrease the thermal stability of the paper fiber and reduce the aspect ratio due to the damage of the fiber.(2)To investigate the effects of fiber pretreatment on the properties of waste newspaper fiber/HDPE composite,we prepared the composites with modified paper fiber and HDPE at the ratio of 4:6 and characterized the properties of composites with universal mechanical testing machine,cantilever beam impact tester,torque rheometer and thermogravimetric analyzer.Results show that NaOH and MTCS pretreatment of newspaper fiber can improve the interfacial compatibility of the waste newspaper fiber/HDPE composites in varying degrees.Meanwhile,the rheological property was greatly improved and the processing property was improved.The compatibilization effect of the modified with MTCS was better than that with NaOH,and the mechanical properties were also better.The water absorption of the two modified composites was up to the wood-plastic material standard(?5%).And the water absorption of the composites modified by MTCS was 0.31%,which was about 1/13 of that of NaOH and was far lower than the existing wood-plastic or paper-based composites.The MTCS concentration,4%(v/w),was the best choice to treatment the waste newspaper fibers after considering the properties of the material.On this condition,the flexural strength,tensile strength,notched impact strength and 24h water absorption rate were 22.88MPa,20.02MPa,8.39KJ/m~2 and0.46%,respectively.The comprehensive properties were much better than the paper plastic composites studied at present.(3)To obtain the optimal ratio of paper and plastic,the composite materials with different paper powder content were prepared.After comprehensive analysis of the mechanical properties,water absorption,rheological and thermal stability of the materials,the optimum ratio of paper and plastic was 5:5.On this condition,the flexural strength,tensile strength,notched impact strength and 24h water absorption rate were 26.65MPa,19.95MPa,5.76KJ/m~2 and 0.53%,respectively,which was up to the standard of Wood-plastic composites material.Meanwhile,under the similar properties and preparation conditions,the addition of paper powder was much higher than that of the present research.(4)We used maleic anhydride grafted polyethylene(MAPE)to form MTCS-MAPE complex reinforced interface to improve the interfacial bonding strength of waste newspaper fiber/HDPE composites further.The optimum addition amount of MAPE was 7%after the analysis of the properties of composites.On this condition,the flexural strength,tensile strength,notched impact strength and 24h water absorption rate were 34.31MPa,32.57MPa,6.42KJ/m~2 and 0.51%,respectively,which were increased of 28.7%,63.25%,11.45%,3.8%,respectively,compared with the composites without MAPE.The comprehensive properties were far higher than the standard of the wood-plastic composite material.