Properties And Degradation Behavior Of Modification Fining Jute Fiber Reinforced PLA Composites

With the development of the technology and progress of the human civilization, people's demanding for environmental protection is becoming higher and higher. So the development of high performance and completely biodegradable composites, one of the hot global research topics in recent years, has great significance to sustainable development. Jute in our country is rich in resource, abundant in variety, and economical in price, and jute fibers have potential value in industrial applications as reinforcement of the composite for its high strength and modulus. With good biocompatibility and low melting point, PLA is easy to process and can be a good choice as the supporting material in the composites. Composite made of jute fibers and PLA, can not only reduce costs effectively, but also promote the development and application of new biodegradable materials.In this paper, jute fiber/polylactic acid (PLA) composite was manufactured by the method of mold pressing process. The mold pressing process of the composites, the effects of jute fiber modification on the properties of the composites, as well as the degradation of the composites and etc, were researched in this paper, and they are as follows:Mold pressing process of the composites: The mechanical properties of the composites and the tensile fracture surfaces were tested and studied. It was found that when the mold pressure was 12Mpa, mold temperature155℃, mold time25min, and cooling time 4min, composite with the best comprehensive mechanical properties was obtained, and therefore the experiments were done under this condition. Since the interfacial adhesion between jute fiber and PLA matrix is poor, modification is needed to improve the interfacial adhesion, as well as the mechanical properties of the composites. The effect of jute fiber mat modification on the properties of the composites: The effects of alkali treatment, silane coupling agent treatment, and fiber contents on the properties of the fine jute fiber/ PLA composites were studied. Experiments were done with different alkali treatment parameters and silane coupling agent treatment parameters. The result shows that, with the increase of the alkali treatment time and alkali concentration, the tensile breaking strength of the fiber mats increased first and then decreased; while the mechanical properties of jute fiber mat was declined with the increasing silane coupling agent treatment time and silane coupling agent concentration.Both the two kind of modification treatments can improve the interfacial adhesion between jute fiber and PLA matrix effectively, resulting in the enhancement of the mechanical properties of the composites, and it is also proved that silane coupling agent treatment has a better effect than alkali treatment. After 2h modification treatment by 1.5% silane coupling agent solution, composite with the best mechanical property was achieved.Through analyzing the effect of fiber volume contents on the mechanical properties of the fining jute fiber/PLA composites, we can conclude that too high or too low fiber content both has an adverse effect on the mechanical properties of the composites, and when the fiber volume content is 40%, the composite has the best mechanical property.The effect of jute yarn modification on the properties of the composites:The research was on the effects of alkali treatment, silane coupling agent treatment, yarn arrangement etc on the properties of the fine jute yarn/PLA composites.Fiber in the modified jute yarns was studied by SEM, FTIR and the mechanical properties test. The results show that after the alkali treatment, the fiber surface becomes rough and fine, and after the silane coupling agent treatment, there is a layer of molecular film covered on the fiber surface. Both the two modification treatments lead to the decline of the O-H content, slight increase of the cellulose content, and removement of lignin. With the alkali treatment time and alkali concentration increasing, the tensile breaking strength of the yarn increased first and then decreased. After the silane coupling agent treatment, the tensile breaking strength of the yarn was improved. Through the mechanical properties testing of the modied jute fiber /PLA composites, we find that, the effect of silane coupling agent treatment on the mechanical properties is better than that of alkali treatment. Jute yarn/PLA composite with the best mechanical property was obtained after 2h modification treatment with 1.5% silane coupling agent solution.Through the study of the effects of arrange means, arrange density and thickness of the fine jute yarn on the tensile mechanical properties of composites, it was found that with the increasing of the yarn arrange density, the mechanical properties increased first and then decreased. The composite gets the best mechanical properties when the arrangement density reached to 25 / cm, as well as when yarns cross-arranged 90°, and composites reinforced with thick yarns have better mechanical properties.The degradation behavior of the fine jute fiber/PLA composites: The degradation behavior of the fine jute fiber/PLA composites in activated sludge was studied; the effects of jute modification and fiber contents on the degradation of the composites were analyzed. The research shows that, after modification of jute mats and yarns, the degradation rate of the composites slow down, and the degradation rate is as follows:UJ/PLA>AJ/PLA>SJ/PLA. With the increase of the fiber volume contents, the degradation rate of the composites raised.