Study On The Structure And Properties Of Plant Fibers Modified Nylon-6 Prepared By In-situ Polymerization

In this paper, nylon6(PA6)/ plant fibers(PF) composites were first preparated by the in-situ polymerization, the technology of preparation of the PA6/PF composites was studied and the structures and properties of the PA6/PF composites were characterized, and then the affection of the pretreatment of plant fiber to the properties of the composites of the composites was studied.PA6/PF composites were prepared at low temperature, the complex catalyst was picked out among four kinds of catalyst firstly, The effects of the amount of catalyst, the content of water, the vacuum, reaction time, reaction temperature, reaction time, PF content on the polymerization were studied. The optimum technology was determined by analysis of single factor: the content of catalyst is 1wt%, the reaction temperature is 180℃, the reaction time is 7h, the content of water is 5wt%, the vacuum is 0.04～0.06Mpa, the content of PF is less than 1.25wt%. The viscosity average molecular weight of the PA6/PF composites preparated at the above condition. The PA6/PF composites were characterized by IR, SEM. The results show that the structures of pant fibers remain unconverted after polymerization.The pulp fibers were pretreated by alkali and bulk graft, On bulk graft, caprolactam had been graft polymerized onto surface of pulp fibers, TG analysis shows that the temperature at the biggest weight loss rate of pulp fibers promoted 13.4℃and the rate of weight loss reduced 4.2%. The properties of the PA6/PF were studied, the results are as follow, the mechanical properties of PA6/PF composites would be promoted if the pulp fibers were pretreated, and the graft modification is better than alkali pretreament. The tensile strength would be highest at the fibers'content of 1wt%, and the composites remained tropism, and the untread, alkali and bulk graft treated fibers/PA6 composites'tensile strength were 60.3MPa, 64MPa, 68MPa, which peromoted 9.6%,16.4%,23.6% than pure PA6 respectively. Pretreatment would improve the impact strenght of PA6/PF composites, the impact strenght of alkali and bulk graft treated fibers/PA6 composites were 8.9, 12 kJ/m2 as the content of the fibers was 2.5wt%, which promote 21.3%, 63.5% respectively of the untread PF composites. The Vicat softening point(VSP) raise and then fell with the increase of the content of fibers, which turned hightest at 2.5wt%, VSP of the untread, alkali and bulk graft treated PF/PA6 composites were 197.3℃, 198℃, 200℃, it was 12.4℃, 13.3℃, 16.3℃higher than that of pure PA6. SEM of the broken surface of composites shows that there was good interface felt force between bulk graft treated fibers and PA6 resin.