The Performance Study Of Modified Cotton Stalk Bast/polylactic Acid Flame-retardant Composites

For the material, strength determinedits purpose.C hanged with the development of material, composite material industry was also the wind to blow the environmental protection, natural fiber through the "dongfeng" gradually began to occupy people’s horizons. And with the development of economy, the concept of low carbon, environmental protection was more and more thorough popular feeling, the light weight, high strength, low cost green materials demand by people. Polylactic acid was a kind of biodegradable material, in order to expand the scope of its use, at the same time guaranteed the biodegradable properties, it could be made with natural fibre composites.The original project was to blend the waste cotton leather fibre and poly(lactic acid)(PLA), at the same time added flame retardant to make automobile interior trim plank named “Study on Cotton Stalk Bast Fibers reinforced PLA automobile interior lining board”. Then,under the condition of without adding cross- linking agent, the tensile strength was 45.70 MPa, flexural strength was 58.57 MPa, impact strength was 10.52KJ/m2, LOI was 28.37, Fogging of the board was 1.28mg(<2mg),and the HDT was 162.14℃. All met the requirements of strength of automobile interior trim panels(automotive interior trim board standard tensile strength was greater than 20 MPa, bending strength was greater than 25 MPa, the notched impact strength was greater than 70 J/m2, limiting oxygen index for the LOI value by more than 26%, the requirement of atomized value was less than 2 mg, thermal deformation temperature was above 100 ℃).But due to surface reverse polarity for natural fibers and the polylactic acid, and the composite material mechanics performance although had reached the requirement of car interior trim panels after addition of flame retardant, but beyond the scope of small.In order to make the interior trim panels of more excellent performance, this topic improved compatibility of matrix and reinforcing fiber using both chemical and physical methods, thus increased its mechanical performances.First, adopted the method of chemical coupling modified cotton leather fiber, using reactive groups of the coupling agent molecules, and with the hydroxy reaction on the fiber surface, reduced the surface polarity, make fibers could strengthen the compatibility with polylactic acid. And to enhanced the structure of large molecules of polylactic acid(PLA) and fiber by adding montmorillonite and micro fibrillating fiber.With coupling agent modified cotton leather fibre with orthogonal experiment focused on the notched impact strength, took into account tensile strength and bending strength, orthogonal experiment of L9(34) was done and multiple sets of single factor experiment, analyzed the influence of mechanical properties of the composites according to the types of coupling agent, the dosage of coupling agent, bath ratio, modification temperature and coupling agent compound, the mixed proportion, total quantity, and it was concluded that the optimal modified polylactic acid composites reinforced cotton leather the optimal proc ess. Then adopt the method of coupling agent distribution modification to improve the mechanical properties of polylactic acid(PLA) fiber reinforced composites. In addition to using the single factor experiment analysis of montmorillonite and micro fiber cellulose two association of impact strength of composite material mechanics.Finally it is concluded that the optimal process for:compound the KH-550 + A-171 silane coupling agent, dosage of 3%, the proportion of 1:1, MFC content 3%.Meanwhile, mechanical strength of the composite material were the best, the tensile strength was 70.54 MPa, the bending strength was 102.83 MPa, the notched impact strength was 11.69 KJ/m2.Than the unmodified cotton leather polylactic acid composites increased by 54.35%, 75.57% and 98.81%.This article prepared flame retardant composites by mixing waste cotton leather and poly(lactic acid)(PLA), and further improved its mechanical properties, dedicated to the research and development of lightweight, high strength of natural biodegradable composites, highlights the theme of the green environmental protection, at the same time, use of waste materials saved production cost, accord with the requirement of "sustainable development", social value and economic value.