Research On The Preparation, Properties And Mechanism Of High Density Functional Plant Fiber Materials

With the exploitation and consumption of oil, coal, ore and other non-renewable resource,serious environmental pollution caused by strong and extensive use of petroleum-based plastics increasing. The high quality use of plant resources is becoming a global hot spot. The natural fiber composite materials with the properties of environmentally friendly, biodegradable and excellent thermal insulation have been one of the fastest growing composite materials. Currently, high-density plant fiber composite material must be extensive use of petroleum-based plastic or resin components, in order to get high-quality composite material. However, its eco-friendly and biodegradable characteristics have been greatly affected. The three-dimensional structure and rich porous of fiber materials is difficult to retain. In this paper, one kind of high density（800～950kg/m³） completely-degraded plant fiber functional materials is prepared from the bagasse fiber and a small amount of chemical aids by wet-hot press technology and equipment. It also studied the changes of physical-chemical characteristics and the relevant mechanism.The micro-structure of the bagasse pulp fiber was analyzed by the X-ray diffraction and CP/MAS ¹³C NMR. The bagasse pulp fiber is composed of monosaccharides glucose, xylose and small amounts of arabinose by the analysis of ion chromatography. The molecular weight of bagasse cellulose is detected by gel permeation chromatography（GPC） get high-performance which obtain the number average molecular weight（Mn） of 3.28×10⁵,weight average molecular weight （Mw） of 2.02×10⁶, mass-average molecular weigh（tMw）of 5.03×10⁶.The pyrolysis performance and thermal decomposition kinetics model of fiber material were studied by TGA pyrolysis. We obtain the theoretical foundation for development a new plant fiber composite material by raw material analysis.In this study, the effect of drying pressure, drying time and drying temperature on the tensile properties, stiffness properties and waterproof performance were researched and obtained the optimizing the preparation condition which were drying temperature of 160℃, drying time of 4min and drying pressure of 0.4MPa. The stress and elastic limit elastic limit strain were 9.24MP and 0.43%.The Elastic modulus was 2.14Gpa. Deformation limit and ultimate strength were 3.26% and stress 35.35MPa. Material tensile energy absorption was 30.88J/m². The strainεIV was 0.12%. Density was about 910kg/m³. The stiffness was 119.5mN.m. Contact angle was increased to 110.54°. The macro and micro structure of high density plant fiber functional material prepared under different conditions was studied using light reflection microscopy scanning electron microscopy （SEM） and atomic force microscope （AFM）. The surface change of fiber was detected by AFM. Also, the deformation of fiber interweave was discussed by light reflection microscopy.The acid content and inner ester of the fiber samples which were made different process conditions was analyzed by the method of conductivity titration. The amount of inner ester was increasing with the increasing of drying temperature, time and pressure which could be one of explanation for fiber cornification. The chemical characteristics of fiber treated under different technical condition were analyzed by XRD、ATR-FTIR and CP/MAS ¹³C NMR.Aluminum hydroxide, magnesium hydroxide and zinc borate were chosen as flame retardants for the high density plant fiber composite material Evaluation based on the principle of toxicity, moisture, suppress smoke generation, smoke effects and cost comparisons. The optimal formula of inorganic flame retardants is the ratio of each component, magnesium: aluminum hydroxide: zinc borate = 2:3:1 which was obtained by orthogonal test analysis. In order to get a good flame resistance while trying to retain their physical strength, flame retardants used in the material content of 30%. The combustion process generates virtually no smoke and the ashe of the last color is black. At these conditions, the maximum tensile stress and strain values were 21.15MPa, 1.68%.The distribution of flame retardants in the samples was observed by SEM and discussed the mechanism of its retention. Adding 1.5% of cationic starch into plant fiber function of flame-retardant materials were the effect of effective intensity compensation. The oxygen functional index of 60%flame retardant addition sample was 31.2% according to the GB/T 2406-92.According to the ASTM E86-08, the flame spread index was 13.6, the smoke index was 108. It reached the A-level standard which was suitable for interior walls and ceiling.The pyrolysis performance and mechanism of single flame retardants, flame-retardant compound and high-density flame-retardant plant fiber material functional was analyzed. The pyrolysis residue was studied by ATR-FTIR. When the pyrolysis temperature is below 300℃, fire-retardant and non flame retardant sample show seldom pyrolysis and no new absorption peak. Two new absorption peak non-flame retardant sample occurred at 1611cm-1 and 1705cm-1,while the flame-retardant samples was no new peak at 350℃. At temperature of 400℃for 30S, the prime characteristic absorption peak of flame retardant product did not disappear while non flame-retardant samples were almost disappeared. Extending time to 2min at 350℃, flame retardant and non flame retardant samples were all fully pyrolysis.The morphological structure of pyrolysis residue was researched by the light reflection microscopy and scanning electron microscopy （SEM） which showed clearly the function of flame retardant in the respect of maintain sample structure. Meanwhile, it was found that the fiber was capsuled by pyrolysis product of fire retardant agents which further improve the mechanism of flame retardant.