Experimental Investigation On Fabrication And Thermal Stamping Of Woven Jute/Polylactic Acid Biocomposite

With the development of automobile industry in China,problems about environmental protection,energy and auto lightweight have become increasing prominent.In order to address these problems,many domestic and foreign automobile manufacturers applied plant fiber reinforced composites in automobile interiors and exteriors.However,the matrices of these composites are still unrecyclable and will pollute environment.Therefore,this project replaced petroleum-based plastics with polylactic acid bio-resin,which is derived from plant,and combined polylactic acid resin with widely cultivated jute fibers to fabricate completely degradable composites,and then applied the biocomposite in automobile interiors and exteriors.In this paper,the chemical structures of jute fiber and polylactic acid resin were analyzed.Jute fibers were treated by sodium hydroxide as a try to enhance the adhesion between fiber and matrix.The biocomposite laminates were fabricated by compression molding.The thermal and mechanical properties of the composite were tested.The impact of alkali treatment on the structure,thermal and mechanical properties of fibers and composites,and the adhesion between fiber and matrix were investigated.Finally,the influences of holding time of temperature,layup sequence,samples size and fiber treatment on the formability of the biocomposite were studied by a hemispherical stamping.And the defects in the forming,such as wrinkling,delamination and cracking,were analyzed.The failure modes of the composites were explored as well.The research results show that alkali treatment removes impurities on the surface of jute fibers,refines the fiber structures and has some impacts on the chemical structure of fiber.All these changes enhance the adhesion between the plant fibers and polylactic acid resin.However,in the other hand,fibers become fluffier and the orientation of fiber become poor after alkali treatment,leading to a weaker strength of composites in the direct of 0/90°.As for the thermal properties,alkali treatment decreases the water content of fibers,but worsens the heat resistance of fibers.The thermal property of the composite mainly depends on the property of the resin while the property of the plant fiber makes little difference to it.The holding time of temperature and the sample size are critical factors in deciding the forming quality of the biocomposite.The number of layers and layup sequence have some influences on it while the impact of fiber treatment is uncertain.Wrinkling is the most common defect in thermal-stamping of the biocomposite while cracking is the most serious one.But these defects can be solved by improving blank holder force,enhancing the adhesion between the fibers and matrix or promoting fiber strength.