Research On Preparation And Properties Of Luffa Fiber/Poly(Butylene Succinate) Composites

With the increasing attention to sustainable development and the increasing pollution caused by traditional plastics on the ecological environment,biodegradable materials have been widely used in various fields.Compared with other general plastics,biodegradable polybutylene succinate(PBS)has excellent performance in thermal,mechanical and processing properties,but its high cost and low mechanical properties limit its application in engineering field.Plant fiber has become an ideal reinforcement material because of its widely range of source,low density,good performance and environmental protection.Plant fiber reinforced PBS composite has been applied in many fields.There are still a big gap between plant fiber and synthetic fiber.People often increase the fiber strength by weaving or winding,of which the processing technology is more complex,and the production cost will be increased.This limits the use of plant fiber/PBS composite material as engineering material.Luffa fibers(LF)are arranged in the natural growth process to form a natural three-dimensional network structure.This spatial structure with different orientations endows LF with excellent mechanical properties.In this paper,PBS/LF biodegradable composites were prepared by molding using the natural three-dimensional network structure of Luffa fiber;the effects of different fiber layers,fiber laying methods,processing parameters and fiber surface modification on the mechanical properties of the composites were studied;the surface groups and micro-morphology of Luffa fiber before and after modification were analyzed and the microstructure,thermal stability,crystallinity and water absorption of the composites were characterized.In order to improve the rigidity of the composites,PBS/LF SiO₂ composites with different SiO₂ content were prepared by introducing nano-SiO₂ as inorganic filler.The effects of SiO₂ content on the mechanical properties,microstructure,thermal stability and crystallization properties of the composites were studied.The results show that:The mechanical properties of PBS/LF composites were better than PBS after the addition of luffa fiber.When the number of luffa fiber layers was 3 and the fiber content was28.1-32.4%.The mechanical properties of the composites were the best when the fiber laying mode was parallel to the fiber stress direction on the inner surface of Luffa.The results showed that the optimum molding temperature,molding pressure and molding time was180?,8 MPa and 8 min,respectively.The tensile strength and flexural strength of the composites were 25.5%and 61.6%,which were higher than that of pure PBS.The tensile modulus and bending modulus increased by 159.4%and 134.7%.The impact strength increased by 8.5%.It was better than the traditional hemp fiber reinforced PBS composite.Alkali treatment can effectively remove hemicellulose,some lignin,pectin,wax and other impurities of luffa fiber.And organosilane film was formed on the surface of luffa fiber after silane treatment,the main failure mode of the fibers parallel to the cross section is fiber debonding in the unmodified luffa fiber composites.While the failure mode of the modified fibers was fiber tearing.The addition of luffa fiber decreased the thermal stability of PBS/LF composites,but the crystallization rate and crystallinity of the composites increased.The thermal stability,crystallinity and crystallization rate of PBS/LF composites were slightly improved.The tensile strength and modulus of the modified luffa fiber reinforced composites were increased by 24.9%and 82.9%,respectively.And the water absorption of the composites was also improved.The results showed that the reinforcement effect of silane treated luffa fiber was better than that of alkali treated.The mechanical properties of the composites were improved by silane coupling agent KH550,and the strength of the composites was almost the same as that of traditional braided fiber composites.The addition of nano SiO₂ increased the tensile modulus and flexural modulus of the materials by 39.5%and 17.4%.The influence on the strength of the material was small.Meanwhile,the thermal stability of the composite was enhanced,and the crystallization speed of PBS was slightly increased.The fiber reinforced polybutylene succinate composites with luffa fiber may replace traditional composites in light structure and engineering materials in the future,which is in line with the trend of developing environmentally friendly composite materials.