Fabrication And Properties Of Biodegradable Ramie/Poly(Butylene Succinate) Composite

With the develepment of science and technology, people has strong sense of environmental protection, and it aslo makes new demands for the composite. Ramie fiber is a typical representative of the natural fibers with high specific strength and modulus, and the preparation of the ramie fiber is environmental friendly. Therefore, by using the natural fiber as the reinforcement and completely biodegradable polymer as the matrix, to develop excellent biodegradable composite materials, meet with the current requirements of low-carbon and green materials. Poly(butylene succinate)(PBS) is obtained by condensation polymerization from succinic and butanediol. It has a low melting point, good processability, excellent mechanical properties and can be biodegraded, that is to say, it is a promising biodegradable polymer material. The ramie fiber reinforced PBS composite can meet the basic mechnical requirements, at the same time, because of the degradable of the raw materials, the composite has a very good prospects in the green composites.However, the research and application of the ramie/PBS composite are relatively rarely, that is because the the hydrophilic nature fibers affects negatively their adhesion to hyydrophobic polymeric matric, thus research and development of this type of composite is restricted. This paper is divided into three main parts:the first part is the interfacial adhesion between ramie fibers and PBS matrix, the ramie fibers were treated by atmospheric pressure plasma, the effects of different treatment voltage on the interfacial bonding properties of ramie/PBS biodegradable resin was discussed; in the second part, a ramie/PBS biocomposites were fabricated by the method of molding, the effect of fabric content and surface modification on the properties of the biocomposites were studied;in the third part, the degradation properties of the ramie/PBS composite and pure PBS were studied with the soil burial test and immobilized lipase degradarion method.In the first part, in order to study the effect of Atmospheric Dielectric Barrier Discharge Plasma on the interfacial properties of ramie/PBS, the ramie fibers were treated with different votage discharge plasma. Then single fiber reinfoced composite material is abtained. SEM results show that with increasing of the actual applied voltage, the etching behaviour of ramie fiber surface becomes significantly; Atmospheric Dielectric Barrier Discharge Plasma have a significant impact on the surface bonding performance of ramie fiber. At a voltage of6kV, the hydrophobicity of the ramie fibers surface can be largely improved. The interfacial adhesion between ramie fibers and PBS matrix was investigated in terms of fiber/matrix interfacial shear strength (IFSS), IFSS values reached the maximum.In the second part, the effects of ramie fabric content,15%,21%,30%and37%, on the properties of composites were researched. The experimental results show that with the increasing the content of the ramie, tensile strength of the composite increases, it performs best when content reaches30%. The elongation at break reduces greatly with the content of ramie increaseing. After plasma treatment, tensile strength of the composite increases with the content increasing, when it comes to a certain value, the strength will decrease. When the ramie content of30%, the tensile strength increase by9.4%than the untreated ramie。the flexural strength almost increase linearly with the increasing of ramie content,and among the content of21%and30%, the flexural strength increase by19%and27%respectively than the pure PBS. After treated with plasma, the flexural strength of the composites first increases then decreases with increasing content of ramie fabric.In the third part, the biodegradability of the ramie/PBS composite and pure PBS was evaluated by the soil burial test and enzmatic degradation in the presence of lipase PS. And their surface morphology after the degradation were abserved, the chemical groups on the surface of the composite and pure PBS were evaluated by using Fourier transforminfrared spectroscopy (FTIR), the crystallization behaviors of composite and PBS were studied by X-ray diffraction and DSC. The results showed that weight-loss of PBS reached93%after buried in the soil for90days. The surface of pure PBS changed obvious relatively.90days later, the surface appeared scaly and scraped through layers. After the enzymatic degradation, the surface of PBS retained some white granules, there were also crack, that means there were a certain degree of degradation. When it comes to the composites, the degradation of ramie/PBS composites was abvious after90days. The surface of the composites emerged holes. What’s more, the surface of composites was relatively tidy after enzymatic degradation for25days, but they also began cracking. FTIR spectra of PBS shows that after buried in the soil, the carbonyl content decreased and a large number of ester bonds of PBS were hydrolyzed and destroyed. The degradation process of the ramie/PBS is similar to that of the PBS, at the very beginning of the degradation, the ester bonds began hydroxyzed and small molecules came into existence. Characteristic diffraction peaks of pure PBS are19.5°and22.5°respectively, the characteristic peaks moved a small angle after buried into the soil, which can be drawn that the crystalline particles decreases after the degradation, the amount of crystallinity changed. DSC analysis suggested melt crystallization temperature of PBS is111.5℃, glass transition temperature decreased after enzymatic degradation.Through this paper, we can conclude that it is feasible to prepare ramie/PBS composite, the plasma treatment has certain influence on the adhension of ramie fibers with PBS matrix through roughening the fiber surface. It provides a better method for the development and application of this kind of composite. Meanwhile, the mechanical properties reach the requirements of general composites, by adjusting the technological parameters to further improve the mechanical properties. What’s more, the ramie/PBS composite keeps good biodegradability under certain conditions, which indicates that this composite will have broad application prospects.