Preparation Of Cassava Residues/PBS Biodegradable Composites And Its Performance Research

As a kind of solid residues after starch extraction from cassava,the output of cassava residues increased gradually with the increasing demands of cassava in China.However,owing to the lack of effective methods of utilizing the cassava dregs,a lot of cassava residues have been discarded in natural directly.And it not only does pollute to the environment,but also a kind of waste of natural resources.Therefore,in order to achieve high value utilization of cassava residues and improve the compatibility of cassava residues and plastic,basing on the principles of green and environmental protection.Biodegradable composite materials were prepared with 4,4'-Diphenylmethane Diisocyanate(MDI)as modifier,using the waste cassava residues and PBS as the main raw materials.The modification results of cassava residues were characterized by FT-IR and contact angle measuring instrument.At the same time,the variation of mechanical properties,thermal stability,water absorption,degradability and tensile fracture surface of the composites were studied.(1)The preparation conditions of the composites were studied by carrying out multiple groups of experiments.Considering the production cost and material properties of composite materials,the amount of cassava residues of 10%,the particles size of 60 mesh,the hot pressing temperature of 130?,the hot pressing time of 10 min and the hot pressing pressure 10 MPa were determined.(2)The water absorption of the pure PBS and the composite material with original cassava residues of 10%were 0.48%and 1.31%after soaking for 24 h.When the content of cassava residues was 30%,the water absorption rate increased to 14%,nearly 29 times that of the pure PBS.MDI modification improves the hydrophobicity of cassava residues,and the contact angle of the surface can be maintained above 100°.At this point the material also has low water absorption,and the rate of water absorption was 0.69%(the cassava residue content is 10%),after soaking for 24 hours.(3)SEM showed that the original cassava residues had poor interface compatibility with PBS,and there were many holes and collapses in the fracture surface,which resulted in poor mechanical strength of the composite materials.After being modificated by MDI,the interfacial adhesion of cassava residues and PBS can be effectively improved and the tensile fracture surface becomes smooth and neat.Compared with the original cassava residues/PBS composite materials,the tensile strength increased from 16.96 MPa to 20.26 MPa when adding 10%of modified cassava residues,which increased by 19.46%,while the change in bending strength was smaller than untreatment.The tensile strength and flexural strength of the material increased by 72%and 20.89%when the modified cassava residues content was 30%.(4)The biodegradation experimental was studied,the results showed that the degradability of the composites was improved by the addition of cassava residues.The rate of mass loss of the material increased when increasing the content of cassava residues.The mass loss rate of the material was up to 15.72%when 30%of cassava residues was added,degradation time of 60 d,nearly 14 times that of the pure PBS(1.12%).In addition,there was no significant change in the degradation performance of the composite after MDI modification.