Preparation And Application Of Isocyanate Type Interfacial Compatibilizer

Wood plastic composite is a new composite material made of thermoplastic plastic,wood flour or agricultural straw as filler,and its comprehensive performance is excellent.However,the interface incompatibility between wood flour and some important non-polar thermoplastic polymers hindered the material preparation process.A new type of interfacial compatibilizer was designed and prepared,and it was successfully applied to the wood plastic composite preparation with straw powder,forestry waste powder and post-consumed PP powder as raw materials.The interfacial compatibilizer can achievetheexcellent interfacial compatibility between PP and the fillers.The properties of the composites are better than that of the requirements of GB/T 24137-2009 national standard for wood –plastic composite.In the first part,polyester polyols were prepared from ethylene glycol and maleic anhydride.The effects of reaction conditions on the preparation were investigated.The optimal reaction conditions were obtained as follows:the mass ratio of maleic anhydride to ethylene glycol was 1:2.5,reacting 0.5 h at 80?,4 h at 145? with dimethylbenzene as dehydrating agent,and the reaction system being gradually heated to 190 ? at 4 h,then vacuum reaction at 135?for 2.5 h,the product was obtained with the acid value <3mgKOH/g and water content <0.03%.In the second part,a new type of interfacial compatibilizer was prepared with self-made polyester polyol and MDI as the raw materials.The effect of reaction time on the content of free isocyanate was studied.The experimental results showed that when the ratio of isocyanate to polyester polyol-NCO/-OH was 1.2,the reaction time of 3.5 h and reaction temprature of 80 ?,the interfacial compatibilizer is obtained with3.3 % of free isocyanate.The structure of the product was characterized and identified by IR and NMR.In the third part: the wood plastic composite was prepared with the shell powder,corn straw powder and the recycled PP powder,and the self-made interfacial compatibilizer and other additives as raw materials.The effect of the mass ratio of the shell powder and corn straw powder to the PP powder and the amount of interfacial compatibilizer on the tensile strength,flexural strength and water absorption rate of the composite were studied.The measured data of mechanical properties showed that when the mass fraction of the interface compatibilizer was 5.0% and the ratio of the shell powder to the recycled PP powder were 6:4,the tensile strength of the wood plastic composite achieved a maximum of 25.44 MPa and the bending strength reached the maximum of 47.84 MPa.When the dosage of the compatibilizer was 5.0%,the mass ratio of straw powder and to the recovered PP powder were 4:6.The tensile strength of the plastic composite reached the maximum of 22.60 MPa and the bending strength reached the maximum of 42.94 MPa.The Scanning Electron Microscope(SEM)analysis of the fracuture area of thecomposite showed that the interface compatibility of wood plastic composite was improved by the addition of interface compatibilizer.The thermal weight loss analysis of the composite showed that the thermal stability of wood plastic composite was improved by adding interface compatibilizer,and the water absorption rate of wood plastic composite material was decreased.This study provides an effective way for the utilization of agricultural and forestry waste and recycling PP.