| The high performance of general plastics was still the focus of research and development of polymer materials,and it was also an important measure to expand the application range of general plastics.The filling modification and blending modification of polymers were important methods for the high performance of general plastics.The main methods of polymer filling modification were to adopt efficient interfacial compatibilizer and designed special internal structure of materials.Interfacial compatibility was an impotant problem in polymer modification.Improving the interfacial compatibility was still a topic of polymer modification.Negative poisson's ratio materials contributed to the preparation of super strong and super tough polymers due to their unique dilation effect different from ordinary materials.at present,negative Poisson's ratio materials had no obvious special properties and no obvious breakthrough principle in principle.Therefore,their application in the market has not been popularized.The solid phase graft of three prepared by monomer graft copolymer as interfacial compatilizer polypropylene was adopted in the paper.The effects of three monomer grafted copolymers on the interfacial compatibility and mechanical properties of polypropylene/wood powder composites and polypropylene/glass fiber composites were studied,and the effects of interfacial compatibility on the Poisson's ratio of the composites were also studied.(1)The graft copolymer(GPP)of maleic anhydride,butyl acrylate and methyl methacrylate with polypropylene was prepared by solid-phase graft reaction.The GPP was used as the interfacial modifier of polypropylene matrix composites to adjust the interfacial compatibility.Polypropylene/wood powder composites were prepared by melt extrusion,and the mechanical properties of polypropylene/wood powder composites were improved and stabilized by GPP and other compatibilizers.The structure and properties of polypropylene/wood powder composites were analyzed and tested by X-ray diffraction,polarizing microscope,differential scanning calorimetry,scanning electron microscopy,infrared spectroscopy and universal tensile test.The results showed that GPP compatibilizer reacted with the hydroxyl group on the surface of wood powder,and could fully penetrate into the wood powder fiber.It was observed by SEM that the GPP compatibilizer formed an interfacial layer on the wood powder well.With the increase of GPP compatibilizer,the mechanical properties of PP/wood powder composites are gradually improved.When 7%GPP is added,the mechanical properties of PP/wood powder composites are in the best state.When compatilizer was combined with wood powder in WPC composites,the wood powder moves during tensile process,so the change range of Poisson's ratio becomes smaller with the increase of wood powder content.(2)Polypropylene/glass fiber composites were prepared by blending the graft copolymer(GPP)with glass fiber and polypropylene as interfacial compatibilizer.The structure and properties of the composites were analyzed and tested by X-ray diffraction,polarizing microscope,differential scanning calorimetry,scanning electron microscopy,infrared spectroscopy,dynamic rheological test and universal tensile test.The results showed that the intermolecular entanglement was increased with the addition of compatibilizer,and the interfacial strength was improved more easily when the network structure was formed.With the increase of the GPP compatibilizer,both the loss modulus and the storage modulus increased,and the storage modulus augmented more than the loss modulus.The results of infrared spectroscopy and scanning electron microscopy showed that the interfacial layer formed by GPP compatibilizer and the interfacial compatibility was improved between resin and glass fiber,and increased the stress transfer of glass fiber in polypropylene matrix.GPP,as a modifier to improve the interfacial strength of PP/GF composites,the deformation of PP/GF composites was increased,and the Poisson's ratio performance appeared in a shorter time,so as to predict the interfacial compatibility of PP/GF composites.(3)With ethylene/vinyl acetate copolymer(EVA)as interfacial compatilizer,coated PTFE and polypropylene blend preparation of polypropylene/PTFE blend,using X-ray diffraction(XRD),polarizing microscope,differential scanning calorimetry,scanning electron microscopy(SEM),poisson's ratio analysis,analysis of dynamic rheological test,mechanical property test and the test structure and properties of the blend.The results show that the dynamic viscoelastic behavior of the blends with PTFE was related to the content of coated PTFE.When the content of PTFE was lower than 13%,the relaxation of PP was prevented.When the content of PTFE was higher than or equal to 13%,the peristalsis of PP molecular chain could be increased locally.With the increase of coated PTFE content,the notched impact strength of the blends was greatly improved,indicating that the PTFE chain formed a double continuous structure in the blends and played a good buffer role.Due to the formation of double continuous structure of PTFE in the blend,PTFE was easy to disentangle and formed a certain negative poisson effect,and the blend adding 10wt%EVA and 5wt% PTFE has obvious tensile transverse swelling effect.(4)Rice husk were treated with alkali to obtain porous cellulose.The porous cellulose was composite with polyurethane to prepare polyurethane/porous cellulose composites with negative poisson's ratio effect.Differential scanning calorimetry,scanning electron microscopy,infrared spectroscopy,Poisson's ratio analysis,BET pore size distribution,mechanical property test and other methods were used to analyze and test the structure and properties of the blend.Polarizing light microscope showed that after the oxidation of rice husk,many small holes were formed.It was obvious that the porous cellulose had the characteristics of sponge structure.The transverse strain of M3 samples increased during0-60 s,which indicated that the M3 samples had transverse swelling effect.The addition of porous cellulose sponge could increase the negative Poisson's effect,which was mainly due to the Poisson's ratio effect formed by the cross structure of the samples.Moreover,scanning electron microscopy(SEM)results showed that the polyurethic-cellulose sponge with higher negative poisson's ratio effect had significantly enriched rod-like porous cellulose in the cross section,and the porous cellulose was mainly distributed in the vertical plane of the tensile direction. |
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