Preparation And Performance Of Epoxy Resin Particle Modified Epoxy Resin Composite Materials

Epoxy resin composites found a plenty of applications in aerospace,aviation,electronics,automotive etc.Moreover,epoxy resin composites still catch more attention for developing a new material.The reinforcement and toughening of epoxy resin is a research focus.Nowdays,epoxy resin composites with higher strength and toughness are prepared by adding materials with better strength or toughness as fillers.Since the filler and the epoxy matrix are totally different,defects such as incompatibility between the two are prone to occur.Owing to this kind of defects,not only the epoxy cannot be modified,but also the performance of the epoxy is deteriorated.The existing solution is to modify the surface of the filler to increase the compatibility of the filler with the epoxy matrix,which often requires complicated and costly processes.Even so,the problems caused by the interfacial defect between fillers and epoxy matrix cann,t be completely solved.Aiming at the interface defects existing in the fillers and matrix in epoxy resin composites,we introduces the concept of self-reinforcement into the preparation of epoxy resin composites.Prepared micro and nano scales of epoxy resin particles were added to the epoxy matrix as fillers to prepare an epoxy resin composite.Since the filler and the matrix are both epoxy resins,the problem of poor compatibility between the filler and the matrix can be overcome,and no surface modification of the filler is required.In this thesis,the micron-sized and nano-sized epoxy resin powders were firstly prepared by suspension polymerization and emulsion polymerization.three epoxy powders with different degrees of cross-linking were prepared by suspension polymerization;two epoxy powders with different degrees of cross-linking were prepared by emulsion polymerization.The particle size and particle size distribution of the powders were measured with a particle size analyzer.The surface composition of the powder was characterized by X-ray photoelectron spectroscopy,especially the surface nitrogen content.In view of the poor homogeneity of the particle size distribution of the powder prepared by suspension polymerization,the three powders were sieved in order to not only improves the uniformity of the powder,but also obtain several powders with different particle sizes,which is convenient for investigating the influence of different particle sizes on performance of the composites.Then,five kinds of powders were added to the epoxy matrix as fillers to prepare the epoxy resin particle modified epoxy composites.The tensile and impact strengths of the composites were tested.The morphology of the fracture surface of the composites were observed with a scanning electron microscope.The effects of filler content,filler particle size,and degree of filler cross-linking on the tensile strengths and impact strengths of the composites were investigated.The reinforcing and toughening of the composites were discussed.The results indicate that epoxy resin powders can be used as fillers to prepare an epoxy composites with tensile strength and impact strength improved although the fillers and the matrix are all epoxy resins.Micron-sized epoxy resin powders can be obtained by suspension polymerization,which can reinforce the matrix epoxy resin,but the particle size is not uniform.Through the emulsion polymerization method,nano epoxy powders with uniform size can be obtained which can significantly improve both tensile strength and impact strength of the epoxy resin.and the epoxy composite filled by nano-epoxy powder have higher tensile strength then one by micon-epoxy powder.within 0wt%-9wt%of micon-epoxy filler,the tensile strength of the composite material is proportional to the filler content,inversely proportional to the filler particle size,and degree of cross-linking of filler.When the content of the low degree of crosslinking of epoxy resin filler is 9wt%,the tensile strength of the composite material is increased by 54.2%.The addition of nano-epoxy resin filler in the range of 0wt%-3wt%,the relationship between the reinforceing/toughening effect and the content is positive.When the content of high crosslinking degree nano-epoxy resin filler is 3wt%,the tensile strength of the composite is increased by 86.2%,and the impact strength is improved by 95.5%.Based on the thesis,it can be proved that the self-reinforced epoxy composite material is really feasible,and the nano-epoxy filler has a high reinforcing and toughening effect on the epoxy.The investigation explores a new method for the preparation of epoxy resin composites.