Preparation And Mechanical Properties Of Short Fiber Reinforced Composites

Short fiber reinforced composites used the short fiber as reinforced phase and resin paste as matrix.The resin paste are made of resins,thickeners,initiators,cross-linking agent,low shrinkage additives,dispersing agent,additives,internal release agents and fillers,etc.Compared with thermoplastic composites,short fiber composites have good impact resistance,corrosion resistance and fatigue performance,especially it have high designability and wide application,so short fiber reinforced composites are prepared and their properties are optimized and characterized in this paper.The main research contents are as follows:1.Study on the effect of fiber content on mechanical properties of short fiber reinforced composites: Resin paste are prepared by mechanical stirring method,and semi-finished short fiber reinforced composites with 10 wt%,15 wt%,20 wt%,25 wt% and30 wt% fibers are prepared by hand paste impregnation of short glass filament.The composites with different mass fraction of short glass fibre filament are prepared by molding process,and the short fiber reinforced composites are subjected to stretching,compression,flexural,impact and ball indentation hardness tests,respectively.The results show that the tensile strength,compression strength,flexural strength,impact strength and ball indentation hardness increase first and then decrease with the increase of fiber mass fraction.When the fiber mass fraction is 20 wt%,short fiber reinforced composites have relatively good mechanical properties.Considering the performance requirements of short fiber reinforced composites in the field of industry appliances,the best fiber quality score is 20 wt%.2.Study on the effect of forming condition on mechanical properties of short fiber reinforced composites: The experiment of forming condition optimization is designed.The short fiber reinforced composites under different forming conditions are prepared,and the composites are subjected to tensile,compression,flexural,impact and ball indentation hardness tests,respectively.The results show that the tensile properties,compressionstrength,compression modulus,flexural strength,flexural modulus,impact strength and hardness increase at first and then decrease and the compression strain and deflection decrease with the increase of molding pressure.With the increase of molding temperature,the tensile properties,compression strength,compression modulus,flexural properties,impact strength and hardness increase at first and then decrease,meanwhile,the compressive strain decreases slowly.With the prolongation of molding time,the change of properties of its is very small,which indicates that molding time has little influence on the properties of short fiber reinforced composites.Therefore,the optimum process parameters are obtained:the molding pressure is 11 MPa,the molding temperature is 150 °C and the molding time is2 min.Comparing short fiber reinforced composites with samples without process optimization,the results show that except for the decrease of deflection,the other mechanical properties of short fiber reinforced composites increase in varying degrees.3.Study on the effect of hollow glass beads on mechanical properties of short fiber reinforced composites: Low density short fiber reinforced composites are prepared by mixing hollow glass beads in resin paste.The density,tensile,compression,flexural,impact and ball indentation hardness of low density short reinforced composites with 0 wt%,2 wt%,4 wt%,6 wt% and 8 wt% hollow glass beads are tested.The results show that the properties all decrease with the increase of the content of hollow glass beads.The decrease of compression modulus,flexural strength,deflection,hardness and impact strength tends to be gentle gradually.Low density short fiber reinforced composites and ordinary short fiber reinforced composites are characterized by scanning electron microscopy,their mechanical properties are compared with those of unfilled hollow glass beads short fiber reinforced composites,considering the density factor and mechanical properties,the final mass fraction of hollow glass beads is 2 wt%.