Preparation And Mechanical Properties Of Polyester Fiber Reinforced Composites Based On 3D Printing Technology

Composite materials as a new generation of structural materials have been widely used in biomedical,aerospace and other fields.Low cost,high efficiency manufacturing technology is an important way to actively promote the application of composite materials,the advent of 3D printing technology makes it possible for low-cost,rapid manufacturing of composites.However,the shortcomings of insufficient mechanical properties of 3D printed materials have become an obstacle to the development of 3D printing technology.At present,the machined parts have more and more requirements on the durability of the molded part.Therefore,improving the mechanical properties of 3D printed parts is very important for the promotion of the application of 3D printing technology.In recent years,fiber-reinforced resin-based composites has become an important direction of 3D printing technology,which enhances the mechanical properties of 3D printed materials by adding fibers to the matrix material.In this paper,polyester fiber is used as the reinforcing body,polylactic acid and photosensitive resin as the resin matrix respectively.The polyester fiber is modified by alkali treatment,silane coupling agent(KH550)treatment and plasma treatment.Polyester fiber reinforced photosensitive resin composites were prepared by photo curing 3D printing technology(SLA),and the process parameters of 3D printing were optimized.The polyester fiber reinforced polylactic acid resin matrix composites were prepared by melt deposition type 3D printing technology(FDM),and the process parameters were optimized.In addition,the effects of the content of polyester fiber on the mechanical properties of the photosensitive resin-based composites and the polylactic acid resin-based composites were discussed respectively.Mainly get the following conclusions:(1)Different modification methods have different effects on the surface morphology of polyester fibers.Through different alkali treatment,polyester fiber surface appears to various degrees of cracks and grooves.The results show that the concentration of alkali solution has the most significant effect on the surface morphology of the fibers,the grooves and cracks on the surface of the treated polyester fibers are significant and the surface roughness increase;lye temperature treatment on the surface morphology of the fiber is small,the surface morphology of polyester fibers appeared a certain degree of grooves and cracks;the alkali immersion time has the least effect on the surface morphology of the polyester fiber.After the polyester fiber is immersed in different time,there is no obvious change on the fiber surface.Silane coupling agent has little effect on the surface morphology of polyester fiber and the surface of fiber is relatively smooth.Polyester fiber after plasma treatment,the fiber surface appeared varying degrees of grooves and cracks.(2)The mechanical properties of the composites after the modification of the polyester fiber were improved in different degrees.After the surface of polyester fiber has been treated with different concentrations of lye,the flexural properties and tensile properties of the composites have different degrees of enhancement.With the increase of the concentration of alkali,the flexural performance of the composite materials is improved.When the concentration reaches 20%,the flexural strength reaches 471 MPa and the tensile strength reaches 80.5MPa.With the increase of the temperature of the lye,the bending and tensile properties of the composites are improved to some extent.When the lye temperature reaches 85?,the flexural strength and tensile strength of the composites are 170 MPa and 68 MPa respectively,which is 57.4% and 44.6% higher than that of the untreated polyester fiber reinforced composites.Polyester fiber surface after different alkali immersion time,with the lye immersion time,the composite material obtained by the bending properties and tensile properties to a certain extent,but the mechanical properties to enhance the effect is weaker than the polyester fiber through the alkali liquid concentration treatment and lye temperature treatment.Polyester fiber treated with silane coupling agent(KH550),the flexural properties and tensile properties of the prepared composites were increased by 44% and 46.8% compared with the untreated polyester fiber reinforced composites respectively.After the plasma treatment,the flexural and tensile properties of the composites were enhanced by 112.8% and 50.6% respectively,compared with untreated polyester fibers.(3)The effects of process parameters such as slicing layer thickness,filling density and heater temperature on the mechanical properties of polylactic acid-based composites were investigated when the polyester fiber reinforced polylactic acid-based composites were prepared by fused deposition 3D printing.The results show that the mechanical properties of the prepared polylactic acid samples decrease with the increase of slice thickness.The increase of the packing density is beneficial to the improvement of the mechanical properties of the polylactic acid sample;The increase of filament feed rate is helpful to improve the interlayer adhesion of polylactic acid samples,thua enhancing the mechanical properties of polylactic acid.The increase of heater temperature is conducive to the improvement of the flow ability of polylactic acid,which increases the interfacial effect of polylactic acid-based composite samples and improves the mechanical properties of polylactic acid-based composites.(4)When the polyester fiber reinforced photosensitive resin matrix composites were prepared by light curing 3D printing method,the effects of process parameters such as slice thickness and exposure time on the mechanical properties of photosensitive resin were studied.The results are as follows: when the sample exposure time is same,the thinner the thickness of the sample slice is conducive to the curing of the liquid photosensitive resin,thereby improving the mechanical properties of the photosensitive resin-based material.When the specimen slice thickness is the same,the increase of the exposure time is beneficial to the condensation and solidification of the liquid photosensitive resin,and enhances the mechanical properties of the photosensitive resin-based material.(5)The percentage of polyester fiber volume is different for the mechanical properties of polylactic acid resin-based materials and photosensitive resin-based materials.The results show that the flexural strength and tensile strength of polyester fiber reinforced photosensitive resin composites can reach 380 MPa and 86 MPa respectively when the volume fraction of polyester fiber reaches 25%,compared with the fiber content of 5% of the composite,flexural strength and tensile strength were increased by 204% and 48.3%.When the volume fraction of polyester fiber is the same,the mechanical properties of polyester fiber reinforced polylactic acid matrix composites are weaker than that of polyester fiber reinforced photosensitive resin matrix composites.