Preparation and Properties of Heat Resistant Polylactic Acid(PLA)/Nano-SiO2 Composite Filament

In order to improve the thermal properties of polylactic acid（PLA） filament,nano-SiO_2 was applied to mix with PLA,then they were spun as composite filament by melt-spinning.The dispersion of nano SiO_2 and the fracture surfaces of filaments were studied by scanning electron microscopy（SEM）.The properties of composite filament,such as orientation degree,mechanical properties,and surface friction properties,were analyzed.The thermal performances of composite filament were analyzed by differential scanning calorimetry（DSC） and thermo gravimetric analysis（TGA）.The results showed that the nano-SiO_2 modified by 5% KH-550 could disperse evenly and loosely in nano-scale,and 1 wt% and 3 wt% nano-SiO_2 dispersed throughout PLA evenly.As the quantity of nano-SiO_2 increased,the properties of composite filament,such as orientation degree,friction coefficient,thermal decomposition temperature,and glass transition temperature,increased more or less.The breaking tenacity increased when 1 wt% SiO_2 was added in PLA,but declined when 3 wt% SiO_2 was added.

Preparation and 3D printing of high-thermal-conductivity continuous mesophase-pitch-based carbon fiber/epoxy composites

To meet the requirements of spacecraft for the thermal conductivity of resins and solve the problem of low thermal conduction efficiency when 3D printing complex parts,we propose a new type of continuous mesophase-pitch-based carbon fiber/thermoplastic polyurethane/epoxy(CMPCF/TPU/epoxy)composite filament and its preparation process in this study.The composite filament is based on the high thermal conductivity of CMPCF,the high elasticity of TPU,and the high-temperature resistance of epoxy.The tensile strength and thermal conductivity of the CMPCF/TPU/epoxy composite filament were tested.The CMPCF/TPU/epoxy composites are formed by 3D printing technology,and the composite filament is laid according to the direction of heat conduction so that the printed part can meet the needs of directional heat conduction.The experimental results show that the thermal conductivity of the printed sample is 40.549 W/(m·K),which is 160 times that of pure epoxy resin(0.254 W/(m·K)).It is also approximately 13 times better than that of polyacrylonitrile carbon fiber/epoxy(PAN-CF/epoxy)composites.This study breaks through the technical bottleneck of poor printability of CMPCF.It provides a new method for achieving directional thermal conductivity printing,which is important for the development of complex high-performance thermal conductivity products.

Mechanical characteristics of oil palm fiber reinforced thermoplastics as filament for fused deposition modeling(FDM)

Fibers are increasingly in demand for a wide range of polymer composite materials.This study^purpose was the development of oil palm fiber(OPF)mixed with the thermoplastic material acrylonitrile butadiene styrene(ABS)as a composite filament for fused deposition modeling(FDM).The mechanical properties of this composite filament were then analyzed.OPF is a fiber extracted from empty fruit bunches,which has proved to be an excellent raw material for biocomposites.The cellulose content of OPF is 43%-65%,and the lignin content is 13%-25%.The composite lilament consists of OPF(5%,mass fraction)in the ABS matrix.The fabrication procedure included alkalinizing,drying,and crushing the OPF to develop the composite.The OPF/ABS materials were prepared and completely blended to acquire a mix of 250 g of the material for the composition.Next,the FLD25 filament extrusion machine was used to form the OPF/ABS composite into a wire.This composite filament then was used in an FDM-based 3D printer to print the specimens.Finally,the printed specimens were tested for mechanical properties such as tensile and flexural strength.The results show that the presence of OPF had increased the tensile strength and modulus elasticity by approximately 1.9%and 1.05%,respectively.However,the flexural strength of the OPF/ABS composite had decreased by 90.6%compared with the virgin ABS.Lastly,the most significant outcome of the OPF/ABS composite was its suitability for printing using the FDM method.