The Performance Research On Short Basalt Fiber Reinforced Polypropylene Composite

With the continuous advancement of the global environmental governance process,a variety of short-fiber reinforced polypropylene composite materials are developed by the world’s major car companies to achieve lightweight,low pollution and low energy consumption of automobile.The application of various short fiber reinforced polypropylene composite is one of the effective methods to achieve the lightweight of automobiles.At present,the reinforcing phases used in automotive short-fiber reinforced polypropylene composites are mainly carbon fiber,glass fiber and natural fiber.However,they have some shortcomings or deficiencies,such as the high price of carbon fiber,the poor resistance of natural fiber to high-temperature and corrosion,the harm of glass fiber to human body health,and the high energy consumption during its production process.Basalt fiber is a new type of green fiber with excellent high temperature and corrosion resistance.Moreover,its low cost and wide sources of raw materials meet the high-volume production requirements of auto parts,attributing to the broad application prospects in the auto body.The injection molding short basalt fiber reinforced polypropylene（BFRPP）composite material has the advantage of low manufacturing cost,short molding cycle and fatigue resistance,and can be widely used in automotive interiors,exteriors,chassis panels and engine covers.The materials used for the auto parts should have good mechanical properties,flame retardancy,corrosion resistance and UV radiation resistance.However,these related properties of BFRPP composites have not been fully studied,and some important properties or laws have not yet been known.In this paper,short basalt fiber reinforced BFRPP composites were prepared by the injection molding method.The strain rate effect,ultraviolet（UV）aging performance,chemical corrosion resistance and combustion performance were systematically studied,which provided rich experimental data and theoretical basis for the application of basalt fiber in automobiles.The specific research contents are as follows:（1）The influence of strain rate on the mechanical properties of BFRPP composites was revealed,and the strength prediction model and strain rate-dependent constitutive model of BFRPP composites were established.The mechanical response properties of BFRPP composites at different strain rates were obtained by tensile tests at different loading rates.The effects of strain rate on the tensile strength of BFRPP composites were clarified.The results showed a linear relationship between the tensile strength of the BFRPP composite and the logarithm of strain rate within the strain rate range of0.001 s^-1～10 s^-1.A tensile strength prediction model for BFRPP composites was established based on the Halpin-Tsai model,and the tensile strength of BFRPP with different fiber contents and strain rates was predicted.Based on the existing constitutive model relation,a strain-rate-dependent one-dimensional phenomenological constitutive model of BFRPP composites was established by introducing strain rate correlation function.This model reveals the strain rate-dependent behavior of the stress-strain relationship of BFRPP composites.（2）The thermal degradation and combustion characteristics of BFRPP composites were clarified,and the influence of external radiant heat flux on the fire characteristic parameters of BFRPP composites was revealed.The effect of basalt fiber on flammability was analyzed by oxygen index analysis.The effect of basalt fiber on the thermal decomposition stability of PP was explored by thermogravimetric analysis（TGA）,and the thermal decomposition kinetics of BFRPP under the nitrogen atmosphere was analyzed using the Ozawa’s and Kissinger’s methods based on the Arrhenius equation.The influence of radiation intensity on the fire characteristic parameters such as heat release rate and smoke release rate of BFRPP composites was revealed through the cone calorimeter test under different radiation intensities,（3）The corrosion resistance and mechanical properties of basalt fiber and BFRPP composites under alkaline conditions（accelerated corrosion）were revealed.The chemical corrosion resistance of basalt fiber was studied by an accelerated aging test method.The corrosion mechanism of basalt fiber in the Na OH solution was ascertained.The corrosion process of basalt fiber in Na OH was analyzed.The tensile strength-corrosion state relationship model of basalt fiber under alkaline conditions was established.This model could better reveal the variation of tensile strength of basalt fiber in Na OH solution.（4）The aging performance of BFRPP composites under the condition of ultraviolet（UV）accelerated aging tests was revealed,and a comprehensive aging performance evaluation method for BFRPP composites was established.The aging properties of BFRPP samples at different aging times were obtained by laboratory UV accelerated aging tests.The change of surface color,hardness and mechanical properties of BFRPP sample was clarified.The main reason for the formation of transverse crack on BFRPP sample surface was analyzed.The comprehensive aging performance evaluation method of BFRPP composites was established based on the principal component analysis method,and the comprehensive aging performance index of BFRPP composites was analyzed by this method.