On-line Molding Process And Product Properties Of Long Glass Fiber Reinforced Polypropylene Composites

Polypropylene has low density,good molding process,high heat resistance,good corrosion resistance and it is non-toxic.It is a widely used plastic matrix material.The advantage of glass fiber is better mechanical strength,its heat resistance is high,and its corrosion resistance is good.It is a very good reinforcement material.And the two are cheap and easy to use and promote.The combination of the glass fiber reinforced polypropylene materials is a high-quality lightweight material that can be widely used in various non-structural parts of automobiles.Usually,short fiber reinforced composites are easy to be processed but have low strength.Continuous fiber reinforced composites have better properties but difficult to be processed.Long fiber reinforced composites can give good consideration to both properties and formability.On-line compression molding is a short-flow processing and forming method for long-fiber reinforced composite materials that has emerged in recent years.It has the advantages of short process,high efficiency,low energy consumption and low cost,and is recognized by the scientific and technological community and welcomed by the industry.In this paper,the on-line molding process and product properties of long glass fiber reinforced polypropylene are studied.The main work and summary of this paper are as below:(1)Using the domestically developed online compression molding equipment,the on-line molding process was studied,and 20%,30%,and 40%glass fiber content of the plate sample and 30%glass fiber content of the automobile bottom plate were prepared.(2)The tensile,bending and impact properties of the samples with different glass fiber content were tested.The results show that the tensile strength,bending strength and impact strength of the samples are directly proportional to the content of the glass fibers.The fiber content of the test sample is 40%,and the orientation is 90°has the best performance.And the tensile strength reached 128MPa,the bending strength reached194MPa,and the impact strength reached 98 kJ/m~2,which was 52%,45%and 48%higher than that of the same orientation 20%fiber content.Fracture elongation increases slightly with the increase of glass fiber content,but bending deflection decreases with the increase of glass fiber content.(3)The relationship between fiber orientation and mechanical properties of composites was studied.The results state clearly,the orientation of long fibers in the composites is certain.The orientation of glass fibers in the 90°oriented specimen is parallel to the tensile direction of the specimen,and the orientation of glass fibers in the0°oriented specimen is perpendicular to the tensile direction.When the glass fiber content is the same,the more parallel the fiber arrangement direction is to the tensile direction,the better the mechanical properties are.The tensile strength of 90°oriented specimens is 45~60 MPa higher than that of 0°specimens.The elongation of 20%fiberglass increased the most,and the elongation of 90°specimens was 67%higher than that of 0°specimens.The bending strength of the 90°sample with different glass fiber content is about 40%higher than 0°.As the glass fiber content increases,the 90°oriented sample increases in impact strength compared to 0°.(4)The fiberglass content and environmental test of 30%fiberglass automotive under-engine protection panel were carried out.The results showed:The sample with the production of 30%glass fiber content has a measured average of 31%,which is not much different from the actual setting.After the samples have passed the tests of the general test of automotive plastic products,there are no abnormal phenomena such as fading,chalking,foaming,cracking,stickiness and dents.It shows good high temperature resistance,cold and heat exchange resistance,impact resistance,heat and humidity resistance,water resistance,solvent resistance and low temperature resistance.And after 600 hours of aging arc lamp aging test,the color fastness is compared with the gray card level of 5,which shows good aging resistance.(5)The simulation analysis of the 40%glass fiber battery cover shows that:From the stress distribution,when the extrusion head moves 10 mm in the X-axis direction,the maximum stress on the edge of the battery cover exceeds 134 MPa,and the edge may begin to crack.When the movement is 38mm,the main part of the cover body is greatly deformed,and the corner of the cover body may be damaged..When the simulation runs along the Y-axis direction to 16mm,the maximum stress on the edge of the battery cover exceeds 194MPa,and the edge may be broken.When the indenter is pressed to 46mm,the stress at the corner of the cover is also 194 MPa,and the main part of the cover may be destroyed.From the distribution of deformation rate,the distribution of deformation rate is similar to that of deformation rate when no large deformation occurs on the surface of battery cover.The deformation rate is the highest in the center near the extruded half,and the deformation rate decreases from the center to the sides.After the main body undergoes large deformation,the deformation in the X-axis direction is concentrated on the convex table,and the Y-axis is concentrated on the convex portion of the upper portion of the cover to the side opening position and the thin side wall on both sides.