Research On Manufacturing Equipment And Process Performance Of High Performance PVC Structural Foam

Semi-crosslinked polyvinyl chloride(PVC)foam is a kind of rigid semi-crosslinked closed-cell foam based on vinyl polymer and through a network of aromatic imides.It has the characteristics of low density,high specific strength,chemical corrosion resistance and high temperature resistance.After the PVC is made into a sandwich structure,the mechanical properties of the component can be greatly enhanced,but the weight of the component is hardly increased.It can be used as an alternative to metals,wood,cement,rubber,etc.in specific applications and mainly used in fan blades,locomotive interior decoration,yacht shell,aerospace,building insulation and other industries.Here in this study,isocyanate and methyl hexahydrophthalic anhydride were used as crosslinker and the melamine was used as the crosslinking aid to prepare a cross-linked PVC structural foam with a certain flame retardancy by using molding method.The measured limiting oxygen index was 26.1,the mechanical properties were moderate,and the compressive strength was 1.7MPa by compression test.The glass transition temperature(Tg)of PVC paste resin was measured by differential scanning calorimetry(DSC).PB 1302 PVC paste resin was selected as the matrix of structural foam plastics.By means of thermogravimetric analysis and single factor experiment,the effect of the amount of foaming agent in the mixed paste on the foaming behavior was investigated,and the results showed that the foaming behavior of PVC paste tree was obtained.Under the condition of 50 g lipid,when the mass ratio of azodiisobutyronitrile(AIBN)and azoxyldimethylamide(AC)was 5:1 and the dosage was 6g,the foam size of PVC foam was uniform,the density was low and mechanical properties were moderate.Toluene diisocyanate(TDI)and methyl hexahydrophthalic anhydride(MHP)were selected as cross-linking agents to prepare PVC foam and the effect of the ratio of isocyanate and methylhexahydrophthalic anhydride on the properties of foamed materials was studied.In the aspect of technology,thepreparation technology of mixed paste was determined.Under the pressure of 10 MPa,the heating temperature is 155 ?,the heat preservation pressure is kept for 90 minutes,and the die opening temperature is 30?,the molding temperature process was determined by PVC gelation test and paste decomposition test.The water temperature suitable for cross-linking foaming was65?by water-boiling foaming experiment.In the design of mold aspect,the mold of the mold pressing stage and boiling and foaming are designed,and the static pressure sealing mode is established as the sealing mode of mold of mold pressing,the continuous adjustment of the mould cavity volume of the water-boiling and foaming mould is realized by adopting a screw transmission mode.The PVC foam with density of 100Kg/m3,200Kg/m3 and 300Kg/m3 is prepared,and the mechanical properties were compared.Finally,the effect of epoxy compound(epoxy soybean oil)on the mechanical and thermal stability of PVC structural foam was studied,and the PVC flame retardant foam with good compression and thermal stability was prepared.