Research Of Preparation Of Low Density Acylamine Polymeric Foams By Supercritical CO₂ Foaming

Acyl(amido)amine polymers have good flame retardancy,chemical resistance,and excellent mechanical properties.They have widely applied in engineering areas.However,their prices are very expensive,Lighter weight can reduce costs and broaden the scope of application.Polyetherimide(PEI)as a special engineering plastic,molecular chain containing benzene ring,imide ring and has a great rigidity and melt strength,so ordinary scCO2 foaming is difficult to prepare a larger cell,higher magnification PEI foam.Nylon(PAs)is one of the five general engineering plastics,of which nylon 6(PA6)is the most widely used,but its molecular chain is linear,the melt strength,elastic modulus is very low,so there is no shear thinning and extrusion swelling behavior,which means poor foamability.This article selects two amide-type polymers and achieves foamable properties through different treatment methods.For pure PEI foaming with scCO2,the maximum expansion ratio at 25 MPa is only 3.6;Then,by adding a co-blowing agent,the co-blowing agent(H2O,C2H5OH)type,foaming temperature,foaming pressure are examined to study the effect on the foam pore structure;the results show that the maximum magnification of PEI foam prepared with H2O as a co-blowing agent is 8.5,the overall foaming zone shifts down to 170-220 ?,and expansion ratio with C2H5OH as a co-blowing agent is 7.5,and the foaming zone also moves down as a whole.For PA6,due to its low melt strength,the kind of modification machinery,the type of elastomers,the content of epoxy chain extenders,and the compounded modifiers were explored to study the effect on the thermal properties,rheological properties,and mechanical properties and so on of the modified PA6,thereby the effect on its foaming properties to determine the optimum foaming range;The results show that the internal mixer show better results than twin screw,that is,the foaming ratio,cell size and foaming zone of modified PA6 are better.Besides,when the epoxy chain extender ADR is added at 4 wt%,we can get PA6 with high viscoelastic ability,which has excellent foamability,foaming range of 205?233 ?,the highest magnification of 25.16,the corresponding pore size and cell density were 14.4 ?m,4.91×109 cells/cm3;Moreover,the addition of POE affect the rheological little,but the compounded ADR/POE had a greater impact on the modified PA6.The expansion ratio,cell size,and cell density were more stable over the entire temperature range,10?13,about 10?m,more than 3×109 cells/cm3,respectively.