Investigations On Synthesis And Structures And Properties Of Styrene-N-phenylmaleimide-Maleic Anhydride Random Copolymer

The random copolymers synthesized from n-phenylmaleimide and styrene monomer could improve heat resistant character of ABS resin as the heat-resistant agent without the damages of blending process.But the traditional prepared processes were complicated and difficult so that copolymers weren't easy to produce. In view of the reasons,the new preparations of copolymers were paid great attentions by the researchers and industries.According to the modified molecule structures of copolymers,n-phenylmaleimide(NPMI),styrene(St),and maleic anhydride(MAH) were selected to be copolymerized.NPMI was used to enhance the heat resistance,styrene to improve the melt flowability,and the polar monomer MAH to adjust the solubility parameter.The St-NPMI-MAH copolymers were synthesized by means of one-shot process with ditertbutyl peroxyphthalate as a novel initiator.The properties of St-NPMI-MAH terpolymers could be controlled by adjusting monomer ratios,the temperature and time of reactions.The new method of preparation,one-shot process,was convenient for the tradition bulk polymerization by adding the monomers.The one-shot process simplified the processing of reaction and reduced the steps of operations.The yield of copolymerization was 86wt%,so that the St-NPMI-MAH tercopolymers could be produced cosmically.The monomer molar ratios,mechanism of reactions and the feeding methods of one-shot process were studied systemically.It showed that the random copolymers could be gained under the appropriate conditions.The synthesis route of one-shot solution precipitation polymerization could simplify the process and cut the cost of preparation.The relationships between yield and time of reaction were also investigated.The results showed that the optimal condition with 30wt%NPMI feed ratio under 125℃for 4hr received greater economy profits.The chemical components and sequence structures characteristics of the St-NPMI-MAH random terpolymers were characterized by FTIR,¹H NMR,¹³C NMR,respectively.The relationships between random chain segments and chemical constitutions were clarified by various experiments.The molecular mass weight (Mw) of random polymers was about 5x10⁴ with PDI in the range of 2.2-2.7 by GPC.The heat resistance and thermal stability of the St-NPMI-MAH random copolymers which contained different NPMI weight percents were analyzed as well as terpolymers of the same NPMI content by DSC.The results showed that the glass transition temperature increased with the increasing of NPMI content of the terpolymers.On the other hand,the thermal degradation kinetics of the copolymers was researched by TGA.The results showed that Ozawa method was suitable to analyze the copolymers with various contents of NPMI.The apparent activation energy values were from 135 kJ/mol to 183 kJ/mol.The reaction order was about 1 by Crane method.So the terpolymers had ideal thermal stability.On the basis of the solubility parameter modifier of St-NPMI-MAH,the heat resistant ABS resins were prepared by blending of the St-NPMI-MAH random terpolymers and ABS resin.The blending materials showed only one glass transition temperature.Simultaneity the heat resistance was improved obviously with the increasing of St-NPMI-MAH content.The micro structures of the heat-resistant ABS resin were characterized by SEM.It was testified that the compatibility of blending between the St-NPMI-MAH random copolymers and ABS resin was expectant states. The mechanics and rheology properties of St-NPMI-MAH/ABS blending materials were investigated.The results showed that tensile strength and processing property of the blending materials were changed slightly.Therefore, Styrene-N-phenylmaleimide- Maleic anhydride random copolymers can be used as an excellent heat-resistant compatilizer to produce novel plastic alloys.