Preparation Of Expandable Polystyrene Nanocomposites By In-Situ Suspension Polymerization

Based on radical in situ suspension polymerization. Polystyrene nanocomposites are prepared by the polymerization of styrene/nano-inorganic particle. Then, the hexane for the polymer beads was added to prepare expandable polystyrene nanocomposites.In this paper, surface modifiers were utilized to obtain better compatibility of nano-inorganic particle with polystyrene matrix. The best type of modifiers and process conditions was confirmed by the means of activation index and infrared spectrum. The impact of different inorganic particles on the stability of the suspension system and the polymerization process was also studied. The function of hydroxyapatite/hydroxyethylcellulose/sodium dodecyl benzene sulfonate(HAP/HEC/SDBS)compound suspending agents was investigated. Under this composite dispersion system,The characteristics of beads formation and control of particle size was studied. Polystyrene composite beads were characterized to research on molecular parameters by means of gel permeation chromatography.The expandable polystyrene composite beads were characterized by infrared spectrum analysis, nuclear magnetic resonance(1H-NMR.13C-NMR),X-ray diffraction, thermo gravimetric analyzer and differential scanning calorimetry. The syntactic foam was produced by prefoaming. aging and molding processing.Then,the micro-morphology of this foam was firstly analyzed to study influence law of nano-inorganic particle on the micro-morphology by the means of scanning electron microscope. The optimized flame-retardant formula was determined by changing the proportion and amount of inorganic flame retardant.Color EPS composite beads were prepared by using the same method.The results showed that.the titanates coupling agent that formed a chemical bond with nano-inorganic particle was best; Some types of inorganic particle can affect the stability of suspension system and increase the reaction time;When the ratio of the amount of compound suspending agents(HAP/HEC=1:1) to styrene monomer is0.43%,The particle size of EPS composite beads is moderate and the distribution is concentrative,the content between6-26mesh is about97%; In a certain range of modified nano-inorganic particle amount,the molecular weight of EPS composite beads has a narrower distribution; The thermal stability of EPS containing modified nano-inorganic particle was improved significantly,but Tg of the composite beads changed slightly. In addition, The nano-inorganic particle showed a nucleation function in the foaming process; The composite particle foam moldings, in the presence of modified nano-inorganic particle that can disperse in styrene well, have a high closed-cell content and the size is small and uniform;When the percentage of HBCD is6%and the percentage of compound flame-retardant system (C/ZnB/Mg(0H)2/RP=1:0.1:1:1)is2.5%by the monomer,the fire retardant effects are good,and the self-extinguish time is only in0.4s. Color EPS composite beads prepared by this new process have rich,brilliant and uniform colour,which will be development direction.