Synthesis And Oil-Absorbing-Releasing Properties Of Chemical-Physical Crosslinking High Oil Absorption Resins With Filler

The concept of physical crosslinking had been introduced into the research field of oil absorption resin which was traditionally synthesized by chemical crosslinking. Though polybutadiene (PB) was filled into resin as physical crosslinker to construct a kind of three dimensional network with high crosslink degree and low crosslink density, it also reacted with other monomers as a chemical crosslinking for the double bond in PB chain. Instead of PB, paraffin or ethylene-propylene copolymer (EPC) as filler would not react with monomers because there was no double bond in their molecular chain. .The acrylic high oil absorbency resins filled with paraffin or EPC were prepared by the suspension polymerization process. The effects of monomer feed ratio, chemical and physical crosslinker concentrations, and initiator concentration on the oil absorbency and gel fraction (crosslink degree) were studied. The recipe and operation conditions were optimized as follows: lwt% benzoyl peroxide (BPO), 0.4wt% ethyleneglycol dimethacrylate (EGDMA) at 80℃ for 7-8 h. For resin filled with paraffin, the concentration of styrene (St) is different from the one filled with EPC. For the former, weight ratio of St to dodecyl methacrylate (DMA) was 2:1, and for the latter is 4:1. After filled with paraffin or EPC, the oil absorbency increased at low EGDMA concentration. On the other hand, for both of them, the gel fraction of the resin hardly changed with the paraffin or EPC concentration, because the fillers did not add the chemical crosslinker. By studying the dynamic mechanical properties of the resins, it found that resins filled with EPC had formed a pure physical crosslinking, while resins filled with paraffin had not.The oil release properties of resins filled with paraffin or EPC were studied which was also affected by the crosslinker concentrations, initiator concentration. Since oil absorption and oil release were two opposite process, the mechanical of both are almost same, which was mainly affected by two opposite factors: resin oil affinity and forbidding force of three-dimensional network. The oil release speed decreased with increasing chemical crosslinker. However, the effect of addition agent (paraffin or EPC) concentration was complex. A related physical model was presented to descript the oil release diffusion process.Temperature and pressure had much influence on the oil release speed in comparisonwith monomer feed ratio and crosslinking agent concentrations and type, especially the former. The oil release properties were studied at various temperatures and pressures. Results showed that the oil release speed increased obviously with increasing temperature and decreasing pressure.The repetitious oil absorbency property was studied and result showed that the maximum oil swelling decreased slowly after several times. To identify whether or not, the resin dissolved partially into solvent was measured by gel permeation chromatography (GPC) and surface of the resin was observed through scanning electric microscope (SEM).