| 1 | VARIATION OF PHYSICO-CHEMICAL PROPERTIES OF RADIATION CROSSLINKED RUBBER WITH STORAGE TIME显示文摘The effect of storage on physico-chemical properties of non-irradiated natural rubber and radiation vulcanized natural rubber (RVNR) were evaluated. The rubber films were stored under two different conditions, namely in open air and sealed polyethylene bags. The antioxidant, tris(nonylated phenyl) phosphite (TNPP) was used for preventing degradation of RVNR films. Gel content, cross-link density, tensile strength at break and 500% elongation of rubber films were measured.The results show that the retention (%) of tensile properties of rubber films with TNPP is higher than that of rubber films without antioxidants. The rubber films stored in polyethylene bags also show better retention of tensile properties than those of rubber films stored in open air. | N.C.Dafader M.E.Haque F.Akhtar | 2005 | Chinese Journal of Polymer Science2005，23，5： | 0 |
| 2 | EFFECT OF GAMMA RAYS IN THE PREPARATION OF POLYMER AND HYDROGEL FROM ACRYLAMIDE MONOMER显示文摘The formation of polymer and hydrogel from aqueous solutions having 20, 30 and 40% concentrations of acrylamide monomer by γ-ray irradiation processing in the dose range 0.06-30 kGy using a Co-60 source and their characterization have been observed. Polymer conversion and gel fraction are found to depend on radiation doses. Polymer conversion increases with the increase of dose, depending on the solution concentration, where maximum conversion is achieved at 0.18, 0.16 and 0.10 kGy for 20%, 30% and 40% concentrations, respectively. On the other hand, gel fraction increases with dose from the gel point (0.12 kGy) for all concentrations, where 100% conversion of gel occurs at doses ≥ 5 kGy. Tensile strength, viscosity and molecular weight (Mw) of polymer samples increase with both the dose and the concentration, showing a high value of Mw up to ≈108. Swelling of hydrogels under water with respect to time varies due to the variation of cross-linking density formed in the gels and the maximum swelling mainly occurs within 24 h. A remarkable change of surface morphology reveals characteristic features of monomer, polymer and hydrogel films. | M.M.Alam M.F.Mina F.Akhtar | 2003 | Chinese Journal of Polymer Science2003，21，4： | 0 |
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