Papers by Author: Wei Ren

Abstract: Formula for microcellular unsaturated polyester using chemical foaming method was studied. With the increase of NaHCO3 content, the cell size of microcellular unsaturated polyester slightly decreased with the increase of styrene content in the range of 1-2 %. The cell size increased in the range of 2-4 %. With the increase of curing agent content, the cell size increased in the range of 0.5-0.9 % and decreased in the range of 0.9-1.3 %. The cell size decreased with the increase of styrene content in the range of 30-40 %. The cell size had little variation when styrene content was in the range of 40-50 %. The average cell size and cell density of microcellular unsaturated polyester were strongly affected by accelerant content. The cell size decreased with the increase of accelerant content. The opposite was for the cell density. The microcellular unsaturated polyester prepared at 2% NaHCO3, 0.3% accelerantt, 0.9% curing agent, 40% styrene had the small cell size, high cell density, and strong compression strength.

Abstract: Microcellular unsaturated polyester was prepared by different foaming agents was studied. Compared with the cell size and density of microcellular unsaturated polyester prepared using azodicarbonamide (AC), the ones of microcellular unsaturated polyester prepared using NaHCO3 were small. For NaHCO3, the cell density of microcellular unsaturated polyester decreased with the increasing temperature. For microcellular unsaturated polyester prepared using NaHCO3 at 100 °C, the average cell size was about 18 μm and the cell density was 1.1×1010 cells/cm3. The compression strength at 100 °C is strongest among that of the materials at the other temperature. The average compression strength was 24.2 MPa. The compression strength-to-weight ratio of microcellular unsaturated polyester prepared at 90 °C and 100 °Cwas about twice that of unsaturated polyester.

Abstract: Formula for glass fiber/microcellular unsaturated polyester composites (GF/MCUP) using supersaturated gas technology was studied by the way of orthogonal experiment. The results showed that these factors affecting average cell size from strongly to weakly were styrene content, accelerant content, glass fiber length, curing agent and glass fiber content, respectively. The factors affecting average cell density from strongly to weakly were accelerant content, styrene content, glass fiber content, curing agent content and glass fiber length, respectively. Curing agent content was the major factor affecting impact strength of GF/MCUP. The factors revealed no obvious difference in affecting tensile strength. Under the optimizing processing condition, the average cell size of GF/MCUP was about 8 μm and the cell density was 1.19×10⁹ cells/cm³. The 153.70 and 255.84 % increase in impact strength were gained over that of GF/UP and UP, respectively. The corresponding 20.24 and 82.51% increase in tensile strength-to-weight ratio were gained over that of GF/UP and UP, respectively.

Abstract: Glass fiber/microcellular unsaturated polyester composites (GF/MCUP) were prepared using the supersaturated gas technology. Technological process included three stages. The effect of processing parameters on average cell size, cell density, impact strength and tensile strength was investigaed by orthogonal experiment. The results indicated that the major factor affecting them was the temperature in stageⅡ(T2). Under the optimizing processing condition, the average cell size of GF/MCUP was about 8 μm and the cell density was 1.57×109 cells/cm3. It was found that impact strength of GF/MCUP increased 88.81 and 188.12 % than that of glass fiber/unsaturated polyester composites (GF/UP) and unsaturated polyester plastics (UP), respectively. The corresponding 16.56 and 69.25 % increase in tensile strength-to-weight ratio were gained over that of GF/UP and UP, respectively.