Methods to determine solubility parameters of polymers using inverse gas chromatography

Experimental values of the Flory–Huggins parameter, χ, between polymers and solvents, are frequently used to determine the solubility parameters of the polymers. A method using nonlinear curve fitting of RTχ/V was compared to the linear regression method commonly used. It was found that the formulas for the solubility parameter were the same, but the linear method produced a slightly different entropy term. The nonlinear method gave a lower correlation coefficient and wider confidence intervals and was more effective at distinguishing systems than the linear model. The effect of the deviation of probes in the solubility parameter model is discussed. Using probes with low solubility parameters to measure the polymer solubility parameter gave wider confidence intervals. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2894–2902, 2004     

Polyamide‐reinforced ethylene–propylene–diene rubber compatibilized with chlorinated polyethylene

Vulcanizates of blends of ethylene–propylene–diene rubber and polyamide copolymers were prepared by reactive compatibilization. A reactive route was employed for compatibilizing these blends with the addition of chlorinated polyethylene (CPE). The influence of the compatibilizers, crosslinking agents, blend compositions, and addition modes of the compatibilizers on the mechanical properties of the blends was investigated. The morphologies of the blends were determined with scanning electron microscopy. The addition of CPE was found to reduce the particle size of the dispersed phase remarkably. The stability of the blends with compatibilizers was measured by high‐temperature thermal aging. The mechanical properties were examined by stress–strain measurements and dynamic mechanical thermal measurements; the addition of polyamide copolymers caused significant improvements in the tensile properties of these blends.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1727–1736, 2003     

残余应力对TiC_p－AIN复合材料的影响

本工作采用热压工艺，以Ｙ＿２Ｏ＿３为烧结添加剂，在１８５０℃下制备ＴｉＣ＿ｐ－ＡＩＮ复合材料。结果表明：复合材料的密度、抗折强度、断裂韧性受第二相ＴｉＣ＿ｐ的影响，通过合理工艺因素选择，可以使复合材料的抗折强度和断裂韧性比基体ＡＩＮ材料分别提高４０％，８０％，达到４３８ＭＰａ，５．５９ＭＰａ·ｍ￣（１／２）。由ＸＲＤ内应力分析和ＴＥＭ显微结构测试结果可知，复合材料性能改善原因在于高弹性用量的ＴｉＣ引入以及ＡＩＮ和ＴｉＣ热膨胀系数不匹配导致的残余内应力。     

甲酸甲酯合成与转化的催化技术

本文评述了甲酸甲酯(MF)合成与转化的催化技术,展示了从MF出发发展C_1化学的可能途径,在MF的合成方面详细地分析了从甲醇出发的羰化法、脱氢法和氧化法催化技术,简介了我们的有关研究工作。     

Catalytic coal partial gasification in an atmospheric fluidized bed

The coal partial gasification catalyzed by limestone, sodium carbonate and dolomite was studied using a bench-scale atmospheric fluidized bed in the presence of air and steam at 900 °C. The effects of limestone, sodium carbonate and dolomite on composition, heating value, gas yield of product gas and carbon conversion in the catalytic coal partial gasification have been examined. The experimental results show that the catalysts can effectively improve the gas quality, the heating value and the gas yield of product gas and carbon conversion. The catalytic effect of sodium carbonate is better than that of limestone and dolomite. The increase of limestone loading can enhance the quality of product gas, such as the content of combustible gas, the high heating value and the gas yield, during coal partial gasification. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Surface properties of block and graft polystyrene–polydimethylsiloxane copolymers

The surface compositions of a series of polystyrene‐b‐polydimethylsiloxane (PS‐b‐PDMS) and polystyrene‐g‐polydimethylsiloxane (PS‐g‐PDMS) copolymers were investigated using ATR‐FTIR and XPS technique. The results showed that enrichment of PDMS soft segments occurred on the surface of the block copolymers as well as on that of graft copolymers. And the magnitude order of the enrichment was as follows: PS‐b‐PDMS > PS‐g‐PDMS, which was attributed to the facilitating of the movement of the PDMS segments in PS‐b‐PDMS copolymer. Meanwhile, the solvent type and the contact medium had influence on the accumulation of PDMS on the surfaces. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Phase Diagram for Liquid Crystalline Polymer/ Polycarbonate Blends

A novel mechanism to form binary polymer blends is through phase separation by spinodal decomposition in the unstable region of the phase diagram. The present work investigates the effects of thermally‐induced phase separation by spinodal decomposition on the morphology development of liquid crystalline polymer/polycarbonate blends. Moreover, a thermodynamic binary phase diagram is obtained using a twin‐screw extruder at various processing melt temperatures. Differential scanning calorimetry and scanning electron microscopy were used to study the miscibility of the blends and the resulting morphology. A thermodynamic binary phase diagram exhibiting a lower critical solution temperature was obtained. The droplet size distribution of the blend was also obtained and discussed in light of the Cahn‐Hilliard theory.     

裂解色谱法对共聚物与共混物的鉴定

李文应用裂解色谱法对丙烯酸酯等物质的共聚物与共混物进行了鉴定。     

Synthesis of SBS thermoplastic block copolymers in cyclohexane in the presence of diethylether used as a structure modifier

Diethylether (DEE) was used as a structure modifier during the synthesis of linear styrene-butadiene block copolymers of poly A-block-polyB-block-polyA type (SBS). The microstructures of synthesized polymers were analyzed, and the effect of DEE on polymerization kinetics was studied. Addition of DEE at 2 wt% concentration results in the highest styrene polymerization rate, while addition at 6 wt% concentration gives the highest butadiene polymerization rate. The vinyl content of the polybutadiene portion increases from 14 to 47% with an increase in the DEE concentration from 500 ppm to 10 wt% while thetrans- l,4 andcis-1,4 isomers decrease. For SBS polymer synthesized via a sequential method, the addition of DEE as a structure modifier minimizes the crossover deficiency which would otherwise result in a skewed molecular weight distribution with a higher polydispersity. For SBS polymers made via a coupling method, the coupling efficiency appears to be constant in a range of DEE concentration from 500 ppm to 1 wt% before declining with a further increase in DEE.     

Pressureless Sintering of Si3N4 Ceramic Using AlN and Rare-Earth Oxides

Using intermediate, liquid-forming compositions in the (Y,La)₂O₃-AlN system as additives, fully dense Si₃N₄ ceramics with high strength at high temperature have been obtained by pressureless sintering. The ceramics contain rod-shaped β-Si₃N₄ with M' or K' solid solutions as grain-boundary phases. The strength of these ceramics is 1150 MPa at 1200°C, and the room-temperature toughness is maintained at }7 MPa·m^1/2. Phase relations that are pertinent to the new additive compositions are delineated to rationalize their beneficial effects on sinterability and mechanical properties.