Pb2+ binding by polyaspartyl polymers and their application to Pb2+ removal from glycyrrhizin

Polyaspartate is an excellent Pb²⁺‐binding agent in comparison with some polyaspartamide derivatives with different side chains, in that it possesses a higher Pb²⁺ uptake and a lower Pb²⁺ equilibrium concentration. Equilibrium sorption data for Pb²⁺ on polyaspartate can be well fitted with the Freundlich and Langmuir models. Experimental results show that a crosslinked polyaspartate hydrogel is superior to poly(acrylic acid)‐based resins and polystyrene‐based chelating resins. IR spectra and X‐ray photoelectron spectra reveal that the polyaspartate hydrogel binds Pb²⁺ by both an ion‐exchange mechanism and a chelating mechanism. The polyaspartate hydrogel is also an effective agent for the removal of Pb²⁺ from glycyrrhizin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2215–2220, 2005     

Production of antimicrobially active silk proteins by use of metal‐containing dyestuffs

The work presented here discusses a new technique for preparing silk fibers and films with persistent antimicrobial activity through use of metallic dyestuffs during the fiber dyeing process. The length of the silk fibers investigated contracted when the fibers were immersed in concentrated neutral salt solutions, such as calcium or potassium nitrate, at elevated temperature levels. The birefringence and molecular orientation of the silk fibroin molecules became less ordered by the action of the neutral salt solutions, resulting in increased dyestuff absorption. Subsequently, contracted silk fibers were dyed with metallic dyestuffs containing Cr or Cu for the purpose of obtaining silk fibers with antimicrobial activity. Silk fibers dyed with metallic dyestuffs showed significant antimicrobial activity against the plant pathogen Cornebacterium and the human pathogen Coli bacillus. Tensile strength of the silk fibers after the salt shrinking and dyeing processes did not show a significant change, whereas the elongation at break was increased slightly. The techniques described here for preparing significantly active antimicrobial silk fibers are effective and economic ways of providing new materials for industrial and biomedical applications. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1181–1188, 2002     

低温快烧无铅精陶釉的研制

采用高温熔融法制备了适用精陶的低温无铅熔块，并应用热膨胀分析仪、SEM等方法研究了精陶釉的光泽度、热稳定性、热膨胀系数等性能。结果表明：采用Li2O，SrO，B2O3等复合熔剂，可以制备出光泽度高，热稳定好，坯釉膨胀系数匹配，结合良好，适于低温快烧工艺的无铅精陶釉。     

耐热性橡胶配合技巧(上)

介绍了耐热橡胶的等级划分，各种橡胶的使用温度和性能特点，及13种橡胶（天然橡胶、聚氨酯橡胶、丁苯橡胶、顺丁橡胶、氯丁橡胶、丁腈橡胶、氯磺化聚乙烯橡胶、氯醚橡胶、丁基橡胶、乙丙橡胶、丙烯酸酯橡胶、氟橡胶、硅橡胶）的78个耐热配方实例，并对配方做了简要说明。所述配方可基本满足橡胶材料从A～I级9个耐热等级的不同要求。     

Dynamic mechanical properties of polycarbonate and acrylonitrile–butadiene–styrene copolymer blends

Blends of polycarbonate (PC) and poly(acrylonitrile‐co‐butadiene‐co‐styrene) (ABS) with different compositions are characterized by means of dynamic mechanical measurements. The samples show phase separation. The shift in the temperatures of the main dynamic mechanical relaxation shown by the blend with respect to those of the pure components is attributed to the migration of oligomers present in the ABS toward the PC in the melt blending process. A comparison with other techniques (dielectric and calorimetric analysis) and the application of the Takayanagi three block model confirm this hypothesis. In all the studied blend compositions (ABS weight up to 28.6%) the PC appears as the matrix where a disperse phase of ABS is present. The scanning and transmission electron microscopy micrographs show that the size of the ABS particles increases when the proportion of ABS in the blend increases. The FTIR results indicate that the interaction between both components are nonpolar in nature and can be enhanced by the preparation procedure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1507–1516, 2002     

Physical characteristics of sweet potato pulp/polycaprolactone blends

Sweet potato pulp (SSP) obtained as a by‐product from starch extraction was blended with polycaprolactone (PCL) to prepare a biodegradable plastic material. In the blends, PCL was used as a reinforcing agent. The SPP/PCL blends were prepared by compression‐molding under high temperature and pressure, at different SPP/PCL ratios, and the mechanical properties of the molded specimens were tested. Matrix structure and thermal properties were measured by using a Fourier transform infrared (FTIR) spectrophotometer, scanning electron microscope (SEM), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). Mechanical properties (tensile and flexural properties) were also measured to find the most suitable ratio in a SSP/PCL blend. During compression molding of the SPP/PCL blends under high pressure and temperature, chemical reaction occurred between SPP and PCL, and thus, thermal stability and mechanical strength of the blends increased and water uptake decreased. Also, by increasing the PCL content in the blend, the matrix in the blend became more homogeneous, and consequently, mechanical strength of the molded specimen increased. At 7/3 or 6/4 weight ratio of SSP/PCL, water uptake of the molded specimen became substantially less than that at 8/2. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 861–866, 2004     

Resistivity and thermal reproducibility of carbon black and metallic powder filled silicone rubber heaters

Flexible heaters were prepared by extruding platinum‐catalyzed silicone rubber composites with conductive carbon black (CB) and metallic fillers. The conductor resistivity of the extruded heaters decreased in order of conductive titanium dioxide (TiO₂) > aluminum powder ≈ zinc powder > copper powder. Thermoelectric switching phenomena were investigated for the silicone rubber/CB/metallic powder systems. The positive temperature coefficient effect was dependent mainly on the CB content rather than on the content of the metallic powders. Resistivity and thermal reproducibility of the extruded heaters were also investigated by periodically applying AC voltage of 110 V. The heaters containing copper and TiO₂ powders exhibited excellent electrical reproducibility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1122–1128, 2005     

Amphoteric water‐soluble copolymer for barium titanate slurries. I. Synthesis and dispersing ability

An amphoteric water‐soluble copolymer, polyacrylamide/[α‐N,N‐dimethyl‐N‐(3‐(β‐carboxylate)acrylamino)propyl] ammonium ethanate (PAM/DAE) was synthesized and used as a dispersion agent for BaTiO₃ particles. PAM/DAE was prepared from acrylamide and [α‐N,N‐dimethyl‐N‐(3‐(β‐carboxylate)acrylamino)propyl] ammonium ethanate in a basic condition through a free‐radical polymerization. The structure of this copolymer was verified by IR and ¹H‐NMR spectra. The dispersing effects of PAM/DAE were examined by measuring the viscosity and sedimentation of BaTiO₃ suspensions, and by analyzing the particle size. The results indicate that this copolymer could uniformly disperse the particles, and the resulting suspensions were less viscous, more stabilized, and contained powder with smaller particle size. The dispersing/stabilizing ability of PAM/DAE is close to, or slightly better than, that of a commercial dispersant, ammonium salt of poly(methacrylic acid). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1443–1450, 2005     

墙地砖边缘检测中的小波去噪

在墙地砖的边缘检测过程中,噪声的引入是不可避免的,有效地消除噪声而不影响检测结果是检测过程中需要解决的关键问题。本文采用了小波去噪方法—对图像进行去噪后再进行边缘检测的方法,其检测结果较好地满足了检测要求。