Polypropylene fibers reinforced with carbon nanotubes

The strength properties of polypropylene fibers were enhanced with single‐wall carbon nanotubes (SWNTs). Solvent processing was used to disperse SWNTs in a commodity polypropylene. After the solvent was removed, the solid polymer was melt‐spun and postdrawn into fibers of unusual strength. For a 1‐wt % loading of nanotubes, the fiber tensile strength increased 40% (from 9.0 to 13.1 g/denier). At the same time, the modulus increased 55% (from 60 to 93 g/denier). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2079–2084, 2002     

Polypropylene fibers melt-spun in the presence of torsional shear

Melt-spun fibers of isotactic polypropylene have been formed using specific combinations of shearing and elongational flow. Such rheological conditions were achieved with a take-up device capable of subjecting molten polymer filaments continuously to various combinations of torsional and elongational strains. Relationships were determined between mechanical properties of the resulting fibers and their molecular organizations. The results obtained indicated that these flow fields would produce fibers whose mean-preferred-chain-orientation directions ranged between being tilted radially from a direction parallel with the fiber axis (no torsional shear strain imposed) and having some additional tilt that is tangential with respect to the fiber circumference (some torsional shear strain imposed). It is not possible to resolve the observed helical chain tilts into contributions from crystalline and amorphous regions, respectively.     

Calculating the relative value of coal in Russian coking-coal markets

In order to improve the pricing of Russian coking coal, a method is proposed for calculating the relative technological value of purchased coking-coal batches. The basic idea is to compare the parameters of optimal coking batch and coking batch that includes the purchased coking-coal concentrate and other coals available to a particular buyer. It is shown that the relative technological value of a particular batch of coking-coal concentrate will depend on the parameters of the other coals included in the coking batch at a particular coke plant.     

Polypropylene matrix composites reinforced with pre-stressed glass fibers

Thermoplastic matrix composites have recently emerged as promising engineering materials because of their desirable properties such as high service temperatures, high impact resistance, and processing advantages. However, residual stresses in composites introduced during fabrication are cited as one of the most significant problems in the processing of composites. In some instances these stresses have been shown to significantly degrade the strength of the material, resulting in matrix cracking, debonding, reduced fracture toughness, and delamination. In this work, studies have been carried out on glass fiber reinforced polypropylene composites formed by compression molding process from co-mingled fabrics. The fibers were pre-stressed during the process to produce high performance composite products with low residual microstresses, which are harmful to the properties of the composite. Mechanical tests showed that pre-stress can increase the tensile, flexural and interlaminar shear properties of the composites, and there exists an optimum pre-stress level to gain best properties for each external loading condition.     

Polypropylene fibers grafted with poly(acrylic acid)

An effective method for the grafting of poly(acrylic acid) on polypropylene fibers has been developed, using diphenyl and a dispersing agent (NNO) in the grafting bath as additives to facilitate the grafting process. The method makes it possible to obtain high grafting degrees of poly(acrylic acid) on polypropylene fibers with a minimal quantity of homopolymer as a side product. The effect of grafting degree on the moisture absorption and swelling of the modified fibers has been examined and described with mathematical equations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2295–2299, 2002     

Protein and oil patterns in U.S. and world soybean markets

The Japan Oilseed Processors Association provided yearly data showing the average protein and oil content of imported soybeans from the U.S. (No. 2 Yellow and IOM grades), Brazil, Argentina, and the People's Republic of China. Throughout the years 1972–1988, U.S. No. 2 soybeans contained about 1–1.5% less oil than Brazilian soybeans. Recently, the protein content of U.S. soybeans has also fallen behind that of Brazil. U.S. IOM soybeans, a designation based on seed size, contained about 1.5% more protein and about 0.5% less oil than U.S. No. 2 soybeans. Surveys of U.S. soybeans in the years 1986, 1987, and 1988 showed consistent state and regional differences in protein and oil content. Soybeans from northern and western soybean-growing states (North Dakota, South Dakota, Minnesota, Iowa, Wisconsin) contained 1.5–2% less protein and 0.2–0.5% more oil than soybeans from southern states (Texas, Arkansas, Louisiana, Mississippi, Tennessee, Kentucky, Alabama, Georgia, South Carolina, North Carolina). State and regional differences in composition represented differences of up to 25 cents per bushel in Estimated Processed Value for one set of soybean meal and oil prices.     

Structure and tensile properties of Nanoclay–Polypropylene fibers produced by melt spinning

Nanocomposite fibers of polypropylene and montmorillonite‐based organoclay were produced by a melt‐spinning process, and their structures and mechanical properties were studied. The addition of nanoclay in polypropylene increased the rate of crystallization and altered the microstructures of the fibers. Increases in the crystal size and a reduction in the molecular orientation were observed in the nanoclay–polypropylene composite fibers. The tensile properties of nanoclay composite fibers were also studied, and decreases in the fiber modulus and tenacity and increases in the strain at break were observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

世界、亚洲和中国锦纶工业长丝/帘布市场分析

分别以世界、亚洲和中国为研究对象 ,根据轮胎行业的现状和发展趋势 ,对锦纶工业长丝 /帘布的市场现状进行了分析 ,对锦纶帘布市场的未来需求和发展进行了预测 ,并对我国帘布行业的发展提出建议 ,即国内帘布行业应进行产业重组 ;积极开拓国际市场 ,提高国际化经营水平 ;与大轮胎厂建立伙伴关系 ;增加品种规格 ,满足客户多品种、小批量、定制化的要求 ;发展聚酯、芳纶等新型骨架材料。