Incorporation of surface-modified UHMWPE powders and fibers in tough polyurethane composites

Ultrahigh molecular weight polyethylene (UHMWPE) powder (60 micron diameter) and chopped fiber (6.5 mm length) were surface treated with a blend of reactive gases (fluorine and oxygen.) These powders and fibers were then compounded into a thermoset polyurethane matrix. Surface-treated and control reinforcements are compared at a 10 vol.% loading level. Tensile testing indicates improved stress transfer with surface treatment. Stress transfer is also improved with fibers versus powders. Fracture toughness is characterized by measuring the essential work of fracture, w_e. Surface-treated fiber composites exhibit work of fracture values almost three times the unfilled polyurethane values. Abrasion resistance was also measured. Surface treatment was found to significantly lower wear rates of powder composites. Fiber composites had lower wear rates than powder composites, although surface treatment had little effect. An approximate inverse relationship was found between wear rate and essential work of fracture.     

Analyses of flavor qualities of vegetable oils by gas chromatography

Soybean oil, hydrogenated soybean oil, and corn oil were exposed to fluorescent light for different periods of time to obtain a wide range of flavor qualities. The flavor qualities of these oils were evaluated by sensory and gas Chromatographic methods. Sensory evaluation was conducted using a 10-point hedonic scale to rate overall flavor quality. The sensory panel was made up of 94 members from 8 different laboratories. The correlation coefficients (r) of the flavor scores between sensory evaluation and instrumental analysis for soybean oil, hydrogenated soybean oil, and corn oil were 0.95, 0.97 and 0.97, respectively. These results were very close to the correlation coefficients (r) 0.99, 0.98 and 0.95 obtained from 10 sensory panel members from one specific laboratory.     

Plastic Deformation and the Fracture Surface Energy of Sodium Chloride

A correlation between plastic deformation at crack tips in sodium chloride and the measured value of the fracture surface energy is presented. Plastic deformation can either aid or hinder crack growth, depending on the mode of deformation at the crack tip. If plane-stress deformation occurs, crack motion is hindered by step formation, dislocation generation, and plastic blunting of the crack tip. If plane-strain deformation occurs, crack motion is aided by stress fields that arise from the deformation. The specific surface free energy of sodium chloride, {100} plane, is estimated to be less than 0.37 J/m².     

Model for the impedance analysis in a three electrode solid state electrochemical cell

A T-network model for the determination of the electrode impedances in a three electrode solid state electrochemical cell is postulated and discussed. The model is applied to a Li solid battery where the electrolyte is the polymer (PEO)₈LiCF₃SO₃ and the positive electrode is the insertion electrode V₆O_{13 + x}. The Li metal reference electrode is found to have an impedance considerably greater than that of the working (V₆O₁₃ + x) or the counter electrode (Li). The significance of these impedances is discussed in relation to the geometry and construction of solid electrolyte cells, and to their suitability for potentiostatic measurements.     

Mechanisms of antioxidant action: The role of nitroxyl radicals in the stabilization of PVC

Hindered amines and their derived oxidation products, the hindered nitroxyls and hydroxylamines are processing stabilizers and photoantioxidants for poly(vinyl chloride). The evidence suggests that oxidation of the amines occurs very rapidly and completely during mechanooxidation and that the resulting redox couple operates by a catalytic mechanism as described previously for hydrocarbon polymers.     

Sulfur content of crude rapesseed oil from aqueous extraction

Dry heating of rapeseed before grinding increased the sulphur content of the crude rapeseed oil. Boiling the seeds in H₂O before grinding caused a slight decrease in the sulphur level of the oil. Control of pH during boiling of the ground rapeseed increased the sulphur content of the oil from ca. 2 ppm at pH 3.1 to ca. 10 ppm at pH 7.6.     

Special features in dyeing modacrylic fibre

Conclusions The possibility of dyeing freshly-spun modacrylic fibre with cationic dyes and in bulk with dyes or pigments of various classes has been investigated under laboratory conditions.It is recommended to use dyeing of modacrylic fibre in bulk with acetone-soluble dyes, which permits one to eliminate the energy-intensive process of pigment dispersion.Translated from Khimicheskie Volokna, No. 6, p. 36, November–December, 1988.     

Preparation of a microporous composite: Encapsulation of paper by polyethylene

A rapid polymerization method for in situ synthesis of polyethylene in a typical paper matrix of cellulose fibers is described. The unique properties of this double matrix, polyethylene in cellulose, are the result of performing the polymerization in a nonsolvent such that simultaneous polymerization and crystallization takes place yielding a nascent morphology. The morphology has been studied by scanning electron microscopy and was found to be different from what is usually obtained for melt crystallized polyolefins. Optical microscopy shows the polyethylene to be present as a complementary matrix with respect to the basic fiber construct. Mechanical, optical, and other properties of encapsulated filter paper have been measured using standard TAPPI tests. The results show a general improvement in physical properties for a range of “add ons” from 0 to 27%. Wet-strength and opacity undergo major changes.     

Development of high‐definition aqueous polyvinylpyrrolidone photoresists for cathode ray tubes

Aqueous photoresists that are capable of higher resolutions than are currently employed by the cathode ray tube (CRT) industry were developed by combining photoactivators, which activate at shorter UV wavelengths with polyvinylpyrrolidone (PVP). Two photoactivators were synthesized: 4,4′‐diazido‐2,2′‐biphenyl disodium disulfonate (DABP), which has a maximum absorbance at 264 nm, and 4,4′‐diazido‐2,2′‐biphenylethane disodium disulfonate (DABPE), which has a maximum absorbance at 258 nm. The PVP/DABP and PVP/DABPE photoresists successfully imaged a pattern with resolution as small as 4.4 μm with photoactivator concentrations greater than 20% of the PVP concentration. Addition of silane and emulgen greatly improved the performance of the photoresists with more uniform coatings of thicknesses of up to 1.4 μm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1637–1644, 2006     

Human interaction with policy flight simulators

Policy flight simulators are designed for the purpose of exploring alternative management policies at levels ranging from individual organizations to national strategy. This article focuses on how such simulators are developed and on the nature of how people interact with these simulators. These interactions almost always involve groups of people rather than individuals, often with different stakeholders in conflict about priorities and courses of action. The ways in which these interactions are framed and conducted are discussed, as well as the nature of typical results.