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  • 1
    Electronic Resource
    Electronic Resource
    The V-notch at weld lines in polystyrene injection moldings (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 931-936 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A major factor that weakens the weld line in injection moldings is the V-notch structure. Though the existence of a V-notch is well known, its depth variation with molding conditions has not been detailed. The aim of this paper is to clarify the V-notch structure and its effect on the strength of general purpose polystyrene injection moldings. A dog bone type tensile specimen with a weld line was molded under several molding conditions. The surface of the weld line was partially eliminated by cutting with a milling machine to seven levels of cut depth (Dc). As a result, the weld strength increased with Dc to about 50%. The relationship between the weld strength and Dc made it possible to determine the V-notch depth, which vas defined as the “depth of the weld line.” From these results, a hypothesis is proposed that the V-notch has a structure with a fine groove on the surface and a poorly bonded inner layer. This study considered the relationships among the weld strength, the depth of the weld line, and molding conditions.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301508
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of chelation on the selective transport of alkaline-earth metal ions in asymmetric cellulose acetate hyperfiltration membranes (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 1795-1800 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rejection of calcium and/or magnesium ion by asymmetric cellulose acetate hyperfiltration membranes is increased significantly by formation of the corresponding alkaline-earth metal chelate. Typically solute fluxes are reduced by a factor of 5 consequent to chelation with ethylenediaminetetraacetic acid (EDTA) at pH 6.0. Selective chelation and, in turn, selective transport of magnesium is observed when equimolar solute mixtures corresponding to 1:1:1 magnesium:calcium:EDTA are hyperfiltered. Under these conditions, calcium successfully competes for the stoichiometrically limiting EDTA, and the rejection of magnesium is lower than the rejection observed for the hyperfiltration of the MgEDTA2- complex in the absence of competitive calcium. Alternatively, the rejection of the CaEDTA2- complex is increased under these identical conditions, presumably as a consequence of specific interactions between the available free magnesium and the cellulose acetate membrane. The effects reported here all seem to be related to reductions in solute diffusivity associated with the increased size of the alkaline-earth metal ion complex.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210707
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  • 3
    Electronic Resource
    Electronic Resource
    Growth of poly(methyl methacrylate) particles in three-component cationic microemulsions (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1161-1168 
    Details
    ISSN: 0887-624X
    Keywords: microemulsion ; polymerization ; methyl methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of methyl methacrylate (MMA) has been studied in ternary microemulsions which were stabilized by tetradecyltrimethylammonium bromide (TTAB) or stearyltrimethylammonium chloride (STAC). The sizes of MMA-swollen polymer particles (Rh) increased continuously during polymerization. This is in contrast to that of the styrene system, where Rh increased very rapidly to a maximum and then decreased continuously towards a constant value. The continuous growth of PMMA particles at 60°C are discussed. The stability of PMMA latexes increased with increasing the hydrophobic chain length of the cationic surfactant used. Traces of the coagulations of PMMA particles in the TTAB system can be seen from TEM. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330719
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  • 4
    Electronic Resource
    Electronic Resource
    Basic structure-property behavior of UV curable polyurethane acrylates (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2095-2102 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effects of hard segment type, soft segment type, soft segment length, and crystallization at various levels of reactive diluent have been studied in polyurethane acrylates. PTMG-IPDI-based PU acrylates gave better soft segment-hard segment phase separation as compared with PTMG-TDI-based ones. Among PTMG-, PCL-, and PTAd-IPDI-based materials, only PTMG-based one gave clean phase separation, and PTAd-based gave the poorest phase separation. With greater phase separation, higher modulus was obtained. Crystallization of soft segment in PTAd-IPDI-based material gave a significant increase in tensile modulus and elongation at break, with a notable difference in dynamic mechanical properties. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hydrodynamic characteristics of dual Rushton impeller stirred vessels (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 332-346 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The flows generated in vessels stirred by two Rushton impellers were investigated in two vessels of diameter (T) 100 and 294 mm with impellers of diameter D = T/3 using flow visualization, power consumption, mixing time, and 360° ensemble-averaged and 1° angle-resolved LDA measurement techniques. The flows depended strongly on the clearance of the lower impeller above the base of the vessel (C1), the separation between the impellers (C2), and the submergence (C3) of the upper impeller below the top of the liquid column height (H). When these distances were varied, three stable and four unstable flow patterns were observed. Comparisons between the two LDA techniques showed that while the 360° ensemble-averaged measurements are useful for characterizing the overall flow structure and turbulence levels in the vessel, care must be exercised when interpreting such data, since in the impeller region they include periodic variations in the mean velocity in addition to the turbulent fluctuations. The trailing vortex structure and flow periodicity produced by the Rushton impellers is shown to decay significantly within a cylindrical region of height 1.2D and radius 1.0D centered around the middle of the vessel, when C1 = C2 = T/3. The turbulence structure within this region is anisotropic, while outside this region it might be considered mostly isotropic. The main flow features scaled well between the vessels.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420204
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  • 6
    Electronic Resource
    Electronic Resource
    Profiles of volatile metabolites in biological fluids using capillary columns (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 423-428 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, nickel ; „Transevaporator“ into packed pre-column as sampling technique prior capillary described ; Application to volatile metabolite body fluid analysis for early detection of disease ; Serum and human breast milk as examples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nickel capillary columns coated with moderately polarstationary phases such as Witconol can be used for the separation of the organic volatile fraction from biological fluids. A “transevaporator” sampling technique for the collection of the organic volatiles on glass beads from as little as 5 to 500 μl of biological fluids (e.g. urine, serum, amniotic fluid, breast milk, saliva, etc.) is described. The organic volatiles are thermally desorbed from the glass beads into a short precolumn cooled in liquid nitrogen, which overcomes the problems associated with sample introduction onto narrow-bore capillary columns. The application of the full analytical technique to problems associated with the early detection of disease is illustrated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020710
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  • 7
    Electronic Resource
    Electronic Resource
    Local shell-side heat transfer coefficients and pressure drop in a tubular heat exchanger with orifice baffles (1960)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 6 (1960), S. 669-675 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: By means of a moveable sensing probe previously described2 local shell-side heat transfer coefficients and friction losses were measured on a model tubular heat exchanger containing orifice baffles. The heat exchanger shell was 6-in. nominal I.D. and 45 in. in length and contained four tubes in triangular arrangement passing through orifice baffles. Baffle hole diameters of 1-/16, 1-2/16, 1-3/16, and 1-5/16 in. and baffle spacings of 4.0 and 9.0 in. were studied. Data were taken at several air flow rates for each of the four baffle hole diameters.The average heat transfer coefficient for the region between two central baffles was correlated with an empirical equation based on only two baffle spacings.An increase in the baffle-to-tube clearance caused a decrease in heat transfer. An increase in the baffle spacing also resulted in a decrease in heat transfer. Four flow zones in the baffle space are postulated from the analysis of Nusselt number distribution along the tube. The heat transfer characteristics in each of the four flow zones were analyzed in terms of the mechanism of the fluid flow.The pressure-drop data were correlated in terms of an annular orifice coefficient of discharge and an orifice-pressure-drop function. As a result of this study a method was developed by which one can predict the average of the local coefficients at the baffle position from the knowledge of pressure drop across a single baffle.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690060430
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  • 8
    Electronic Resource
    Electronic Resource
    On-line optimizing control of a nonadiabatic fixed bed reactor (1985)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 667-675 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A scheme of on-line optimizing control is presented for a nonadiabatic fixed bed reactor which experiences a highly exothermic reaction. The control scheme has been devised to perform adaptive control of bed temperature and on-line steady state optimization simultaneously.Experiments were conducted with a pilot scale fixed bed reactor where partial oxidation of n-butane to maleic anhydride occurs. The reactor system was interfaced with a microcomputer for real-time control and optimization. With an objective function consisting of a net profit by producing maleic anhydride plus a penalty term on high bed temperature, it was clearly shown that the reaction conditions were driven to the expected optimum region.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690310417
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  • 9
    Electronic Resource
    Electronic Resource
    Diffusion of ethylene glycol accompanied by reactions in poly(ethylene terephthalate) melts (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 707-716 
    Details
    ISSN: 0887-6266
    Keywords: poly(ethylene terphthalate), diffusion of ethylene glycol in melts of ; diffusion coefficient of ethylene glycol in PET melts ; diffusion with chemical reaction of ethyleneglycol in PET melts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Diffusion coefficients of ethylene glycol (EG) have been measured in poly(ethylene terephthlate) (PET) melts by a quartz-spring sorption apparatus. A simple mathematical model was developed to investigate the sorption behavior accompanied by chemical reactions of EG and PET at high temperatures. Diffusion coefficients are deduced from experimental data for an asymptotically thin sample in order to minimize the effects of reactions. The diffusion coefficient of EG is strongly dependent on the vapor pressure of EG and temperature but not on the molecular weight of PET in this experimental range (degree of polymerization 80-120). The diffusion coefficient of EG in PET melt at 265°C is 2.58 × 10-7 cm2/s at the limit of zero concentration of EG. The activation energy for diffusion is 38.4 kcal/gmol, and the heat of solution for sorption is -44.9 kcal/gmol. The concentrations of the volatile materials resulting from reactions in PET-EG system were analyzed with gas chromatography. In addition, a fit of the current model to experimental data yields frequency factors for the polymerization reaction (k1) and the acetaldehyde formation reaction (k2) to be 5.84 × 108 cm3/mol ċ min and 3.90 × 1011 min-1, respectively.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300708
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  • 10
    Electronic Resource
    Electronic Resource
    Structure and property development in poly(p-phenylene terephthalamide) during heat treatment under tension (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1-14 
    Details
    ISSN: 0887-6266
    Keywords: poly (p-phenylene terepthalamide) ; Kevlar® ; heat treatment ; structure development ; mechanical properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The evolution of several structural characteristics during isothermal heat treatment of poly(p-phenylene terephthalamide) was studied. In this work, heat treatment was interrupted after different treatment times, with the specimens immediately quenched to room temperature. These specimens were then characterized by tensile testing, wide- and small-angle x-ray scattering, and optical microscopy. Structural parameters obtained from these measurements relate to crystal perfection (via the paracrystalline axial distortion parameter), axial crystallite size, transverse crystallite size, degree of chain misorientation, and degree of pleating. Structural and mechanical parameters were then plotted against heat-treatment time to obtain kinetic isotherms for each parameter. The kinetics of the removal of chain misorientation parallels that of tensile modulus increase under all conditions. Of the other structural parameters, only the kinetics of pleat removal mimics that of modulus change, indicating that pleat removal is the effective cause of increased chain alignment and thereby of increased axial stiffness. ©1995 John Wiley & Sons, Inc.
    Additional Material: 27 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330101
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