Flow patterns in granulating systems

Particle flow patterns were investigated for wet granulation and dry powder mixing in ploughshare mixers using Positron Emission Particle Tracking (PEPT). In a 4-l mixer, calcium carbonate with mean size 45 μm was granulated using a 50 wt.% solution of glycerol and water as binding fluid, and particle movement was followed using a 600-μm calcium hydroxy-phosphate tracer particle. In a 20-l mixer, dry powder flow was studied using a 600-μm resin bead tracer particle to simulate the bulk polypropylene powder with mean size 600 μm. Important differences were seen between particle flow patterns for wet and dry systems. Particle speed relative to blade speed was lower in the wet system than in the dry system, with the ratios of average particle speed to blade tip speed for all experiments in the range 0.01–0.25. In the axial plane, the same particle motion was observed around each blade; this provides a significant advance for modelling flow in ploughshare mixers. For the future, a detailed understanding of the local velocity, acceleration and density variations around a plough blade will reveal the effects of flow patterns in granulating systems on the resultant distribution of granular product attributes such as size, density and strength.     

Understanding why adult participants at the World Senior Games choose a healthy diet

Background

Identifying those seniors most likely to adopt a healthy diet, the relative importance they place on certain perceived benefits associated with a healthy diet, and whether these perceived benefits are associated with selected demographic, lifestyle, and health history variables is important for directing effective dietary health promotion programs.

Methods

Analyses are based on a cross-sectional convenience sample of 670 seniors aged 50 years and older at the 2002 World Senior Games in St. George, Utah. Data are assessed using frequencies, bivariate analysis, analysis of variance, and multiple logistic regression analysis.

Results

Fruit and vegetable consumption was significantly higher in individuals aged 70–79, in women, in those not overweight or obese, and in those with excellent overall health. Dietary fiber consumption was significantly higher in former or never smokers, current and previous alcohol drinkers, in those not overweight or obese, and in those with excellent health. The strongest motivating factors identified for adopting a healthy diet were to improve the quality of life, to increase longevity, and to prevent disease. Of intermediate importance were the need to feel a sense of control and to satisfy likes or dislikes. Least important were the desire to experience a higher level of spirituality, social reasons, and peer acceptance.

Conclusion

Seniors who have adopted a healthy diet are more likely to have chosen that behavior because of perceived health benefits than for personal and social benefits. Overweight or obese individuals and those in poor health were less likely to be engaged in healthy eating behavior and require special attention by dieticians and public health professionals.

     

Analysis of the polyethylene glycol glucosides and FA esters thereof by atmospheric-pressure ionization MS

Polyethylene glycol (PEG) glucosides (PEGG) and the PEGG esters of lauric acid were analyzed by atmospheric-pressure ionization MS (API-MS) with electrospray ionization. Straightforward mass characterization of the complex mixtures could be achieved without prior chromatographic separation. The constituents were identified on the basis of quasi-molecular ions. Individual components could be observed as protonated molecular ions [M+H]⁺ and/or as their NH₄ ⁺, Na⁺, or K⁺ adducts in positive ion mode. The mass spectrometric investigation showed that mixtures of PEGG consisted of monoglucoside, diglucoside, polyglucoside, and free PEG. The esterification product is a mixture of two types of nonionic surfactants: PEG-laurates and PEGG-laurates. The reasons for distortion of the quasi-molecular ion intensities and the stabilization of adduct ions were discussed. The rapid and highly sensitive API-MS analysis technique proposed here is well suited for direct characterization of complex mixtures and suitable for development as a routine analytical method.     

Morphological, mechanical and gas-transport characteristics of crosslinked poly(propylene glycol): homopolymers, nanocomposites and blends

Linear polyethers possess unusually high CO₂ solubility and, hence, selectivity due to the presence of accessible ether linkages that can interact with the quadrupolar moment of CO₂ molecules. In this work, membranes derived from crosslinked poly(propylene glycol) diacrylate (PPGda) oligomers differing in molecular weight (M), as well as PPGda nanocomposites containing either an organically-modified montmorillonite clay or a methacrylate-terminated fumed silica are investigated and compared with highly CO₂-selective poly(ethylene glycol) diacrylate (PEGda) homopolymer and nanocomposite membranes previously reported. The rheological and permeation properties of PPGda depend sensitively on M, with the elastic modulus decreasing, but CO₂ permeability and CO₂/H₂ selectivity increasing, with increasing M. Incorporation of either nanofiller into PPGda enhances the elastic modulus and reduces the gas permeability in the resultant nanocomposites without strongly affecting CO₂/H₂ selectivity. Blending PPGda and PEGda prior to chemical crosslinking yields binary membranes that exhibit intermediate gas-transport properties accurately described by a linear rule of mixtures.     

Foam fractionation of spent sulphite liquor: Part I: Separation of surfactants

The surface activity of spent sulphite liquor (SSL) and the separation of surface active components by foam fractionation were studied. The maximum activity (lowest surface tension) of SSL was observed at a high pH. The surface tension was found to be 42 mN/m and 38 mN/m at acidic and basic pH values, respectively, and also a maximum foaminess (Σ) of 7 min was observed at pH 10. Foam fractionation reduced the surfactant concentration by 90% at an optimum pH of 10. The surfactants were concentrated in the collapsed foam as shown by the fact that the critical micelle concentrations of the unfractionated SSL and foam were 70% (v/v) and 10% (v/v), respectively. The removed surfactants were concentrated in 20% of the original liquid volume.     

Frying quality and stability of low-and ultra-low-linolenic acid soybean oils

To determine effects of very low levels of linolenic acid on frying stabilities of soybean oils, tests were conducted with 2% (low) linolenic acid soybean oil (LLSBO) and 0.8% (ultra-low) linolenic acid soybean oil (ULLSBO) in comparison with cottonseed oil (CSO). Potato chips were fried in the oils for a total of 25 h of oil use. No significant differences were found for either total polar compounds or FFA between samples of LLSBO and ULLSBO; however, CSO had significantly higher percentage of polar compounds and FFA than the soybean oils at all sampling times. Flavor evaluations of fresh and aged (1, 3, 5, and 7 wk at 25°C) potato chips showed some differences between potato chips fried in different oil types. Sensory panel judges reported that potato chips fried in ULLSBO and aged for 3 or 7 wk at 25°C had significantly lower intensities of fishy flavor than did potato chips fried in LLSBO with the same conditions. Potato chips fried in ULLSBO that had been used for 5 h and then aged 7 wk at 25°C had significantly better quality than did potato chips fried 5 h in LLSBO and aged under the same conditions. Hexanal was significantly higher in the 5-h LLSBO sample than in potato chips fried 5 h in ULLSBO. The decrease in linolenic acid from 2 to 0.8% in the oils improved flavor quality and oxidative stability of some of the potato chip samples.     

Comparison of relative viscosity measurement of polyvinylpyrrolidone in water by glass capillary viscometer and differential dual‐capillary viscometer

The relative viscosity (RV) of polyvinylpyrrolidone (PVP) with different molecular weights was measured with a glass capillary viscometer and with a differential dual‐capillary viscometer in water at different concentrations. For the differential dual‐capillary viscometer, RV increases with a decreasing flow rate, especially for high molecular weight PVP at a 1% concentration. A good agreement in the RV between the two methods can be obtained for PVP with different molecular weights and at various concentrations if an appropriate flow rate is selected for the differential dual‐capillary viscometer. Special precaution is needed when using the differential dual‐capillary viscometer to measure the viscosity of a pure solvent. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1312–1315, 2002     

Mechanical properties of biorenewable fiber/plastic composites

Plastic fiber composites, consisting of polypropylene (PP) or polyethylene (PE), and pinewood, big blue stem (BBS), soybean hulls, or distillers dried grain and solubles (DDGS), were prepared by extrusion. Young's modulus, tensile and flexural strengths, melt flow, shrinkage, and impact energy, with respect to the type, amount, and size of fiber on composites, were evaluated. Young's moduli under tensile load of wood, BBS, and soybean‐hull fiber composites, compared with those of pure plastic controls, were either comparable or higher. Tensile strength significantly decreased for all the PP/fiber composites when compared with that of the control. Strength of BBS fiber composites was higher than or comparable to that of wood. When natural fibers were added there was a significant decrease in the melt flow index for both plastic/fiber composites. There was no significant difference in the shrinkage of all fiber/plastic composites compared to that of controls. BBS/PE plastic composites resulted in higher notched impact strength than that of wood or soybean‐hull fiber composites. There was significant reduction in the unnotched impact strength compared to that of controls. BBS has the potential to be used as reinforcing materials for low‐cost composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2484–2493, 2004     

A simplified method for analyzing mold filling dynamics. Part II: Extensions and comparisons with experiment

A dimensional analysis based on four parameters has been developed previously to predict injection pressure; clamp force, and bulk temperature for the injection molding of amorphous materials in center-gated disk-shaped cavities. In this paper geometric and semicrystalline-materials approximations are introduced and tested for extending the previous analysis to include multigated thin cavities and semicrystalline materials. The combination of these approximations and the previous analysis, known hereafter as the Radial Flow Method (RFM), greatly simplifies the analysis of mold filling. The geometric approximation, which is based on a simple model for the axial stress distribution in the cavity, is shown to give reasonable predictions when compared with experimental data and a numerical two-directional flow simulation for the filling of an off-center-gated rectangular cavity with acrylonitrilebutadiene-styrene copolymer (ABS). The semicrystallinematerials approximation, in which heat capacity and viscosity changes during crystallization are neglected, is shown to give good agreement with experimental data for the filling of a center-gated disk-shaped cavity with polypropylene. As an illustration, the Radial Flow Method is used to analyze the molding of a large, thin-wall automobile interior trim panel. The inlet melt temperature, mold-wall temperature, part thickness, injection rate, viscosity and gate locations are varied in a series of calculations to determine the relative effectiveness of these variables in lowering the injection pressure and Clamp force. The results obtained with the Radial Flow Method are in good agreement with those obtained by a finiteelement simulation of two-directional flow.     

Surface properties of surfactants derived from natural products. Part 1: Syntheses and structure/property relationships—Solubility and emulsification

Several novel and some previously known, mostly sugar-based, surfactants have been synthesized and some of their surface properties have been characterized and compared with those of commercial nonylphenol ethoxylates. The surfactant solubility in water, ethanol, and dodecane was studied. The properties of these compounds as emulsification agents in systems composed of the surfactant with water/isopropyl myristate, water/rapeseed oil, and water/dodecane are presented. The aqueous solubility of the surfactants follows the general trend expected from their hydrophilic-lipophilic balance according to Griffin (HLBG), but it is also clear that the nature of the headgroup and the structure of the nonpolar part affect the solubility in a manner not aptured in the standard HLBG concept. An ester or amine group as the connecting unit between the hydrophile and the hydrophobe produces a more water-soluble surfactant than the corresponding amide derivative. Some effective emulsifiers were found. For instance, the surfactants with a dehydroabietic nonpolar group appear to be promosing emulsifiers. Most sugar-based surfactants were able to form macroemulsions of up to around 2 wt/vol% of oil. The stability of many of these amulsions was very high, extending for months.