bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling the reactive modification of HDPE in a nonintermeshing twin screw extruder
Authors: Thompson M. R. , Hrymak A. N. , Hamielec A. E. 
Published: April 2003

AbstractThe chemical modification of high density polyethylene (HDPE) in a counter‐rotating nonintermeshing twin screw extruder is modeled using a simultaneous random scission and cross‐linking integro‐differential equation. The roles of mixing and kinetics in the free‐radical reaction are investigated. The modification experiments use a masterbatch feed of HDPE with various concentrations of 2,5‐dimethyl‐2,5‐(t‐butylperoxy)‐3‐hexyne. The extruder operating parameters studied were barrel temperature, screw speed, and the degree of screw flight stagger. The reaction model is fit using the molecular weight averages and the gel content measured experimentally. The reaction time for HDPE is determined by use of the residence time distribution of the extruder with a segregation (macromixing) assumption. The segregation model is compared against the plug flow assumption, where the mean residence time of the measured distribution is used for the length of reaction of all polymer species within the extruder. The calculated molecular weight distributions are insensitive to the mixing model used. © 1995 John Wiley & Sons, Inc.
A process for coupling wood to thermoplastic using graft copolymers
Authors: Chen Meng‐Jiu , Meister John J. , Gunnells David W. , Gardner Douglas J. 
Published: April 2003

AbstractA chemical modification method has been developed to convert lignin into lignin–styrene graft copolymers. The graft products are macromolecular surface active agents because, within each molecule, a hydrocarbon sidechain has been grown off of a natural oxyphenylpropyl backbone. Surface activity of the graft copolymers was indicated by their capacity to form stable emulsions between incompatible fluid phases and to adhesively bond to wood surfaces. Dynamic contact angle measurement using the Wilhelmy plate technique showed that the graft copolymers changed the contact angle of water on wood from 50° to 110°. Coating birch wood (Betula papyrifera) with lignin–styrene graft copolymerization product increases the water contact angle and the binding strength of polystyrene on the wood. Lap shear strengths increased 56%, from 1826 to 2840 kPa, when the wood was coated with a graft copolymer containing 51.7% lignin. Binding was tested by coating the birch with a solution of graft copolymer, drying the wood, injection molding polystyrene onto the surface of the wood, and pulling the polystyrene off the wood surface in a lap shear brace. These properties of the copolymers were used to design a process for forming wood‐thermoplastic composites. © 1995 John Wiley & Sons, Inc.
Weldlines in injection‐molded parts: A review
Authors: Fellahi S. , Meddad A. , Fisa B. , Favis B. D. 
Published: April 2003

AbstractIt is a well‐known fact that weldlines are unavoidable in most injection‐molded products of even moderate complexity. While there are many situations where they are barely perceptible, weldlines represent a potential source of weakness in molded parts. In injection molding weldlines are generated when two separate melt streams join either in multigated molds or as a consequence of flow around obstacles. The development of many interesting materials has been hampered by poor weldline strength. Among such materials are plastics reinforced with fibers or platelets, liquid crystal polymers, and a number of multiphase polymer blends. Weldlines have ever been called the “Achilles' heel” of these multiphase materials. This article is a review of the literature published on weldlines in injected parts. It deals primarily with the aspects related to the mechanical behavior of weldline‐containing parts. It begins with a brief description of the phenomena important for the part formation in the mold, including those leading to weldlines, in addition to the techniques used to characterize weldline‐containing parts. The following three sections consider the structure and properties of weldlines in neat amorphous and semicrystalline polymers, filled and reinforced plastics, and finally in polymer blends and alloys. In the last section methods developed for increasing the weldline strength are discussed. © 1994 John Wiley & Sons, Inc.
Applications of on‐line rheometry in reactive compounding
Authors: Xanthos M. 
Published: April 2003

AbstractOn‐line rheological measurements are usually employed to monitor the reactive modification of single polymers during extrusion. This article provides data on the use of an on‐line rheometer to monitor the reactive compatibilization of polyamide/polyolefin blends in a corotating twin‐screw extruder. The type of functionalized compatibilizer and the choice of compounding conditions are among the variables examined. On‐line and off‐line rheological data are correlated with the morphologies of the extrudates and the mechanical properties of injection‐molded samples in attempts to establish general relationships between on‐line rheology, microstructure, and properties of polymer blends. © 1995 John Wiley & Sons, Inc.
A new approach to reclaimed PET utilization—blends of recycled pet suitable for extrusion blow‐molding technology
Authors: Tsiourvas D. , Tsartolia E. , Stassinopoulos A. , Barrell M. , Bontemps J. 
Published: April 2003

AbstractPolymer blending of reclaimed PET with various types of polyethylene was utilized for the production of materials suitable for the manufacturing of containers using conventional extrusion blow‐molding equipment. Several marketed polymers bearing functional groups that are potentially reactive to PET end groups were used as compatibilizers. A number of blends were produced and found to possess melt properties suitable for the production of extrusion blow‐molded containers having acceptable mechanical characteristics. Containers were tested for compatibility with different chemicals and permeability of commonly used organic solvents. © 1995 John Wiley & Sons, Inc.
Chemical recycling of mixed plastics of pyrolysis
Authors: Kaminsky W. 
Published: April 2003

AbstractMost plastics are produced from oil and have a high potential as hydrocarbon sources for the chemical industry. Pyrolysis is a practicable way to pyrolyze mixed plastics. The fluidized bed pyrolysis has turned out to be particularly advantageous. Twenty‐five to 45% of product gas with a high heating value and 30–50% of an oil rich in aromatics could be recovered. The oil is comparable to that of a mixture of light benzene and bituminous coal tar. Up to 60% of ethene and propene are produced by using mixed polyolefins as feedstock. Under appropriate conditions the pyrolysis could be successful on the market. © 1995 John Wiley & Sons, Inc.
The relationship between economic value added and stock market performance: A theoretical analysis
Authors: Keef Stephen P. , Roush Melvin L. 
Published: April 2003

AbstractRecently in this journal, Turvey et al. (2000, p. 415) report that “… there is absolutely no relationship between EVA and stock market performance” with their sample of Canadian agribusiness firms. We examine the implied relation by invoking a set of perfect market assumptions that are not radically out of kilter with a semistrong form efficient market. We use a simple project as the focus of the analysis. We initially explore the way that the market value of the project evolves over time. We then effect a similar analysis on the project's economic profit. The latter is the theoretical construct underlying EVA. A comparison of these two time series argues that Turvey et al.'s (2000) result is not unexpected from a theoretical perspective. Notwithstanding, we offer brief suggestions as to why executives adopt EVA as a measure of financial performance. [EconLit citations: D81, G30, M41.] © 2003 Wiley Periodicals, Inc. Agribusiness 19: 245–253, 2003.
The role of consumer ethnocentrism in food product evaluation
Authors: Orth Ulrich R. , Firbasová Zuzana 
Published: April 2003

AbstractDespite the abundance of literature on country‐of‐origin (COO) effects there is a need for additional empirical research into antecedents of the COO effect. This study examines to what extent consumer ethnocentrism (as measured by the CETSCALE) can singularly, as well as in concert with other variables, predict consumers' evaluation of a domestic versus foreign food product. A conjoint experiment was utilized in an exploratory analysis to ascertain the value consumers in Czech Republic place on yogurt being from their own or other countries. The resulting utilities were related to a consumer's level of ethnocentrism. The findings suggest that consumer ethnocentrism is a strong and significant predictor of consumer product evaluations. Adding the ethnocentrism variable to a set of demographic and psychographic variables significantly improves the predictive ability of the set. Potential applications at the practitioners' level include the identification of market segments that react more favorably to domestic produce. [EconLit citations: M310, Q130, C120.] © 2003 Wiley Periodicals, Inc. Agribusiness 19: 137–153, 2003.
Evidence of neuronal migration disorders in Knobloch syndrome: Clinical and molecular analysis of two novel families
Authors: Kliemann Susana E. , Waetge Ricardo T.L. , Suzuki Oscar T. , Passos‐Bueno M. Rita , Rosemberg Sérgio 
Published: April 2003

AbstractKnobloch syndrome is an autosomal recessive disease characterized by the early onset of severe myopia, vitreoretinal degeneration with retinal detachment, macular abnormalities, and midline encephalocele, mainly in the occipital region. Intra and interfamilial variability is present since the encephalocele is not found in all patients, and the degree of myopia is variable. Analysis of the associated malformations suggests alterations during early neuroectodermal morphogenesis. Only 24 cases have been reported. Recently, the gene responsible for the syndrome, mapped to 21q22.3, was identified. The present study reports on four new cases, revealing the existence of neuronal migratory defects associated with the disorder for the first time. © 2003 Wiley‐Liss, Inc.
Initial droplet size distribution in miniemulsion polymerization
Authors: Sood A. , Awasthi S. K. 
Published: April 2003

AbstractThe initial droplet size distribution of miniemulsions has not yet been measured. It is deduced from previous experimental results that the distribution is broad. Furthermore, the small fraction of the distribution, depending on the nonideality of the cosurfactant–monomer system, may not be stable. This may lead to a rearrangement of the distribution leading to a bimodal distribution. The stability criterion is based on the phenomenon of molecular diffusion or Ostwald ripening. Experimental proof in support of the conclusion regarding the bimodal distribution is cited. The practical significance of the conclusion for making emulsion polymers with high solid contents is given. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3058–3065, 2003
Elongational rheology of LLDPE / LDPE blends
Authors: Ajji A. , Sammut P. , Huneault M. A. 
Published: April 2003

AbstractThe objective of this study is to investigate the effect of low density polyethylene (LDPE) content in linear low density polyethylene (LLDPE) on the crystallinity and strain hardening of LDPE / LLDPE blends. Three different linear low density polyethylenes (LL‐1, LL‐2 and LL‐3) and low density polyethylenes (LD‐1, LD‐2 and LD‐3) were investigated. Eight blends of LL‐1 with 10, 20, 30 and 70 wt % of LD‐1 and LD‐3, respectively, were prepared using a single screw extruder. The elongational behavior of the blends and their constituents were measured at 150°C using an RME rheometer. For the blends of LL‐1 with LD‐1, the low shear rate viscosity indicated a synergistic effect over the whole range of concentrations, whereas for the blends of LL‐1 with LD‐3, a different behavior was observed. For the elongational viscosity behavior, no significant differences were observed for the strain hardening of the 10–30% LDPE blends. Thermal analysis indicated that at concentrations up to 20%, LDPE does not significantly affect the melting and crystallization temperatures of LLDPE blends. In conclusion, the crystallinity and rheological results indicate that 10–20% LDPE is sufficient to provide improved strain hardening in LLDPE. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3070–3077, 2003
Comparison between the effects of alcohols and diols on polymethyl‐methacrylate and polyacrylamide with positron annihilation lifetime and electric conductivity measurements
Authors: Gomaa E. , Mazzroua A. , Mohamed M. 
Published: April 2003

AbstractComparison between the effect of alcohols and diols on poly(methylmethacrylate) (PMMA) and polyacrylamide (PAA) was investigated by positron annihilation lifetime (PAL) spectroscopy and electric conductivity measurements. The samples were prepared by adding alcohols, such as ethanol (E), isopropyl alcohol (P), and butyl alcohol (B), and diols, such as ethanediol (E1,2), isoproponendiol (P1,2), and butanediol (B1,2, B1,3, B1,4). The o‐Ps lifetime values (τ3) of PMMA–alcohol or PMMA–diol composites are shorter than the τ3 value of the virgin PMMA, whereas the τ3 values of PAA–alcohol or PPA–diol composites fluctuate above and blow the corresponding value of virgin PAA. On the other hand, a significant increased was observed in the o‐Ps intensities (I3) of both PMMA and PAA composites with added alcohols and diols compared with pure PMMA and PAA. The electric conductivity (σ) also increased for both PMMA and PAA composites with added alcohols and diols compared with the virgin PMMA or PAA polymer. A correlation was found between positron annihilation lifetime parameters and electric conductivity of PAA composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3078–3083, 2003
H2O2 as a modifier of phenol–formaldehyde resin used in the production of particleboards
Authors: Czarnecki Rafał , Łȩcka Janina 
Published: April 2003

AbstractThe purpose of the research was to study the influence of H2O2 on the properties of fluid phenolic (PF) resin, the curing process, the cured resin structure, and the properties of the particleboards produced with its use. The influence of added H2O2 on resin usability at 20°C, on the gel time of the modified PF resin in the temperature range 110–140°C, and on the activation energy of the curing process were studied. Also, the structure of the cured resin was examined by Fourier transform infrared spectroscopy. Finally, the properties of the obtained particleboards were determined. The results indicate that the H2O2 modification leads to greater reactivity of the phenolic resin and increases the mechanical properties of particleboards. In contrast, there is no significant influence of H2O2 on the water resistance of the particleboards. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3084–3092, 2003
Study on PET/PP microfibrillar composites. I. Morphological development in melt extrusion
Authors: Lin X. D. , Cheung W. L. 
Published: April 2003

AbstractPoly(ethylene terephthalate)/polypropylene (PET/PP) blends of different compositions were extruded through a 2‐mm capillary die using a corotating twin‐screw extruder. The extrudates were cryogenically fractured and examined using scanning electron microscopy. The viscosity ratio of the constituent polymers alone was found not suitable for explaining the polymer blend morphology. At a PET concentration of 20%, the extrudate consists of three regions: The skin layer, about 10 μm thick, has a lower concentration of the dispersed PET phase than that of the overall concentration. The intermediate region, about 400 μm thick, has profuse PET fibers and some small PET particles. The central region, approximately 800 μm in diameter, contains mainly PET particles that are generally bigger. A low barrel temperature, low die temperature, and fast cooling rate helped to retain the fibers near the extrudate skin. Meanwhile, variation of the barrel temperature, die temperature, and cooling media did not affect the PET particle‐size distribution significantly in the central region of the extrudate. A high screw speed and a high postextrusion drawing speed were very effective in producing fibers in the extrudates through elongation of the particles. At a PET concentration of 30%, coalescence of the PET phase was prevalent, leading to the formation of PET platelets near the extrudate skin and irregular PET networks in the central region of the extrudate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3100–3109, 2003
Surface characteristics of hydrosilylated polypropylene
Authors: Long J. , Tzoganakis C. , Chen P. 
Published: April 2003

AbstractPolypropylene containing terminal unsaturation was modified with a hydride‐terminated polydimethylsiloxane (PDMS) at three different temperatures through a catalytic hydrosilylation reaction in the melt phase. A comprehensive study on the surface characteristics of hydrosilylated polypropylene (SiPP) was conducted by combining macroscopic thermodynamics, microstructure, and chemical composition measurements. Axisymmetric drop shape analysis–profile (ADSA‐P) was used to characterize the surface wettability. The morphology, roughness, and heterogeneity of the surfaces were investigated by the lateral‐force mode of atomic force microscopy (LFM). X‐ray photoelectron spectroscopy (XPS) was used to quantify the surface chemical composition. LFM images showed that all sample surfaces were rough and heterogeneous on a micrometer scale. XPS analysis showed that the surfaces investigated were complicated in composition and that various oxides existed on the surfaces. The surface wettability was well correlated to the surface microstructure and composition. The surfaces investigated were modeled based on the microstructure observed, and a new scheme was developed to calculate surface free energy and adhesion work. For SiPPs, the lower the reaction temperature, the more PDMS incorporation was observed, the smaller the surface free energy and the work of adhesion, the more hydrophobic the surface, and the lower the permeability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3117–3131, 2003
Foam extrusion of high density polyethylene/wood‐flour composites using chemical foaming agents
Authors: Li Qingxiu , Matuana Laurent M. 
Published: April 2003

AbstractA one‐way analysis of variance and thermal analysis were performed in this study to examine the influences of the contents, types (exothermic vs. endothermic), and forms (pure vs. masterbatch) of chemical foaming agents (CFAs), as well as the use of coupling agents, on the density reduction (or void fraction) and cell morphology of extrusion‐foamed neat high density polyethylene (HDPE) and HDPE/wood‐flour composites. The CFA types and forms did not affect the void fractions of both the neat HDPE and HDPE/wood‐flour composites. However, a gas containment limit was observed for neat HDPE foams whereas the average cell size achieved in the HDPE/wood‐flour composite foams remained insensitive to the CFA contents, irrespective of the foaming agent types. The experimental results indicated that the use of coupling agent in the formulation was required to achieve HDPE/wood‐flour composite foams with high void fraction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3139–3150, 2003
Chemical modification of controlled‐pore silica with N‐propylsalicylaldimine
Authors: Abou‐El‐Sherbini Khaled , Kenawy I. M. M. , Issa R. M. 
Published: April 2003

AbstractTwo controlled‐pore silica phases were prepared with a sol–gel precursor from a sodium silicate solution. N‐Propylsalicylaldimine was immobilized on these silica species to be used as chelating ion exchangers (IE11 and IE2). The monomer phase was also prepared for comparison. The N‐propylsalicylaldimine moiety was detected by Fourier transform infrared and ultraviolet in both the ion exchangers and the monomer phases. 1H‐NMR and mass spectrometry of the monomer also confirmed the structure. The capacity (C) of the ion exchangers was dependent on the porosity of the ion exchanger (CIE11 = 0.36 mmol of Cu/g and CIE2 = 0.026 mmol of Cu/g). The uptake behavior of IE11 toward some metal ions was studied, and log distribution coefficient (kd) was within the range of 2.19–5.16. Also, thermogravimetric and differential thermogravimetric analysis data were used to study the kinetics of the thermal decomposition process of IE11. Some thermodynamic parameters for the ion exchanger were calculated by the application of the rate theory of the first‐order reaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3159–3167, 2003
A new type synthetic filter material for biofilter: Poly(vinyl alcohol)/peat composite bead
Authors: Chan Wu‐Chung , Lu Ming‐Cun 
Published: April 2003

AbstractIn this study, a new type of poly(vinyl alcohol) (PVA)/peat composite bead was prepared and was proved suitable as a filter material in the biofiltration process. The composite bead is a porous spherical particle and has a diameter of 2.4–6.0 mm and a density of 0.69 kg/cm3. It contains 3.25 mg N/g dry solid and 2.91 mg P/g dry solid. The equilibrium moisture content of the composite bead for adsorption and holding experiments is 50.5 and 66.8% by wet basis, respectively. The initial compression strength of the composite bead is 0.32 kg/cm2. It has higher moisture holding capacity and compression strength than pig manure compost filter material. The adsorption behavior of ethyl acetate and composite bead follows the Freundlich adsorption isotherm. The composite bead has buffer capacity and could keep the filter bed at pH = 6.9–7.2 during operating. The percentage of removed ethyl acetate was 99% for up to 33 days as the composite bead adsorbed nutrients. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3248–3255, 2003
Steady viscoelastic diffusion
Authors: Vrentas J. S. , Vrentas C. M. 
Published: April 2003

AbstractA viscoelastic constitutive equation is derived for the diffusion flux of an infinitely dilute solute diffusing in a polymeric fluid under steady flow conditions. It is shown that the mass transfer rate of gas into an ideal polymer jet increases with increasing elasticity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3256–3263, 2003