bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of steel fiber orientation on frictional properties of asbestos‐free friction materials
Authors: Qu Xiongwei , Zhang Liucheng , Ding Huili , Liu Guodong 
Published: March 2004

AbstractThe frictional properties of the composites reinforced with continuous steel fibers have been evaluated in LNBR modified phenolic resin based friction materials. The fiber orientations are introduced regarding the sliding direction, i.e. parallel (P) along the fiber direction, normal (N) and antiparallel (AP). The specific wear rates are increased if the sliding path is shifted from the P to the AP and N direction. The coefficient of friction is also dependent on the fiber alignment directions. The coefficients of these materials fall in the range of 0.49 to 0.54. The initial sliding interaction is plowing action if the turnplate temperature is below 250°C. Meanwhile, with the increase of the temperature, as ironed transfer film developed on the specimen, the interaction became adhesive and steady‐state friction is established. The wear resistance of the composite is found to relate to the stability of the film.
Diabetes in the young: past, present and future
Authors: Swift PGF 
Published: March 2004

AbstractOptimal management of diabetes in children and adolescents continues to present difficult challenges. Constant and unpredictable changes in growth, development and physiological maturity are compounded by problems of brittle families, social and cultural habits and behavioural upheavals. The dilemma of balancing metabolic control against quality of life is accentuated in childhood.Adverse societal influences sabotage attempts at achieving good glycaemic control and cardiovascular protection. UK children often have unstructured meal patterns, eat poor quality food (high in saturated fats) and consume excessive sweet foods.To counterbalance increasing expectations of improved metabolic control there is an ever increasing incidence of type 1 diabetes, the emerging numbers of type 2 and rising numbers of secondary causes of diabetes in the larger children's diabetic clinics.National surveys of children's services have shown considerable improvements but major deficiencies remain. Outcomes in the UK in terms of metabolic control do not compare favourably with some international centres and the challenges for the future include improvements in the organisation of care, staffing levels and structures, and improved collaboration between children's and adult services in expanded centres of excellence for the management of childhood diabetes. Copyright © 2004 John Wiley & Sons, Ltd.
Nutritional advice for people with diabetes: past, present, what next?
Authors: Thomas B 
Published: March 2004

AbstractThe dietary management of diabetes has undergone enormous change in the last 20 years following the realisation that inflexible regimens dominated by carbohydrate and sucrose restriction were inappropriate. Modem dietary guidelines aim to optimise not just the management of glycaemia but other parameters which influence microvascular and cardiovascular risk such as dyslipidaemia, adiposity and hypertension. Patients are no longer expected to follow standardised diets, but are encouraged to make adjustments to existing eating habits in a way which achieves permanent and beneficial change. Future management is likely to be dominated by the rising prevalence of type 2 diabetes in both adults and children and the need to find effective ways of preventing and correcting obesity. Copyright © 2004 John Wiley & Sons, Ltd.
Vascular disease and diabetes: the change in emphasis in the last 20 years
Authors: Fisher M 
Published: March 2004

AbstractThe approach to vascular disease in people with diabetes has been transformed in the last 20 years. Epidemiological studies have confirmed the excessive morbidity and mortality from cardiovascular disease in type 2, and more recently in type 1, diabetes. Many pharmacological studies have shown that this excess risk can be reduced by reduction of blood pressure or cholesterol, but blood glucose lowering studies have been few in number and disappointing in vascular outcomes. Modern cardiological interventions are also beneficial in this high‐risk group of patients. Looking forward to the next 20 years, two key areas for further study can be identified: a greater understanding of the pathophysiology, prevention and treatment of vascular disease in type 1 diabetes, and more information on the pathophysiology and treatment of stroke disease in all forms of diabetes. Copyright © 2004 John Wiley & Sons, Ltd.
Diabetes care in Brazil: now and in the future
Authors: Pedrosa HC 
Published: March 2004

AbstractBrazil, like many other developing countries, faces the dual problem of an increasing burden of chronic disease together with many communicable diseases. The organisation of diabetes care and the provision of drugs have improved considerably over the last 20 years, and the Brazilian Diabetes Society has had a major role in these improvements. However, many people remain unaware that they have diabetes and some diagnosed patients receive no treatment. Copyright © 2004 John Wiley & Sons, Ltd.
Diabetes care in The Netherlands: now and in the future
Authors: Bakker K , Bilo Henk JG 
Published: March 2004

AbstractThe prevalence of diabetes mellitus (DM)‐in The Netherlands is rapidly increasing. In 2000, the total number of people with DM is estimated at 462‐000 out of a total of 16 million inhabitants. The rapid growth is especially found in the group with type 2 DM (85%). The financial burden of direct and indirect costs is high. Access to care is at present easily available and almost fully reimbursable. Most hospital organisations have diabetes teams available for type I DM patients. The care for type 2 DM is mainly concentrated in primary care. The role of diabetes specialist nurses and podiatrists has grown in importance in the last decade. Guidelines on care and prevention are amply available but not fully implemented. A nationwide reduction (34%) on lower extremity amputations during the last 10 years has been reported recently. Looking at the future, shared care initiatives are underway. There are concerns about the rapid growth in prevalence, the increase of obesity and the possible shortage of general practitioners. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of gate freeze‐off time in injection molding
Authors: Pantani R. , De Santis F. , Brucato V. , Titomanlio G. 
Published: March 2004

AbstractGate solidification time is an important topic in injection molding technology, as it determines cycle time, which itself is an important issue in the balance of the production process. In this work, a study of the effect of both gate and cavity geometries on gate solidification time was conducted, using a commercial polymer, injection molded with constant holding pressure into a rectangular cavity. Three cavity lengths were used, and for each, two cavity thicknesses were adopted. Special dies containing different gates were assembled in the mold. Gate thickness was found to be the most important factor determining gate sealing time. However the cavity geometry is also quite important. A clear indication on gate solidification could be drawn by analyzing time evolution of pressure distribution inside the mold. The solidification phenomenon leading to gate sealing was analyzed by a simple model, which also takes into account the effect of cavity geometry, by comparing the heat flow through the gate walls and the energy required to solidify the packing flow rate. Model results satisfactorily describe the main features of the experimental data.
Measurement of interfacial tension in PS/LDPE melts saturated with supercritical CO2
Authors: Xue Anle , Tzoganakis Costas , Chen Pu 
Published: March 2004

AbstractThe effect of supercritical carbon dioxide (scCO2) on the interfacial tension between a polymer melt pair—polystyrene (PS) and low density polyethylene (LDPE)—was studied using the pendant drop method at temperatures varying from 200 to 240°C and CO2 pressures up to 18 MPa. The LDPE melt was prepared in a high pressure optical cell and the PS pendant drop was injected into the LDPE melt with a special high pressure syringe. For measurements with scCO2, the optical cell was first pressurized with scCO2 and measurements were taken after the saturation of scCO2 into both polymer melts. Excellent agreement was found with literature data for the same system without using scCO2. For the polymer pair saturated with scCO2, it was found that the interfacial tension decreases significantly with increasing CO2 pressure and appears to level off at higher CO2 pressures.
Surface characteristics of hydrosilylated polypropylenes: Effect of co‐catalyst and reaction temperature
Authors: Long J. , Tzoganakis C. , Chen P. 
Published: March 2004

AbstractPolypropylene (PP) was modified through a peroxide‐induced degradation and a catalytic hydrosilylation reaction in the melt phase. The effects of temperature and co‐catalysts on the reaction and the surface characteristics of the hydrosilylated polypropylene (SiPP) were studied. Axisymmetric Drop Shape Analysis‐Profile (ADSA‐P) was used to characterize the surface wettability. The morphology, roughness and heterogeneity of the surface were investigated by the lateral force mode of atomic force microscopy (LFM). Proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to quantify the conversion of terminal double bonds. X‐ray photoelectron spectroscopy (XPS) was used to quantify the surface chemical composition. LFM images showed that the surfaces of the PP and DPP samples were rough but heterogeneous and that the surfaces of the SiPP samples appeared rough but homogeneous. The surface wettability was well correlated to the surface microstructure and surface chemical 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. Results showed that there is an optimum reaction temperature in terms of the conversion of double bonds, and that increasing the amount of co‐catalyst promotes the conversion.
Variations in surface gloss on rubber‐modified thermoplastics: Relation to morphological and rheological behavior
Authors: Edwards S. A. , Roy Choudhury N. 
Published: March 2004

AbstractThe parameters that promote the formation of surface defects on multi‐phase polymer systems during injection molding are not yet clearly understood. The objective of this work is to establish the influence of composition, particularly the role of rubber, on the rheological properties of such multi‐phase systems and relate that to variations in gloss that appear on the surface of ASA and PC/ASA blends. Analysis of morphology by micro‐thermal analysis (μTA™) in combination with oscillatory rheology, time‐temperature‐superposition (TTS), creep recovery and PVT testing revealed distinct trends of surface gloss with each material's viscoelastic behavior and surface finish. It has been shown that influential properties such as rubber content, particle size and distribution, molecular weight, viscosity ratios and the degree of acrylonitrile mismatching play key roles in each material's rheology, developed morphology and subsequent trends in surface gloss after injection molding.
On the modeling of quiescent crystallization of polymer melts
Authors: Rao I. J. , Rajagopal K. R. 
Published: March 2004

AbstractIn this paper we present a way of modeling crystallization in polymers within the confines of a new general framework that has been developed to describe materials undergoing dissipative processes. Crystallization in polymers is in general an irreversible process, and a characteristic of all such processes is the production of entropy. In addition to postulating constitutive forms for the internal energy and entropy, we prescribe a constitutive relation for the entropy production. This in turn aids in deriving the crystallization rate equation from the second law, under the constraint that all real processes tend to maximize the rate of entropy production. After developing the general framework we derive specific models and compare the predictions of the model against experimental data available for quiescent crystallization in the literature. The predictions of the theory compare very well with the available experimental data for Nylon‐6 obtained by Patel and Spruiell (1).
Color of pigmented plastics—Measurements and predictions
Authors: Ariño Ingrid , Kleist Ulf , Rigdahl Mikael 
Published: March 2004

AbstractThe effect of the concentration of a colorant (masterbatch) and the surface texture on the color of an opaque injection‐molded plaque is experimentally described by means of the spectral reflectance and the CIELAB coordinates. It was noted that the surface texture had a marked influence on the experimental results and on the perceived color. The relation between the color of these pigmented plastic plaques and intrinsic physical material properties, such as light absorption and scattering coefficients, is described by means of the Kubelka‐Munk equation for pigment/paste mixtures. The concentration dependence of this Kubelka‐Munk equation for different masterbatch‐polymer mixtures can be modeled in terms of the color of the individual constituents using a fitting parameter. Further experiments were carried out which indicated that the fitting parameter had a physical meaning. The effect of the surface texture on the optical appearance of the plaques can also be accounted for by this parameter.
Shear rate and wall slip velocity functions of polyvinyl chloride melts based on slit die viscometry data
Authors: Yeow Y. Leong , Leong Yee‐Kwong 
Published: March 2004

AbstractShear stress versus shear rate and wall shear stress versus slip velocity relations of polymer melts are key material property functions needed in the design of polymer processing equipment. These properties are normally measured using capillary or slit viscometers. The presence of slip greatly complicates the processing of the resulting viscometry data. This paper describes the conversion of the viscometry data of a number of polyvinyl chloride melts through slit dies with different gaps into these two material property functions. The conversion procedure, based on Tikhonov regularization, has the advantage that it is independent of rheological constitutive equation and does not require extrapolation of the experimental data. It also has the ability to cope with the unavoidable noise in the experimental data. Consequently, the property functions thus obtained are likely to be closer to true material properties than those from some of the existing methods. For each of the polyvinyl chloride melts investigated, these properties' functions will be compared with published results and their differences discussed.
A study on sliding wear of ultrahigh molecular weight polyethylene/polypropylene blends
Authors: Liu Gongde , Xiang Ming , Li Huilin 
Published: March 2004

AbstractThe wear and friction behavior of ultrahigh molecular weight polyethylene (UHMWPE)/ polypropylene (PP) blends was studied. The addition of PP improves processability and the anti‐wear properties of UHMWPE. The friction coefficient and wear rate of pure UHMWPE are much higher than those of UHMWPE/PP blends under the same conditions, and the wear rate of UHMWPE is more sensitive to load and wear time than that of the UHMWPE/PP blend. Long scratch grooves and cracks occurred in the worn surface of UHMWPE, while no such serious damage was observed in the worn surface of the UHMWPE/PP blend. Atomic Force Micrograph using the contact mode indicated that the friction force between pure UHMWPE and Si3N4 tip is much higher than that for the UHMWPE/PP blend, which is consistent with the results from macro‐friction testing.
Characterization, morphology, thermal and mechanical properties of conductive polyaniline‐functionalized EPDM elastomers obtained by casting
Authors: Domenech S. C. , Bortoluzzi J. H. , Soldi V. , Franco C. V. , Gronski W. , Radusch H.‐J. 
Published: March 2004

AbstractConductive elastomeric blends based on ethylene–propylene–5‐ethylidene–2‐norbornene terpolymer (EPDM) and polyaniline doped with 4‐dodecylbenzenesulfonic acid [PAni(DBSA)] were cast from organic solvents. Functionalization of the elastomer was promoted by grafting with maleic anhydride. Vulcanization conditions were optimized with an oscillating disk rheometer. The conductivity, morphology, thermal stability, compatibility, and mechanical behavior of the obtained mixtures were analyzed by in situ direct current conductivity measurements, atomic force microscopy, transmission electron microscopy, wide‐angle X‐ray scattering, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical thermal analysis, stress–strain and hysteresis tests. The vulcanization process was affected by temperature, the PAni content, and maleic anhydride. A reinforcement effect was promoted by the vulcanizing agent. The formation of links between the high‐molar‐mass phases and oligomers of PAni(DBSA) in the elastomeric matrix enhanced the thermal stability and ultimate properties of the blends. By the appropriate control of the polymer blends' composition, it was possible to produce elastomeric materials with conductivities in the range of 10−5–10−4 S · cm−1 and excellent mechanical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1767–1782, 2004
Thermal and mechanical properties of syndiotactic polystyrene/organoclay nanocomposites with different microstructures
Authors: Park Cheon Il , Choi Won Mook , Kim Mun Ho , Park O Ok 
Published: March 2004

AbstractThe fabrication of syndiotactic polystyrene (sPS)/organoclay nanocomposite was conducted via a stepwise mixing process with poly(styrene‐co‐vinyloxazolin) (OPS), that is, melt intercalation of OPS into organoclay followed by blending with sPS. The microstructure of nanocomposite mainly depended on the arrangement type of the organic modifier in clay gallery. When organoclays that have a lateral bilayer arrangement were used, an exfoliated structure was obtained, whereas an intercalated structure was obtained when organoclay with a paraffinic monolayer arrangement were used. The thermal and mechanical properties of sPS nanocomposites were investigated in relation to their microstructures. From the thermograms of nonisothermal crystallization and melting, nanocomposites exhibited an enhanced overall crystallization rate but had less reduced crystallinity than a matrix polymer. Clay layers dispersed in a matrix polymer may serve as a nucleating agent and hinder the crystal growth of polymer chains. As a comparison of the two nanocomposites with different microstructures, because of the high degree of dispersion of its clay layer the exfoliated nanocomposite exhibited a faster crystallization rate and a lower degree of crystallinity than the intercalated one. Nanocomposites exhibited higher mechanical properties, such as strength and stiffness, than the matrix polymer as observed in the dynamic mechanical analysis and tensile tests. Exfoliated nanocomposites showed more enhanced mechanical properties than intercalated ones because of the uniformly dispersed clay layers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1685–1693, 2004
Fracture morphology and mechanical properties of ethylene/vinyl acetate rubber vulcanizates reinforced by in situ prepared sodium methacrylate
Authors: Du Aihua , Peng Zonglin , Zhang Yong , Zhang Yinxi 
Published: March 2004

AbstractEthylene/vinyl acetate rubber (EVM) was reinforced by sodium methacrylate (NaMAA) that was in situ prepared through the neutralization of sodium hydroxide and methacrylic acid in EVM during mixing. The mechanical properties of EVM vulcanizates with different NaMAA loadings and at different crosslink densities were studied and compared with those of high abrasion furnace carbon black (HAF) filled EVM vulcanizates. The fracture surfaces of gum and filled EVM vulcanizates were observed with scanning electron microscopy. The results showed that NaMAA‐reinforced EVM vulcanizates had better mechanical properties than HAF/EVM vulcanizates. When the NaMAA loading was 50 phr, the tensile strength of the NaMAA/EVM vulcanizate was 30 MPa, the tear strength was 102 kN/m, and the elongation at break was over 400%. Fourier transform infrared analysis confirmed that NaMAA formed in the compounding process and underwent polymerization during vulcanization. Scanning probe microscopy analysis revealed that nanoscale particles dispersed in the NaMAA/EVM vulcanizates. The mechanical properties were correlated with the fracture morphology of all the vulcanizates. The tensile rupture of NaMAA‐filled EVM vulcanizates occurred through tearing from a crack in the bulk of the samples. Tear deviation occurred with the addition of NaMAA and resulted in a rough surface, leading to an improvement in the tear strength of NaMAA‐filled EVM vulcanizates. The micrographs of the tear surfaces of the vulcanizates indicated that the different fracture modes depended on the NaMAA loading and the crosslink density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1715–1724, 2004
Fracture toughness of nylon‐6 blends with maleated rubbers
Authors: Okada O. , Keskkula H. , Paul D. R. 
Published: March 2004

AbstractThe fracture toughness of blends of nylon‐6 with maleated ethylene–propylene rubber and maleated styrene/hydrogenated butadiene/styrene triblock copolymer was investigated with a single‐edge‐notched three‐point‐bending instrumented Dynatup test. The blends for which the rubber particle size was less than 0.7 μm fractured in a ductile manner over the whole range of ligament lengths, whereas the blends with particles larger than 0.7 μm showed a ductile‐to‐brittle transition with the ligament length. In this regime, ductile fracture was observed for specimens with short ligaments, whereas brittle fracture was seen for those with long ligaments. The ductile fracture behavior was analyzed with the essential‐work‐of‐fracture model, whereas linear elastic fracture mechanics techniques were used to analyze the brittle fracture behavior. The fact that the ductile fracture energy was larger for the blends with the styrene/hydrogenated butadiene/styrene triblock copolymer than for those with ethylene–propylene rubber was due to the larger dissipative energy density of the blends based on the styrene/hydrogenated butadiene/styrene triblock copolymer. Both the critical strain energy release rate (GIC) and the plane‐strain critical stress intensity factor (KIC) increased as the rubber particle size decreased for both blend systems. The GIC and KIC parameters had similar values, regardless of the rubber type, when the rubber particle size was fixed. The transition ligament length was near the size criterion for plane‐strain conditions for both blend systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1739–1758, 2004