bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical simulation of double‐layer flow from tube‐in‐orifice spinnerets
Authors: Watanabe Haruhiko , Kihara Shin‐Ichi , Funatsu Kazumori 
Published: April 2004

AbstractNumerical simulations of double‐layer flow from tube‐in‐orifice spinnerets have been carried out using a differential constitutive equation. The streamline‐upwinding finite element method with 4 X 4 sub‐elements on stress components and over‐relaxation method for equation of motion were used. In addition, the extrudate swell and interface shape have been experimentally observed for PVP(polyvinyl‐pyrrolidone) aq./water system to check the validity of numerical results and to relate the flow geometry to the extrudate swell and interface shape. It was found through both numerical predictions and experiments that extrudate swell shape is strongly dependent on the location of the center tube edge in a tube‐in‐orifice spinneret. In particular, the minimum of the outer diameter swell was found when the center‐tube edge was flush with the outer‐orifice edge. These results give useful information for choosing the optimal design of a tube‐in‐orifice spinneret.
Calculating morphology development of polymer blends in extruders on the basis of results of boundary and finite element simulations using the sigma simulation software
Authors: Potente H. , Bastian M. 
Published: April 2004

AbstractModels have been developed for binary, incompatible polymer blends that can be used to estimate the morphology development that takes place in drops of the second component that are dispersely embedded in the matrix. The calculations are based on the results of flow simulations using the boundary element (BEM) and finite element (FEM) methods and, more particularly, on an analysis of the stresses that act on fluid particles over their trajectories as a function of the residence time. The models formulated are converted into algorithms, which can then be implemented in the SIGMA simulation software for designing and simulating the process behavior in tightly intermeshing co‐rotating twin‐screw extruders. In this way, it is possible to estimate the morphology development that takes place in incompatible polymer systems by describing the mean drop size and the drop size distribution as a function of the material properties, the geometry of the barrel and the screw, and the process parameters.
Solid state complexes of poly(L‐lysine) with metal chlorides from the 1st row of the d‐block
Authors: Belfiore Laurence A. , McCurdie Mary Pat 
Published: April 2004

AbstractSolid state characterization of poly(L‐lysine)hydrobromide was obtained via differential scanning calorimetry, thermogravimetric analysis, optical microscopy and infrared spectroscopy. The glass transition temperature of poly(L‐lysine)hydrobromide is 178°C. This thermal transition has not been reported previously. Poly(L‐lysine)'s Tg decreases when complexes are produced with the following divalent transition metal chlorides; cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride dihydrate and anhydrous zinc chloride. At 10 mol% salt, nickel, chloride decreases Tg by 45°C, and the general trend is Ni2+Co2+Zn2+Cu2+. The depression of poly(L‐lysine)'s Tg correlates well with ligand field stabilization energies for pseudo‐octahedral and pseudo‐tetrahedral dn complexes (n = 7, 8, 10) from the 1st row of the d‐block. However, d9 copper(II) complexes cannot be included in this empirical correlation. Infrared spectroscopic evidence suggests that Co2+, Ni2+ and Zn2+ coordinate to the carbonyl oxygen in the main chain of the polymer. When transition metal ions coordinate to CO, the network of hydrogen bonded amide groups is disrupted, which lowers the glass transition. The amide I region of the infrared spectrum reveals a hydrogen bonded CO stretch @ 1655 cm−1 that is characteristic of poly(α‐amino acid) random coil conformations, and a metal‐ligand coordinated CO stretch @ 1625 cm−1 in complexes with divalent cobalt, nickel and zinc. The amide II region of the infrared spectrum near 1550 cm−1 is also sensitive to the formation of coordination complexes with these d‐block metal chlorides.
Surface topography and gloss of polyolefin blown films
Authors: Wang Lei , Huang Tao , Kamal M. R. , Rey Alejandro D. , Teh Joo 
Published: April 2004

AbstractAtomic Force Microscopy (AFM) was used to obtain a comprehensive characterization of the surface roughness of polyethylene blown films based on a variety of resins. The quantitative description of surface roughness was achieved using a number of statistical parameters. Surface gloss of the sample films was calculated using the general Kirchhoff solution for rough surfaces. The calculated gloss values showed good agreement with experimental measurements. The quality of the correlation suggests the utility of AFM in characterization of surface roughness. It also suggests that the proposed mathematical and statistical description of roughness is a useful tool for the estimation of surface gloss.
Environmental stress cracking of poly(vinylidene fluoride) in sodium hydroxide. Effect of chain regularity
Authors: Maccone Patrizia , Brinati Giulio , Arcella Vincenzo 
Published: April 2004

AbstractThree commercial samples of poly(vinylidene fluoride) (PVDF) homopolymers with different crystallinity degree have been evaluated for chemical stress cracking behavior in 30 wt% sodium hydroxide solution. The polymers were submitted to thermal and mechanical analyses before environmental experiments. These were carried out at 23°C on 3‐mm‐thick PVDF sheets, using three different levels of constant strain applied (3%, 5%, 7%). The time for crack appearance decreases with the increase of the degree of crystallinity. This behavior has been related to the presence of head‐to‐head VDF additions (defect “a”), as well as to the overall chain regularity. The head‐to‐head sequences inhibit the degradation mechanism because of the dehydrofluorination reaction activated by alkaline media. The less crystalline PVDF polymer, with the higher content of head‐head VDF additions and a limited number of chain‐branching defects, presents the best crazing resistance.
Effect of blending sequence on the morphology and impact toughness of poly(ethylene terephthalate)/polycarbonate blends
Authors: Wu Jingshen , Xue Pu , Mai Yiu‐Wing 
Published: April 2004

AbstractThe morphology of PET/PC/E‐GMA‐MA blends made by different mixing sequences was studied by transmission electron microscopy (TEM). The results suggest that migration of the E‐GMA‐MA copolymer from the PET phase to the PC phase occurred during the mixing of the (PET/E‐GMA‐MA) pre‐blend with the PC at 10% copolymer content. As a result of the migration, the E‐GMA‐MA particles are located in the PC phase rather than in the PET phase. This finding is not in agreement with the prediction made previously by others based on the possible reaction between the epoxy group of GMA and carboxyl group of PET. Core‐shell (PC/E‐GMA‐MA) particles formed in situ during blending and the size of the core‐shell particles was controlled by the blending sequence used. Mechanical properties of the ternary blends were tested at various temperatures. Although the blending sequence does not have a noticeable effect on the yield strength and modulus of the blends, it has a strong influence on the morphology formed, which determines the impact toughness. For blends made under optimum processing conditions, the brittle‐ductile transition occurred at a lower temperature and lower elastomer content. A study of the toughening mechanism suggested that the major toughening events were cavitation plus matrix shear yielding. It is postulated that the very high impact toughness found with the (PC/E‐GMA‐MA)/PET blend (at 10% E‐GMA‐MA) originated from the bimodal particle size distribution of the core‐shell particles formed in situ.
Constitutive equations in nonlinear viscoelasticity of glassy polymers based on the concept of traps
Authors: Drozdov Aleksey D. 
Published: April 2004

AbstractConstitutive equations are derived for the nonlinear viscoelastic response of amorphous polymers. The model treats a glassy polymer as an ensemble of independent relaxing regions that randomly hop in their cages being thermally activated. Rearrangement occurs when a flow unit reaches some liquid‐like state. Stress‐strain relations are verified using experimental data in tensile relaxation tests for polyester resins with two types of flexibilizers. Fair agreement is demonstrated between observations and results of numerical simulation.
Numerical and experimental studies on the ejection of injection‐molded plastic products
Authors: Wang H. , Kabanemi K. K. , Salloum G. 
Published: April 2004

AbstractNumerical and experimental studies have been conducted on the ejection stage of plastics injection molding process. A numerical approach is proposed to predict the ejection force from the mold‐part constraining and friction forces as the product cools in the mold cavity up to the moment of ejection. The finite element thermoviscoelastic solidification analysis has taken into account the stress and volume relaxation behavior of polymers under the cavity‐constrained condition. The predicted ejection force and its distribution over ejector pins are validated by injection molding experiment of rectangular boxes using a polycarbonate resin. Different cases of the ejector pin layout are evaluated to examine the effect of the number, location and dimension of ejector pins, so as to identify the balanced layout causing minimum stress and deformation to the product. The approach is also applied to another product geometry which shows complex distribution of the mold‐part constraining and friction forces and involves multi‐step operations in the demolding stage.
Effects of particle size of Al(OH)3 on electrical properties of EPDM compounds
Authors: Lee Cheol Ho , Kim Sang Wook , Nam Jin Ho , Suh Kwang S. 
Published: April 2004

AbstractEffects of particle size of Al(OH)3 (ATH) filler on electrical properties of ethylene propylene diene terpolymer (EPDM)/ATH compounds were studied. It was found that tracking and erosion resistance of EPDM/ATH compounds decreased while dielectric properties and 90°C water resistance were improved with the increase of particle size. Homocharge accumulates in the compounds, which increases first and then decreases with the increase of particle size. This was explained by the change of particle‐to‐particle distance due to filler size.
Separation, size reduction, and processing of XLPE from electrical transmission and distribution cable
Authors: White C. C. , Wagenblast J. , Shaw M. T. 
Published: April 2004

AbstractThe recycling of power transmission cable insulated with crosslinked PE (XLPE) was investigated by using different methods of separation and reprocessing. Separation was attempted by thermo‐chemical, thermo‐mechanical and microwave‐mechanical means, the latter being the most successful. A mechanism encompassing all of these was formulated. Compression molding, extrusion, and injection molding with and without preheating of the material were also investigated. It was found that by preheating the XLPE and injection molding under high injection pressure, the neat XLPE could be formed into shapes with tensile strengths equal to that of the original insulation. In view of available observations, possible mechanisms for the flow and reconsolidation of XLPE crumb are proposed and discussed.
Viscoelastic predictive laws of linear polyurethane: Rheological changes during bulk polymerization
Authors: Cassagnau P. , Michel A. , Aulagner‐Revenu P. , Carrot C. , Guillet J. 
Published: April 2004

AbstractThe rheological behavior during the bulk polymerization of urethane systems made from diphenyl methane 4,4′ diisocyanate (MDI) and poyether macro diol was studied in connection with the kinetics of the reaction. The linear viscoelastic behavior in the terminal zone has been reasonably predicted using the molecular weight distribution obtained from size exclusion chromatography (SEC) and owing to only a few rheological parameters, namely, the scaling law relating the zero shear viscosity to the average weight molecular weight and the plateau modulus. These parameters were previously determined from oscillatory shear experiments performed on model samples of various molecular weights. The combination of this predictive model together with a reasonable kinetic scheme for such systems, enables to calculate the evolution of the viscoelastic parameters (storage and loss moduli) during bulk polymerization. The overall calculation was shown to give a reasonable depiction of the viscosity function. However, some discrepancies were noted as far as the elasticity of the melt is concerned. This was attributed to an additional relaxation mechanisms in the earliest stage of the polymerization connected to hydrogen bonding. Nevertheless, the procedure remains fundamental for apprehending some aspects of the viscoelastic changes of the material during a reactive processing technique such as extrusion for example.
Experimental validation of numerical simulations of the kneading disc section in a twin screw extruder
Authors: Jaffer Shaffiq A. , Bravo Victor L. , Wood Philip E. , Hrymak Andrew N. , Wright Joseph D. 
Published: April 2004

AbstractA comparison of the results of a 3D model for the simulation of flow in the kneading disc region of a fully intermeshing twin screw extruder has been done against particle image velocimetry (PIV) experimental data. Experimental results using a geometry with an extended first and last kneading disc to capture the simplified inlet and outlet boundary conditions, are in good qualitative agreement for low flow rates. The results showed good agreement at flow rates less than 5 mL/s and rotation speeds of 60 rpm, while above that there was poor agreement. These results highlight the importance of the use of appropriate boundary conditions for the accurate prediction of the flow field. The flow field within the kneading discs with forward conveying elements placed before and after the kneading discs was also measured. For a flow rate of 8.5 mL/s and 60 rpm, results showed good agreement when conveying elements were deployed before and after the kneading blocks whereas for lower flow rates there was poor agreement.
Structure development in melt spinning filaments from polybutylene terephthalate based thermoplastic elastomers
Authors: Li Hang , White James L. 
Published: April 2004

AbstractStructure development in polybutylene terephthalate (PBT) and thermoplastic elastomers (TPEs) based on PBT during the melt spinning process was investigated. Melt spun filaments were examined using wide angle X‐ray diffraction and birefringence. Crystalline orientation was characterized in terms of Hermans‐Stein orientation factors. Crystalline orientation and birefringence were found to correlated with spinline stress better than drawdown ratio. Crystalline orientation development was strongly dependent on spinline stress. The TPEs with low PBT content had low birefringence although the crystalline orientation was often high.
Scratch resistance of mineral‐filled polypropylene materials
Authors: Chu J. , Xiang C. , Sue H.‐J. , Hollis R. Damon 
Published: April 2004

AbstractPigmented mineral‐filled polypropylene (PP‐PMF) is marketed as a potential alternative to acrylonitrile‐butyldiene‐styrene (ABS) and Polycarbonate/ABS for automotive interior components. PP‐PMF is more easily damaged by surface scratch/mar, thus limiting its acceptance for such applications. This study focuses on investigating the scratch/mar mechanisms of PP‐PMF having different mineral fillers and additives. A new method is introduced to characterize the scratch visibility by image analysis. A correlation is found between scratch visibility and scratch hardness measured by interferometer. It is found that Wollastonite filler imparts higher scratch/mar resistance. Addition of an interface modifier and a lubricant can further improve scratch/mar resistance. It is also found that Talc‐filled PP‐PMF has poor scratch/mar resistance, irrespective of the addition of an interface modifier or a lubricant.
Mechanical studies on poly(vinylidene fluoride) based polymer electrolytes
Authors: Jacob M. M. E. , Arof A. K. 
Published: April 2004

AbstractThe mechanical strength of the poly(vinylidene fluoride) (PVDF) based polymer electrolyte deteriorates with increasing salt content. For a salt concentration of 2 wt% the Young's modulus is 10−5 Pa. The Young's modulus reduces by 60% when the salt concentration increases five‐fold. The decrease in mechanical strength of the polymer electrolyte by the incorporation of the salt is attributed to the intramolecular interaction between the chains of the polymer and the salt. The mechanical strength of the polymer electrolyte was also analyzed for different plasticizer content. The plasticizer used was ethylene carbonate (EC). The Young's modulus of the plasticized polymer electrolyte decreased with increased in EC content, but the elongation of the material and the energy at break increased with EC content, showing increased flexibility.
A model study for the recovery of polymides using the dissolution/reprecipitation technique
Authors: Papaspyrides C. D. , Kartalis C. N. 
Published: April 2004

AbstractA model dissolution/reprecipitation process is studied for the recycling of both polyϵ‐caprolactam (PA 6) and polyhexamethyleneadipamide (PA 6 6). This process comprises dissolution of each of the aforementioned polyamides in an appropriate solvent, reprecipitation by addition of a nonsolvent and finally recovery of the polymers through washing and drying. Dimethylsulfoxide/methyl‐ethyl‐ketone (DMSO/ MEK) proved to be the most suitable solvent/nonsolvent system for the recovery of PA 6, while formic acid/methyl‐ethyl‐ketone was used as a potential pair of solvent/ nonsolvent in the case of recovering PA 6 6. The recycled polyamides were evaluated in terms of the following characteristic properies: molecular weight (based on end‐group analysis and intrinsic viscosity determination), crystallinity and grain size analysis. In all cases, the recycled materials present excellent retention of the properties studied. Finally, the solvent mixtures involved are separated by distillation for reuse.
Application of the essential work of fracture concept to high temperature deformation in polyoxymethylene
Authors: Plummer C. J. G. , Scaramuzzino P. , Kausch H.‐H. , Steinberger R. , Lang R. W. 
Published: April 2004

AbstractEssential Work of Fracture (EWF) tests have been carried out on double edge notched samples machined from injection molded sheets of commercial grades of polyoxymethylene homopolymer with different molecular weight averages. Most of the measurements were made at 1000C and over a range of test speeds in which polyoxymethylene is anticipated to undergo a macroscopic ductile‐brittle transition with decreasing strain rate. The results reflect both the existence and the molecular weight dependence of this transition, and are argued to be valid in terms of the European Structural Integrity Society's EWF draft test protocol under certain test conditions. However, it is shown that the applicability of the test method used here becomes highly questionable for test speeds in the immediate vicinity of the transition, owing to the influence of the initial ligament length on the crack tip deformation mechanisms.
Water transport in crosslinked 2‐hydroxyethyl methacrylate
Authors: Chou K. F. , Lee Sanboh , Han C. C. 
Published: April 2004

AbstractWater transport in crosslinked 2‐hydroxyethyl methacrylate (HEMA) was investigated. Crosslinked HEMA was irradiated by gamma ray in vacuum for this study. The sorption data of de‐ionized water transport in crosslinked HEMA subjected to various gamma ray dosages are in excellent agreement with Harmon's model which accounts for Case I, Case II, as well as the anomalous transport processes. The diffusion coefficient for Case I transport and velocity for Case II transport satisfy the Arrhenius equation for all dosages. The transport process was exothermic and the equilibrium‐swelling ratio satisfied the van't Hoff plot. The pH value of de‐ionized water after the sorption/de‐sorption treatment of the irradiated crosslinked HEMA specimen was analyzed. The transmittance of irradiated crosslinked HEMA treated by de‐ionized water was also studied. The effect of irradiation on the polymer chains was revealed by the measurement of glass transition temperature and the quantitative determination of water structures in crosslinked HEMA hydrogel. The UV cut‐off wavelength of crosslinked HEMA shifted to longer wavelength side with increasing irradiation dosage, but the trend of transmittance after water treatment was opposite. The effect of specimen thickness on water transport was also studied.
The effect of calcium chloride dihydrate on the optical properties and mass transport of methanol in poly(methyl methacrylate)
Authors: Chou K. F. , Lee Sanboh 
Published: April 2004

AbstractThe effect of calcium chloride dihydrate on optical properties and the mass transport of methanol in poly(methyl methacrylate) (PMMA) has been investigated. The solvent transport was analyzed based on the Harmon model accounting for Case I, Case II, and anomalous diffusions. Both Case I and Case II transports satisfy the Arrhenius equation. Calcium chloride dihydrate depresses Case I diffusion and enhances Case II diffusion. From the mass transport data, the equilibrium solvent content of methanol with various concentrations of calcium chloride dihydrate in PMMA is obtained and satisfies the van't Hoff plot. A comparison of movement of sharp front and mass transport is made. The increase of UV transmittance of specimens treated with a mixture of methanol and calcium chloride dihydrate is attributed to the reduction of the carbonyl group. The critical solvent content to change transmittance from a slow increase to a fast increase occurs when the sharp fronts meet at mid‐plane. The decrease of transmittance in UV range is due to void creation for a large amount of solvent. The visible light transmittance of the specimen with small solvent content is the same as that of the specimen without solvent treatment. The visible wavelength dependence of transmittance of specimens with large solvent content is attributed to the void of which the size is smaller than the wavelength of visible light. The void is enlarged during the mass uptake, then it is fully closed after desorption of a small solvent amount and shrinks to a small size after desorption for a large solvent content.
Surface modification of plasma‐pretreated high density polyethylene films by graft copolymerization for adhesion improvement with evaporated copper
Authors: Ng C. M. , Oei H. P. , Wu S. Y. , Zhang M. C. , Kang E. T. , Neoh K. G. 
Published: April 2004

AbstractSurface modification of Ar plasma‐pretreated high density polyethylene (HDPE) film via UV‐induced graft copolymerization with glycidyl methacrylate (GMA) and 2‐hydroxyethylacrylate (HEA) was carried out to improve the adhesion with evaporated copper. The surface compositions of the modified HDPE surfaces were characterized by X‐ray photoelectron spectroscopy (XPS). The adhesion strengths of evaporated copper with the graft‐copolymerized HDPE films were affected by the Ar plasma pretreatment time, the monomer concentration used for graft copolymerization, and the graft concentration. Post‐treatments, such as plasma post‐treatments after graft copolymerization and thermal treatment (curing) after metalization, further enhanced the adhesion strength of the Cu/HDPE laminates. The T‐type peel strengths of the laminates involving the graft‐modified and plasma posttreated HDPE films were greater than 15 N/cm. The enhanced adhesion strength resulted from the strong affinity of the graft chains for Cu and the fact that the graft chains were covalently tethered on the HDPE surface. XPS characterization of the delaminated surfaces of the Cu/HDPE laminates revealed that the failure mode of the laminates with T‐peel adhesion strengths greater than 5 N/cm was cohesive in nature.