bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of fillers and oil on mill processability of brominated isobutylene‐co‐paramethylstyrene and its blends with EPDM
Authors: Kumar Bhuwneesh , De P. P. , De S. K. , Bhowmick A. K. , Majumdar S. , Peiffer D. G. 
Published: April 2004

AbstractMilling behavior of brominated isobutylene‐co‐paramethylstyrene (BIMS), and its blends with ethylene propylene diene rubber (EPDM), with special reference to the effect of addition of different fillers, filler loadings and processing oil, was investigated over a range of temperatures in a drop mill operation. The critical nip gap (CNG, at which a front to back roll transition (F‐B transition) occurs, was also measured. Addition of different fillers reduced the value of the critical nip gap and the mill band formation indices for BIMS as compared to the gum polymer, indicating a decrease in the tendency to go to the back roll. The systems containing reinforcing fillers showed a lower value of the critical nip gap, as compared to systems containing low or non‐reinforcing fillers. For different filled blends of BIMS and EPDM, the CNG decreased on increasing the EPDM content, indicating a decrease in the tendency for a F‐B transition. The CNG decreased on increasing the N330 carbon black‐loading, while it increased with the addition of procesing oil. The results were explained in terms of rubber to metal adhension and viscosity of the polymers.
Oil resistant thermoplastic elastomers of nitrile rubber and high density polyethylene blends
Authors: Setua D. K. , Soman C. , Bhowmick A. K. , Mathur G. N. 
Published: April 2004

AbstractDifferent grades of oil resistant thermoplastic elastomers (TPE) based on blends of nitrile rubber (NBR) and high density polyethylene (HDPE) have been developed. Chemical treatment of HDPE to evolve compatibility with NBR and dynamic vulcanization with different curatives have been studied. Determination of physico‐mechanical and thermal properties and relative crystallinity of these blends have been carried out. Oil resistance characteristics of the blends have been evaluated in different commercially used oils and fuels for applications as a substitute for NBR/polyvinyl chloride (PVC) blends.
A physical‐mathematical model for the dispersion process in continuous mixers
Authors: Potente H. , Kretschmer K. , Flecke J. 
Published: April 2004

AbstractTo modify the properties of polymers, mineral fillers are frequently added during the compounding process. Because of adhesive forces, these pulverized fillers tend to agglomerate. Therefore, in order to achieve good homogenization, it is essential not only to distribute them but also to break down the solid agglomerates. A number of relating models have been published, describing observations (agglomerate rupture, erosion, clustering) made during the dispersion process in a mostly isolated manner. New models for each observed effect have been developed and later superimposed in order to get a comprehensive model of the dispersion process. To verify the model, it was implemented into a program for the process simulation of co‐rotating twin‐screw extruders. It was then compared to experimental data. The results showed that the model is able to describe the experimentally determined data.
A full 3D finite element analysis of the powder injection molding filling process including slip phenomena
Authors: Hwang C. J. , Kwon T. H. 
Published: April 2004

AbstractA full 3D finite element analysis system has been developed to simulate a Powder Injection Molding (PIM) filling process for general three‐dimensional parts. The most important features of the analysis system developed in this study are i) to incorporate the slip phenomena, the most notable rheological characteristics of PIM feedstock, into the finite element formulation based on a nonlinear penalty‐like parameter and ii) to simulate the transient flow during the filling process with a predetermined finite element mesh with the help of a volume fill factor and a melt front smoothing scheme. The treatment of the nonlinear slip boundary condition was successfully validated via a steady state pipe flow. For the purpose of comparisons, not only the numerical simulations but also experimental short‐shot experiments were performed with two 3D mold geometries using two typical materials of slip and no‐slip cases. The good agreements between the numerical and experimental results indicate that the melt front tracking scheme successfully simulates the transient filling process.
A new process for crosslinking thermoplastic polyurethanes using rubber industry techniques
Authors: Lambour Stéphanie , Mechin Françoise , Pascault Jean‐Pierre 
Published: April 2004

AbstractNew polyurethane materials were obtained after chemical modification of a commercial thermoplastic polyurethane (TPU) using diisocyanates and diols or diamines. The reaction can be easily processed by the well‐known calendering technique often used by the rubber industry. It leads to a remarkable improvement of the thermomechanical properties of the material, due to the formation of chemical crosslinks between the TPU chains (“vulcanization”). As this new processing consists only of an intimate mixing of the starting TPU with solid reagents, followed by molding and curing stages, it allows the use of any and possibly highly reactive solid monomer (especially damines), which could not otherwise be considered except with constraining techniques like RIM; in the same way, the incorporation of organic or inorganic fillers also becomes possible.
Percolation phenomena in polymers containing dispersed iron
Authors: Mamunya Ye. P. , Muzychenko Yu. V. , Pissis P. , Lebedev E. V. , Shut M. I. 
Published: April 2004

AbstractMetal‐polymer composites based on polyethylene (PE), polyoxymethylene (POM), polyamide (PA) and a PE/POM blend as matrix and dispersed iron (Fe) as filler have been prepared by extrusion of the appropriate mechanical mixtures, and their electrical conductivity, dielectric properties and thermal conductivity have been investigated. The filler spatial distribution is random in the PE‐Fe, POM‐Fe and PA‐Fe composites. In the PE/POM‐Fe composite the polymer matrix is two‐phase and the filler is contained only in the POM phase, resulting in an ordered distribution of dispersed Fe in the volume of polymer blend. The transition through the percolation threshold ϕc is accompanied by a sharp increase of the values of conductivity σ, dielectric constant ε′ and dielectric loss tangent tan δ. The critical indexes of the equations of the percolation theory are close to the theoretical ones in the PE‐Fe and POM‐Fe composites, whereas they take unusually high values in the PE/POMFe composite. Thus, t in the equation σ ∼ (φ – φc)t is 2.9–3.0 in the systems characterized by random distribution of dispersed filler and 8.0 in the PE/POM‐Fe system. The percolation threshold φc depends on the kind of polymer matrix, becoming 0.21, 0.24, 0.29 and 0.09 for the composites based on PE, POM, PA and PE/POM, respectively. Also the thermal parameters of the PE/POM‐Fe composite are different from those of all other composites. A model explaining the unusual electrical characteristics of the composite based on the polymer blend (PE/POM‐Fe) is proposed, in agreement with the results of optical microscopy.
Study on the residual wall thickness at dimensional transitions and curved sections in gas‐assisted molded circular tubes
Authors: Yang S. Y. , Chou H. L. 
Published: April 2004

AbstractPlastic tubes and hollow rods can be fabricated using gas‐assisted injection molding technology with reduced cost. The residual wall thickness around dimensional transitions and curved sections is of great concern. This research investigated the uniformity of the residual wall thickness distribution in circular tubes with dimensional variations and curved sections. It was found that the wall thickness was not uniform near transitions. With the addition of fillets with proper angles around transitions, the uniformity of residual wall could be greatly improved. The residual wall thickness in curved sections was thick around the outer wall and thin around the inner wall. Low melt temperature and high gas pressure were found to reduce the deviation in the wall thickness around curved sections.
Investigation of structure development in polyamide 11 and polyamide 12 tubular film extrusion
Authors: Rhee Sangkeun , White James L. 
Published: April 2004

AbstractThe processability of single bubble polyamide 11 and polyamide 12 films was investigated. The development of crystalline structure and chain orientation of polyamide 11 and polyamide 12 films in single bubble film blowing was studied by differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXS), infrared (IR) spectroscopy, and birefringence. DSC measurements of both films revealed a spontaneous increase in glass transition temperature (Tg) and cold crystallization temperature (Tc) during aging at room conditions, with crystallinity and melting point remaining constant. Single bubble polyamide 11 and polyamide 12 films exhibited triclinic α and monoclinic γ crystals, respectively. The level of biaxial orientation was evaluated by calculating White‐Spruiell biaxial orientation factors with pole figure data. We were not able to produce biaxially oriented double bubble films with either polyamide 11 or polyamide 12.
A microscopy study of the transition from yielding to crazing in polypropylene
Authors: Dijkstra P. T. S. , Van Dijk D. J. , Huétink J. 
Published: April 2004

AbstractThe deformation mechanisms in polypropylene as a function of strain rate have been studied by scanning electron microscopy. Injection molded, dogbone specimens were tested in tension at a temperature of 50°C and strain rates from 10−4 to 90 s−1. With increasing strain rate a gradual transition from cold drawing and necking to nearly homogeneous deformation was observed. The transition is characterized by a strong elastic recoil after fracture. At \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \dot \varepsilon } $\end{document} = 90 s−1, the elastic recovery has its maximum value of 70% of the strain at break (ε = 0.3). The morphology was studied post mortem at small strains outside the neck using permanganically etched samples. The transition in the macroscopic behavior was found to coincide with a change in the deformation mechanism. Whereas yielding is the dominant mechanism at low strain rates, homogeneous voiding is found at \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \dot \varepsilon } $\end{document} = 90 s−1. A correlation is suggested between the failure of chain slip within the lamellae and the occurrence of voiding, leading to distinct voiding patterns in the spherulites.
Measurement of the residual mechanical properties of crazed polycarbonate. II: Design of experiments analysis
Authors: Clay Stephen B. , Kander Ronald G. 
Published: April 2004

AbstractThe Design of Experiments (DOE) approach was used to build quantitative empirical models of the residual mechanical properties of crazed polycarbonate as functions of relative craze density, crazing stress, and strain rate. Crazing did not affect the yielding behavior of polycarbonate, but increasing the strain rate increased the yield stress according to the Eyring theory. The Eyring activation volume for yielding of crazed polycarbonate was measured to fall between reported values for conformational changes of a dilute solution of polycarbonate chains and yielding of uncrazed polycarbonate. Also, with as little as 1% relative craze density, the failure stress was approximately 10% lower and the ductility was, on the average, 50% lower than for uncrazed polycarbonate properties. It was also found that increasing the crazing stress from 40 to 45 MPa increased the failure stress and ductility for a given magnitude of relative craze density.
Modeling of a Buss‐Kneader as a polymerization reactor for acrylates. Part II: Methyl methacrylate based resins
Authors: Troelstra E. J. , Van Dierendonck L. L. , Janssen L. P. B. M. , Renken A. 
Published: April 2004

AbstractThe Buss‐Kneader has proven to be a suitable reactor for the polymerization of acrylates. In this second part, the polymerization of methyl methacrylate and the ter‐polymerization of methyl methacrylate (MMA), hydroxyethyl methacrylate and n‐butylmethacrylate is carried out in a pilot Buss‐Kneader. The reactor had to be pressurized up to about 10 bars to avoid evaporation of MMA. Instabilities in output rate and temperature profiles were observed as a result of fluctuating die pressures. Because of good mixing there may be no diffusion limitation for radicals. As a result, even at high conversions, no gel effect was observed.
Numerical analysis of surface‐tension‐driven coating flow
Authors: Blunk Richard H. J. , Wilkes James O. 
Published: April 2004

AbstractBondline readout (BLRO) is a coating defect frequently exhibited on adhesively bonded, polymeric automotive body panels painted with high‐glamour/flow clearcoats. BLRO or telegraphing results from Marangoni‐type, surface‐tension‐driven flows. The goal of this study is to use an efficient one‐dimensional numerical code (based on the lubrication approximation) to obtain further insight into the mechanism of temperature‐ and concentration‐induced BLRO flows in order to validate a proposed BRLO mechanism and ultimately to help eliminate the highly undesirable BLRO coating defect. Further insight is realized by investigating numerically the effects on BLRO of gravity and five parameters—initial film thickness, heating rate, viscosity, solvent volatility, and solvent‐to‐resin surface‐tension ratio. Possible solutions to the BLRO problem are discussed.
The effect of stoichiometry on the fracture toughness of a liquid crystalline epoxy
Authors: Robinson Elizabeth J. , Douglas Elliot P. , Mecholsky John J. 
Published: April 2004

AbstractThe fracture toughness of a liquid crystalline epoxy was compared with that of a standard bisphenol‐A based epoxy to understand how both the liquid crystalline structure and the crosslink density affect fracture toughness. For the liquid crystalline epoxy, the liquid crystalline domain size decreased with increasing temperature of cure and away from the stoichiometric formulation. Quantitative fractography showed that there is a competition between the liquid crystalline domain structure and the stoichiometry in determining the fracture toughness. At some cure conditions the effect of the domains is dominant. When the cure conditions are adjusted to reduce the domain size, the domains become too small to affect the fracture toughness, and thus the effect of the stoichiometry is dominant. The result is that the formation of liquid crystalline structure only increases the fracture toughness relative to that of a traditional epoxy at and near the stoichiometric formulation.
Tools for multiaxial validation of behavior laws chosen for modeling hyper‐elasticity of rubber‐like materials
Authors: Chevalier L. , Marco Y. 
Published: April 2004

AbstractWe present an experimental approach to discriminate hyper‐elastic models describing the mechanical behavior of rubber‐like materials. An evaluation of the displacement field obtained by digital image correlation allows us to evaluate the heterogeneous strain field observed during these tests. We focus on the particular case of hyper‐elastic models to simulate the behavior of some rubber‐like materials. Assuming incompressibility of the material, the hyper‐elastic potential is determined from tension and compression tests. A biaxial loading condition is obtained in a multiaxial testing machine and model predictions are compared with experimental results.
Polyimide and nylon 6 blend film: Preparation, characterization and thermal behavior
Authors: Niyogi Sobhan , Maiti Sukumar , Adhikari Basudam 
Published: April 2004

AbstractA polyimide blend system has been prepared from a base polyimide of BTDAODA by adding ε‐caprolactam at the poly(amic acid) stage where ε‐caprolactam undergoes polymerization to form nylon 6 during the thermal cyclodehydration of poly(amic acid). The blend has been characterized by elemental analysis. IR, 13C CPMAS NMR, XRD and simple chemical methods. The thermal analysis study (TGA and DTA) shows that the stability of the blend systems is more in the lower temperature region (up to 300°C) in comparison to the control polyimide system. The isothermal study at 400°C in inert atmosphere shows that the blend system is equally stable but the isothermal study in air at 400°C shows that the thermooxidative stability of the blend films (except BB 4) is higher. Also, isothermal study in air at 500°C shows more than 90% weight loss for all the films within 3 h, but in an inert atmosphere, the blend films show lower weight loss compared to the control film. Although the XRD pattern of all the blend and control films shows an amorphous character, the films developed some crystallinity when treated with boiling NMP where the blend films developed higher crystallinity.
Moisture diffusion behavior in bismaleimide resin subjected to hygrothermal cycling
Authors: Li Yanmei , Miranda John , Sue Hung‐Jue 
Published: April 2004

AbstractAbsorption‐desorption‐reabsorption hygrothermal cycling was performed in bismaleimide resin. Dynamic mechanical analysis and swelling experiments were conducted to investigate the effect of hygrothermal cycling on the moisture diffusion behavior in the resin. Non‐Fickian diffusion behavior was observed in both the absorption and the reabsorption processes, while the desorption process is found to be Fickian. The molecular network structure of BMI appears to have changed during the hygrothermal cycling. This, in turn, altered the subsequent reabsorption process.
Investigation of appropriate cooling times for electrofusion jointing of PE pipes for gas distribution
Authors: Higuchi Yuji , Nishimura Hiroyuki , Inoue Fumio , Ishikawa Tetsuo , Miyaki Seiji 
Published: April 2004

AbstractThis study evaluates three types of fusion zones between electrofusion (EF) joints and pipes that were laid underground after three different cooling times following fusion. The study establishes the relationship between the cooling time and the fusion performance. The object was to determine an appropriate cooling time for EF jointing. Only a slight difference was observed in the molecular structure, e.g., the degree of crystallinity, while distinct differences were observed in deformation, morphology, and tensile creep strength. Based on these results, the effect of a temperature profile during the cooling process on the fusion zone was simulated. The simulation showed that the state of the fusion zone (melting, semi‐solid, or solid) when the pipe was laid underground was the main factor affecting the tensile creep strength, i.e. long‐term performance. These analyses provided criteria for choosing an appropriate cooling time.
Analysis of multiaxial impact behavior of polymers
Authors: Duan Y. , Saigal A. , Greif R. , Zimmerman M. A. 
Published: April 2004

AbstractImpact performance is a primary concern in many applications of polymers. In this paper, finite element analysis (FEA) and ABAQUS/Explicit are used to simulate the deformation and failure of polymers in the standard ASTM D3763 multiaxial impact test. The specimen geometry and loading mode in this multiaxial impact test provides a close correlation with practical impact conditions. A previously developed constitutive model (“DSGZ” model) for polymers under monotonic compressive loading is generalized and extended for any loading mode and takes into account the different behavior of polymers in uniaxial tensile and compression tests. The phenomenon of thermomechanical coupling during plastic deformation is also included in the analysis. This generalized DSGZ model, along with thermomechanical coupling and a failure criterion based on maximum plastic strain, is incorporated in the FEA model as a coupled‐field user material subroutine to produce a unique tool for the prediction of the impact behavior of polymeric materials. Load‐displacement curves from FEA simulations are compared with experimental data for two glassy polymers, ABS‐1 and ABS‐2. The simulations and experimental data are in excellent agreement up to the maximum impact load. It is shown that not accounting for the different behavior of the polymer in uniaxial tensile and compression tests and thermomechanical coupling effects leads to an overestimation of the load and impact energy, especially at large displacements and plastic deformations. Friction also plays an important role in the impact behavior. If one neglects the friction between the striker and polymer disk, the predicted impact loads are lower as compared with experimental data at large displacements.
Interlaminar contact development during thermoplastic fusion bonding
Authors: Yang F. , Pitchumani R. 
Published: April 2004

AbstractFabrication of layered thermoplastics and thermoplastic‐matrix composites using processes such as tow placement, tape laying, and resistance welding is fundamentally based on the principle of fusion bonding, which involves applying heat and pressure to contacting thermoplastic surfaces. One of the important processing steps—intimate contact development—is considered in this paper. Interlaminar intimate contact development has a strong dependency on the thermoplastic surface geometry. Profilometric measurements of common thermoplastic prepreg tows, such as AS4/PEEK and IM7/PIXA, show that surface roughness features appear at several length scales and that the surfaces have fractal asperity structures. In this paper, principles of fractal geometry are used to describe prepreg surfaces. Based on this description, a microscale fluid flow model is developed to relate a degree of intimate contact to the process parameters (pressure, temperature, and time) and the fractal parameters of the surface. The model development and comparisons with experimental data are presented and discussed.
Crystallization and melting behavior of zenite thermotropic liquid crystalline polymers
Authors: Pramoda K. P. , Chung T. S. 
Published: April 2004

AbstractThe crystallization and melting behavior of a DuPont ZeniteTM series, namely, Z 6000 and Z 8000B, thermotropic liquid crystalline polymer (TLCP) have been investigated by differential scanning calorimetry (DSC). Both, non‐isothermal and isothermal crystallizations were carried out. From the non‐isothermal experiments, the crystallization temperature was found to be 234°C for a cooling rate of 10°C/min whereas it was only 228°C for 40°C/min for Z 8000B, and was found to be 296°C and 290°C, respectively, for Z 6000. In the isothermal experiment both the thermal and crystallization behaviors were studied as a function of the annealing temperature and annealing time. Two types of transition processes were evidence in the low temperature region of the isothermal crystallization. One is fast transition, which may be regarded as liquid crystal transition, and is characterized by the enthalpy, which is independent of annealing time. The other is slow process, related to crystal perfection, and it shows increases in the transition temperature and enthalpy, which is dependent on annealing time.