bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the effects of internal heating and cooling during the rotational molding of plastics
Authors: Sun Da‐Wen , Crawford Roy J. 
Published: May 2005

AbstractIn rotational molding, shortening the cycle time is one of the most important requirements for increasing production rates and reducing product cost. A characteristic feature of the process is that the mold and plastic powder are heated from room temperature to the melting temperature of the plastic and then back to room temperature. In addition, in the vast majority of cases the heat input and subsequent heat extraction occur at the outside surface. In order to improve the heat transfer, this paper considers the effects of internal heating and cooling. A mathematical model has been developed in which an internal heating term can be incorporated. The experiments with rotomolding powders show that the predictions made by the model are accurate. In particular, it is found that the introduction of internal heating is very effective in shortening the cycle time and that the introduction of internal cooling in rotational molding provides a more uniform structure and less likelihood of warpage.
Measurement and correlation of mutual diffusion coefficients for styrene‐butadiene rubber(SBR)‐n‐nonane systems
Authors: Iwai Yoshio , Miyamoto Shinji , Ikeda Hideaki , Arai Yasuhiko , Kobuchi Shigetoshi , Sano Yuji 
Published: May 2005

AbstractThe mutual diffusion coefficients for styrene‐butadiene rubber(SBR)‐n‐nonane systems were measured using a sorption apparatus with a quartz spring at 100 and 130°C for mass fractions of n‐nonane ranging from 0 to 0.16. The mutual diffusion coefficients were correlated with good agreement by the free‐volume theory.
Dynamic mechanical properties of poly( ε‐caprolactam)/polypropylene alloy
Authors: Wippler C. 
Published: May 2005

AbstractThe results of a round‐robin testing on the dynamic mechanical properties of a poly(ε‐caprolactam)/polypropylene PA‐6/PP compatibilized blend (an alloy) are reported. The alloy was a commercial product (Orgalloy R‐6000, from Atochem). The samples were prepared by extrusion, injection or compression molding. The greatest difficulty in comparing the data arose from the moisture content since the position of the PA‐6 transition peaks depend on the drying conditions. For the extruded specimens only minor effects could be attributed to the anisotropy introduced by the extrusion process. Overall, there was good agreement between the contributing laboratories for the frequency dependence of the transition peaks, but agreement between the measured values of the storage moduli was poor. This discrepancy is suspected to be partially due to the differences in sample geometry and in the processing conditions.
Filling of a complex‐shaped mold with a viscoelastic polymer. Part II: Comparison with experimental data
Authors: Kamal M. R. , Papathanasiou Thanasis D. 
Published: May 2005

AbstractAn experimental program has been carried out on a reciprocating screw injection molding machine in order to establish the validity of a proposed mathematical model for the filling stage of injection molding. A cavity of complex shape with an insert and variable thickness was constructed and used in these experiments. Good agreement between predicted (through computer simulation) and observed (through short‐shot experiments and transducer response) results is obtained for free surface shapes and free surface locations with time. The theoretical pressure predictions are in fairly good agreement with experiments, with the maximum deviations occurring towards the end of filling and for longer filling times. This points towards the possibility that wall solidification during filling interacts with the flow processes across the gap of the cavity and makes necessary a more detailed characterization of the heat transfer at the melt/mold interface.
Pneumatic bursting characteristics of plastics films
Authors: Tseng H. H. , Lai F. S. , Lee C. K. 
Published: May 2005

AbstractThe bursting strength and inflated deflection of linear low density polyethylene (LLDPE), oriented polypropylene (OPP), flexible poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET), and polyurethane (PUR) films of different thicknesses were investigated with the pneumatic bursting method. The study showed the bursting air pressure is directly proportional to the thickness of LLDPE, OPP, and PET films. The effect of different membrane diameters on the change of the bursting properties in OPP and PUR film was also investigated. The results showed that the bursting properties are inversely proportional to the membrane diameter. Furthermore, biaxial stress‐strain exerted on the pole region of the tested films was studied. The results denoted that the relationship between the biaxial and uniaxial tensile stress‐strain was considered for two types of film: (1) Film that presented an isotropic tensile behavior showed that the tangential stress‐strain is higher than the tensile stress‐strain. (2) Film that presented an anisotropic tensile behavior showed that the tangential stress‐strain is determined by the weaker tensile stress‐strain values between two directions.
Model filled polymers. XIV: Effect of modifications of filler composition on rheology
Authors: Sun Liqing , Aklonis J. J. , Salovey R. 
Published: May 2005

AbstractSteady shear vxiscosity, dynamic moduli and the appearance of fracture surfaces of model composites, consisting of monodisperse crosslinked polymeric spheres of varied composition in a polymethyl‐methacrylate matrix, depend on the compatibility of filler particle and matrix. After intensive mixing, “compatible” systems form uniform and stable dispersions. Filler particles cluster in incompatible composites producing a highly non‐Newtonian response. At 40 w% filler, yield behavior results, with a yield stress of 3100 Pa for polystyrene particles and 1900 Pa for copolystyrene‐acetoxystyrene particles. The flow properties of compositionally complex particles from seeding are determined by particle surface composition.
Studies on miscibility of blends of ethylene methyl acrylate and polydimethyl siloxane rubber
Authors: Santra Robin N. , Roy Sanjoy , Bhowmick Anil K. , Nando G. B. 
Published: May 2005

AbstractBlends of ethylene methyl acrylate (EMA) and poly(dimethylsiloxane) rubber (PDMS) are demonstrated to be miscible. The miscibility results in a single and composition‐dependent glass transition temperature. IR spectra of the blends provide direct evidence of chemical reaction between EMA and PDMS rubber.
Double Arm pulfrich refractometer: Application to the optical characterization of biaxially stretched polystyrene
Authors: Warenghem M. , Lefebvre J. M. 
Published: May 2005

AbstractAn experimental setup is presented that enables the whole optical characterization of an anisotropic medium to be achieved at the same spot. Based on total internal reflection measurements, the Double Arm Pulfrich Refractometer provides high precision simultaneous refractive index data, which are gathered without moving the sample. This technique is particularly well suited to the case of biaxial materials. Illustration of its potential is given on some preliminary orientation measurements of biaxially stretched polystyrene films.
Energy absorbing double‐beam concept for thermoplastic automotive bumpers
Authors: Stokes Vijay K. 
Published: May 2005

AbstractBecause of the inability of existing automotive bumpers to absorb energy during impacts over the supports, energy absorbers have to be used to make bumpers effective in barrier impacts. A parametric analysis of a novel double‐beam bumper concept has shown that its performance, in terms of energy absorption and impact forces, is insensitive to the location of the point of impact. Physical realizations of this concept, which may not require more material than existing designs, and which are particularly suited to thermoplastic materials, have been developed.
Reaction mechanisms of polyacrylonitrile on thermal treatment
Authors: Kim J. , Kim Y. C. , Ahn W. , Kim C. Y. 
Published: May 2005

AbstractA high‐temperature radical scavenger, 2,2‐diphenyl‐l‐picryl hydrazyl (DPPH), has been used to study the reaction mechanisms of polyacrylonitrile (PAN) on thermal treatment. The effect of DPPH on the cyclization reaction of PAN in both air and nitrogen, investigated by differential scanning calorimetry (DSC), helped to verify the proposed reaction mechanisms, i.e., the free radical and the ionic ones. For PAN homopolymer, the peak temperature of the reaction exotherm shifted to higher temperatures and the heat of reaction was decreased with increasing DPPH concentration. For PAN copolymer with methylacrylate and itaconic acid, however, the effects of DPPH on DSC thermograms were insignificant. The effects of IPPH suggest that the reaction of the nitrile groups proceeds by free radicals for the homopolymer while by ions for the copolymer. The activation energies for the thermal reactions of PAN in both air and nitrogen were also estimated by the dynamic DSC method, and they proved to be highly dependent on reaction mechanism, environment of thermal treatment, and DPPH concentration.
A predictive model for the mechanical behavior of particulate composites. Part I: Model derivation
Authors: Vratsanos Lori Anderson , Farris Richard J. 
Published: May 2005

AbstractA method for predicting the highly nonlinear stress‐strain behavior and dilatation induced by cavitation of highly filled particulate composites from constituent properties has been developed. The approach presented uses a variation of linear elasticity throughout and has no adjustable parameters, unlike the methods currently used, which require large numbers of fitting factors and complicated nonlinear analyses. An energy balance derived from the first law of thermodynamics calculates critical strain values at which filler particles will debond when subjected to deformation. Repeated calculations of critical strain values using re‐evaluated material properties accounting for the damage caused by debonding give very nonlinear stress‐strain and dilatation curves. Experimentally observed dependencies on particle size, filler concentration, adhesion, and matrix and filler properties are correctly predicted. The method can be generalized for any state of stress or particle shape. Comparisons of experimental data with the model results give good agreement.
Thickness‐direction thermal expansion of polyimide films
Authors: Tong H. M. , Saenger K. L. , Su G. W. 
Published: May 2005

AbstractThe coefficient of thermal expansion (CTE) for thin polymer films is a property of considerable practical importance. In contrast to the abundance of CTE data in the in‐plane or film direction, data in the thickness or z‐direction is rarely available, in part due to the high sensitivity required for measurement of the small thickness changes involved. In this paper, we will describe both a capacitance change and a Fabry‐Perot laser interferometric method for measuring z‐direction CTE's. Results are presented for a variety of commercially available polyimide films of thickness 50 to 130 μm. Upilex and Kapton were found to have z‐direction CTE's of about 55 and 81 ppm/°C, respectively. These CTE's for the thickness direction are many times higher than the corresponding values in the in‐plane direction. This anisotropy is attributed to the preferential in‐plane molecular orientation of the polymer chains.
Estimation of critical stability parameters by asymptotic analysis in multilayer extrusion
Authors: Anturkar Nitin R. , Wilkes James O. , Papanastasiou Tasos C. 
Published: May 2005

AbstractIn industrial coextrusion operations, multiple layers are frequently brought in contact with each other at different temperatures to “match” viscosities and to reduce interfacial instability. Here, a linear stability analysis of multilayer plane Poiseuille flow is carried out for real, specific polymer melts in terms of process parameters, such as temperatures and flow rates. However, heat transfer across the layers is neglected as a first approximation. Previously, it was observed that below a certain Reynolds number and above a certain relaxation time, the flow‐rate ratio (or the depth ratio), above which the flow is stable to all wavelengths, can be estimated by the long‐wavelength asymptotic analysis (1,3). The Reynolds numbers for the industrial flows are smaller, and the relaxation times are larger than the corresponding critical values by several orders of magnitude. Therefore, the critical stability parameters can be estimated in the present study for industrial cases using the asymptotic stability analysis at long wavelengths. Although a large number of earlier parametric studies of model fluids indicate the influence of various theological parameters, only the viscosity stratification plays an important role in the interfacial instability within the operating range of industrial coextrusion processes.
Impact toughening mechanisms in rubber‐dispersed polymer alloy
Authors: Okamoto Y. , Miyagi H. , Uno T. , Amemiya Y. 
Published: May 2005

AbstractThe toughening mechanisms of rubber‐dispersed polymer alloys were investigated with respect to two factors: (i) characteristic ratio, C∞, as a measure of chain flexibility of the polymer matrix and (ii) the rubber particle size in high impact polystyrene/poly(2,6‐dimethyl‐ 1,4‐phenylene ether) blend systems. Measurements of the specific gravity, synchrotron radiation small angle X‐ray scattering (SR‐SAXS) tests, and finite element analysis were carried out to gain understanding of plastic deformation (crazing and shear yielding) of these materials. Shear yielding was found to be enhanced when the C∞ value of the matrix polymer was relatively low and the rubber particles were small (submicron). From these results, we presumed the impact energy absorption mechanisms to be governed by these two factors.
Effects of kinetic and transport parameters on accelerated migration of reactive additive from plastic sheet
Authors: Atiqullah M. , Shamsur Rahman A. K. M. , Zaidi S. M. J. 
Published: May 2005

AbstractThe effects of kinetic parameters Hatta number Ha and ϕ, and transport parameters Biot number Bi and ψ on the migration of a reactive additive have been modeled. The convective boundary layer can be considered inert to fully reactive for Ha → 0 to 2, respectively. The migration is controlled by diffusion, reaction rate, equilibrium partitioning of the migrant between the plastic film and the solvent, and boundary layer resistance, depending on the time scale and values of the above parameters. For a nonreactive boundary layer, at high Bi, migration is initially diffusion‐controlled but becomes reaction‐rate controlled at later times. However, under similar conditions, a slight increase in the reactivity of the boundary layer immediately changes the transport process from diffusion‐controlled to reaction rate‐controlled. With further increase in reactivity, migration spontaneously reaches equilibrium. At low Bi, equilibrium partitioning and reactive depletion of the migrant in the fluid phase change predominantly to boundary layer‐controlling mass transport phenomenon. For a given sampling time (τ = 1.0), the migration increases with the increase in Bi only for a reactive boundary layer. At low Bi and (τ = 1.0), migration decreases only up to ϕ ≅ 0.3 for nonreactive to partially reactive boundary layer, but for intermediate and high Bi, ϕ and Ha do not influence migration.
High temperature thermosets based on the cocuring of a novel spirodilactam bisallylether and bismaleimide
Authors: Chuah Hoe H. , Wang P. C. 
Published: May 2005

AbstractSpirodilactam bisallylether is a new high temperature performance monomer. It melts at 154°C, and is thermally inactive in forming a homopolymer. However, it reacts readily with a bismaleimide via “ene” reaction. Therefore, it could be used as a comonomer and an effective toughening modifier for bismaleimide. The properties of the blends of spirodilactam bisallylether and 4,4'‐bismaleimidodiphenyl‐methane were studied. The cocured resins have high glass transition temperature, > 300°C. By adding 30 to 40 mole % of the bisallylether, the compact tension toughness of the bismaleimide was improved to 0.7 MPa‐m1/2. Therefore, the resins have a combination of high glass transition temperature and toughness. They also showed good flexural properties. Despite the high water absorption, 5 to 7%, the resins retained high hot/wet flexural properties because of the high glass transition.
Viscoelasticity of some engineering plastics analyzed with the modified stress‐optical rule
Authors: Hwang Eui Jeong , Inoue Tadashi , Osaki Kunihiro 
Published: May 2005

AbstractThe complex Young's modulus, E*(ω), and the complex strain‐optical coefficient, O*(ω), of poly(ether sulfone) (PES), polysulfone (PSF), and polyethermide (PEI), were measured over the frequency range 1 to 130 Hz. The data were analyzed with a modified stress‐optical rule: The Young's modulus was decomposed into two complex functions, E(ω) and E(ω); the modified stress‐optical coefficient, CR and CG, associated with the rubber (R) and glass (G) components, respectively, were determined. The results for six polymers, including polystyrene, poly(α‐methyl styrene), and bisphenol A polycarbonate were compared with each other. One of the coefficients, CR, equivalent to the stress‐optical coefficient in melts, mainly depended on the way in which phenyl groups were connected to the chain. The other, CG, was in the range of 20 to 40 Brewsters, and did not strongly depend on the details of polymer structure. The component function, E(ω), which was located in the glassy region and originated from the high glassy modulus, was almost the same in shape when plotted against ω with double logarithmic scales. The R component, E(ω), located at the long time end of the glass‐to‐rubber transition zone, was slightly sensitive to the molecular structure of polymers.
A closer look at the MWD‐viscosity transform
Authors: Shaw Montgomery T. , Tuminello William H. 
Published: May 2005

AbstractWhile there is abundant evidence that the molecular weight distribution (MWD) of a linear polymer has an influence on the shape of the viscosity function, the ability to convert the viscosity function to an MWD has been questioned. Using strictly numerical techniques, we have shown that the viscosity function can be transformed to the MWD, but always with some distortion. However, distinct bimodality can be qualitatively preserved through both the MWD‐viscosity and viscocity‐MWD transforms.
Analysis of a reactor with surface renewal for poly(ethylene terephthalate) synthesis
Authors: Yoon K. H. , Park O. O. 
Published: May 2005

AbstractA mathematical model of a polycondensation reactor that can be used in the final stage for poly(ethylene terephthalate) (PET) is established and compared with experimental data obtained from a laboratory scale reactor with film renewal. Detailed side reactions are considered along with the diffusional removal of the small molecules through thin film. Among several kinetic constants, the polycondensation reaction rate constant k1(= k8) and diester group degradation reaction rate constant k7 have an influence over the degree of polymerization. The values of k1(= k8) and k7 for 0.05 wt% Sb2O3 were obtained as curve‐fit values: (1) k1(= k8) = 3.4 × 106 exp(− 18.500/RT′) (L/mol‐min); (2) k7 = 1.3 × 1011 exp(− 37,800/RT′) (min−1). Effects of the film exposure time, reduced pressure of vacuum, temperature, the initial terephthalic acid (TPA)/ethylene glycol (EG) mole ratio, the initial degree of polymerization, and catalysts were well explained by the model.
The effect of annealing on stretched trans‐1,4‐polyisoprene networks
Authors: Chou Der‐Gun , Smith K. J. 
Published: May 2005

AbstractVariations of stress with temperature for stretched networks of trans‐polyisoprene networks in the crystallization region are reported. Such profiles are characteristically U‐shaped with the stress at lower temperatures often climbing to high levels. Valley widths of the profiles narrow as annealing temperature increases to about 50°C, then widen at yet higher temperatures. The degree of crystallization at 22°C is 37% and independent of deformation and annealing temperature. The β crystal form is overwhelmingly present with traces of other crystal forms appearing only at high deformations. The theory of stress‐induced crystallization provides a good description of experimental results provided the nucleation parameter σ is dependent upon deformation. Therefore, the data provide good qualitative support for the theory in its current form.
Mechanical properties and deformation mechanism of polyoxymethylene chain in the crystalline state
Authors: Tashiro Kohji , Kobayashi Masamichi , Tadokoro Hiroyuki 
Published: May 2005

AbstractThe true crystallite modulus of polyoxymethylene (POM) was evaluated experimentally and thoeretically as a function of temperature. The mechanical deformation mechanism of POM was lattice‐dynamically predicted and confirmed by measuring the stress‐induced vibrational frequency shifts of the infrared and Raman spectra, which were interpreted on the basis of anharmonic potential field.
Functionalized elastomeric compatibilizer in PA 6/PP blends and binary interactions between compatibilizer and polymer
Authors: Holsti‐Miettinen R. M. , Seppälä J. V. , Ikkala O. T. , Reima I. T. 
Published: May 2005

AbstractSuperior impact properties were obtained when maleic anhydride grafted styrene ethylene/butylene styrene block copolymer (SEBS‐g‐MAH) was used as a compatibilizer in blends of polyamide 6 (PA 6) and isotactic polypropylene (PP), where polyamide was the majority phase and polypropylene the minority phase. The optimum impact properties were achieved when the weight relation PA:PP was 80:20 and 10 wt% SEBS‐g‐MAH was added. The blend morphology was systematically investigated. Transmission electron microscopy (TEM) indicated that the compatibilizer forms a cellular structure in the PA phase in addition to acting as an interfacial agent between the two polymer phases. In this cellular‐like morphology the compatibilizer appears to form the continuous phase, while polyamide and polypropylene form separate dispersions. In microscopy, PA appeared as a fine dispersion and PP as a coarse dispersion. The mechanical properties indicated that in fact PA, too, is continuous, and the blend can be interpreted as possessing a modified semi‐interpenetrating network (IPN) structure with separate secondary dispersion of PP. The coarser PP dispersion plays an essential role in impact modification. Binary blends of the compatibilizer and one blend component were also investigated separately. The same cellular structure was observed in the binary PA/SEBS‐g‐MAH blends, and SEBS‐g‐MAH again appeared to form the continuous phase when the elastomer concentration was at least 10 to 20 wt%. By contrast, in PP/SEBS‐g‐MAH only conventional dispersion of elastomeric SEBS‐g‐MAH was observed up to 40 wt% elastomer. Impact strength was improved and the elastic modulus was lowered in both PA/SEBS‐g‐MAH and PP/SEBS‐g‐MAH blends when the elastomer content was increased. The changes in modulus indicate that the semi‐IPN‐like structure is formed in the binary PA/SEBS‐g‐MAH blends as well as in the ternary structure.