bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of reactive compatibilization on the interfacial slip in nylon‐6/EPR blends
Authors: Van Puyvelde P. , Oommen Z. , Koets P. , Groeninckx G. , Moldenaers P. , Leuven K. U. , Eindhoven T. U. , Leuven K. U. 
Published: April 2004

AbstractThe viscosity of uncompatibilized polymer blends often shows a negative deviation from a log‐additivity rule at shear rates relevant to processing. This deviation has been attributed to interfacial slip, which is related to the loss of entanglements at the interface. In this work interfacial slip and the effect of reactive compatibilization on this phenomenon are studied in blends consisting of ethylene‐propylene rubber and nylon‐6. The viscosity and morphology of blends with various compositions and compatibilizer content are investigated systematically. The results indicate that interfacial slip can indeed be important in uncompatibilized systems whereas it is suppressed in compatibilized blends. This is further supported by a study of the viscosity of multilayer structures. Both the effect of reactive compatibilization and of the number of layers on the rheology are studied. Again it is demonstrated that reactive compatibilization suppresses interfacial slip.
Novel ultrasonic process for in‐situ copolymer formation and compatibilization of immiscible polymers
Authors: Isayev A. I. , Hong Chang Kook 
Published: April 2004

AbstractIn‐situ copolymer formation and compatibilization of immiscible polymers in blends were discovered to occur during ultrasonic‐assisted extrusion in the melt state under high pressures. Residence times were of the order of seconds. The mechanical performance of plastic/rubber and rubber/rubber blends subjected to ultrasonic treatment was significantly enhanced compared to those of identical blends not subjected to ultrasonic treatment and having similar phase morphologies. The appearance of a high molecular weight tail in the rubber/rubber blends, stabilization of phase morphology in the melt state, the presence of a transition interface nanolayer and a decrease in the amount of extractable components in the plastic/rubber blends after ultrasonic‐assisted extrusion point towards the occurrence of in‐situ copolymer formation at the interfaces.
Application of ultrasound in the determination of fundamental extrusion performance: Residence time distribution measurement
Authors: Sun Z. , Jen C.‐K. , Shih C.‐K. , Denelsbeck D. A. 
Published: April 2004

AbstractBy means of new probe design and rapid data acquisition, we have succeeded in in‐line ultrasonic monitoring of residence time distribution (RTD) at the melting, mixing, and pumping zones as well as at the die exit of a Werner & Pfleiderer 30‐mm twin‐screw extruder by mounting the ultrasonic probes on the extruder barrel over the screw elements and at the die. The experimental systems were LDPE, CaCO3‐filled LDPE, and a Kraton/LDPE blend. The ultrasonic data at each of the extruder functional zones are presented. The ultrasonic results have been used to evaluate an opical RTD measurement method by using an optical sensor side by side with one ultrasonic probe at the mixing zone of the extruder. The comparison of the ultrasonic and optical results has shown that the presented ultrasonic technique could be a good complement to the optical technique in the monitoring and understanding of RTD during polymer extrusion processes.
Impact behavior and modeling of engineering polymers
Authors: Duan Y. , Saigal A. , Greif R. , Zimmerman M. A. 
Published: April 2004

AbstractBecause of their many unique and desirable properties, engineering polymers have increasingly been applied in applications where impact behavior is of primary concern. In this paper, the impact behavior of a glassy polymer acrylonitrile‐butadiene‐styrene (ABS) and a semicrystalline polymer alloy of polycarbonate and polybutylene‐terephthalates (PBT) are obtained as a function of impact velocity and temperature from the standard ASTM D3763 multiaxial impact test. As computer simulation of destructive impact events requires two material models, a constitutive model and a failure model, uniaxial mechanical tests of the two polymers are carried out to obtain true stress vs, true strain curves at various temperatures and strain rates. The generalized DSGZ constitutive model, previously developed by the authors to uniformly describe the entire range of deformation behavior of glassy and semicrystalline polymers for any monotonic loading modes, is calibrated and applied. The thermomechanical coupling phenomenon of polymers during high strain rate plastic deformation is considered and modeled. A failure criterion based on maximum plastic strain is proposed. Finally, the generalized DSGZ model, the thermomechanical coupling model, and the failure criterion are integrated into the commercial finite element analysis package ABAQUS/Explicit through a user material subroutine to simulate the multiaxial impact behavior of the two polymers ABS and PBT. Impact load vs. striker displacement curves and impact energy vs. striker displacement curves from computer simulation are compared with multiaxial impact test data and were found to be in good agreement.
Properties of rapid prototype injection mold tooling materials
Authors: Rodet Vincent , Colton Jonathan S. 
Published: April 2004

AbstractEpoxy acrylate‐based sterolithography resins have been used successfully as tools for injection molding. Molds made out of these resins fail at distinct times: during the first injection of plastic; during the first part first ejection; during either injection or ejection, but after a certain number of parts have been produced, which can be compared to a fatigue process. This paper presents corelations between measured properties of stereolithography molds and injection molding processing conditions so as to understand and predict mold failure. The study focuses on two stereolithography resins (SL 7510 and SL 7510) and one epoxy‐based composite material used for the high speed machining of prototype molds (Renboard). Rapid tooling materials are studied in fatigue, tensile, and fracture at injection molding operating temperatures and at room temperature. Finally, a method to address failure of molds is proposed using the theory of fracture.
Dynamic mechanical signatures of Viton A and plastic bonded explosives based on this polymer
Authors: Mark Hoffman D. 
Published: April 2004

AbstractThe complex shear moduli of the fluorelastomer Viton A and four plastic bonded explosives LX‐04, LX‐07, LX‐10, and LX‐11, which use this polymer as a binder, have been investigated. LX‐10, LX‐07, LX‐04 and LX‐11 are composites of 94.5, 90, 85 and 80% 1, 3, 5, 7‐tetranitroazacyclooctane (HMX) explosive, respectively, and Viton A. Viton is a random copolymer of 7 vinylidene fluoride and 2 perfluoropropene monomers. In the temperature range from −150 to 120°C, two relaxations, the β relaxation at −80°C and the glass transition at −22°C, were observed as peaks in the loss modulus in Viton A at 0.1 Hz. A third relaxation, Tα, was found above Tg in all four explosive formulations. The plastic bonded explosives (PBX's) showed antiplasticization phenomena. Tg of the explosives increased 2–3°C as the concentration of binder was reduced in 5% steps. Samples from the same original lot of LX‐04 were evaluated after 20–23 years of service. The alpha relaxation occurred at 60°C as a peak in the loss modulus at 1 Hz. Both the beta and alpha relaxations were very broad and an accurate maximum for these relaxations was difficult to determine.
Effect of process conditions on the weld‐line strength and microstructure of microcellular injection molded parts
Authors: Turng Lih‐Sheng , Kharbas Hrishikesh 
Published: April 2004

AbstractThis study was aimed at understanding how the process conditions affect the weld‐line strength and microstructure of injection molded microcellular parts. A design of experiments (DOE) was performed and polycarbonate tensile test specimens were produced for tensile tests and microscopic analysis. Injection molding trials were performed by systematically adjusting four process parameters (i.e., melt temperature, shot size, supercritical fluid (SCF) level, and injection speed). For comparison, conventional solid specimens were also produced. The tensile strength was measured at the weld line and away from the weld line. The weld‐line strength of injecton molded microcellular parts was lower than that of its solid counterparts. It increased with increasing shot size, melt temperature, and injection speed, and was weakly dependent on the supercritical fluid level. The microstructure of the molded specimens at various cross sections were examined using scanning electron microscope (SEM) and a light microscope to study the variation of cell size and density with different process conditions.
Industrial solidification processes in polybutene‐1. Part I—quiescent melts
Authors: Braun J. , Pillichshammer D. , Eder G. , Janeschitz‐Kriegl H. 
Published: April 2004

AbstractIn the first paper of this series the principles for solidification of crystallizable polymers under heat transfer conditions are discussed for the case of the absence of flow. For industrial polymers, which, in general, are forced to crystallize at large undercoolings, the pertinent kinetic data are extremely rare. In the present paper the growth speeds of spherulites and the number of nuclei per unit volume are presented as functions of temperature for two industrial polybutene‐1 grades.
A study of the effect of surfactants on the properties of polystyrene‐montmorillonite nanocomposites
Authors: Xie Wei , Hwu Jyh Ming , Jiang George J. , Buthelezi Thandi M. , Pan Wei‐Ping 
Published: April 2004

AbstractPolystyrene‐Organo Montmorillonite (PS‐MMT) nanocomposites were prepared by suspension free radical polymerization of styrene in the dispersed organophilic montmorillonite. The results of X‐ray diffraction (XRD) and Transmission Electron Microscopy (TEM) indicated that exfoliated nanocomposites were achieved. The effect of organic modifiers (surfactants) on the properties of the synthesized nanocomposites was studied. It is found that polystyrene‐MMT nanocomposite with 5.0 wt% of organo‐MMT gave the greatest improvement in thermal stability, and polystyrene‐MMT nanocomposites with 7.5 wt% of organo‐MMT showed the greatest improvement in mechanical properties, compared with that of pure polystyrene (PS) in our experimental conditions. The alkyl chain length of surfactant used in fabricating organo‐MMT affects the synthesized PS nanocomposites: the longer the alkyl chain length that the surfactant possesses, the higher the glass transition temperature of the PS nanocomposite, However, the organoclay in the nanocomposites seems to play a dual role: (a) as nanofiller leading to the increase of storage modulus and (b) as plasticizer leading to the decrease of storage modulus. This results in a lower storage modulus of PS‐TMOMMT and PS‐TMTMMT nanocomposites than that of PS‐TMDMMT and PS‐TMCMMT nanocomposites. Further study is needed to confirm the above hypothesis.
Essential work of fracture of polypropylene and polypropylene blends over a wide range of test speeds
Authors: Grein C. , Plummer C. J. G. , Germain Y. , Kausch H.‐H. , Béguelin P. 
Published: April 2004

AbstractThe mechanical properties of extruded films of isotactic polypropylene (iPP) and ethylene‐propylene rubber toughened iPP (iPP/EPR) have been analyzed in terms of the specific essential and non‐essential work of fracture using high speed tensile test apparatus modified for quasi‐static testing in the range 0.0001 to 3 ms−1. Three iPP/EPR grades with modifier contents of 15, 21 and 30 vol% were investigated. As the deformation rate increased, relatively uniform necking of the whole ligament and extensive plastic deformation were progressively replaced by more localized plastic deformation in the blends, and by fully brittle fracture in the unmodified iPP. The non‐essential work of fracture and the total fracture energy were highly sensitive to these changes in deformation mechanism. However, the essential work of fracture, although dependent on the test speed, was less correlated with the extent of global plasticity.
Selectivity of peroxide‐initiated graft modification of ethylene copolymers
Authors: Parent J. Scott , Tripp Michael , Dupont John 
Published: April 2004

AbstractExperimental data on the kinetics and selectivity of peroxide‐initiated graft modification of ethylene copolymers with vinyltriethoxysilane (VTEOS) and maleic anhydride (MAn) are presented. Rate data for the VTEOS modification and crosslinking of poly(ethylene‐co‐vinyl acetate) demonstrate the controlling influence of peroxide decomposition rates. Analysis of the selectivity for grafting versus crosslinking showed considerable scope for optimization of VTEOS modifications through variation of monomer and peroxide loadings. However, the MAn system was found to be less amenable to optimization, most likely because of differences in the graft propagation cycle and radical termination preferences.
Investigation of the rheological and mechanical properties of a polystyrene‐polyisobutylene‐polystyrene triblock copolymer and its blends with polystyrene
Authors: Antony Prince , Puskas Judit E. , Kontopoulou Marianna 
Published: April 2004

AbstractThe rheological and mechanical properties of a polystyrene‐polyisobutylene‐polystyrene (SIBS) block copolymer containing 30 wt% polystyrene (PS) and its blends with PS (SIBS/PS) were investigated. Atomic Force Microscopy (AFM) was used to visualize the nanostructured phase morphology of the SIBS, which is responsible for the mechanical strength of this thermoplastic rubber. The order‐disorder transition (ODT) for the SIBS block copolymer was found to be above 250°C. SIBS/PS blends with 10–30 wt% PS showed improved moduli and tensile strengths. Blends containing up to 40 wt% PS behaved as thermoplastic elastomers. In the region of linear viscoelasticity the blends revealed pronounced non‐Newtonian behavior and enhanced elasticity. This paper also reports the role of this styrenic block copolymer in the impact modification of PS.
Influence of chemical composition on the rheological behavior of condensation reaction resins
Authors: Doyle M. , Hagstrand P.‐O. , Månson J.‐Å. E. , Svensson L. , Lundmark S. 
Published: April 2004

AbstractIn this paper, the chemorheological and dynamic mechanical behavior of melamine‐formaldehyde (MF) resins of four different formaldehyde/melamine (F/M) molar ratios (1.25, 1.5 1.75 and 2.00) are investigated. MF resins polymerize via a polycondensation reaction involving formation of up to 10 wt% of H2O on cure. This typically results in rapid and extensive foaming of the resin when it is cured under atmospheric pressure. Experimental adaptation for the foaming behavior of MF resins is used to gather rheological information concerning the curing kinetics and the mechanical response of neat MF resins of different molar ratios. Likewise, the procedures developed allow curing of the resins under atmospheric pressure, hence allowing volatile evacuation as occurs during venting procedures (commonly used during compression molding of MF molding compounds) or as a result of absorption by hydrophilic fillers or substrates. The results show that increased moisture content in the B‐stage leads to faster reaction rates and greater foaming. Gelation and vitrification times are identified for each molar ratio, and are found to increase with decreasing molar ratio. The dynamic mechanical behavior of carefully molded neat MF samples of different molar ratios is studied using DMTA. Tg is found to be 200°C for the resin with the lowest formaldehyde content (F/M = 1.25), and around 230°C for the other resins. The storage shear modulus above Tg is studied, and the results show that the crosslink density increases with increasing molar ratio.
On the dynamic mechanical behavior of polyimides based on aromatic and alicyclic dianhydrides
Authors: Bas Corine , Tamagna Cécile , Pascal Thierry , Dominique Alberola N. 
Published: April 2004

AbstractA series of polyimides has been synthesized based on different dianhydrides and diamines. The microstructure of polyimide films has been analyzed by performing density measurements, X‐ray diffraction and UV‐visible spectrophotometry. The dynamic mechanical behavior was investigated according to both chemical and microstructural aspects. Thus, it was pointed out that the broadness of the β subglass transition is dependent not only on dianhydride flexibility but also on para‐ or meta‐diamine links. Such behavior is discussed in terms of intra‐charge transfer complex. On the contrary, the temperature location of the γ‐transition appears to be controlled by interchain packing. Based on a statistical approach, a correlation between microstructural data and gamma relaxation temperature is established.
In‐line color monitoring of polymers during extrusion using a charge coupled device spectrometer: Color changeovers and residence time distributions
Authors: Gilmor C. , Balke S. T. , Calidonio F. , Rom‐Roginski A. 
Published: April 2004

AbstractA fiber‐optic–assisted, charge‐coupled device spectrometer was used to monitor the color of molten polymer concentrates during extrusion. Color coordinates L*, a* and b* were calculated from each of the reflectance spectra as polyethylene color concentrate was replaced by a purge material and as the purge material was replaced by another color concentrate. A method of calculating replacing component residence time distributions and component washout residence time distributions from the spectra was developed and applied. Results with a red and a blue concentrate showed that dimensionless time (time/average residence time) superimposed both residence time distributions and color coordinate variations during changeover from two different extruder screw speeds.
Dynamic modeling of blown‐film extrusion
Authors: Carl Pirkle J. , Braatz Richard D. 
Published: April 2004

AbstractPast dynamic studies of blown‐film extrusion have been confined to the stability analysis of the linearized equations. The full set of nonlinear equations comprises a system of partial differential and algebraic equations with boundary conditions that vary from author to author. In this paper, the Numerical‐Method‐of‐Lines, which combines finite‐difference methods with ordinary differential/algebraic equation integrators, is used to solve the full system. Appropriate boundary conditions are selected to give physical results that compare well with experiment. An important boundary condition is the “minimum order reduction” condition on the gradient of the bubble‐tube radius with respect to distance above the extrusion die (the axial position). Transient startups and operational disturbances are examined. Calculations show the influence of oscillations in operating conditions such as heat transfer or inflation pressure on the bubble‐tube radius and film thickness. Steady‐state results obtained by integrating the transient equations for a sufficiently long time are qualitatively in agreement with experiment, in contrast to past simulations of these equations.
Mechanical properties of low nano‐silica filled high density polyethylene composites
Authors: Zhang Ming Qiu , Rong Min Zhi , Zhang Hai Bo , Friedrich Klaus 
Published: April 2004

AbstractModification of nanoparticles through graft polymerization is able to change the chemical nature of the particles' surfaces and provides an effective means for the preparation of nano‐fillers specified for composites manufacturing. The present work focuses on the mechanical role of grafted nano‐SiO2 particles in high density polyethylene composites prepared by melt compounding. The experimental results show that at a content of 0.75 vol%, the modified nano‐silica results in a rise in tensile stiffness, tensile strength and impact strength of the composites. The grafted nanoparticles can improve the mechanical performance of the matrix polymer more effectively than the untreated version. In addition, a further enhancement of the composites stiffness and strength can be achieved by crosslinking the concentrated masterbatches, which has not yet been revealed in the authors' previous works on grafted nano‐SiO2 particles/polypropylene composites. It is thus revealed that the introduction of the grafting polymers onto the nanoparticles increases the tailorability of the composites.
Theoretical influence of polyester molecular weight distribution variation on melt viscosity during injection molding and extrusion as influenced by ester‐ester interchange
Authors: Sudduth Richard D. 
Published: April 2004

AbstractIn this study Flory's initial molecular weight derivation involving polyester polymerization and ester‐ester interchange was expanded to address two types of blends relative to both the number average molecular weight and the weight average molecular weight. First, an add blend was considered where the numbers of molecules of the same length were simply added together to calculate new number and weight average molecular weights. Second, the complete transesterification blend was calculated using Flory's most probable distribution with the same number average as the add blend but with a very different weight average molecular weight. The ratio of the weight averages of the add blend to the transesterification blend were found to be significantly larger if the initial blending molecular weights were significantly different from one another. This ratio was also found to go through a maximum that occurred at approximately 50% by weight if the two different molecular weights had the same monomer molecular weight. If the monomer molecular weights were different, the location of this maximum could be quite different from 50% by weight. Since melt viscosity is proportional to the weight average molecular weight to a power ranging from 1 to 3.4, a very large ratio between weight average molecular weight of the add blend and the ester‐ester interchange blend was found to have a significant influence on the melt viscosity. A polyester blend mixture of micro‐domains of both a nearly pure add blend and a nearly complete ester‐ester interchange blend was used to explain how a short shot could be followed a few shots later with a part that flashed the mold in an injection molding application.
Ternary miscibility in blends of three polymers with balanced binary interactions
Authors: Woo E. M. , Mao Yung‐Jen , Wu Pi‐Ling , Su Chean‐Cheng 
Published: April 2004

AbstractThis study demonstrates and discusses ternary miscibility in a three‐polymer blend system based on balanced binary interactions. A truly miscible ternary blend comprising poly(ε‐caprolactone) (PCL), poly(benzyl methacrylate) (PBzMA), and poly(vinyl methyl ether) (PVME), was discovered and reported. Miscibility with phase homogeneity (excluding the PCL crystalline domain) in a wide composition range has been demonstrated using criteria of thermal transition behavior, cloud point, and microscopy characterization. At ambient temperature, the three‐polymer ternary system is completely miscible within the entire composition range (i.e., no immiscibility loop). However, at slightly elevated temperatures above the ambient. phase separation readily occurred in this originally miscible ternary blend. A quite low “lower critical solution temperature” (LCST) near 75°C was found for the ternary blend, which is much lower than any of those for the binary pairs. Balanced interactions with no offsetting Δχ among the three binary pairs were a key factor leading to a ternary miscible system.