bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Numerical Investigation on the Cure Cycle of Composite Brake Blocks
Authors: Shojaei A. 
Published: December 2013

Abstract
Composite friction materials used in the braking system of vehicles are composed of different ingredients (typically up to 20 materials). The overall physical properties of these products are determined by the type and percentage of the individual ingredients in the final composition and consequently, may differ from one product to another. This paper studies the cure characteristics of railroad composite brake blocks during compression molding. Numerical simulations using the control volume/finite element method (CV/FEM) are utilized to predict temperature fields and cure conversion during the process. As railroad brake blocks are normally thick-sectioned parts, a three-dimensional modeling routine is developed. The model combines heat conduction and mass balance equations employing an appropriate cure kinetics equation. The required material data for the numerical simulation is obtained experimentally for a brake block available commercially. The effect of processing parameters and material properties on cure is studied by performing numerical simulations for different molding conditions and materials with different thermophysical properties. The effect of the heat of reaction on the thermal events of cure is also investigated using the numerical simulation in absence and in presence of that parameter, and assuming different values. For a rubber-based friction material, temperature distribution and molding time are not influenced by the heat of reaction released during cure. Moreover, the results indicate that the thermophysical properties of the brake blocks are much more effective than molding conditions in reducing the cycle time. Since the thermophysical properties are governed by the ingredients of the friction material, these properties can be improved in the formulation designing stage by including the appropriate ingredients. The results obtained by numerical simulation can be helpful to the designer of the compound, in order to achieve a brake block with both good braking performance and suitable processing properties.
Influence of a ‘Rotating Tip’ on the Properties of Tubing Made Using a Cross-Head Tubing Die
Authors: Gupta A. , Hsu T.-C. , Harrison I. R. 
Published: December 2013

Abstract
A novel ‘Rotating Tip’ die has been designed and built that offers the tubing processor the ability to produce a wide variety of tubing ID's and OD's from a single fixed geometry die. Furthermore the device permits, amongst its many other advantages, the production of variable ID tapered tubing, increased hoop stress tubing and ease in production of microbore tubing.
Drawing of β-Crystal Nucleator-Added PP
Authors: Fujiyama M. 
Published: December 2013

Abstract
Extruded sheets were prepared from homo-isotactic poly-propylenes (PP) with 0 to 10 ppm of quinacridonequinone which is a β-crystal nucleator for PP and the characteristics of drawing behavior and properties of drawn sheets were studied. The sheet without the nucleator consisted of usual α-crystals (hereinafter called α-PP), whereas the sheets with the nucleator contained much β-crystals (hereinafter called β-PP), whose content slightly increased with increasing nucleator content. While the tensile yield stress of the β-PP is lower than that of the α-PP, the drawing stress of the former is higher than that of the latter at the higher strain region after yielding. Even after drawn, the β-crystals remain in the α-crystals with low crystallinity at low drawing temperatures. However, the β-crystals and amorphous phase gradually decrease with increasing drawing temperature, and the α-crystals dominate above 80°C. The resultant tensile modulus and strength of the drawn sheets show maxima at drawing temperatures of 40 to 80°C on a balance between the effects of crystallinity and molecular orientation. The tensile modulus and strength of drawn sheet prepared from the β-PP are higher than those prepared from the α-PP by about 10% at those temperatures. The tensile elongation of drawn sheet prepared from the β-PP is slightly higher than that prepared from the α-PP at low drawing temperatures due to the remained β-crystals.
Crosslinking Modification of UHMWPE Fibers by Ultra-violet Irradiation
Authors: Yu J. R. , Chen Z. L. , Zhu J. , Liu Z. F , Wang Q. R. 
Published: December 2013

Abstract
By means of ultra-violet (UV) irradiation with photoinitiator and multifunctional crosslinking agent, the crosslinking modification of ultrahigh molecular weight polyethylene (UHMWPE) fibers prepared by gel spinning was performed. Thermal and mechanical properties of fiber samples were examined using differential scanning calorimeter, thermo-mechanical analysis apparatus and tensile tester, the gel content of fibers was measured by a standard device, the fiber surface was examined by scanning electron microscope. The results indicate that the optimal irradiation time is 1 to 2 hours. The modified fiber can then preserve its original mechanical properties, or may have better behavior, meanwhile, such fibers have improved heat- and creep-resistant behaviors.
Characterization of the Behavior and Blending Performance of a Continuous Mixer
Authors: Galle F. N. , White J. L. 
Published: December 2013

Abstract
An experimental study is presented of the residence time distribution, the melting/fusion process, power consumption, melt temperature and blending in a Kobe Steel Nex-T continuous mixer. Attention is given both to phenomena occurring in the mixing chamber and the associated bottom extruder. The variables considered include throughput rate, rotor speed, exit orifice position and mixing chamber temperature.
Stability of a Blown Film Extrusion Process
Authors: Yoon K.-S. , Park C.-W. 
Published: December 2013

Abstract
The stability of a blown film extrusion process has been investigated using a simple isothermal Newtonian model. Although the Newtonian model may be an oversimplification for polymer melts, it serves as a reasonable first approximation for linear polymers (e.g., linear low density polyethylene) in extensional flow situations. The results obtained by the method of linear stability analysis indicate that the blown film process becomes unstable if the blow-up ratio (BUR) or the film thickness reduction is larger than a certain critical value. In addition, existence of an optimum freeze-line-height is predicted at which the region of stable operation is largest in terms of the BUR and the film thickness reduction. These predicted trends are in qualitative agreement with experimental observations for linear polymers such as LLDPE.
Bulk Polymerization of ∊-Caprolactone in Twin Screw Extruder
Authors: Gimenez J. , Boudris M. , Cassagnau P. , Michel A. 
Published: December 2013

Abstract
The ∊-caprolactone bulk polymerisation, initiated by tetra-propoxy titanium, was investigated in a co-rotating twin screw extruder. On the basis of pressure measurements, the process dynamic modelling was achieved. The pressure drop at the exit die of the extruder was correlated to the rheological behaviour of the melt polycaprolactone owing to equations which characterise the flow inside the die. The residence time distribution modelling was determined with an in-line Ultra-Violet fluorescence method. Thus, the combination of both modellings leads to the process dynamic modelling. This work constitutes the basis for an approach of the process regulation by the way of an internal model control. Simulation has given good results. However, the large response time to the control, relative to the process dynamic, constitutes effectiveness limiting factor for experimental control of the process.
Analysis of Flow and Heat Transfer in Liquid Composite Molding
Authors: Yu B. , Chiu H.-T. , Ding Z. , Lee L. J. 
Published: December 2013

Abstract
An analysis of flow and heat transfer in Liquid Composite Molding (LCM) is presented. Analytical solutions for the velocity profiles including the boundary effects and temperature distributions are derived for constant viscosity fluids. The heat transfer during mold filling is also analyzed numerically. It is found that the boundary effect has a significant influence on heat transfer when the Reynolds number, Res, is greater than 1. When the Reynolds number is less than 1, the boundary effect on heat transfer can be negligible and Darcy's law is applicable. The results also show that the inertia effect can be neglected during mold filling in LCM. Experiments on heat transfer with a non-reactive fluid lead to measurements of the dispersion effect and test of the boundary effect on heat transfer. Several non-isothermal mold filling and curing experiments on two rather different reactive systems lead to an assessment of the factors a model must include to capture the curing behavior.
Solidification Criterion on Shrinkage Predictions for Semi-crystalline Injection Moulded Samples
Authors: Pontes A. J. , Pantani R. , Titomanlio G. , Pouzada A. S. 
Published: December 2013

Abstract
The phenomenon of shrinkage in injection moulding is particularly evident in semi-crystalline polymers. During cooling, these materials experience a transition from a completely amorphous to a partially crystalline status, which results in a severe change of all material characteristics, including volumetric parameters. In this study an iPP was injection moulded in a rectangular impression (120 mm × 30 mm × 2 mm) with a 1.5 mm thick line gate. The influence of holding pressure and time, and geometry constraints on linear shrinkage was explored. In-mould shrinkage was measured by means of a recent method based on strain gauges. Experimental results are compared with predictions for shrinkage obtained by C-Mold and a code developed at the University of Salerno, which takes into account crystallisation kinetics. The solidification criterion resulted to be extremely relevant for shrinkage predictions.
Flow Analysis of Injection-Press Molding Process
Authors: Tsutsubuchi M. , Kitayama T. , Togawa Y. , Nishio T. , Kutschera H. 
Published: December 2013

Abstract
We developed a method to determine the characteristics of a press machine required for the injection-press molding process. In this paper, a model based on a serial spring connecting two different springs was used. One was spring represented apparent machine rigidity and the other the resistance to compression of the resin. Using this model, we calculated the flow between parallel plates and flow behavior in a “tray” mold.
Properties of Injection Molded In Situ Composites Based on PPS and a Melt Processable Glass
Authors: Young R. T. , Baird D. G. 
Published: December 2013

Abstract
This work was concerned with evaluating the properties of injection molded composites consisting of polyphenylene sulfide (PPS) reinforced with various loadings of a melt processable phosphate glass. During injection molding, both the PPS and melt processable glass were deformable, facilitating the processing of higher glass loadings than are possible in conventional solid glass fiber reinforced materials. The stiffness of the composite blends was found to increase with glass concentration with a composite containing 60 wt% (44 vol%) phosphate glass showing moduli over 4 times greater than that of the neat PPS. Composites possessing stiffness comparable to a conventional E-glass reinforced material (40 wt% fiber) could be produced utilizing higher phosphate glass loadings on the order of 60 wt%. While the addition of the phosphate glass led to significant enhancements in the stiffness of the composites, the strength of the blends of ten fell to values below that of the neat resin. Although the use of phosphate glass typically resulted in strengths 2–3 times lower than those found for the E-glass filled material, these composites offered several advantages including lower anisotropy in mechanical properties, lower viscosities, and smoother surfaces.
Injection Blow Molding Technology for Polyethylene Terephthalate
Authors: Bubeck R.A. , Barger M.A. 
Published: December 2013

Abstract
A review of patents and the literature addressing the in ection blow molding (IBM) technology specific to PET bottles and containers is presented. Fabrication and polymer modification issues were cited. It was found that there is no model that includes all factors which enables a complete a priori prediction of in ection blow molded PET container performance, but there are several which cover certain aspects of the preform blowing step. Hot fill capability for PET is currently managed by both the control of crystallinity and container design considerations (i.e., wall profile, ribs, etc.). Depending on the desired result, both processing routes to enhance the level of crystallinity (generically referred to in the industry as heat set technology), and molecular modification to disrupt crystallinity have been patented, some quite recently. A number of patents address technologies that can be used to modify melt elasticity for blow molding. The modification of PET with PEN presents some new challenges due to transesterification during processing and fabrication. Biaxial stretch ratios of 18 are usually required for the blow molding of PET/PEN blends, and maximum filling temperature noticeably decreases only one day after fabrication.
Polymer Processing Technology in the 21st Century from the Viewpoint of the Japanese Plastics Industry
Authors: Sakai T. 
Published: December 2013

Abstract
Recent progress in polymerization easily allows the control of precise structure of a base polymer and accelerates lower-cost production using larger-scale-plants. In addition to this, today's more important issue in our industry is the development of the key-technology corresponding to a sustainable society. Under these circumstances, the polymer industry in Japan has been focussing on down-stream products from upper-stream using advanced processing technology. To meet today's trends, the polymer industry should establish more sophisticated technology in both higher functionality and hybridization to survive in the 21st century. In particular, various hybridized polymer-processing systems such as the combination of reactive extrusion and injection molding should be applied to create cost-effectiveness and less environmental burdens as well as higher performance.
Prediction of Screw Length Required for Polymer Melting and Melting Characteristics
Authors: Liu T. , Wong A.C.-Y. , Zhu F. 
Published: December 2013

Abstract
The previous study on the dynamic processing characteristics of co-rotating twin-screw extruder based on a visible technique (which employed a “transparent” extruder) performed by the authors Wong et al. [1 and 2] had enabled a quantitative treatment to be carried out in the present paper on the melting behaviour of polymer during an extrusion process. The qualitative analysis performed previously [1] had led to the development of a melting model which was capable of revealing some of the fundamental melting behaviour. The model also enabled the determination of the length of screw required for completing melting (Zr). Melting characteristics in terms of effects of solid feeding rate, temperature, screw speed and channel depth on the predicted Zr were discussed to further our understanding on melting performance of polymer melt in intermeshing corotating twin-screw extruder.
A Dynamic Model for Multiple Steady States in Reactive Extrusion
Authors: Janssen L. P. B. M. , Rozendal P. F. , Hoogstraten H. W. , Cioffi M. 
Published: December 2013

Abstract
The existence of multiple stationary values of the fully filled length in reactive extrusion is studied on the basis of a mathematical model describing dynamic extruder behavior. The extruder is modelled as a plug flow type of reactor. Through the introduction of travel time for a fluid element in the extruder, time dependent viscosity models following from rheokinetics can be used. Special attention is paid to ionic and radical polymerization reactions. Hysteresis behavior for stationary values of the fully filled length exists when die resistance and rotational speed are varied. The effects of reaction rate, viscosity levels and degree-of-fill on stable operation at high conversions are studied. The mathematical dynamic model presented here can account for some of the experimentally observed dynamic phenomena in the reactive extrusion of radical polymers.
Bulk Polymerization of ε-Caprolactone in an Internal Mixer and in a Twin Screw Extruder
Authors: Kim B. J. , White J. L. 
Published: December 2013

Abstract
Bulk polymerization of ε-caprolactone has been carried out both in a laboratory internal mixer (Brabender Plasticorder) and in a modular intermeshing co-rotating twin screw extruder. Various initiators, such as titanium n-butoxide, aluminum triisopropoxide, and sodium hydride were used to polymerize ε-caprolactone in an internal mixer. The continuous polymerization of ε-caprolactone was performed using aluminum triisopropoxide under a range of processing conditions, including barrel temperature profiles, throughput, and screw speed. This polymerization was investigated for various ratios of monomer to initiator. GPC analysis demonstrated that significant quantities of oligomers were produced together with high molecular weight polymer at different reaction temperatures. H NMR detected the hydroxylation of growing chain end group for bulk polymerization at high barrel temperature. The molecular weight was reduced along the screw axis once the maximum molecular weight was obtained after the first kneading disk block. Increasing screw speed caused further reductions in molecular weight.
Use of the Fast-cool pVT Data for Shrinkage Analysis in Injection Molding
Authors: Han S. , Wang K. K. 
Published: December 2013

Abstract
The prediction of shrinkage and warpage of crystalline polymers is quite difficult. This is because of the complications of the crystallization process and associated material property changes. Particularly, the pVT behavior is dependent on the cooling rate during injection molding. Traditionally, the pVT data were measured in a device where the cooling rate is very slow compared to that in the actual injection molding process. This cooling-rate dependent pVT data is considered to affect the shrinkage and warpage calculation significantly. In the present study, a method has been developed to obtain pVT behavior at the same cooling rate as in the actual injection molding process. Obtaining other material data such as viscosity, thermal conductivity and heat capacity at the cooling rate of the actual injection molding process has also been considered.
Injection-molding experiments have been conducted to measure the shrinkage of a part using semi-crystalline polymers. The polymers used in this study are polyamide 66 (PA 66) and polybutylene terephthalate (PBT).
Simulation has been done to calculate the shrinkage using the cooling-rate dependent material properties. Using the fast-cool pVT behavior, the agreement between the simulation and the experiment improved significantly compared to the traditional approach.
In-line Ultrasonic Monitoring of Filler Dispersion during Extrusion
Authors: Tatibouët J. , Huneault M. A. 
Published: December 2013

Abstract
Mechanical and rheological properties of filled polymers are very sensitive to the filler dispersion. Classical methods for evaluating dispersion are based on optical or scanning electron microscopy observations on extruded specimens. They cannot be used in-line and are generally time consuming. We present here an in-line characterisation technique to evaluate the dispersion of calcium carbonate, CaCO3, in polypropylene. The technique is based on the monitoring of velocity and attenuation of ultrasounds in the flowing material. These properties are measured in a specially instrumented die placed at the end of a single screw extruder. Measurements were made for filler concentrations up to 60 wt.%. In-line data are compared to dispersion indexes measured by an optical method on 25 micron thick films.
Squeeze Flow Rheology of Glass Mat Thermoplastic (GMT) in Large Tools and at High Closing Velocities
Authors: Vahlund C. F. , Gebart B. R. 
Published: December 2013

Abstract
Rheological measurements on materials with fibre-like inhomogeneities will be significantly affected by sample size when the in-plane dimensions of the sample are comparable with the length of the fibres. In this paper, a 310 t hydraulic press has been modified for squeeze flow rheology studies so that large tools that will minimize the influence of sample size can be used in combination with high closing velocities. Isothermal squeeze flow rheology experiments of GMT have been performed for closing velocities up to 30 mm/s corresponding to maximum closing forces of 1000 kN. Successful power law fits of closing velocity versus closing force have been performed for the velocity interval. Four different analytical models have been fitted to the experimental data and the accuracy in these has been investigated. The force prediction of the biaxial extension model is acceptable for the major part of mould closure, but better fits during the last part of mould closure were obtained using an additive model incorporating both shear and extensions flow.
A 3D Numerical Study of Fluid Flow and Heat Transfer in a Single Screw Extruder
Authors: Kwag D.-S. , Lyu M.-Y. , Kim W.-S. 
Published: December 2013

Abstract
A numerical study of three-dimensional fluid flow and heat transfer in the metering section of a single screw extruder has been performed. The screw channel was simplified by unwinding the channel and the coordinate system was fixed on the screw root in the present model. The pressure distribution over the inlet region was to be extrapolated from the solution of interior pressure. The prescribed mass flow rate was imposed on the outlet of the unwinding screw channel. The three-dimensional velocity fields, temperature, viscosity, and pressure profiles in the screw channel were calculated by using the commercial code, STAR-CD, based on the finite volume method.
Some of the results of the present full 3D model were compared with the results from the marching-type 3D model. It is shown that the present work can capture the back flow by the pressure gradient near the screw root in the cases of small mass flow rates. There exist significant discrepancies in temperature between the marching-type 3D model and the present 3D model. The present work well describes the effects of heating-up through the circulation flow and viscous dissipation. The cross-section contours of velocities, temperature, viscosities and pressures along the down-channel direction are also shown in this study.