bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design Sensitivity Analysis Applied to Injection Molding for Optimization of Gate Location and Injection Pressure
Authors: Kabanemi K. K. , Hétu J. F. , Derdouri A. 
Published: December 2013

Abstract
In this work, we develop a numerical simulation method to optimize the injection molding process using the design sensitivity analysis (DSA). The optimization concerns the filling stage and focuses on the location of gates in the mold cavity as well as the injection pressure profile, in order to minimize the fill time. Since the problem to be solved involves transient flow with free surface (flow front), the direct differentiation method is used to evaluate the sensitivities of the Hele-Shaw, filling fraction and energy equations with respect to the design variables used in the analysis. The search domain parameterization is coped with using B-spline functions. Sensitivity and state equations are solved by means of finite element method. The proposed numerical approach is combined with the sequential linear and quadratic programming method of the design optimization tools (DOT) to find new design variables at the end of each complete filling simulation. Starting from any initial gate locations and injection pressure profile, the iterative optimization procedure enables us to find the optimal gate locations together with the optimal injection pressure profile. Finally, numerical results involving complex mold geometries are presented and discussed to assess the validity and robustness of the proposed method.
Polymer Melt Impregnation of Glass Roving
Authors: Bates P. J. , Zou X. P. 
Published: December 2013

Abstract
Much attention has been recently focussed on the melt impregnation of thermoplastic polymers as a consequence of the difficulty involved in driving viscous polymer melt into a tightly packed fiber bundle. This work studies an impregnation process consisting a series of staggered cylindrical pins in a melt pool. A numerical model for evaluating the pressure generation in the wedge region between the roving/pin, the impregnation velocity of the melt through the glass mesh, and the resulting impregnation depth along the wedge is developed using relationships for pressure build-up in foil bearings and Darcy's law. The model results are compared with experimental melt impregnation data. The model adequately predicts the effect of melt impregnation process conditions on impregnation quality.
Operational and Design Study of RIM Machines
Authors: Santos R. J. , Teixeira A. M. , Costa M. R. P. F. N. , Lopes J. C. B. 
Published: December 2013

Abstract
Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) data is presented and used to characterize the dynamic behaviour of the flow field in a RIM machine, and the main flow patterns and mixing mechanisms are examined and established. A two-dimensional CFD model is used for the simulation of mass transfer and chemical reaction in the mixing chamber of a RIM machine. Some design and operational parameters are considered and its influence on the mixing behaviour of a RIM machine is analysed.
Flow Properties and Morphology of PC/LCP Blends Affected by the Addition of Glass Fiber and Resulted Mutual Influences
Authors: Zheng X. , Zhang B. , Zhang J. , Xue Y. , He J. 
Published: December 2013

Abstract
In-situ hybrid composites containing matrix polycarbonate, glass fiber and LCP are prepared. The morphology of LCP and the rheological behavior of the composites are described. The relationship between flowability and morphology is discussed. It is interesting to find that in some hybrid systems, composites containing more glass fiber have better flowability than composites containing less glass fiber. Glass fiber aspect ratio is an important factor that determines the flowability. Materials with short glass fiber have lower viscosities than the materials with long glass fiber. LCP morphology is another important parameter that determines the flowability of the composites. If LCP forms fibrils, the composites have better flowability. If spheres dominate the morphology of LCP, the materials have larger viscosity. The addition of glass fiber brings about new factors that influence the morphology of LCP. The LCP morphology is not only affected by LCP content, but also by glass fiber content and glass fiber length. LCP fibrils are promoted in some in-situ hybrid composites. A model is proposed to describe how fibrillation of LCP is promoted due to the addition of glass fiber.
Diameter Profile Measurements for CO2 Laser Heated Drawing Process of PET Fiber
Authors: Okumura W. , Kanegae T. , Ohkoshi Y. , Gotoh Y. , Nagura M. 
Published: December 2013

Abstract
Poly (ethylene terephthalate) (PET) fiber was heated by carbon dioxide laser radiation in the continuous drawing process. By this procedure, the position of the deformation region could be fixed precisely in the air. The location of neck-like deformation fluctuated within a range of about 0.2 mm for draw ratios of 4.0 to 4.5 and within a range of about 0.5 mm for draw ratios of 5.5 to 6.0, but the location fluctuated over a range of 1.0 mm for a draw ratio of 5.0. Fiber diameter profiles, which were used to calculate Hencky strain rate profiles and apparent elongational viscosity profiles, were obtained from high-speed video camera images of the deformation region. Regardless of draw ratio, apparent elongational viscosity exhibited almost the same minimum value. Apparent elongational viscosity is much lower than the value obtained by measurement at a low, constant strain rate, but the elongational stress acting at the point where apparent elongational viscosity begins to increase steeply (Hencky strain of about 1.0) is of the same order of magnitude as the reported value. For draw ratios less than 5.0, the temperature where apparent viscosity is lowest is about 100 to 120°C, which corresponds to the flow temperature of amorphous PET, whereas for draw ratios exceeding 5.0 the temperature where apparent viscosity is lowest is about 80°C, which corresponds to the glass transition temperature. Thus, the former corresponds to so-called neck-like deformation typically observed in high-speed spinning, and the latter corresponds to necking typically observed in cold drawing. These two types of deformation appear in turns for a draw ratio of 5.0, and therefore the location of the deformation region fluctuates greatly. This measurement system can be used as a high-strain-rate elongational rheometer for analyzing practical polymer processing systems, which can easily measure the precise on-line deformation history with a time resolution in the μs level.
Cast Film Problem: A Non Isothermal Investigation
Authors: Sollogoub C. , Demay Y. , Agassant J. F. 
Published: December 2013

Abstract
An important problem arising in the cast film process is the so-called neck-in phenomenon, which may induce a drastic film width reduction as well as an inhomogeneous film thickness distribution (with the so called “dog-bone” defect on each side of the film). This neck-in phenomenon is highly influenced by the polymer rheology (increasing polymer elasticity leads to decrease markedly the neck-in), the stretching distance, the cooling conditions and the draw ratio. In this paper, we present a 2D Newtonian non-isothermal model based on a membrane approximation for the film. Stress balance, mass balance and temperature balance equations are solved iteratively using various finite element methods adapted to free surface problems and to transport equations. Coupling between mechanical and thermal equations is achieved introducing an Arrhenius temperature dependance for the viscosity. The influence of the heat transfer coefficient has been carefully investigated.
Single Screw Extrusion of Natural Fibre Reinforced Thermoplastics (NFRTP)
Authors: Torres F. G. , Ochoa B. , Machicao E. 
Published: December 2013

Abstract
Natural fibre reinforced thermoplastics are usually processed in twin screw extruders. The present work studies the single screw extrusion process for different systems of natural fibre reinforced thermoplastics. For this study different polymer-fibre systems have been characterised in terms of the material properties that are relevant to the processing behaviour of these materials. The extrusion process has been investigated using an open-barrel single screw extruder. This equipment can be stopped at any point in operation, cooled down and opened in order to study the material transport processes that take place inside the extruder. The polymer matrices used in this study have been mainly polyethylene and polypropylene (with MFIs varying from 0.3 to 4). Fibres including jute, sisal, and cabuya have been used as discrete reinforcements of a length of 5 to 10 mm.
The experiments presented here study the transport processes during single screw extrusion with special emphasis on the bubble formation mechanisms. The bubble formation process has been studied in terms of the variation in the initial fibre dispersion at the entrance of the feeding zone of the extruder. A relationship between solids conveying, plastication and bubble formation has been proposed considering the different typical cases occurring in the single screw extrusion of NFRTPs. The use of coupling and dispersion agents has been studied in terms of its relationship to bubble formation and to the final quality of the extrudates produced.
Finally, morphological characterisation techniques have been adapted to understand the structure-property relationships in these materials during the extrusion process.
Study on Functionalization of Isotactic PP with Maleic Anhydride in an Internal Mixer and a Twin-screw Extruder
Authors: Ghahari S. M. , Nazokdast H. , Assempour H. 
Published: December 2013

Abstract
The grafting reaction of maleic anhydride to molten iPP was investigated in both an internal mixer and a twin- screw extruder. The influence of peroxide content, added maleic anhydride and process variables such as residence time, screw speed and reaction temperature were considered. The rate and level of grafting were quantitatively measured by FTIR and titrometery technics. Maximum level of grafting at constant peroxide content was obtained when concentration of added maleic anhydride reached up to 6%, above which is declined. The rate of grafting increased with increasing the peroxide content. However the β-scission of polypropylene was found to be taken place as a parallel competitive reaction which was intensified with increasing peroxide content. It was demonstrated that it is possible to make an optimization on the grafting reaction on the basis of experimental results in conjunction with a free radical kinetic model developed for this reaction.
A Powerful Universal Plasticating System for Single-screw-extruders and Injection-moulding Machines
Authors: Grünschloβ E. 
Published: December 2013

Abstract
The plasticating principle, named HELIBAR for single-screw-extruders [1 to 5] is described and recent experimental results with a HELIBAR - extruder Ø 50×34 D are presented. They prove, that with only one barrier-screw the most different thermoplastic polymers can be processed successfully with very high throughput, good process stability, low melt-temperature and good melt-homogeneity. This concerns standard polymers (PE, PP, PS) and so-called technical polymers (PA, PC, PET, PBT, PMMA) as well as soft polymers and elastomers (PVC-W, PUR, TPE, EVA). Besides, this system in a standard design was tested successfully with a fast-running injection moulding machine Ø 70 × 23 D with different polymers (PS, PP, PE-HD). Compared to previous high-performance screws - with the same installed driving power - lower melt temperatures, good melt homogeneities and enhancements of the plasticating power between 20% and 100% were achieved.
Scale-up Rule for Double Bubble Tubular Process of PA6 Film
Authors: Takashige M. , Kanai T. , Yamada T. 
Published: December 2013

Abstract
The analysis of scale-up rule for double bubble tubular film process of PA6 was investigated. The scale-up rule previously proposed for a blown film process by the authors was applied to a double bubble tubular film process with a small-scale plant for research (pilot plant) and a large-scale plant for commercial production (production plant).
According to the scale-up rule based on the equivalent stretching stress between the pilot and production plants, the equivalence of stretching stability, birefringence pattern and deformation pattern were confirmed.
It has been confirmed that the proposed scale-up rule is applicable to predict the physical properties such as film impact strength and the bubble stability for the large-scale tubular film process on the basis of the experimental results obtained from the pilot plant.
Physico-Mathematical Model for the Description of the Temperature Development and the Power Consumption in Co-Rotating Twin Screw Extruders
Authors: Potente H. , Kretschmer K. , Pohl T. 
Published: December 2013

Abstract
Tightly intermeshing, co-rotating twin-screw extruders are commonly employed for tasks requiring good mixing. The modular constitution of both barrel and screw makes it possible to optimise the extruder configuration for a given task. Even today this optimisation is frequently done by applying the “Trial and Error”-method. Physico-mathematical models enable the process engineer to predict the process behaviour of a chosen extruder configuration and to optimise existing extrusion processes.
Increasing demands in mixing quality and efficiency of the processing unit result in efforts to optimise existing extruders with respect to those factors. For this reason knowledge concerning the temperature profile along the screw and the power consumption is essential. We present a new physico-mathematical model for the description of the temperature development. At stages where the analytical solution itself would result in a not satisfying degree of accuracy we used descriptions based on finite element simulation results to achieve the desired exactness. As a result we got a model to describe the temperature development in the screw channel and a model to describe the power consumption in different screw sections. Applying these models it is possible to optimise the process parameters and the screw configuration with only a minimum of preceding experimental investigations.
In-line Monitoring of PVC Melt Viscosity Using Dielectric Measurements
Authors: Abu-Zahra N. H. 
Published: December 2013

Abstract
A dielectric sensor, mounted in an extrusion die, was used to measure the dielectric properties of PVC melt during extrusion process. The dielectric permittivity and loss factor, of the polymer melt, were used to calculate the ionic viscosity and a dielectric viscosity index, which were correlated to the melt viscosity measured by slit rheometry equations. The viscosity of the PVC melt was varied by varying the level of chemical blowing agent (AZO) and processing aid (K400) in the polymer compound. The extrusion conditions; screw speed and heating zones, were fixed throughout the experiments. Strong correlation between the measured dielectric parameters and the melt viscosity was found to be consistent with established theoretical models. Therefore, this technique is capable of monitoring the viscosity of polymer melts accurately and reliably, in realtime, without disturbing the flow stream.
Extensional Rheology of Polypropylene in Relation to Processing Characteristics
Authors: Ivanov I. , Muke S. , Kao N. , Bhattacharya S. N. 
Published: December 2013

Abstract
Transient extensional rheological behaviour of several polypropylene (PP) homo- and co-polymer grades was studied at different temperatures. In addition, shear rheological characterisation was completed. The structure of PP grades was characterised by using gel-permeation chromatography (GPC), differential scanning calorimetry (DSC) and hot-stage optical microscopy (HS-OM). It was found that the extensional viscosity of the polymers followed the three-fold transient shear viscosity curves when the tests were conducted in fully molten state, as expected for linear polymer melts. However, the strain hardening behaviour was evident when PP was stretched in the semi-molten state, i. e. below its melting temperature (Tm). Similar to results of a recent study by Rauschenberger, three temperature zones of different extensional behaviour were found: linear viscoelastic behaviour and uniform drawing in the molten state (180 °C), unstable drawing just above Tm (170°C) and stable drawing with strong strain hardening below Tm (165°C). The strain hardening behaviour was quantified and related to molecular structure and morphology of PP. It was found that none of the investigated parameters alone was sufficient to predict the extensional behaviour of PP. The definition of Extensional Viscosity Index (EVI) as the ratio of extensional viscosities at the Hencky strain of 3 and 1, respectively, was found to be practical for the evaluation of the polymers' processability for the important industrial processes, such as BOPP film manufacturing, where extensional deformation predominates.
Deformation Behavior, Processability and Physical Properties for Biaxially Oriented Film of LLDPE
Authors: Uehara H. , Sakauchi K. , Kanai T. , Yamada T. 
Published: December 2013

Abstract
The bubble deformation behavior of double bubble tubular film (DBTF) of linear low density polyethylene (LLDPE) is experimentally analyzed. Also investigated is how the bubble deformation behavior of the stretched films are changed by stretching conditions, especially stretching temperature, and how the properties of stretched films are influenced by stretching conditions.
From the results, the optimum conditions required to obtain a stable bubble and good properties for the DBTF of LLDPE are indicated. The relationship between the DBTF and laboratory tenter stretched film (LTSF) is investigated in order to predict the processability and the properties of the DBTF by using the laboratory tenter biaxial stretcher. This method is not only more time efficient, but also reduces overall costs of developing the DBTF.
Engineering Analysis of Devolatilization of Various Additives in Intermeshing Co-rotating Twin Screw Extruders
Authors: Keum J. , White J. L. 
Published: December 2013

Abstract
An experimental study of devolatilization of nonane, xylene and 1-hexanol from molten polyethylene in a modular co-rotating twin screw extruder is described. Various modular screw designs, as well as different feed rates, screw speeds, and barrel temperatures were used. It was found possible to correlate the extent of devolatilization in different modular screw designs with a mass transfer coefficient which depends on screw speed and LDPE feed rate. The mass transfer coefficient depended on the liquid being devolatilized, being highest with 1-hexanol and lowest with nonane. In addition, the values of the mass transfer coefficient were obtained through experiments on the twin-screw extrusion of PE with nonane, xylene and hexanol. Interpretations of these results are described.
Reactive Extrusion of SAN/EPDM Blends
Authors: Hrnjak-Murgić Z. , Kratofil L. , Jelčić Z. , Jelenčić J. , Janović Z 
Published: December 2013

Abstract
The blending of styrene-acrylonitrile copolymer (SAN) and three different types of ethylene-propylene-diene terpolymer (EPDM) by reactive extrusion was studied and the free radical initiators: 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane (Luperco 101 XL), 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3 (Luperco 130 XL), α,α′-di(t-butylperoxy)diisopropyl-benzene (Peroximon F40) and 2,2-azo-di-(2-acetoxy)propane (Luazo AP) were used. Besides, structural characteristics of the obtained blends, some rheological and mechanical properties were also established. The rheological behavior was determined using rheometer and corotating extruder. Measurements of mechanical properties included: tensile strength, impact strength and elongation at break have been made. Blends were separated on its structural components SAN, EPDM, graft (EPDM-g-SAN) and gel content, which were further characterized by solution viscosimetry and IR spectrophotometry. The obtained results elucidate the reactions that occur during extrusion process. The dominant grafting reaction was observed in blends prepared by using a Peroximon F40 as an initiator also showing outstanding mechanical and processing characteristics.
Studies on Methacrylate-hydroethyl Methacrylate Oil-absorptive Fiber
Authors: Feng Y. , Xiao C. F. 
Published: December 2013

Abstract
A concept of potential crosslinker was introduced into the synthesizing process of highly oil-absorptive resin which is traditionally prepared by single chemical crosslinking. The resin was dissolved in DMAc and then span into fiber. The fiber was heated after spinning to obtain three-dimensional network structure. The effects of potential crosslinker content, crosslinked time and crosslinked temperature on the absorptive properties of fiber were studied. The structure of oil-absorptive fiber was analyzed by FTIR, DMA and SEM.
Flow Balancing in Extrusion Dies for Thermoplastic Profiles
Authors: Nóbrega J. M. , Carneiro O. S. , Pinho F. T. , Oliveira P. J. 
Published: December 2013

Abstract
A computer code, previously developed by the authors for the automatic die design, is used to optimise the flow distribution in a profile extrusion die using two alternative strategies: one based on length optimisation and the other on thickness optimisation. The numerical predictions are then compared with experimental data gathered during extrusion experiments. The numerical predictions and the experimental results agree within the experimental uncertainty thus showing the effectiveness of the computer code, the optimisation algorithm and the design strategies implemented. Generally speaking, measured and predicted values of pressure drop and flow rate are in good agreement (within 8 % and 6 %, respectively). It also is confirmed that optimisation based on thickness control leads to final profiles that are more prone to distortion.
Numerical and Physical Modeling of Polymer Crystallization
Authors: Haudin J.-M. , Chenot J.-L. 
Published: December 2013

Abstract
In this first paper, we have revisited Avrami's model and cast its basic equations into a differential system. This system is integrated numerically, which avoids unnecessary simplifying assumptions generally used in order to get analytical expressions. This allows us to introduce the variations of nucleation and growth parameters as a function of processing ones (temperature, cooling rate, shear rate, etc.). Our analysis shows that it is necessary to take into account the variation of the initial number of potential nuclei with temperature, which was usually ignored. Finally, an outpout of our calculations is the size distribution of the morphological entities, i. e., a quantitative information on microstructure.