摘要:

AbstractThe coefficient of dynamic friction is often the controlling factor for solids conveying, pressure generation, and thermal decomposition of a resin in the feed section of a single‐screw plasticating extruder. The coefficients of friction are, however, very poorly understood, and the interpretation of the measurements are complicated by the dissipation of frictional energy at the sliding interface. A new instrument was recently built to help understand dynamic friction, and a numerical technique was developed to estimate the interface temperture. Coefficients of dynamic friction for several polyethylene resins are presented in this paper as a function of the surface temperature, pressure, and velocity. The relationship of the data with respect to the extrusion process is discusse

ISSN:0032-3888    

DOI:10.1002/pen.760350702

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractReaction injection molding of amine terminated butadiene acrylonitrile copolymer (ATBN) modified epoxy resin was investigated through computer simulation and experiment. The epoxy system composed of diglycidyl ether of bisphenol A (DGEBA) and triethylene tetramine (TETA) was employed since this system indicated a relatively high reaction rate. The coupled balance equations of momentum, chemical species, and energy within the disc‐type mold cavity were solved using finite difference techniques. The predicted temperature and conversion profiles within the mold were compared to experimental results. The domain correlation length data calculated from the simulation model were compared with the results of SEM micrographs. A moldability analysis was performed to find the optimum molding conditions. The moldability window decreased as the mold thickness was increase

ISSN:0032-3888    

DOI:10.1002/pen.760350703

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractA one‐dimensional flow model for non‐Newtonian liquids inside a dual‐cavity slot die is presented. The model is capable of analyzing slot dies of any cavity shape, cavity taper, slot‐length variations, and slot‐gap variations. The proposed model incorporates a truncated‐power‐law model for the viscosity of non‐Newtonian liquids. According to flow models with power‐law approximation for liquid viscosity, the distribution of non‐Newtonian liquid through a slot die depends on the slot Reynolds number only. With our model, we find that the zero shear viscosity and the relaxation time of a non‐Newtonian liquid have large effects on its distribution. For non‐Newtonian liquids which are expected to experience shear‐thinning over portion of a slot die, it is concluded that a flow model with a truncated‐power‐law approximation for liquid viscosity be used to predict the liq

ISSN:0032-3888    

DOI:10.1002/pen.760350704

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThe copolymerization of n‐butylmethacrylate with 2‐hydroxypropylmethacrylate was studied in a closely intermeshing counterrotating twin‐screw extruder. The average molecular weight of the product can be increased by increasing the screw rotation rate or the die resistance or by decreasing the throughput or the barrel temperature. The conversion can be improved by decreasing the throughput, increasing the die resistance, and (within limits) increasing the barrel temperature, as well as through post‐initiation. Compared with various classical polymerization processes, this situation requires that particular attention be paid to the occurrence of a gel effect, the existence of a thermodynamic ceiling temperature, and the reactivity ratio of the monome

ISSN:0032-3888    

DOI:10.1002/pen.760350705

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper deals with the residence time distribution (RTD) in a non‐intermeshing counter rotating twin screw extruder.The RTDs were measured in three vent zones of the extruder sparately, and in the adjacent zones combined, using a soluble dye as the tracer. Assuming that the RTDs in the adjacent zones are independent of each other, the overall RTD was also calculated using a previously developed statistical theory. The theory has also confirmed the consistency of the present measurements.A predictive RTD model for the non‐intermeshing twin screw extruder, based on the flow analysis of the individual screw zones and their statistical superposition, was also developed. The predictions are in good agreement with experim

ISSN:0032-3888    

DOI:10.1002/pen.760350706

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThe present study develops a numerical simulation program to predict the transient behavior of fiber orientations together with a mold filling simulation for short‐fiber‐reinforced thermoplastics in arbitrary three‐dimensional injection mold cavities. The Dinh‐Armstrong model including an additional stress due to the existence of fibers is incorporated into the Hele‐Shaw equation to result in a new pressure equation governing the filling process. The mold filling simulation is performed by solving the new pressure equation and energy equation via a finite element/finite difference method as well as evolution equations for the second‐order orientation tensor via the fourth‐order Runge‐Kutta method. The fiber orientation tensor is determined at every layer of each element across the thickness of molded parts with appropriate tensor transformations for arbitrary three‐dimensi

ISSN:0032-3888    

DOI:10.1002/pen.760350707

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThe flow‐induced phase morphological development under different extrusion conditions was studied in terms of the rheological property and interfacial tension of various elastomers and thermoplstics. The interfacial tension for elastomers and thermoplastics was investigated by using a breaking thread method (1‐4). We found that the method is suitable for measuring interfacial tension without degradation. The droplet‐fibrillation transition phenomenon was observed in various extrudates of fluoroelastomer/polycarbonate blends. The criteria for the flow‐induced morphology, in particular the droplet‐fibrillation transition, are critically discussed in t

ISSN:0032-3888    

DOI:10.1002/pen.760350708

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760350701

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY