摘要:

AbstractA 2‐D finite element model of the packing phase using an Augmented Lagrangian approach is described. The model is tested for various geometrical configurations. The influence of the cavity thickness, length, and shape on the packing time and flow patterns is investigated, showing a good agreement with published dat

ISSN:0032-3888    

DOI:10.1002/pen.760331902

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractA boundary element model is used for simulating the fountain flow in injection molding. The particle orientation caused by the fountain effect is illustrated with a tracer‐in‐domain technique which is similar to the Marker‐And‐Cell technique. The efficiency and accuracy of the boundary element model are shown through this simulation, in determination of the free surface shape, and the particle orientation patterns. Clear and correct information is obtained to interpret the complicated effects upon formation of the orientation, especially regarding the “V” shape pattern in the skin areas. The simulation is in agreement with both Schmidt's experiment and some finite eleme

ISSN:0032-3888    

DOI:10.1002/pen.760331903

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractThe blends of two different ultra high molecular weight polyethylenes (UHMWPE) and high density polyethylene (HDPE) were prepared in melt at different compositions and mixing rates in Brabender Torque Rheometer. The temperature build‐up due to the internal friction during melt blending was recorded and evaluated with respect to the change in the torque. The temperature at maximum torque was considered the fusion point temperature of the UHMWPE in the blend. This fusion point temperature was found to depend on the composition, mixing rate, and molecular weight. The effect of mixing rate on the mechanical properties (measured as yield and tensile strengths and elongation at break), thermal oxidative degradation and melting behavior were studied. The morphology of the blends were investigated by optical microscop

ISSN:0032-3888    

DOI:10.1002/pen.760331904

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractSignal deterioration of optical discs depends strongly on the substrate surface roughness. Characteristics of surface roughness of the molded substrate have been studied in order to clarify the transcription mechanism of smooth surfaces in injection molding of polycarbonate resin. When the melt temperature, mold temperature, and injecting rate are low, microscopic flow marks more than 5 nm deep are observed on the surface. These flow marks are formed when the melted resin near the mold wall is cooled to the no‐flow temperature of resin before it comes into contact with the mold wall. Molding transcription improves by optimizing the molding conditions for preventing these flow marks. As a result, the surface roughness of the molded substrate obtained is 3.2 nm in maximum heightRmax, which is nearly equal to that of the mold stamper at 2.7 nm inRma

ISSN:0032-3888    

DOI:10.1002/pen.760331905

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractSolid state friction reduction has been found to be an effective method for extrusion stabilization of a high coefficient of friction (COF) thermally sensitive polymer. A poly(vinylidenechloride) copolymer (PVDC) was studied alone and blended with various polyolefins to change its frictional behavior. COF of the polymer rubbing on a metal surface was measured under conditions typical of an extrusion process. These results correlated well with the measured mechanical energy consumed during extrusion. Of the polyolefins studied, high and low density polyethylene were found to be very effective for lowering friction and improving extrusion performance of the PVDC. Polypropylene was found to be much less effective. Interface temperature where melting occurs due to frictionally generated heat has been experimentally shown to be a function of COF and the bulk metal temperature.

ISSN:0032-3888    

DOI:10.1002/pen.760331906

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractFlow in a three‐dimensional channel with a sinusoidally‐wavy, vertical wall is examined for the case of applied down‐ and cross‐channel velocity components. An important parameter for the analysis of the nature of laminar mixing in the flow field occurs when the changes in the downstream direction can be decoupled from the changes in the cross‐channel direction, thereby allowing for a two‐dimensional solution of the system of equations. This paper shows the effect on the nature of laminar mixing when the decoupling of the momentum equations from a fully three‐dimensional case to one where a two‐dimensional solution can be performed. Experiments are performed on a channel with sinusoidally varying vertical walls that cover the range of decoupling criteria. Silicone pigmented either white or black was run in the apparatus, cured, and cross‐sectioned. The cross sections embody a local, detailed history of the state of mixing as it proceeds down the mixer. The amount of mixing is presented as a function of position at each cross section for the different channel configurations. The nature of mixing changes from a linear growth rate in the amount of interfacial area to an exponential rate as the amplitude of the wave is increased. Results demonstrate the existence of chaos, islands, and the factors affecting th

ISSN:0032-3888    

DOI:10.1002/pen.760331907

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractA finite element numerical analysis of preform inflation associated with the injection blow molding process has been developed using a neo‐Hookean constitutive model. The analysis is capable of predicting final wall thickness distributions for axisymmetric mold geometries. Experimental studies were conducted on a Uniloy injection blow molding machine (Model 189‐3 and Model 122). A twelve ounce (355 mL) cylindrical bottle mold was instrumented with contact sensors, thermocouples, and pressure transducers. Visualization studies of the inflation process were performed using specialized tooling and high‐speed video cameras. The experimental studies provide justification for analyzing the deformation by means of a static elastic approach. The predicted wall thickness distribution is in reasonable agreement with the experimental data. Nonuniformities in the temperature distribution in the preform were found to have the most significant impact on the inflation behavior and the resulting wall thic

ISSN:0032-3888    

DOI:10.1002/pen.760331908

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractAn analysis is presented of the process of die drawing isotropic polymers, in the form of circular rods, to produce highly oriented materials with enhanced mechanical properties. The stresses in a small element of material undergoing the drawing process have been analyzed using a force‐equilibrium approach and the initial yield and flow stresses in the material have been predicted from the von‐Mises yield criterion. The stress‐strain‐strain rate characteristics of the polymer used in the analysis were deduced from uniaxial tensile test data obtained at the same temperature at which the die drawing occurred. Experimental results are presented of the stress in polypropylene GSE‐108 rods when die drawn at 90°C in a purpose‐built die drawing facility. Novel techniques were used to determine the stress and strain distributions along the die. A comparison of the experimental results and the analytical predictions shows go

ISSN:0032-3888    

DOI:10.1002/pen.760331909

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760331901

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY