Transverse core fiber alignment in short-fiber injection-molding

Malzahn, J.C.; Schultz, J. M.

doi:10.1016/0266-3538(86)90009-6

Cited by 26 publications

(11 citation statements)

References 10 publications

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“…The observed state of fiber orientation at the skin layer, which is located exactly below the surface of the mold wall, and in the shell layer, which is the region in between the skin and the core layers, are in agreement among various studies [2-4, 10, 11]. However, because of different observations for the state of fiber orientation at the core layer, various contradictory explanations are observed in the conclusion of many studies [2,3,10,12]. Fischer [12] explained that in the core of the part, the melt being pushed forward develops a flattened profile and fibers within this region do not orient without a well-developed shear flow.…”

Section: Introductionsupporting

confidence: 81%

“…Gupta and Wang [3] concluded that the in-plane stretching flow causes the fibers at the mid-plane to align transverse to the flow. The authors [3] in contrast to the study of Malzahn and Schultz [10] believed that the fiber orientation should be only weakly dependent upon the postfilling stage of injection molding due to the decreased flow field. Bay and Tucker [2] concluded that if there is significant in-plane stretching, as in a center-gated disk, the core is aligned in the principal stretching direction and if there is no in-plane stretching, as in the case of a strip geometry, the core orientation is generated by the flow just inside the gate and is carried down the cavity with little change and these cores are more likely to have random-in-plane orientation.…”

Section: Introductionmentioning

confidence: 83%

“…Fischer [12] explained that in the core of the part, the melt being pushed forward develops a flattened profile and fibers within this region do not orient without a well-developed shear flow. But Malzahn and Schultz [10] believed on the orientation of fibers at the core region and concluded that the complete transverse alignment at the core region develops only after the instant of fill. Gupta and Wang [3] concluded that the in-plane stretching flow causes the fibers at the mid-plane to align transverse to the flow.…”

Section: Introductionmentioning

confidence: 99%

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Effect of packing pressure on fiber orientation in injection molding of fiber‐reinforced thermoplastics

Shokri

Bhatnagar

2007

Polymer Composites

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Injection molding of fiber-reinforced polymeric composites is increasing with demands of geometrically complex products possessing superior mechanical properties of high specific strength, high specific stiffness, and high impact resistance. Complex state of fiber orientation exists in injection molding of short fiber reinforced polymers. The orientation of fibers vary significantly across the thickness of injection-molded part and can become a key feature of the finished product. Improving the mechanical properties of molded parts by managing the orientation of fibers during the process of injection molding is the basic motivation of this study. As a first step in this direction, the present results reveal the importance of packing pressure in orienting the fibers. In this study, the effects of pressure distribution and viscosity of a compressible polymeric composite melt on the state of fiber orientation after complete filling of a cavity is considered experimentally and compared with the simulation results of Moldflow analysis. POLYM. COMPOS., 28:214 -223, 2007.

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Section: Introductionsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Effect of packing pressure on fiber orientation in injection molding of fiber‐reinforced thermoplastics

Shokri

Bhatnagar

2007

Polymer Composites

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“…Another factor is the orientation of the clay platelets in the test specimens. The platelets tend to orient in the direction of flow in the surface region of an end‐gated injection molded bar and to change progressively to transverse orientation near the core 47. Because the notch is machined to a depth of 2 mm, it can expose the transverse region.…”

Section: Resultsmentioning

confidence: 99%

Validation of a tool for identifying women at high risk for hereditary breast cancer in population‐based screening

Hoskins

Zwaagstra

Ranz

2006

Cancer

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BACKGROUNDRecent scientific advances provide the opportunity to identify women in the general population at increased breast cancer risk and to offer effective early detection and disease prevention interventions.METHODSA pedigree assessment tool (PAT) was designed to identify women in primary care settings who are at increased risk for hereditary breast cancer, including potential BRCA mutation carriers. The PAT is a simple point‐scoring system based on family cancer history with points weighted to account for features associated with a higher probability that a BRCA mutation is present. The ability of the PAT and the Gail model to accurately identify potential BRCA mutation carriers in 3,906 women without a personal history of breast cancer presenting for a screening mammogram at a community hospital was tested.RESULTSEighty‐six (2.2%) women had a family history indicative of a high probability (>10%) that a BRCA mutation was present within the family. The PAT performed better than the Gail model in correctly assigning women to the “high BRCA probability” cohort. The area under the receiver operating characteristic (ROC) curve for the PAT was 0.9625 compared with 0.389 and 0.5861 for the Gail model 5‐year and lifetime risk estimates, respectively. At the optimal threshold score, the PAT performed with 100% sensitivity and 93% specificity.CONCLUSIONSThe PAT is a simple and accurate tool for identifying women at risk for the hereditary breast cancer syndromes that can be employed as part of a comprehensive breast cancer risk‐screening strategy in the primary care setting. Cancer 2006. © 2006 American Cancer Society.

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“…The flat velocity profile, resulting from the non-Newtonian rheology of the melt, preserved that transverse fiber orientation as the melt advanced to fill the whole mold [18]. In addition, the greater orientation of fibers in the W direction could have occurred during the packing stage [21]. Of particular interest to this work were the results of fiber orientation in the T direction (through-plane).…”

Section: Fiber Characterizationmentioning

confidence: 99%

Improved through‐plane electrical conductivity in a carbon‐filled thermoplastic via foaming

Motlagh

Hrymak

Thompson

2008

Polymer Engineering & Sci

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Flow-induced orientation of the conductive fillers in injection molding creates parts with anisotropic electrical conductivity where through-plane conductivity is several orders of magnitude lower than in-plane conductivity. This article provides insight into a novel processing method using a chemical blowing agent to manipulate carbon fiber (CF) orientation within a polymer matrix during injection molding. The study used a fractional factorial experimental design to identify the important processing factors for improving the through-plane electrical conductivity of plates molded from a carbon-filled cyclic olefin copolymer (COC) containing 10 vol% CF and 2 vol% carbon black. The molded COC plates were analyzed for fiber orientation, morphology, and electrical conductivity. With increasing porosity in the molded foam part, it was found that greater out-of-plane fiber orientation and higher electrical conductivity could be achieved. Maximum conductivity and fiber reorientation in the through-plane direction occurred at lower injection flow rate and higher melt temperature. These process conditions correspond with foam flow during filling of the mold cavity, indicating the importance of shear stress on the effectiveness of a fiber being rotated out-of-plane during injection molding.

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Transverse core fiber alignment in short-fiber injection-molding

Cited by 26 publications

References 10 publications

Effect of packing pressure on fiber orientation in injection molding of fiber‐reinforced thermoplastics

Effect of packing pressure on fiber orientation in injection molding of fiber‐reinforced thermoplastics

Validation of a tool for identifying women at high risk for hereditary breast cancer in population‐based screening

Improved through‐plane electrical conductivity in a carbon‐filled thermoplastic via foaming

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