Weldline strength in glass fiber reinforced polyamide 66.: An article from: Polymer Engineering and Science

This digital document is an article from Polymer Engineering and Science, published by Society of Plastics Engineers, Inc. on June 15, 1995. The length of the article is 4488 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

From the author: Presence of weldlines introduces an element of uncertainty to the performance of injection molded parts. Weldlines are particularly problematic in reinforced plastics because, unlike molecular orientation in neat polymers, the flow induced fiber orientation does not relax. This paper deals with the structure and mechanical behavior of weldlines in glass fiber reinforced nylon 66, a plastic known for excellent fiber-matrix adhesion. Two molds were used to generate weldlines: a double gated tensile sample shaped cavity in which the weldline is formed by a head-on collision of melt fronts flowing in opposite directions and a film gated rectangular plaque with a circular insert in which the weldline formation behind the insert is followed by additional flow. In both cases the weldline zone is several millimetres wide: in the plane where the melts fronts have met fibers are oriented parallel to this plane (random-in-plane in the double-gated cavity and unidirectional in the cavity with insert). The transition zone between the weldline plane and the rest of the sample is characterized by an increased presence of microvoids. Weldline tensile depends little on the fiber concentration and on the sample shape or thickness: values close to the matrix strength are found; in samples without weldlines strength increases with the fiber content. However, in instrumented impact penetration test during which the material is subjected to multiaxial loading, the weldline effect appears negligible.

Citation Details
Title: Weldline strength in glass fiber reinforced polyamide 66.
Author: A. Meddad
Publication:Polymer Engineering and Science (Refereed)
Date: June 15, 1995
Publisher: Society of Plastics Engineers, Inc.
Volume: v35 Issue: n11 Page: p893(9)

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