Hydrostatically extruded glass‐fiber‐reinforced polyoxymethylene. I: The development of fiber and matrix orientation

Abstract

This paper describes the determination of fiber and matrix orientation in oriented short‐glass‐fiber‐reinforced polyoxymethylene (POM) composites produced by hydrostatic extrusion. The starting material was random glass fibers (25 wt% and average length 150 μm) in an isotropic POM matrix, and the oriented composites were produced by extrusion through a reducing conical die at 15°C below the polymer melting point: after extrusion the average fiber length was reduced slightly to 133 μm. Fiber orientations were measured using an image analysis method developed at Leeds University, and the matrix orientation was determined using wide angle X‐ray diffraction. The development of fiber orientation with extrusion ratio was found to be close to that predicted by the pseudo‐affine deformation scheme although the fiber orientation was greater than that predicted by the model at low draw ratios and slightly less at the highest draw ratio. The development of the orientation of the crystalline portion of the matrix was found to be always significantly greater than that predicted by the pseudo‐affine scheme.

Polypropylene hybrid composites reinforced with long glass fibres and particulate filler

“…An XY stage allows a large area to be scanned, allowing a determination of fibre orientation over a large area. For further details of the system and the analysis routines see [13]. Fibre length characterisation is achieved by taking a chosen section of the sample, burning off the PP matrix in a furnace for 8 h at 450°C, and then spreading the resulting glass fibres thinly on a glass plate.…”

“…Thus, the present paper is an attempt to clarify the mechanical behaviour of hybrid composites based on the PP matrix, LGF reinforcement and calcium carbonate particulate filler, by a systematic study on flow-induced fibre alignment, fibre length degradation, matrix crystallinity and fracture mechanisms. Fibre orientation produced by injection moulding of plate shaped sample specimens was studied using a purpose built image analysis facility [12,13], to establish whether the addition of the calcium carbonate affects the orientation of the moulded components. The average fibre length in the moulded components was also determined, again to assess any effect of the filler on glass fibre properties.…”

Using startup of steady shear flow in a sliding plate rheometer to determine material parameters for the purpose of predicting long fiber orientation

“…Fiber orientation of the sheared samples was measured using a micrographic technique proposed by Hine et al (1996). In this method, a solidified sample is cut and carefully polished to expose the elliptical cross-sections of the intersecting fibers within the polymer sample.…”

Assessment of Current Process Modeling Approaches to Determine Their Limitations, Applicability and Developments Needed for Long-Fiber Thermoplastic Injection Molded Composites

“…Orientation measurements were preformed by ORNL staff at GM using a Leeds image analysis system developed by Hine et al [29]. The important orientation descriptors are the orientation tensor elements A 11 , A 22 , A 33 , and A 31 .…”