New Process for Long-Glass Fibre Reinforced Extruded Sheet
September 26th, 1995
Paper to the Polymer Processing Society European Meeting, Stuttgart, Germany, 26th-28th September 1995.
S F Bush with E S Erdogan
Introduction
The work reported here results from a long-term programme of research under the generic title of Self Assembling Fibre Reinforcement (SAFIRE) processes. This work is aimed at providing means by which deformable lace-like structures are obtained within resins and melts in ways which do not interfere with established processing methods such as extrusion, injection moulding and blow moulding. Earlier results, principally on the resultant solid properties, have been reported at PPS conferences (1, 2) and elsewhere3. The processes involved are now patented world-wide (4, 5) and products dependent on the processes have entered commercial production.
The SAFIRE processes provide: (a) masterbatch granules consisting of the chosen polymer matrix in which fibres of any defined length are disposed to minimize breakage during processing, and (b) fibre management devices which when placed in the melt flow, manoeuvre the filaments into deformable but coherent lace-like structures which persist into the solid state(4, 5). The devices are introduced upstream of dies or moulds in ways which do not interfere with the functioning of the process or add materially to its mechanical complexity. Criteria for obtaining fibre mat or lace structures, and factors affecting the polymer-fibre interface are described elsewhere(2, 3). Hitherto work has concentrated on extruded pipe(1, 3) and injection mouldings(2, 3) using polypropylenes and high, medium and low density polyethylenes, and polybutylene. The present paper describes the application of the SAFIRE concepts to sheet extrusion. As it stands this application is not optimized so the results should be seen as preliminary ones only.
References
[1] Bush S F, Extrusion of Melts Containing Semi-Coherent Fibre Structures, 5th Poly Proc Soc Ann Mtg, Kyoto, Japan (1989) paper 11-02.
[2] Bush S F, Ademosu O K, Blackburn D R and Yilmaz F B, Factors Affecting the Strength of Long-Fibre Reinforced Injection Moldings, Poly Proc Soc, European Mtg, Prague (21-24 Sept 1992) paper 6-06.
[3] Bush S F, Yilmaz F and Zhang P F, Impact Strengths of Injection Moulding Polypropylene Long Glass Fibre Composites, VI Inst. Mats. Conf. Fibre Resin Comp., Newcastle (29-31 March 1994) paper 1-05.
[4] Bush S F, Fibre Reinforced Polymer Compositions and Process and Apparatus for Production Thereof. US Patent 5,264,261 (23 Nov 1993)
[5] Bush S F, Filament Separation in Liquids, US Patent 5,035,848 (30th July 1991)