Paper to the Polymer Processing Society 12th Annual Meeting, Sorrento, Italy, 27th-31st May 1996.

S F Bush with J D Tonkin

Introduction

Continuing the work of processing long glass fibre reinforced thermoplastics, under the generic title of Self Assembling Fibre Reinforcement (SAFIRE), the blow moulding of 2-litre bottles has been achieved, complementing advances made using other major processing techniques (injection moulding and pipe and sheet extrusion).

The sample bottles were processed on a Latymer HYD6 accumulator head blow moulding machine. The initial problems encountered when processing the long fibres were the reduced levels of parison die swell compared with the unreinforced material. The thinner walled parison produced a thinner blown bottle and the narrower width parison resulted in the incomplete blowing of complex non-symmetrical geometries. To compensate for this reduced parison die swell, larger diameter dies with larger width annuli were used.

Besides a fully blown shape, a good quality SAFIRE glass fibre granule is required that allows the separation of fibre bundles into individual filaments that can form a network structure. Some characteristics that determine a quality granule include wetting the glass fibre-polymer interface and the presence of a coupling agent⁽¹, 2). In addition the use of a Fibre Separating Device (FSD)³, a mechanical unit that forces the fibre-bearing melt through narrow channels, using differences in flow velocities to cause separation of the filaments from the bundles, improves the final fibre network structure.

References

[1] S F Bush, F Yilmaz and P F Zhang, “Impact strengths of injection moulded polypropylene long glass-fibre composites, Plast Rubb Comp Proc, App 24, (1994) 139-147

[2] D R Blackburn and O K Ademosu, Poly Proc Soc 9th Ann Mtg (5-8 April 1993) paper 06-14

[3] S F Bush, “Filament Separation in Liquids”, Euro Pat 0355 116B1 (31 March 1993)

US Patent: 5,035,848, 30th July 1991

S F Bush

Abstract

A method of separating filaments from a clump thereof in a liquid flow from each other by sub-dividing the flow across its lateral extent to pass through an array of plurality filament separating channels having a cross-section at least large enough to accommodate the cross-section of the clumps such that flow along the channels imparts a shearing force to filaments at the edge of the flow in the channel to separate these axially from each other and from filaments at the center of the clump.

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