MATERIALS | REINFORCEMENTS
Warpage comparisons of a 30% glass fibre filled PBT compound (left) with a 20% glass fibre/10% Fleka glass flake filled PBT Source: Dreytek/Dreyplas
Fleka and Fineflake are used in various applica- tions where dimensional stability and good mechanical properties are required. Examples include small components such as electronic connectors where accuracy in mating of one part to another is critical, and where warpage or differen- tial shrinkage cannot be tolerated, especially when exposed to significant thermal cycling. Other applications include large thin wall parts where high shrinkage and warpage cannot be tolerated. “Very often these applications do not require the complete replacement of glass fibre by glass flake but make use of a formulation that optimises the balance between mechanical properties and shrinkage/warpage,” Gershon says. She cites the case of a 30% glass-fibre filled PBT compound in which one third of the glass fibre was replaced with 10% Flekaglass flake to result in a 79% reduction in warpage.
Cord reinforcement Dr Tanvir Ahmmed is Product Development Manager for NGF Canada, which manufactures reinforcing cord for use in thermoplastics to provide enhanced longitudinal stiffness and dimensional stability. According to the company, cord-reinforced thermoplastic articles exhibit longer service life under continuous linear and bending stresses. The cords are generally treated with chemicals
to provide optimal adhesion to the matrix. This treatment is typically applied either by dipping or impregnation.
NGF manufactures reinforcing cords treated with
thermoplastic polyurethane (TPU) and polypropyl- ene (PP), providing compatibility with TPU, PP, PVC, and other thermoplastic elastomers. There are two different TPU treatments, one based on aliphatic polyester and another on aliphatic polyether. The company offers glass, polyester, carbon,
and aramid reinforcing cords. It says the cords offer advantages over traditional steel alternatives used in some reinforced thermoplastic articles, such as belts, hoses, and profiles for automotive and construction applications. In particular, it claims that the use of a carbon cord will save up to 80% weight over a steel alternative. In addition to continuous reinforcing cords, NGF also supplies thermoplastic impregnated chopped strands (TISC) that can readily be incorporated into thermoplastics. Usually, the company supplies these chopped strand products at 1.5, 3, 6 and 12mm lengths. European glass fibre manufacturers are lobbying
hard to ensure that the current energy crisis does not put their businesses in jeopardy. Glass Fibre Europe — the trade association representing the European continuous filament glass fibre industry — counts 3B, Johns Manville, Lanxess, Nippon Electric Glass, Owens Corning and Saint-Gobain Vetrotex among its members, together accounting for more than 90% of continuous filament glass fibre production in Europe.
Energy concerns
In a position paper issued in May, Glass Fibre Europe noted that the European Commission had announced in its Communication “RePowerEU” its desire to reduce, by the end of the year, EU depend- ency on Russian fossil fuel imports; Russia provides over 40% of all natural gas consumed in the EU. Glass Fibre Europe said it wanted to “inform the authorities on the critical need for an uninterrupted supply of energy (natural gas and electricity) to the continuous filament glass fibre manufacturing sector to preserve the furnace and industrial equipment, prevent industrial accidents and protect the safety of workers.” Glass fibres are produced in furnaces that
Figure 2: Graph showing typical tensile performance for 1.05mm diameter NGF cords produced in different materials Source: NSG Group
36 COMPOUNDING WORLD | June 2022
operate at high temperatures – approximately 1,500°C. “While many manufacturing processes are well suited to intermittent operation, continuous
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