Please note that we only supply polymer in granular form for Injection Moulding or Extrusion applications. We do not supply polymer in rod, sheet or block form.

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    Sulphur: From the Underworld to Thermoplastics

    In 1839, by inserting sulphur atoms as bridges between polymer chains, Charles Goodyear transformed Natural Rubber from an interesting curiosity into a superb engineering material that has had a huge impact on society.  It took another 100 years before sulphur links began to appear in thermoplastics. However, natural polymers such as proteins and DNA rely on such sulphur links.

    Air duct in Fortron PPS Sulphur
    Air duct in Fortron PPS

    Today sulphur, in the form of sulphide and sulphone links, enhances properties of high temperature stability, chemical resistance and fire performance in thermoplastics such as polyphenylene sulphide (PPS) and polyethersulphone (PES).

    PPS, essentially replaces the oxygen links in polyethylene oxide (PPO) with sulphur links in the polymer backbone. It offers excellent dimensional stability at high temperature (particularly when filled), broad chemical and solvent resistance and good fire performance.   However, the melt temperature is high (285oC). Also there are some other moulding issues to be aware of. Namely, the low melt viscosity makes it eminently suitable for thin sections.

    Unfilled PPS can be used as high performance fibres, for technical textile applications, including filters, flame resistant clothing and advanced composites for the aerospace industry.

    Moulding grades of PPS are generally filled with glass fibre and mineral filler to improve stiffness at high temperature.  Unlike most other thermoplastics, PPS can accept filler loadings up to 65% to produce very stiff, heat resistant mouldings. My students mistook these for metal castings, even down to the metallic ‘ring’, until the more discerning realised that the mouldings, although heavier than other thermoplastics, were significantly lighter than most metals.

    Trade Names: Fortron, Ryton

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    Coping with weld lines

    In injection moulding, weld lines (knit lines) form when two melt fronts meet. If the melt fronts do not coalesce completely, at best there will be a cosmetic flaw. At worst there will be a mechanical weak-spot, with strengths of the order of 10 - 90 % of the material potential.

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    What determines friction between thermoplastic components?

    Friction is an important property for thermoplastics in bearings and gears but also has a part to play in assembly of plastic parts (snap-fit and interference-fit) and ejection during moulding.

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    Polypropylene: the Workhorse of the Plastics Industry

    Polypropylene. Little did Karl Zeigler or Giulio Natta realise, 60 years ago, when they were developing a catalyst system to produce a useful thermoplastic from the inexpensive monomer, propylene, that their work would have such far reaching consequences.

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    What makes medical grade plastics so special?

    Toughness and transparency are important properties for the constituents of intravenous lines.

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    The Long and the Short of Fibre Reinforcement of Thermoplastics

    Fibre Reinforcement. The advantages of adding glass fibre to thermoplastics to increase stiffness (modulus), strength, heat distortion resistance and dimensional stability are well known.

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    What causes mouldings (and moulders) to be off-colour?

    When mouldings are not the intended colour, the first thing to check is the raw material, particularly the dosing rate, if you are using masterbatch, and the quality of regrind.

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    Transparent ABS can be a clear winner

    Transparent ABS. Mentioning transparency in the context of ABS moulding materials can raise a few eyebrows. This is because ABS is normally taken to be opaque and indeed the vast majority of grades of ABS are opaque.

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    Understanding the difference between SBS & SEBS thermoplastic elastomers?

    The difference between SBS and SEBS thermoplastic elastomers explained.

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    Is MFR really much help to moulders these days ?

    Often a moulder has to change material grades. One of the first properties to be consulted on the new data sheet is usually the MFR. This is to establish if the new grade has the same melt viscosity performance.

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    What gives Moulders a Warped View on Life?

    Warping is one of the most frustrating injection moulding faults. This is because it does not always appear immediately, the causes are complex and prevention is difficult.

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