Moulding compounds processing properties

This is also known as Bulk Moulding Compound (BMC). It is blended through a mix of unsaturated polyester resin, crosslinking monomer, catalyst, mineral fillers and short-length fibrous reinforcement materials such as chopped glass fibre, usually in lengths of 6-25 mm. They are all mixed in different proportions to obtain the required electromechanical properties. The mix is processed and cured for a specific time, under a prescribed pressure and temperature, to obtain the DMC. 

Today s vinyl moulding compounds are successfully meeting the combined challenges of physical properties, appearance, processability, and cost requirements in a variety of specialty injection moulding applications such as appliance parts, business equipment, and electrical enclosures. One of the major reasons why vinyl materials are so versatile is that the PVC resins on which they are based can be easily modified with a variety of additives to tailor the particular performance features of the compounds to their intended applications. Determination of an appropriate combination of PVC resin and additives to produce an effective and cost-competitive compound,... 

Foly(ethylene terephthalate) (PET). A microcrystalline thermoplastic polyester. As a man-made fibre, it is suitable for producing clothing, domestic textiles, and industrial fabrics. PET films are excellent packaging and electrical insulating ma-terials with high mechanical strength, thermal stability, low vapour and gas permeability, favourable electric properties. PET moulding compounds are processed into... 

The advantage of knowing the process route and property level is attractive for many applications, but this has to be offset by either cost (prepregs) or tooling requirements (moulding compounds and GMT). 

The moulding compounds separate into those using thermosetting resins (SMC, BMC, DMC) and thermoplastics (TSC, GMT) and are used with specific processes (Table 11.9). These can contain either random, chopped or orientated glass fibres (Table 2.7). As compounds are developed for specific properties and applications, both the process route and property level are known and will be reproducible. 

J. P. Nunes (1998) A study of the processing and properties of sheet moulding compounds and unidirectional carbon fiber towpregs, PhD Thesis, University of Minho, Portugal. 

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