Bulk moulding compounds

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. 

Dough or bulk moulding compounds can suffer from a number of disadvantages of which the most important are ... 

Reinforced plastics first became commercially available in the 1940s. Unsaturated polyester reinforced with fibrous glass is the most widely used reinforced plastic today. Chopped glass mats are used for sheet moulding compounds (SMC), bulk moulding compounds (BMC) and hand lay-up composites. 

Compression moulding (hot press moulding) Moulding compounds (often complex mixtures, e.g. dough or bulk moulding compounds) prepared in Z-blade mixer and heated under pressure in closed mould Small to medium articles, especially electrical mouldings large capital outlay... 

As indicated earlier, the materials may be either in the form of compounds or resins and fibres separately. Sheet moulding compound (SMC), dough moulding compound (DMC) and bulk moulding compound (BMC) use polyester resin plus filler, catalyst, pigment, low profile additive, etc. 

Krigbaum [12] has reported on the use of glass fibre reinforced composites, both from Cytec Industries, based on Cyglas 685 unsaturated polyester [bulk moulding compound (BMC)] and Cyglas 695 vinyl ester resin (BMC) in automotive valve covers and other engine cover applications. The recycling of these valve covers is also discussed. 

Polyester/resin fibre premix, for injection or transfer moulding. It is also called bulk moulding compound (BMC). 

In thermosetting compounds (which are in various forms for moulding by compression or by a modified form of injection), fibre lengths can be much higher. These are known as bulk moulding compounds (BMCs) or dough moulding compounds (DMCs). 

Automotive is by far the largest market for polyetherimide, representing 50% of total world volume in 2002. Polyetherimide usage in automotive applications has been increasing in recent years due to its replacement of metal, thermosets and bulk moulding compounds (BMC). There is still scope for further use of PEI in car electrical and under-the-boimet applications, which will underpin good growth prospects. 

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