Moulding material polyester resin

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. 

Polyesters are eneountered in many forms. They are important as laminating resins, moulding compositions, fibres, films, surface coating resins, rubbers and plasticisers. The common factor in these widely different materials is that they all contain a number of ester linkages in the main chain. (There are also a number of polymers such as poly(vinyl acetate) which contain a number of ester groups in side chains but these are not generally considered within the term polyester resins.)... 

Allyl resins Polyester Moulding Compositions Fibre-forming and Film-forming Polyesters Polyfethylene terephthalate) Moulding Materials... 

Nowadays the major thermosetting resins used in conjunction with glass fibre reinforcement are unsaturated polyester resins and to a lesser extent epoxy resins. The most important advantages which these materials can offer are that they do not liberate volatiles during cross-linking and they can be moulded using low pressures at room temperature. Table 3.1 shows typical properties of fibre reinforced epoxy. 

Shellac [124,125] is a natural resin used in very old times for varnishes and moulding compounds. The resin secreted by the lac insect, Kerriar paca, is collected by scraping the shellac-encrusted trees found in southern parts of Asia. It consists of a complex mixture of cross-linked polyesters derived from hydroxy acids, principally aleuritic acid (9,10,16-trihydroxyhexadecanoic acid). From a structural point of view, it appears that this material can be used as a crosslinking agent and/or as a monomer for developing dentrite-like polymers. The question is whether it is possible to produce this material from shellac by controlled hydrolysis. 

Plastic composites such as glass- or carbon-fibre reinforced materials are often based on polar epoxy or polyester resins, and are therefore compatible with the common adhesives as well as being readily bondable. Surface treatment is required simply to remove contaminants such as oils, dirt, and especially fluorocarbon mould release agents. The two main techniques used to achieve this are ... 

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. 

The processing of polyester matrix composites has also been modelled (3). In reference (3) the resin transfer moulding process (RTM) was modelled and the predictions were experimentally verified. Different m epoxy based materials, in this case the polyester resin gelled fi om the skin to the core as shown in Figure 25. 

Fully cured unsaturated polyester resins used for glassfibre laminating are crosslinked thermosetting materials. Moulded structures will, therefore, be dimensionally stable, even at elevated temperatures. Rigid PU foam also has a crosslinked structure and is stable. The effect of dimensional changes resulting from thermal expansion of the foam can be ignored because the modulus of PU foam is low compared with that of the GRP skins. 

Many highly crosslinked polymers have been synthesised and reported since the emergence of Bakelite as a synthetic moulding material [6, 7]. However, to keep the subject matter of this chapter within reasonable bounds, we have restricted our discussions of filled polymers to examples of the more common crosslinked matrices, unsaturated polyesters, epoxies, methacrylics and phenolics. The resins are cured by different mechanisms ... 

The principal thermosetting moulding materials are the phenol-formaldehyde (PF), urea-formaldehyde (UF). melamine-formaldehyde (MF). polyester, and epoxy resins (8.N.3, 6.N.1, 6.N.2). The prices of the cheapest resins are just... 

The first two materials are based on an unspecified epoxy resin, though the resin and size will be compatible. The second two composites are made with Stratyl 108, a polyester resin. The S-2 glass composite is an epoxy prepreg system. Manufacture was achieved by contact or prepreg moulding. 

Typical Use Leather with ABS fibre-moulding materials. Typical Use Foams - polyurethane, PVC, phenolic-resin. Polyester, ... 

The marine industry provides good opportunities for the use of adhesives. Boats made of composite materials dominate the boating industry. Manufacturers of fibreglass boats use various raw materials such as glass roving, woven fabrics, mats, sheet moulding compounds, vinyl ester resins, polyester resins, epoxy, balsa core, teak, foam, honeycomb cores, and gel coats for the production of boat hulls, decks, bulk heads, cock-pit, hatches, lids, and interiors. 

Most thermosetting materials are available in two forms, ie resins and moulding compounds. The resins may be used alone as in encapsulation processes but they are normally used in conjunction with other materials. The resins may be used with reinforcement, eg polyester/glass laminates, or with fillers and reinforcement, eg moulding compounds. This differs from the thermoplastic field where, generally, the polymeric material is used without fillers and/or reinforcement. 

These thermosetting materials are produced by reacting together an alcohol and an acid and are more correctly classified as unsaturated polyester resin. Saturated polyester moulding materials are available but they are thermoplastic. 

Unsaturated polyester resins are used alone, in conjunction with glass reinforcement or compounded with fillers and glass strands to prepare moulding materials. Table 10 gives an approximate breakdown of polyester consumption in the UK. 

Alkyd resins saturated and unsaturated polyester resins used to produce polyurethanes and for laminating and casting. Thermosetting alkyd moulding material has various moulding advantages over aminos and phenolics. See diallyl phthalate. 

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