Reaction injection moulding RIM

The basic principles of the RIM and RRIM processes are shown in Fig. 7.37. The mixing chamber is mounted directly on the mould. Micro-mixing of the 

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FRISCH, K. c.. Recent Developments in Urethane Elastomers and Reaction Injection Moulded (RIM) Elastomers, Rubber Chem. Technol., 53, 126 (1980)... 

The mixing can be done by hand, or in low pressure mixer/dispensers, and in reaction injection moulding (RIM) machines. In the latter operation the de-gassing operation is not required. 

Cast nylon is used for prototypes and small production runs processed by casting, roto-moulding and reaction injection moulding (RIM), possibly with structural reinforcements (SRIM) such as glass mat or fabric. 

Reaction injection moulding (RIM), commonly used with thermosets, is sometimes used for specific thermoplastics such as Nyrim. Nyrim is supplied in two parts ... 

The metathesis polymerisation of dicyclopentadiene, an inexpensive monomer (commercially available cyclopentadiene dimer produced by a Diels-Alder addition reaction containing ca 95 % endo and ca 5 % exo form), leads to a polymer that may be transformed into a technically useful elastomer [144-146, 179] and thermosetting resin [180,181]. The polymerisation has characteristics that make it readily adaptable to the reaction injection moulding ( rim ) process [182], The main feature of this process comes from the fact that the polymerisation is carried out directly in the mould of the desired final product. The active metathesis catalyst is formed when two separate reactants, a precatalyst (tungsten-based) component and an activator (aluminium-based) component, are combined. Monomer streams containing one respective component are mixed directly just before entering the mould, and the polymerisation into a partly crosslinked material takes place directly in this mould (Figure 6.5) [147,168,183-186],... 

The global consumption in 1997 was 7 x 1()6 t. The market is dominated by flexible foam (49 % in the USA, 38 % in Western Europe) and rigid and semi-rigid foam (28 % USA, 35 % Western Europe). Reaction injection moulding (RIM) products account for about 6 % and cast rubbers 2 %, and about 15 % is used as thermoplastic rubbers, surface coatings, sealants, adhesives and synthetic leathers. 

Formulations for producing polyurethanes (PUs) by reaction injection moulding (RIM) usually contain mixtures of polyols and diols in order to achieve the desired properties in the moulded part. The present work forms part (1) of a systematic investigation into the effects of polyol blends and glass fibres on the physical properties of unfilled and filled PUs formed by RIM. In the case of unfilled PUs, by using a multi-component polyol mixture, it is possible to investigate the effects on properties of (a) polyol structure, molar mass and functionality, (b) the relative proportions of diol-based hard blocks and triol-based soft blocks and (c) polyol blend compatibility. The... 

Reaction injection moulding (RIM) is a low-pressure process that allows two reactive streams, A and B say, to meet and react to form a cured polymer in the mould. Figure 6.16 shows the process in a simplified form. 

Figure 6.16. A schematic diagram of reaction injection moulding (RIM).

PHD polyols are successfully used for high resilience flexible PU foams (made by the cold cure process), for continuous slabstock flexible PU foams and for elastomers obtained especially by reaction injection moulding (RIM) technology. 

At one time it seemed likely that the high-tra 5 polymer of cyclopentene formed in reaction (2) would find use as an all-purpose elastomer. Raw materials were cheap and the product had properties akin to those of natural rubber. However, its early promise has not been fulfilled. Other high-/ran5 polymers, such as those formed from norbomene, eqn. (11), and cyclooctene, eqn. (12), have found their way on to the market as components of elastomeric products, and the ROMP of enc o-dicyclopentadiene, eqn. (13), is being used to produce large objects by reaction injection moulding (RIM) see Ch. 17. 

The cheapness of DCPD, obtained as a by-product from the cracking of oil, makes it an attractive candidate for the production of objects by metathesis polymerization, using the reaction injection moulding (RIM) technique. 

In reaction injection moulding (RIM), two monomers are injected into a mould, where polymerisation and crosslinking occur. It is used mainly with polyurethanes to make large automotive panels. The chemistry of polyurethanes was described in Chapter 4. Other systems used include a block copolymer between a crystalline polyamide (nylon 6) and a rubbery polyether (polypropylene oxide). In principle, any polymerisation reaction that can be substantially completed after about 30 s in the mould is a candidate for RIM. 

Reaction injection moulding (RIM) Premixed thermosetting resin and short fibres are injected using vacuum or pressure into cavity where cure reaction takes place Large mouldings e.g. vehicle body panels... 

Control of fibre orientation with short fibres, such as those sometimes used in injection moulding or reaction injection moulding (RIM) is also important. The flow in the mould may be constrained in two directions such as width and thickness, giving linear flow only in one direction. Or, the flow can instead be radial, that is, constrained in just one direction, for example the thickness, in which case the usual shear forces due to the mould walls will operate, but there will be an additional extensional force, caused by the expanding flow front. This results in fibre orientation being normal to the flow direction. The orientation angle is usually very small at the surface, but it can be almost 90° at the mid-plane [7]. 

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