Structural reaction injection moulding

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. 

SRIM or SRRIM - structural (reinforced) reaction injection moulding - mats or fabrics are placed in the mould before injection of the resin, possibly reinforced with short glass fibres. 

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... 

Stanford JL, Powell JR, Wilkinson AN, Structural composites formed by Reaction Injection Moulding, FRC2000 Conference, Newcastle, Sep 13-14, 2000. 

Rigid integral skin structural foams are produced in polyurethane materials by the reaction injection moulding (RIM) process. Components of the polymer are metered via a mixing chamber to give a measured short shot in a tool cavity where the polymerisation and the foaming action, which expands the material to fill the cavity, take place. At the cavity-moulding interface the bubbles formed by the... 

Ryan, A. J., Stanford, J. L., Xao, X. Q. (1993), Copolyureas formed by reaction injection moulding Correlations between chemical structure, thermal properties and microphase separation. Polymer, 34,4020-31. 

The most commonly used group of plastics in this class are polyurethanes which are resistant to most solvents, with the exception of n-methyl pyrollidone which swells the substrate but improves adhesion. RIM (reaction injection moulded) polyurethane finds use in the automotive sector for bumpers, spoilers and external trims. Polyurethanes are affected by heat because of their cellular structure, often craters or pimples are formed in the coating as a result of the substrate s porosity. Hence components are often manually prepared with primer filler, pore filler and several de-nib stages prior to the application of a topcoat. In recent years this high labour requirement has resulted in the replacement of polyurethane by alternative plastics. 

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