Sheet moulding compound SMC

A mixture of glass fibres, 12-55 mm long, fillers, and catalysed polyester resin sandwiched between 2 polythene sheets to prevent adhesion of the layers and facilitate handling. Two processes are used to make SMC s giving laminates with slightly differing properties  

Thermoplastic additives are sometimes added to SMC compositions to improve surface finish and further reduce shrinkage. 

The main ingredients of typical sheet moulding compounds are  

In contrast to the hand lay-up process hot press moulding is ideally suited to long production runs of relatively small components. The moulding operation is as follows  

Note SMCs are compounded with internal release agents, thus eliminating the need to apply external mould release agents between every cycle. 

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Figure 25.12. Outline of machine for preparing sheet moulding compounds (SMC)...

This paper summarises an initial feasibility on reeyling scrap automotive plasties and eomposites using a eatalytie conversion process. The eharaeterisationofhydroearbon products is presented for sheet moulding compound (SMC), auto shredder residue (ASR) and reinforeed polypropylene (R-PP) materials and mixtures of body panels. Gas chromatography and scanning electron microscopy is used for the material characterisation. 26 refs. 

Increase viscosity, e.g. magnesium oxide in unsaturated polyester resins increases the viscosity so much that a liquid resin becomes a tackfree solid, suitable for making sheet moulding compound (SMC). A relatively high viscosity is also desirable for latex compounds used to coat textiles. 

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. 

Sheet Moulding Compound (SMC)—A mixture of fibres, fillers and thermosetting resin in sheet form similar to DMC, but having longer fibres and higher fibre content. It is used in hot press moulding processes. 

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. 

Reinforcement fibres—Sampling plans applicable to received batches Plastics—Prepregs—Definitions of terms and symbols for designations Textile glass reinforced plastics—Sheet moulding compound (SMC)—Basis for a... 

A successful production model sports has commenced manufacture in the USA. This is General Motors Pontiac-Fiero. The body panels are made in RRIM hung on a steel sub-frame. The roof and bonnet lid are made in sheet moulding compound (SMC) for greater stiffness. 

ERF Ltd of Sandbach, Cheshire produce lorry cabs clad with glass-reinforced plastics (GRP) panels. The panels are hot-press moulded from sheet moulding compound, (SMC) then fitted to the steel frame of the cab (the safety cage) using an ERF patented assembly technique. 

Scott Bader Ltd, 173, 176, 191 Screen printing, 150 Selby coal mine, 226-51 Sheet moulding compound (SMC), 159, 162 in lorry cab, 174... 

Curatives have been prepared via condensation of (meth)acrylonitrile with various hydrazides such as carbohydrazide, oxalyl dihydrazide, and succinyl dihydrazide (Eq. 16). When these cyanoethylated and cyanopropylated hydrazides are mixed with DGEBA-type resins, viscosity increases are noted in 4-5 days at room temperature. However, these partially reacted mixtures are still uncrosslinked and flowable at temperatures near their final cure temperature of around 120°C. At this temperature reaction occurs very rapidly for a variety of epoxide-to-amine ratios. Adhesive compositions of DGEBA-type epoxy resins and the cyanoalkylated hydrazides give extremely strong bonds on substrates such as sheet moulding compound (SMC) and steel. 

A German company, BASF, patented one such process. It is known as particle recycling and involves recycling a common thermoset material called sheet moulding compound (SMC). This is a thermoset material mainly used for structural purposes and has a high level of fibre reinforcement in it. A closed loop system was proposed and set up, with the first recycled parts being used in 1992. The process involves several stages. The... 

These materials compete with sheet moulding compounds (SMC) for applications which are generally of high volume (section 11.4). Compared with SMC (Table 11.11) they have a lower modulus, and a higher failure strain. 

The weathering of a sheet moulding compound (SMC) has been investigated after exposure up to a period of 18 months outdoors in a sun-facing direction. 

Manufacturers Comments Heat curing adhesive for bonding Sheet Moulding Compound (SMC). Initial mixing provides non-slump compound. 

Compression moulding is carried out on moulding powders or sheet moulding compounds (SMC). The presses are vertical, with the hydraulic cylinder above or below the horizontal platens. The mould is heated to between 160 to 200 C, being thermally insulated from the platens (Figure 1.9). The required amount of prepolymer (mixed with catalyst or curing agent) is placed into the open mould it is then closed and pressure is applied to cause the material to flow around the cavity. The mould remains closed until the... 

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