Virgin material

As with all thermoplastic elastomers, the copolyesterethers can be processed as thermoplastics. They are linear polymers and contain no chemical cross-links, thus the vulcanisation step needed for thermosetting elastomers is eliminated and scrap elastomer can be re-used in the same process as virgin material (176—180). 

A sidestream of material boiling between about 650°F/925°F is withdrawn as cat feed. This stream is made up of virgin material from the crude and recycle cat products. When it is available additional extraneous virgin feed also may be blended into the cat feed stream. Fractionator bottoms are withdrawn and may be sent to fuel oil. 

When RPs are granulated, the lengths of the fibers are reduced. On reprocessing with virgin materials or alone, their processability and product performances are definitely change. So it is important to determine if the change will affect final product performances. If it will, a limit for the amount of regrind mix should be determined or no recycled RP is to be used. Use it in some other product such as simulated wood. 

DuPont has recently announced plans to build a demonstration plant in Maitland, Ontario, to show that the quality of the recycled product is equivalent to the virgin material (64). BASF converts post-consumer carpet into caprolactam in Ontario. Rhodia has several European plants for depolymerising nylon 6. 

A pyrolysis technique was investigated as a method for the chemical recycling of glass fibre-reinforced unsaturated polyester SMC composites. The proeess yielded liquid products and gases and also a solid residue formed in the pyrolysis of glass fibres and fillers. The solid residue was used as a reinforeement/filler in unsaturated polyester BMC composites, and the influenee on mechanical properties was studied in comparison with BMC prepared entirely from virgin materials. 

The recycling of plastic materials becomes more and more important, but unfortunately it is not possible to make materials from the same quality as that of the virgin material. For PVC, this problem is even more pronounced than for other plastics. A process is studied which is able to destroy the waste PVC, but which can recover the most important component of it - chlorine - as a raw product for VCM manufacture, with a very high yield. Most of the energy contained in the PVC can be recovered as electrical power and steam. 4 refs. 

Details are given of a visit by RECOUP to BP Chemical s feedstock recycling demonstration unit in Sunbury. The feedstock recycling technology has been developed by a consortium of companies, and will enable polyolefin rich plastic waste from domestic and commercial sources to be vapourised and then condensed to form a hydrocarbon wax. This can then be used to feed existing petrochemical crackers to produce polymers indistinguishable from virgin material, it is claimed. 

Regeneration of virgin material and their reuse in elastomeric products... 

The approach is to formulate the entire burning problem using conservation laws for a control volume. The condensed phase will use control volumes that move with the vaporization front. This front is the surface of a regressing liquid or solid without char, or it is the char front as it extends into the virgin material. The original thickness, l, does not change. While the condensed phase is unsteady, the gas phase, because of its lower density, is steady or quasi-steady in that its steady solution adjusts to the instantaneous input of the condensed phase. 

The importance of diffusion and absorption on the rate of chemical degradation of polymers must be emphasised, even if the rate of diffusion can often only be described empirically. The rate of oxidation depends on the supply of oxygen at a depth below the surface, complicated by the fact that a proportion of the oxygen is consumed on the way (see Section 4.12.2). Degradation products and radicals produced by the reaction process will diffuse either back to the surface or deeper into virgin material, all at different rates, in some cases promoting further reaction. 

The stated 25 % recycled content provision is not a limitation of the technology or regulations, but a business choice with the economic consequences shown. For processes that can use recycled PET more cheaply than those which use virgin material, the percentage-recycled content may be greater than 25 %. The 25 % content level has traditionally been seen as sufficiently high enough to represent substantial content. Marketers who advertise recycled content considerably less than 25 % are frequently met with scorn and derision. 

Currently marketed wood composites are based on 30% to 70% natural-fibre-filled polypropylene, polyethylene, polystyrene and PVC. Formulations have high performances and are more expensive than the virgin material. 

Multimaterial parts can be processed with, for example, a foamed core of recycled material and a dense skin made of the same virgin material. 

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