Plastics virgin

Fig. 6-25 Flow diagram virgin plastics, molded products with runners, granulating runners, to regrind blend with virgin plastics.

The success of any continuous extrusion process depends not only upon uniform quality and conditioning of the raw materials but also upon the speed and continuity of the feed of additives or regrind along with virgin plastic upstream of the extruders hopper. Variations in the bulk density of materials can exist in the hopper, requiring controllers such as weight feeders, etc. 

Post-industrial waste and sorted post-consumer wastes (PCW) are suitable raw materials. However, they contain different amounts of inhomogeneities formed during the service life and non-polymeric impurities. These contaminants account for differences in mechanical properties and ageing resistance between recyclates and the respective virgin plastics. Recycled plastics are often used in low-grade applications, and it is generally believed that the mechanical performance of recyclates is lower than that of virgin materials. 

Recycling rarely reproduces virgin plastic materials. With repeated recycling, quality decreases, and potential uses decrease. At some point, the final step should be incineration. This produces useful energy, returns carbon dioxide and water to the ecocycle, and reduces final solid waste to an absolute mini-... 

There are different types of plastics that are usually identified by their composition and/or performance. As an example there are virgin plastics. They are plastic materials that have not been subjected to any fabricating process. NEAT polymers identify plastics with Nothing Else Added To. They are true virgin polymers since they do not contain additives, fillers, etc. They are very rarely used. Plastic materials to be processed are in the form of pellets, granules, flakes, powders, flocks, liquids, etc. Of the 35,000 types available worldwide there are about 200 basic types or families that are commercially recognized with less than 20 that are popularly used. Examples of these plastics are shown in Table 1.1. 

Technologies, such as coextrusion and coinjection, allow PET and other plastics to package foods and other products.225 226> 227 Care must be taken to control the process so that the melt when blown will not have micro-voids in the container walls or will delaminate. Coextrusion and coinjection (or multilayer processes) are essential technique in the production of high performance BM products (Chapters 4 and 5). The parison or preform is coextruded with a number of different layers, each of which contributes an important property to the finished product. Increasingly, a mid layer may consist of recycled material which is encapsulated between inner and outer layers of virgin plastics. 

AIST A process for converting PET (polyethylene tererephthalate) into virgin plastic. The scrap PET is first depolymerized by heating with ethylene glycol and a metal salt catalyst. 

The naphtha produced by the feedstock process is treated in a steam cracker, and the monomers (e.g. ethylene, propylene, butadiene) are recovered. These raw materials are then used for the production of virgin plastic materials. High-boiUng oils can be processed into synthesis gas or conversion coke and then be transferred for further use. All these products have outlets in the local BASF production plants. 

Ideally we would like to reuse plastic waste to form directly new plastic products, but mechanical reprocessing of used plastics into new products has so far limited application. It is restricted to the treatment of relatively pure and well-defined waste, mainly from polymer processing factories. Mechanical reprocessing of municipal plastic waste results in new products of quality inferior to their virgin plastic ones. Separation of waste to streams of the same polymer type on the other hand is still very expensive. This fact restricts the applicability of mechanical reprocessing in polymer waste that is homogeneous in type and properties. 

Explain sustainable development and the triple bottom line. (P) How does polymer regeneration differ from standard recycling methods 10) Are the properties of recycled plastics as good as the properties of virgin plastics 11) Discuss the life cycle of plastics and why reducing is better than recycling and reusing. 12)... 

Disposal of waste plastics is expensive. Plastics deteriorate but never decompose completely and they involve a high percentage ( 42% by weight) of waste. Fortunately, in recent years recycling of plastics has become an important technology. Some plastics can be blended with unused virgin plastics to reduce the cost of waste disposal. 

Packaging reduction has been achieved by simultaneously following several approaches. These include the use of recyclable plastics to reduce the use of virgin plastic and create a market for recycled plastic, introduction of lightweight bottles and refills, which use less plastic than conventional containers, and development of concentrated products. Recycled paper has also been used for cartons made from paper, to reduce the amount of wood fiber used and provide a market for recycled paper [35], This enabled the launch of concentrated fabric softeners, which were successfully formulated due to product and packaging improvements... 

Manufacturers of wood-plastic composites in North America have used about 600 million pounds of thermoplastics in 2005, of which polyethylene accounts for about 90% of the volume and polypropylene and PVC for the remaining 10%. Of these, reclaimed resin is about 35-40% of the total resin demand, virgin plastics is 60-65% [1],... 

It seems that both amount of antioxidants and recycled or virgin plastic do not effect the fading of composite materials. Some other factors prevail, such as the color of the composite. 

Very low density PE (VLDPE), 52 Vinizene BP 5-5, 449 Vinyl alkoxysilanes, 172 Vinyl silanes, 172 Vinyl trimethoxysilane grafted polyethylene, 172 Vinyltriethoxy-silane, 194 Virgin plastics, 51 Viscoelastic behavior, 225 Viscoelastic fluid, 622 Viscoelastic materials, 631 Viscosity of polyethylene hot melts, 633 Viscosity of polymers, 620 Viscosity of water, 620 Viscosity, 622... 

There is no shortage of sources of plastic waste on this planet (see Figure 10.24), but at present the potential resource they offer is only very partially exploited. Their use is not really a financially viable option, because while virgin plastics are inexpensive to manufacture, waste plastics need to be treated and transported, have poorer properties than the virgin material and the applications of recycled plastics have only little added value. 

The principle is simple if we wish to expand the market for recycled plastic, we have to win back a market share from virgin plastics, which have very good technical performances. It is obviously necessary to supply industries which require low-grade plastics, but if we wish to develop the avenue of recycled plastics, it is essential to make recycled polymers whose performances are similar to those of virgin materials, thereby helping to increase volumes and margins. 

As for virgin plastics, any recycled plastic that can melt and process below the degradation point of wood (200°C) is usually suitable for manufacturing WPC materials. The choice of plastic, however, depends on the particular application requirements. 

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