Recycled Polymer Blend Compounds

We have previously discussed recycled polymer blends in Section 5.11 and 6.7. We noted that binary (or indeed ternary) blends involving polyethylene, polystyrene, polyvinyl chloride, polyamides, etc., have poor mechanical properties because of a lack of adhesion between the components (Section 5.11). We indicated in Section 6.7 that introducing compatibiHzing agents such as styrene-hydrogenated butadiene-styrene triblock copolymer and maleated polyolefins can enhance the mechanical properties. However, this in itself is not enough. 

In recycling of used plastic products (recyclates), technical processes such as separation, purification, introduction of reinforcements, and additives, are usually included, depending on the source of the plastic, because thermoplastic products contain various different types of additives such as stabilizers, fillers, pigments, processing additives, and compatibilizers. The most common additives used for the recycling/reproduction of recyclates are phenolic antioxidants, phosphates, and costabiHzers such as anti-acids and light stabilizers. 

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Recyclable polymer blends. Here, the recyclability is conditional on re-generation of morphology, by means of re-compatibilization, re-stabilization, and re-compounding. 

The total cost calculations of a product made of polymer blends includes the materials, compounding, forming, assembling, decorating, customer satisfaction, esthetics, service life-spans, ease of disposal, and recycling. Thus, recycling enters into the initial part design. Before a part... 

By improving the quality of material produced to meet molders expectations, the compounding industry and its customers benefit while energy and waste generated in recycle is reduced. Further work is needed to commercialize intelligent extrusion technology for manufacturing polymer blends. 

Lyondell BaseU Polymers sells compounded polyolefins. The base polyolefin is blended with impact modifiers, fillers and reinforcements, pigments, and additives. Customer applications include automotive components, electrical appliances, wire and cable, pipe and sheet, building and construction, and furniture. The properties of the product include a broad range of stiffness from very soft to very rigid, excellent aesthetic characteristics and colorability, good processability, high stiffness/ impact balance, high mar and scratch resistance, low carbon emissions achievable, and excellent recyclability. 

Ishiaku, U.S., Chong, C.S., and Ismail, H., Cure characteristics and vulcanizate properties of blends of a rubber compound and its recycled DE-VULC, Polym. Polym. Comp., 6, 399, 1998. 

It is now clear that state-of-the-art technologies in polymer processing are required to convert recycled plastics into useful blends with marketable properties. As with virgin materials, blend formulation, compounding, and mold fabrication are used to achieve specific properties for targeted applications. 

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