Waste Plastic Blends

Polymer blending techniques have been used to combine the best characteristics of each polymer. This improves the performance of polymeric materials, but it is necessary to combine the polymer blends in a relatively economic way [63, 64]. 

A mixture of a polymer with chemicals or other plastics is called blend. The basis for creating polymer blends is to exploit certain unique properties of individual polymers in multicomponent systems to the benefit of the overall properties. Polymer blends are gaining greater importance due to their unique properties, which differ from those of the basic polymers. Blending of one polymer with another polymer is a very common practice [65-70]. 

The selection of a suitable blend can be drawn from knowledge of the mechanical behaviour of the different polymers, as these will contribute to the design and quantitative scientific basis [71-75]. With the preparation of polymer blends, the synthesis of new polymers can be avoided. It is a comparatively cheap method, and another field of special interest. The creation of blends of waste or recycled plastics is very comparable to the synthesis of a polymer. 

The mechanical compatibilisation of polymer blends is conceptually an attractive route, leading to unique property combinations and the recycling of mixed polymer scrap. There is considerable impetus behind discovering polymers that exhibit such compatibilising effects and to understand the mechanisms by which they function. Blends would result if certain types of plastic soft-drink bottles were granulated and processed. A bottle type of interest consists of a PET container with an HOPE pedestal, which is needed because the blown bottle has a rounded bottom. It is quite obvious that PET and any PO would be grossly incompatible and that a very effective compatibiliser would be needed to give the blend adequate mechanical properties for any subsequent application [76]. 

Manson and L.H. Sperling in Polymer Blends and Composites, Plenum Press, New York, NY, USA, 1976, p.378. 

---

Reactive compatibilization is also carried out by adding a monomer which in the presence of a catalyst can react with one or both phases providing a graft copolymer in situ that acts as a compatibilizer. Beaty and coworkers added methyl methacrylate and peroxide to waste plastics (containing polyethylene [PE], polypropylene [PP], PS, and poly(ethylene terephthalate) [PET]). The graft copolymer formed in situ homogenized the blend very effectively [19]. 

The main advantage of rotary kiln pyrolyzers is that the rotation of the pyrolyzing chamber guarantees the permanent turning and mixing of the waste plastic, so that the mixture is continuously homogenized and blended with inert pyrolysis gas. A rotary kiln pyrolyzer is shown in Figure 27.3. 

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. 

Mangaraj D. 2004. Role of compatibilization in recycling rubber waste by blending with plastics. 166th Rubber Division Meet, (Fall 2004) Columbus paper 27, 16. Rubber Chem. Technol. 2005. 78(3) 536 7. 

Sharp Develops New Technology to Blend Plant-Based Plastic with Waste Plastic, Omnexus, July 12, 2005. 

The variety of plastic wastes Plastics in municipal solid waste (MSW) are a very heterogeneous collection of materials that encompass not only a broad range of types made from a single resin, but also an increasing number of items that include a blend of resins, either mechanically or chemically bonded together. The varieties are made additionally diverse through the use of plastic additives to yield specific product qualities. 

Chemicals that help to blend different types of waste plastics and ingredients. 

Recycled and waste thermoplastics are some of the major components of global municipal solid waste (MSW) and they present a promising raw material source for WPG, especially because of the large volume and low cost of these materials. As detailed in Table 5.1, high-density polyethylene (HOPE), low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE), PP, PET, PS and PVG are the primary constituents of plastics in MSW. The blend of the mixed waste plastics can be changed depending on the regional habits and seasons of the year, and also on... 

Workers in India [18] have also blended both waste plastic and waste rubber. In this instance they took scrap computer plastics (e.g., acrylonitrile-butadiene-styrene and styrene-acrylonitrile) and blended them with waste NBR powder. The blends were analysed by TGA in a nitrogen atmosphere and their activation energies of decomposition determined using Friedman and Flynn-Wall-Ozawa methods. 

Kaimal, V.K., Vijayabalan, R, 2015. A detailed smdy of combustion characteristics of a D.I. diesel engine using waste plastic oil and its blends. Energy Conversion and Management 105, 951-956. 

The thermal degradation of mixtures of the common automotive plastics polypropylene, ABS, PVC, and polyurethane can produce low molecular weight chemicals (57). Composition of the blend affected reaction rates. Sequential thermolysis and gasification of commingled plastics found in other waste streams to produce a syngas containing primarily carbon monoxide and hydrogen has been reported (58). 

Fig. 5. Equipment foi surface treating plastic components. Parts ate loaded into one of the two lower chambers which is then evacuated to remove most of the air. This chamber is then flooded with a dilute mixture of fluorine and nitrogen which is made and stored in the upper chamber. After the treatment is completed, the fluorine mixture is pumped back up to the upper chamber for storage and the lower chamber repeatedly flooded with air and evacuated to remove any traces of fluorine gas. Two treatment chambers are cycled between the loading/unloading operation and the treatment step to increase equipment output. The fluorine—nitrogen blend may be used several times before by-products from the treatment process begin to interfere. AH waste...

---