Green polymers classification

A nylon-clay hybrid (nanocomposite NCH) was originally developed by the authors and was the first polymer nanocomposite to be used practically. Since 1990, when it was first used, various studies and analyses of it have been reported. An excellent review was published in 2003 [1]. In the present review, which focuses on the authors studies, details on the NCH that we reported initially and further developments in polypropylene and polyethylene will be described. In Sect. 2, comprehensive classifications of the production methods developed previously will be described, according to the synthesis method employed. Thereafter, nylon will be discussed in Sect. 3, polyolefin in Sect. 4, and renewable polymer (green polymer) will be discussed in Sect. 5. 

Figure 7.4 Classification and image processing results of a typical situation in polymer waste recycling (a) digital image (b) initial classification result (c) calculation of separation data based on the initial classification result (d) classification result after real-time image processing. A, B Polyethylene terephthalate (PET) bottles with paper labels, C PE bottle with paper label, D PE bottle with PE film label, E PP cup, F PS cup. Classification colour code red high-density PE green PS dark blue PET yellow PP light blue paper.

Figure 7.5 Classification result of shredded mixed electronics waste, superimposed onto a greyscale image of the waste fraction. Only objects that could be identified with a likelihood >95% have been classified. Classification colour code yellow metal, mostly aluminium red polymethyl metacry-late (PMMA) orange polyolefines (PE, PP) pink styrene polymers (PS, PS-E, etc.) violet polyamides (PA 6, PA 6.6, etc.) green acrylonitrile-butadiene-styrene (ABS) blue polyvinyl chloride (PVC).

However, different classifications can be proposed, the bottom line being that every new key discovery in any area of polymer science (e.g., nanomaterials, biomaterials, green and sustainable processes, etc.) will need the application of PRE principles to turn it into a useful commercial application. 

In materials science we often divide materials into distinct classes. The primary classes of solid materials are ceramics, metals, and polymers. This classification is based on the types of atoms involved and the bonding between them. The other widely recognized classes are semiconductors and composites. Composites are combinations of more than one material and often involve ceramics, such as fiberglass. Semiconductors are materials with electrical conductivities that are very sensitive to minute amounts of impurities. As we will see later, most materials that are semiconductors are actually ceramics, for example, gallium nitride, the blue-green laser diode material. 

A 2011 study by Lithner et al. (2011) assessed the environmental and health hazards posed by plastics, based on the toxicity of their monomers. The classification is not inherent to the polymer as it is based primarily on residual monomer (with selected additives, plasticizer, and flame retardants). The ranking (see Table 8.8) can have relevance only for occupational exposures and in some food-contact uses of plastics. Also, future advances in residual monomer reduction technology and green substitution of additives can change the status of a polymer in this assessment. Where recyclabihty" is used as a ranking criterion, it generally refers to technical recyclabihty that has little to do with if the resin will in fact be recycled in practice. 

---