Role of Plastics in Packaging

Energy recovery from packaging waste is discussed, with particular reference to the co-combustion of mixed plastics with other conventional fuels such as wood, coal and peat. Experimental work is described in which a project was established to evaluate the possibility of energy recovery from a circulating fluidised bed boiler using packaging from different sources as fuel. The role of sulphur in the formation of PCDD/F in the combustion process was also studied. 

More information on the role of plastics additives can be found in ref. 17, and refs 18 and 19 provide information on packaging materials. More information on the methods and research projects conducted in the field of food contact safety and legislation can be found on the following websites ... 

The purpose of plastic in the role of packaging is to act as a barrier between the contents of the package and the surrounding environment, reducing the rate of spoilage of the contents and decreasing or eliminating the transmission of flavors and aromas. 

It is important to note that a major role of solder in area array solder joints at the chip and package level is to accommodate plastic strain without cracking that is, the solder is a plastic strain absorber. This implies that weak solders are potentially good candidates for this application. It has been demonstrated that solders with low shear strengths exhibit the greatest thermal cycling lifetimes [124], and this explains the lower thermal mechanical fatigue resistance of tin-based solders compared to lead-based solders (Table 5). 

In addition to protection from breakage, the brown plastic bottles in which hydrogen peroxide is commonly sold enhance the shelf-life of this product. Packaging plays an important role in limiting the light-induced chemical reactions of hydrogen peroxide. 

Ethanol and aqueous ethanol mixtures play important roles as food simulants for the determination of migration of substances from packaging into foods. Depending on the polarity of the plastic one can use pure ethanol (for nonpolar plastics) or aqueous ethanol mixtures up to 50/50 % (for polar plastics) as alternative simulants to edible oils (see Chapters 9,10 and 11). The estimation of partition coefficients in poly-mer/simulant systems is consequently of practical importance. It is possible to do this for polyolefins in contact with alcohol and aqueous alcohol mixtures with the help of an equation analogous to Eq. (4-100) (Piringer, 1993) ... 

Plastics undoubtedly have an increasingly useful role to play in both the packaging and administration of pharmaceutical products. To summarise, emphasis is placed on their advantages and disadvantages together with advice on the information required to prove their general suitability. 

The history of plastics dates back to the mid nineteenth century when celluloid and Bakelite were discovered. Bakelite (phenol formaldehyde) and urea formaldehyde, both thermosetting plastics, found wide use in the pharmaceutical industry in the form of screw closures and are still used today. Although recognised as plastics, the thermosets play only a minor role as a packaging material and it was not until around 1953 onwards, when the first thermoplastics were used as low density polythene squeezee packs, that the real plastic revolution began. In 1996 five, in fact the most economical five, were the ones most widely used. These include the ... 

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