Plastics are now being used on a large scale for the packaging of fatty and aqueous foodstuffs and beverages, both alcoholic and non-alcoholic. This is evident for all to see on the supermarket shelves, margarine is packed in polystyrene tubs, beer is packed in PVC bottles and meats and bacon in shrink-wrap film. Foods are also increasingly being shipped in bulk, in plastic containers. Additionally, there is the area of use of plastics utensils, containers and processing equipment in the home and during bulk preparation of food in producing factories, at home and in restaurants and canteens. Thus it is likely that some transfer of polymer additives will occur - adventitious impurities such as monomers, oligomers, catalyst remnants and residual polymerisation solvents and low molecular weight polymer fractions - from the plastic into the packaged material with the consequent risk of a toxic hazard to the consumer.The actual hazard arising to the consumer from any extractable material is a function of two properties, namely, the intrinsic toxicity of the extracted material as evaluated in animal feeding trials (not dealt with in this book) and the amount of extracted from the polymer which enters the packed commodity under service conditions, that is, during packaging operations and during the shelf life of the packaged commodity at the time of the consumption. This book covers all aspects of the migration of additives into food and gives detailed information on the analytical determination of the additives in various plastics. It will be of interest to those engaged in the implementation of packaging legislation, including management, analytical chemists and the manufacturers of foods, beverages, pharmaceuticals and cosmetics and also scientific and toxicologists in the packaging industry.
Although plastics are extremely successful commercially, they would never reach acceptable performance standards either in properties or processing without the incorporation of additives. With the inclusion of additives, plastics can be used in a variety of areas competing directly with other materials, but there are still many challenges to overcome. Some additives are severely restricted by legislation, others interfere with each other-in short their effectiveness varies with circumstances.
Professional engineers engaged in the design and structural analysis of plastic components will appreciate this ground-breaking work, which uniquely applies the stress category approach to plastics materials. Written in an engaging, easy-to-read style, this reference offers a comprehensive discussion of various stress categories utilizing over 150 annotated, instructive examples. An overview of the theory of elasticity is presented along with techniques governing plastics design. From simple press-fits to matrix structural analysis, the concept of stress category analysis is introduced and utilized to discuss a wide range of practical problems more compactly. What to do with computed stress is the most pressing issue addressed in Applied Stress Analysis of Plastics , as Krishnamachari presents fresh methodologies to deal with these problems effectively. Stressing understanding over theory, Applied Stress Analysis of Plastics makes the perfect desktop reference for design and test engineers, or as an intermediate textbook for students.