Acrylic sheet was widely used in aircraft windows and canopies during World War II. A transparent polyester resin (CR-39), vinylidene chloride film (Saran), polyethylene and silicone resins were also developed. The first polyethylene bottles and cellulose acetate toothpaste tubes were manufactured during this time period.
The postwar era saw the production of vinyl resins, the use of vinyl films, the introduction of molded automotive acrylic taillights and back-lighted signs, and the development of the first etched circuit boards. The injection molding process entered commercial production. Due to the newness of the materials, the properties and behaviors of the plastic materials were not completely understood. Many products were introduced that failed, creating a negative impression about plastics in the public’s mind.
Chemists continued the development of materials such as ABS, acetals, polyvinyl fluoride, ionomers and polycarbonate. The injection molding, thermoforming, extrusion, transfer molding and casting processes were all improved. This allowed the industry to provide an even greater number of cost-effective products suitable for many more demanding engineering applications.
Occasionally, plastics are still improperly used and draw negative comments. It is frequently forgotten that materials don’t fail, designs do, and the thousands of successful applications that contribute to the quality of our life are seldom noticed and are taken for granted.
The number of variations or formulations possible by combining the many chemical elements is virtually endless. This variety also makes the job of selecting the best material for a given application a challenge. The plastics industry provides a dynamic and exciting opportunity.
Plastics encompass a large and varied group of materials consisting of different combinations or formulations of carbon, oxygen, hydrogen, nitrogen and other elements. Most plastics are a solid in finished form; however, at some stage of their existence, they are made to flow and may be formed into various shapes. The forming is usually done through the application, either singly or together, of heat and pressure. There are over 50 different, unique families of plastics in commercial use today and each family may have dozens of variations.
Excerpt taken from IAPD’s Introduction to Plastics: A training manual. © 2007 International Association of Plastics Distribution. Available in English, French, German and Italian.