In today’s information age, customers are more aware of the products they are using and the standards they must meet to safely and reliably be consumed. In the past, testing of materials were afterthoughts and a nuisance. However, technological and scientific advances have made testing a must, because with knowledge come responsibility and liability.
Before one can begin to understand plastics testing one must first have a basic concept of the characteristics of the material tested and why they behave in the manner observed. Plastics are very complex materials in that their behavior is governed by chemistry, architecture, molecular weight, distribution of molecular weights, physical state, configuration, and use mechanisms. In this section an attempt will be made to demystify and explain these characteristics in an elementary and picturesque manner.
Mechanical properties are among the most important properties for material selection and end–use applications. Virtually all applications involve some type of material loading and responses. Consequently, such properties as modulus, tensile strength, and impact are essential for product design, material selection, and specifications. Mechanical behavior in general terms is concerned with the deformation that occurs under loading.
Thermal analysis consists of techniques in which a sample’s response to time and temperature are measured when exposed to a programmed temperature change. There are many tests that take on the form of thermal analysis. Issues regarding heating, cooling, melting crystallization, and degradation are the primary concerns.
Flow behavior of polymers is extremely important for the processor, material supplier, the end user, and the polymer scientists. This property determines whether a material can be used in a given manufacturing process; it establishes processing conditions; it determines if there are undesirable residual stresses; it classifies materials and aids in material development. As mentioned earlier, plastics are viscoelastic materials. That is, they have both a viscous (flow) property and an elastic (solid) property simultaneously. In the liquid state the viscous component is dominant.
In the late 1980s and early 1990s there was a major quality initiative within the American industry to educate and instill the concept of high quality and continuous improvement. This was triggered by the tremendous threat the industry in the United States was feeling from foreign entities. It led to such programs as the Malcolm Baldridge Award, ISO certification, and Six Sigma, to name a few. Many employees, including this author, were carted off to classrooms to learn and become indoctrinated to the new quality initiatives of their respective companies.
