1.4 Mechanical Properties

The mechanical behavior of polymers is dependent on many factors, including polymer type, molecular weight, and test procedure. Modulus values are obtained from a standard tensile test with a given rate of crosshead separation. In the linear region, the slope of a stress-strain curve will give the elastic or Young s modulus, E. Typical values for Young s modulus are given in Table 1.2. Polymeric material behavior may be affected by other factors such as test temperature and rates. This can be especially important to the designer when the product is used or tested at temperatures near the glass transition temperature where dramatic changes in properties occur as depicted in Fig. 1.5. The time-dependent behavior of these materials is discussed below.