Thermoplastics processing tests

This is not of course the complete story. Most often, thermoplastic elastomers are processed on plastics machinery and it will be convenient, and sensible, that test pieces are produced in the same way. The thermoplastics processability tests are also likely to be more relevant and, certainly, curemeter tests are irrelevant. 

Filler or Reinforcement Content Thermoplastics Processing Tests... 

Although the new polymer softened at high temperatures, it didn t decompose. This 1 us to consider it as a candidate for another search we were engaged in, the search for a family of materials which behaved like rubbers but could be labricated using efficient thermoplastic processing. Although the urethane product we were testing had excellent properties and was a thermt lastic, it was prohibitively expensive as a replacement for rubbers. 

Certain common tests are used to determine how the filled polymer will process. The most important processing tests for thermoplastics are melting temperature and melt viscosity. 

Ionomer resins are produced in multiple grades to meet market needs, and prospective customers are provided with information on key processing parameters such as melt-flow index. Nominal values for many other properties are Hsted in product brochures. The ASTM test methods developed for general-purpose thermoplastic resins are appHcable to ionomers. No special methods have been introduced specifically for the ionomers. 

The degree of bonding analysis has been verified for both compression molding and online consolidation of thermoplastic composites. In these studies, composite test specimens were consolidated under controlled processing conditions. The most common types of tests performed to measure the interply bond strength were the interlaminar (short beam) shear test [21,25] or the lap shear test [12,21,26]. 

As discussed above, series of experiments and even a limited number of tests in longitudinal strain under constant-force conditions are representative and very informative in terms of behavior of thermoplastics in processing. However, unfortu-... 

Figure 2.37 presents plots of elongational viscosities as a function of stress for various thermoplastics at common processing conditions. It should be emphasized that measuring elongational or extensional viscosity is an extremely difficult task. For example, in order to maintain a constant strain rate, the specimen must be deformed uniformly exponentially. In addition, a molten polymer must be tested completely submerged in a heated neutrally buoyant liquid at constant temperature. 

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