Monday, 15 June 2020

Design Properties for Engineers: Flexural Properties of High Performance Polymers

In this post we compare the flexural properties of 12 unfilled high performance polymers.

In the standard ISO 178, a method for determining the flexural properties of rigid and semi-rigid plastics under defined conditions is described. A bar-shaped test specimen will be placed on both ends over a block and a force is placed in the middle of the specimen with a constant speed. In this way, stress and strain behavior for bending can be estimated. This is similar to the tensile properties, however for the load case of bending.

In the bending test, the resulting stresses and strains are located mainly on one side of the specimen. This leads to different stresses in the edges of the specimen. One side of the specimen will be bended, while the other side will be strained at the same time. The resulting stresses are distributed in a uniform way compared to the tensile test. Further, the maximal loads which are applied in the bending test can result in higher strength values compared to the strength values obtained from the tensile test.

In general, flexural test data can be used for indicating the behavior of the selected polymer in use.

Flexural properties of high performance polymers reflect the findings of the tensile test results. Ultrapolymers such as PEEK, PBI, and PAI, as well as LCP have excellent flexural properties. Fluoropolymers on the other hand, have a low bending strength.

Flexural properties of 12 unfilled high performance polymers

Further design property data of high performance polymers are listed on my start here page as well as on my SlideShare page.

Thank you for reading!
Till next time!
Herwig Juster

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