Standards Development

Scope

This standard is a classification of measurement methods for Prepreg Tack.

Purpose

Recently, there has been a growing interest in materials used to maximize the effect in areas requiring lightweight application. Carbon composites have recently attracted attention in various industrial fields because of their excellent properties, such as high specific rigidity and specific strength, corrosion resistance, and light weight.

Prepregs are composite materials in which a reinforcement fiber is pre-impregnated with a thermoplastic or thermoset resin matrix in a certain ratio. Prepregs have unique properties as they are cured under high temperatures and pressures. Generally, prepregs are being applied to manufacture composite parts.

Current commercially available prepregs often show significant variations in tack strength, from point to point within a sheet and from sheet to sheet. Such inconsistencies can lead to void formation in the final composites laminate. Therefore, a clear standard for determination of prepreg tack is required. Generally, a method to determine the prepreg tack is ‘Thumb’ evaluation; however this method has a problem for quantifying tack due to its low reliability and different feelings each person. Also, this method does not necessarily achieve the same results when the test parameters are changed. The other methods for measuring prepreg tack are Ball Tack (ASTM D3121), Loop Tack (ASTM D6195), and Probe Tack (ASTM D2979). The above methods have different test standards. The prepreg tack is measured by the force when each jig is separated from the prepreg surface. However, in the case of ball tack and loop tack are difficult to obtain reliability and objectivity data, and Probe Tack can measure only the local area. Therefore, in order to solve the above problem, it is necessary to develop the standard for determination of prepreg tack objectively and quantitatively.