Chemours in the Semicon Manufacturing Industry
Fluorocarabon co-monomers and crystallization characteristics
The structure of Teflon™ PFA HP was optimized to have the highest rated temperature performance, similar to PTFE. When this polymer solidifies, the pendant groups are excluded from crystal formation and larger PTFE type crystals are formed.
Teflon™ PFA HP Plus contains a precise comonomer, in type and amount to produce a slightly shorter pendant group. When this polymer crystallizes, the pendant groups, being precisely in a transition region of size, and are about half excluded and half included into crystal formation. Inclusion causes crystallization to take more energy, inhibits crystal growth and leads to smaller spherulites.
The resulting morphology has more disorder at the spherulite boundaries. The opportunity and probability increases for the long molecules to be involved in more than one crystalite. This produces a toughened mechanical structure.
Chemours investigations have determined that using shorter pendant groups outside of this transition size leads to complete incorporation of the pendent group into crystalization which reduces spherulite size, but also seriously degrades the physical properties of the polymer. This effect can readily be observed in another manufacturer's fully fluorinated terpolymer that uses a small pendant group to develop small spherulites.
Teflon™ PFA HP Plus provides a large increase in flex resistance, while retaining, to above 200 degrees centigrade, the physical properties of Teflon™ PFA HP.
The physical property comparison is shown in this chart. This combination of strength, elongation and flexural modulus will continue to allow the design and manufacture of components similar to those that have performed reliably over the past decade.