Thermal analysis of poly(2-methylpentamethylene terephthalamide)

Abstract

Poly(2-methylpentamethylene terephthalamide) (Nylon M5T) is a new high temperature aromatic polyamide developed by Hoechst Celanese. In this paper thermal properties of Nylon M5T chips, as well as as-spun and drawn fibers were studied by DSC, DMA, hot stage microscopy and WAXS. Tg of the fully amorphous Nylon M5T is 143~ when measured by DSC; T~ increases with crystallinity to 151~ The temperature dependence of the solid and melt specific heat capacities has also been determined. The heat capacity increase at the glass transition of the amorphous polymer is 103.9 J ~ mol -l. Tg by DMA for the as-spun fiber is 155~ for a drawn fiber is 180~ Three secondary transitions were observed by DMA in addition to the glass transition. These correspond to a local mode relaxation of the methylene groups at -120~ onset of rotation of the amide-groups at -65~ and the onset of the rotation of the phenylenegroups (at 630C). The erystallinity of Nylon M5T strongly depends on the rate of cooling from the melt. The isothermal crystallization data are melt temperature dependent: two-dimensional crystallization takes place when the samples are crystallized from higher melt temperatures, and this phase changes into a spherulitic structure during cooling to room temperature. Spherulitic crystallization occurs when lower melt temperatures are used. This polymer has three crystal forms as indicated by DSC, DMA and WAXS data. The crystal to crystal transitions are clearly visible when amorphous samples are heated in the DSC, or the DMA curves of as-spun fibers are recorded. It is experimentally shown that a considerable melting of the lower temperature crystal forms takes place during the crystal to crystal transitions. The equilibrium melting point as measured by the Hoffman-Weeks method, has been determined to be 339~

Polyamides – Still Strong After Seventy Years

“…This molecule is shown in Formula 10. Menczel et al [133] prepared polyamide from 2-MPMD and TPA: they found the polymer slow to crystallize on solidification and to possess three different crystal forms. Villasenor et al [134] prepared polymers of 2-MPMD with adipic acid (six carbons) and sebacic acid (ten carbons) and they observed quite different crystal structures from the simple polyamides 56 and 510 which also have a 5-carbon linear diamine chain.…”