Glass transition and melting behavior of poly(oxy-2,6-dimethyl-1,4-phenylene)

Thermodynamics and kinetics of crystallization of flexible molecules

“…First experiments of this polymer by standard DSC revealed already that there was no glass transition below the melting region, that is, the %30% crystalline sample had a 70% RAF content. 81 Annealing the sample below the melting peak improved the crystals somewhat, as expected, but it also slowly melted the crystals! The T g of a bulk-amorphous sample is not far below the melting temperature, but increases sufficiently when in the RAF phase, as indicated by the TMDSC experiments in Figure 7(d).…”

“…69,80 (d) Poly(oxy-2,6-dimethyl-1,4-phenylene) (PPO). 81,82 A final possibility is the absence of a mobile-amorphous phase below the melting temperature, as illustrated for poly[oxy-1,4-(2,6-dimethylphenylene)] (PPO) and seen in Figure 7(d). First experiments of this polymer by standard DSC revealed already that there was no glass transition below the melting region, that is, the %30% crystalline sample had a 70% RAF content.…”

“…The glass transition is sufficiently high that any nucleation leads immediately to the formation of the RAF below its glass transition and stops any further crystallization. 81 To crystallize PPO, the glass transition needs to be lowered by the addition of a diluent. On orienting fibers, one expects orientation not only of the crystals, but also the mobile-amorphous phase.…”

New crystalline polymers: poly(2,5-dialkyl-1,4-phenylene oxide)s

“…[21] However, once the crystal part had been totally melted, recrystallization never occurred during slow cooling (T c and T m2 not detected) or after annealing in the temperature range between T g (209 8C) and T m1 . [21] Since thermoplastic polymers are mainly used as melt-moldings and the moldings of P-2,6-Me 2 P show non-crystallinity, P-2,6-Me 2 P is regarded as an amorphous polymer.…”

D.m.a. and d.s.c. investigations of the β transition of poly(vinylidene fluoride)

“…A fraction of rigid amorphous component as high as 70% has been accordingly calculated for stiff polymers, i.e. poly(oxy-2,6-dimethyl-l,4-phenylene) (PPO) [18], poly (thio-l,4-phenylene sulfide) (PPS) [19], poly(ether ether ketone) (PEEK) [20][21], and poly(ethylene terephthalate) (PET) [21]. The crystal-amorphous interfacial fraction in flexible polymers, e.g.…”