The morphology of poly(aryl-ether-ether-ketone)

Influence of carbon nanotubes on the thermal, electrical and mechanical properties of poly(ether ether ketone)/glass fiber laminates

“…Glass transition temperatures were determined as the mid-point of the baseline shift, and the crystallization and melting temperatures were taken as the peak maxima or minima in the calorimetric curves. The crystallinities were estimated by the relation: X m ¼ DH m;PEEK =ðDH m;PEEK Â w PEEK Þ, where DH m;PEEK is the heat of fusion of an infinitely thick PEEK crystal ($130 J/g) [30], DH m,PEEK is the apparent melting enthalpy of PEEK and w PEEK is the weight fraction of the polymer.…”

Crystallization and melting behavior in syndiotactic polypropylene: Origin of multiple melting phenomenon

“…In the studies of isothermal crystallization under quiescent conditions (i.e., crystallization is only a function of temperature), the multiple melting behavior of these semicrystalline polymers may be designated as being the result of one of the following reasons: the presence of two (or more) crystal modifications, 13,15 the presence of two (or more) crystalline morphologies, 28 the presence of two populations of crystal lamellae of different thicknesses, 35,38,40,[43][44][45] and the simultaneous melting, recrystallization, and remelting of the lamellae initially formed at the crystallization conditions. 22,34,37,39,42,46 Among these models, simultaneous meltingrecrystallization-remelting and the dual-lamellar population models seem to receive much attention in explaining the multiple melting behavior in various semicrystalline polymers that do not exhibit multiple crystal modifications upon crystallizing at the crystallization conditions studied. The simultaneous melting-recrystallization-remelting model first proposed by Holdsworth and Turner-Jones 22 hypothesizes that the primary lamellae formed at the crystallization temperature (T c ) undergo a partial melting process that gives rise to an observation of the lowmelting endotherm (usually observed at ca.…”

High performance PEEK/carbon nanotube composites compatibilized with polysulfones-I. Structure and thermal properties

“…where ∆H m,PEEK is the apparent melting enthalpy of PEEK, w PEEK is the weight fraction of PEEK in the composites and ∆H°m ,PEEK is 130 J/g, the theoretical value of enthalpy for a 100% crystalline PEEK sample [27].…”