Wide‐angle x‐ray scattering study of heat‐treated peek and peek composite

Abstract

We report the results of a study of poly(etheretherketone) (PEEK) neat resin and APC‐2 carbon fiber composite samples which were processed from the melt and then subjected to a variety of thermal treatments. Wide‐angle x‐ray scattering was used to study the effects of quenching and annealing treatments. For both neat resin and composite, annealing resulted in perfection of the crystalline microstructure. In addition to the crystalline and amorphous scattering usually observed, disorder is frozen‐in by fast cooling after heat treatment. The disordered component is detected as an additional low‐angle scattering peak at 14 degrees, well separated from the crystalline reflections, and is observed in low molecular weight material synthesized in our laboratory, and in commercially available neat resin PEEK and APC‐2 carbon fiber composite samples. When disordered material was subsequently heated above the glass transition, and then cooled very slowly, only the crystalline and amorphous scattering remained. Application of stress also resulted in formation of the disorder in the necked down regions of samples drawn in tension, suggesting that residual stresses may occur as a result of rapid cooling after heat treatment.

Structure-property relationships in commercial polyetheretherketone resins

“…and Table ) as processing conditions (thermal history) were similar between resins and grades (Tables S1, Supporting Information). The decreased crystallite size of STD as compared with HF grades was also most likely due decreased chain mobility in higher molecular weight resins, but may have also been influenced by other factors, such as paracrystallinity .…”

Prediction and analysis of nonisothermal crystallization of polymers

“…(23) and (24) ture of the spherulites is achieved through a hetwere being used in modelling nonisothermal polyerogeneous process than through a homogeneous mer crystallization and in predicting the evolution one. 28,29 In other words, the absolute crystallinity of absolute crystallinity as a function of cooling at equilibrium under heterogeneous nucleation, history. X cϱ,het is higher than that under homogeneous nucleation, X cϱ,hom .…”

“…For instance, the value given for PP is not method used in their determination. 6,12,27,28 Nevprecisely defined. 6 Furthermore the value of g s ertheless, the experimentally determined values and g e as experimentally determined by Blundell of C ij give a good correlation between the experiand Osborn 26 for PEEK and PET lead to a value mental and modelled evolution of crystallinity as of g 2 s g e , higher than what is usually encountered a function of time for PEEK, POM, PET, and PP with polymer crystals.…”

Crystallization of poly(aryl‐ether‐ether‐ketone): Effect of thermal history of the melt on crystallization kinetics

“…For this reason control of heat treatment processes during fabrication can greatly influence the performance of the end product. Consequently, a great deal of research has been performed observing the development of crystallization (6)(7)(8)(9)(10)(11)(12)(13)(14) and in studying the factors which are important in controlling the rate of crystallization (1 5-23), the final degree of crystallinity (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34), and morphology (35)(36)(37)(38).…”