Nonisothermal and isothermal crystallization kinetics of nylon‐12

Abstract

The isothermal and nonisothermal crystallization behavior of Nylon 12 was investigated using differential scanning calorimetry (DSC). An Avrami analysis was used to study the isothermal crystallization kinetics of Nylon 12, the Avrami exponent (n) determined and its relevance to crystal growth discussed and an activation energy for the process evaluated using an Arrhenius type expression. The Lauritzen and Hoffman analysis was used to examine the spherulitic growth process of the primary crystallization stage of Nylon 12. The surface-free energy and work of chain folding were calculated using a procedure reported by Hoffmann and the work of chain folding per molecular fold (r) and chain stiffness of Nylon 12 (q) was calculated and compared to values reported for Nylons 6,6 and 11. The Jeziorny modification of the Avrami analysis, Cazé and Chuah average Avrami parameter methods and Ozawa equation were used in an attempt to model the nonisothermal crystallization kinetics of Nylon 12. A combined Avrami and Ozawa treatment, described by Liu, was used to more accurately model the nonisothermal crystallization kinetics of Nylon 12. The activation energy for nonisothermal crystallization processes was determined using the Kissinger method for Nylon 12 and compared with values reported previously for Nylon 6,6 and Nylon 11.

Parameters characterizing the kinetics of the non-isothermal crystallization of polyamide 5,6 determined by differential scanning calorimetry

“…Therefore, it is concluded that the Ozawa model is not appropriate to provide an adequate description of non-isothermal crystallization kinetics of PA56. Similar results have been reported that the plots deviate from a good linearity with the Ozawa model [27,28]. The reason for that failure may be the inaccurate assumption of a constant cooling over the entire crystallization process.…”

Crystallization Behavior of Pebax–Graphene Composite Matrix with and without Supercritical Carbon Dioxide Assisted Polymer Processing Technique

“…The n values for neat Pebax lies between 2.42 to 2.70, indicating complex plate-like lamellar -spherulite aggregates nearing three-dimensional growths. Similar experimental results were reported by Wunderlich and McFerran et al for Nylon 12[50][51][52] . This suggests that the inclusion of graphene particles along with scCO 2 processing might have favoured heterogeneous nucleation through exfoliation of graphene particles and this exfoliation/interaction may have initiated a complex crystallisation process (where the adhesion of graphene might act as nuclei).This increasing n value suggests that graphene particles at a lower concentration may have aligned/well dispersed, where these particles act as nucleation sites, thereby increasing the rate of crystallization.However, a higher graphene ratio increases the nucleation sites but hinders the diffusion of polymer chains to the growing crystallite, which caused a decrease in the rate of crystallization.…”

Isothermal and nonisothermal crystallization kinetics of poly(ϵ‐caprolactone)

“…4 The crystallization behavior 4,5 and kinetics of polymeric materials have been reviewed previously. [6][7][8] In particular, the isothermal and nonisothermal crystallization kinetics of commodity and engineering polymers, such as isotactic polypropylene, [9][10][11][12] filled polypropylenes, 13,14 poly(ethylene terephthalate), 15,16 poly(trimethylene terephthalate), 17,18 poly(butylenes terephthalate), 19 nylon, [20][21][22] and poly(sulfides), [23][24][25] have been investigated in detail, and to much lesser extent, those of biopolymers, such as poly(lactic acid) [26][27][28][29] and poly(e-caprolactone) (PCL), [30][31][32][33] have been studied, although they have found wide commercial importance.…”