Crystallization of polymers. Part I : Polydispersed polymers quenched from the liquid state

Abstract

Résumé. 2014 Nous avons mesuré les longues périodes de plusieurs polymères trempés à partir de l'état fondu. Nous donnons la relation entre la longue période mesurée dans la phase semi-cristalline et la rigidité de la chaîne dans l'état liquide juste avant la cristallisation. On montre que la mesure des longues périodes d'échantillons préala-blement recuits à l'état fondu, à différentes températures, et pendant des temps différents, nous permet de remonter à un temps de relaxation des pelottes dans le fondu.Abstract. 2014 The long spacing L of several crystalline polydispersed polymers quenched from the liquid state at various temperatures has been measured. We correlate the variations of the long period L with the variations of the dimension r0 > of the ideal coils in the melt just before the crystallization. The relationship between L and the rigidity C of the liquid chain is given. The annealing of the melt at different temperatures and for different times, and the subsequent crystallization allow us to measure the relaxation time of the coils in the liquid state.

Crystallization of quenched polyethylene. Part III : Mixtures of fractions

“…This effect has been analysed in Parts I [1] and II [2]. (1). In quenched polydispersed commercial materials, in general the long period is believed to be independent of the molecular weight and its distribution.…”

“…Therefore, these relations imply that in quenched fractions the long period is a function of the melt temperature, just before crystallization. This effect has been analysed in Parts I [1] and II [2]. (1).…”

“…It should be noted that, for high molecular weight, the lamellae are highly curved and that the spherulitic organization is highly deteriorated [28]. 4M,,) and the large deviation from the linear curves for the fractionated samples as given by relations (1) and (2). The larger the polydispersity, the larger the deviation.…”

“…Introduction. -We have reported recently [ 1,2,3] the correlations existing between the solid state and the melt of polyolefines. In quenched polyethylene fractions of molecular weight M M*, the long period L varies as the end-to-end distance ro of the coils in the liquid state, and is of the same order of magnitude.…”

“…This fact is to be related to the independence of the growth rate with the molecular weight for high molecular weight materials [7] and to the independence of the density and surface energy with MN for materials having a number molecular weight higher than a critical value of the order of M * [8]. For (2) and Slutsker (1,3) analysis as a function of the square root of the molecular weight. effect shows that the polydispersity decreases somewhat the regularity of the lamella structure.…”