Ultrasonic characterization of the crystallization behavior of poly(ethylene terephthalate)

Abstract

Based on previous observations that the ultrasonic signals are sensitive to the crystallization of polymers (Tatibouet, J., Pich\ue9, L. Polymer 1991, 32, 3147), we have expanded our efforts to study the detail relationship between the ultrasonic signals and crystallization process in the present work. The nonisothermal and isothermal crystallization of virgin poly(ethylene terephthalate) (PET) and PET samples after degradation were studied by using a specially designed pressure-volume-temperature (PVT) device, with which an ultrasonic detector was combined. The results showed that the evolution of the ultrasonic signals not only can be used to probe the crystallization process, but also can qualitatively characterize crystallization rate, crystallinity, crystallite size and amorphous. DSC measurement was used to verify such results. Ultrasonic signals could be as a complementary tool to polymer chain movement and well be applied to characterize the crystallization behaviour. Furthermore, the ultrasonic measurement has the potential use to characterize crystallization of products in-line during processing (i.e., injection molding, microcoulding).Sur la base d\u2019observations pr\ue9c\ue9dentes indiquant que les signaux ultrasoniques sont sensibles \ue0 la cristallisation des polym\ue8res (Tatibouet et Pich\ue9, Polymer 1991, 32, 3147), on a poursuivi nos efforts afin d\u2019\ue9tudier en d\ue9tail la relation entre les signaux ultrasoniques et le processus de cristallisation. On a \ue9tudi\ue9 la cristallisation isotherme et la cristallisation non isotherme d\u2019\ue9chantillons de poly(t\ue9r\ue9phtalate d\u2019\ue9thyl\ue8ne) (PTE) vierge et d\u2019\ue9chantillons de PTE apr\ue8s d\ue9gradation au moyen d\u2019un dispositif pression volume-temp\ue9rature sp\ue9cialement con\ue7u et d\u2019un d\ue9tecteur \ue0 ultrasons. Les r\ue9sultats montrent que l\u2019\ue9volution des signaux ultrasoniques peut non seulement servir \ue0 suivre le processus de cristallisation, mais aussi permettre de caract\ue9riser qualitativement la vitesse de cristallisation, la cristallinit\ue9, la taille des cristallites et le caract\ue8re amorphe. On a utilis\ue9 des mesures de CCP pour v\ue9rifier ces r\ue9sultats. Les signaux ultrasoniques pourraient servir d\u2019outil compl\ue9mentaire pour le mouvement de la cha\ueene polym\ue8re et pourraient \ueatre utilis\ue9s pour caract\ue9riser le comportement \ue0 la cristallisation. De plus, la mesure ultrasonique peut \ueatre utilis\ue9e pour caract\ue9riser la cristallisation de produits en ligne pendant leur traitement (p. ex., moulage par injection et micromoulage).Peer reviewed: YesNRC publication: Ye