DSC and X-ray study of structure and phase transitions of low molecular compounds incorporated into crazes

Abstract

Orientation, phase composition and phase transitions of a series of long chain low molecular weight compounds (LMC), such as heneicosane, cetyl alcohol, normal fatty acids, introduced into porous structure (crazes) of polymeric matrices oriented in liquid medium have been studied by means of DSC and SAXS techniques. Different types of LMC crystallites orientation in crazes of polymeric matrices have been observed. LMC phase state in crazes is shown to be characterized by higher stability of high-temperature polymer midifications. LMC melting temperature in crazes usually decreases as well as melting enthalpy (heat) and entropy. The origin of LMC properties changes observed is high dispersity (40-100nm) of LMC particles in crazes resulting in a marked growth of polymer/LMC interface influence on principal thermodynamic parameters of the systems studied.

Specific features of structure and properties of solutions, melts and solid states of polymers in confined nanometric volumes

“…Heats of melting (1) and IR dichroic ratios of an absorption bans at 2925 cm 71 (2) of TDA introduced into a crazed PETP matrix vs. the TDA content in the polymer. 208 nucleation and crystallite growth stages in confined volumes where formation of crystallites becomes easier, whereas their growth is restricted by a small (nanometre-sized) space. The comparative analysis of the effects of spatial restrictions on crystallization of polymers and low-molecular-mass compounds shows that the above listed changes in the thermodynamic characteristics are common to both high-and low-molecular-mass compounds.…”