Phase separation and glass transition point versus composition diagrams of binary mixtures with covalent bond between components

Abstract

Abstract:The geometric thermodynamics approach has been used for investigation of the possible glass transition point versus composition curves and their dependence on various parameters for both mixtures and systems with covalent bond between the components (block-, graft-and star-polymers) in which phase separation is possible. Predicted relationships are compared with the experiment. Conditions have been determined under which glass transition hinders the liquid-liquid separation.

Crystallization-induced composition inhomogeneities in PVDF/PMMA blends

“…These particular conditions result in a large variety of supermolecular structures. [1][2][3][4][5][6][7][8][9][10] The actual morphology depends decidingly on the rates ratio between that diffusional displacement (v D ) and crystallization (v c ). This ratio, in turn, can be controlled by suitable choice of the crystallization temperature T c : the diffusion rate increases evenly with temperature, whereas the crystallization rate, particularly the spherulite growth rate, exhibits a maximum anywhere between the glass transition temperature T g and the equilibrium melting temperature T m 0 , and is zero outside this temperature range (Fig.…”

Interrelation of phase and relaxation behavior in polymer blends and block copolymers with crystallizable components

“…Let us consider each blend separately. The examples of the blends on which apparently superposition of demixing and glass transition has been first observed and studied are the oligomer blends and block copolymers of polyacrylate (PA) and polyethyleneoxide (PEO) [1][2][3][4] and the oligomer blends of polystyrene (PS) and polymethylphenylsiloxane (PMPS) [5,6]. Recently, studies have begun on the coupling of demixing and glass transition in the atactic PS solutions [7][8][9].…”

“…When the representative point is below the F point (although above the T O curve), we have coupling of demixing and glass transition related to transition of one of the phases, formed in the process of demixing, into the glasy state [1][2][3][4][5]. In the initial moment of time, development of concentration fluctuations occurs by Cahn mechanism with increasing fluctuation amplitude (Fig.…”

“…1). (Here, as in [2,3,5], we believe that glass transition occurs in a point rather than in a range, as is described below.) Further concentration growth at these halfcycles is retarded due to the substance transition from the liquid to glassy state.…”

“…After quenching from the one-phase region to the two-phase one, below F-point there forms a heat capacity jump characterizing transition of one of the phases in time from the liquid to glassy state ( Fig. 3) [3]. The time of half-transition into the glassy state is around 3 h, and the full transformation time is ca.…”