Abstract
A mathematical model and computer simulations are used to describe the dynamics of thermally induced phase separation (TIPS) by spinodal decomposition for polymer blends (single quench and double quench) using the nonlinear Cahn-Hilliard theory and the Flory-Huggins-de Gennes free energy. The importance of TIPS is to enhance material properties such as toughness, impact resistance and elasticity. Therefore, controlling the morphology is a critical factor in optimizing performance. The numerical results for the single quench are consistent with known characteristics of phase separation by spinodal decomposition observed in polymer blends. The numerical results for double quenching replicate recently published experimental and numerical work. Under a double quench the numerical work shows that a critical quench depth exists before secondary phase separation occurs, the growth rate of the primary and secondary structures are dependent on domain size and early stage dynamics for the secondary structures, after the second jump, appears to follow the linear Cahn-Hilliard theory.
Highlights
A number o f industrial processes use the technique of phase separation to produce materials for everyday use [Leblond, 2002]
Key features are examined for a critical and an off-critical quench case to ensure that the one-dimensional model exhibits the same known trends for the early to the beginning o f the intermediate stage typical o f phase separation by spinodal decomposition (SD): (i) The evolution of the concentration fluctuations (ii) The evolution of the dimensionless structure factor (iii) The effect o f a shallow and deeper quench
The results presented in this chapter for the critical and off-critical quench case are for a value o f the dimensionless diffusion coefficient D* = 200 000 unless otherwise specified
Summary
A number o f industrial processes use the technique of phase separation to produce materials for everyday use [Leblond, 2002]. Applications include the formation of membranes, for separation processes [Mulder, 1996], the formation o f polymer dispersed liquid crystal films for electro optical devices [Doane, 1989; Nwabunma et a i, 2000], the production of high impact resistant materials [Chow, 1980; Utracki, 1991] in the plastics industry, coatings o f capsules [Leblond, 2002] in the pharmaceutical industry, and the production of low fat spreads [Harding et al, 1995] in the food industry. Research, both experimental and numerical, in understanding how phase separation occurs in polymer blends to control the morphology for specific applications is important.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
