Paper22-Surface_Interfacial_tension_PMMA_PnBMA_PS_J_Phys_Chem_74(3)_632_Wu(1970)

Paper22-Surface_Interfacial_tension_PMMA_PnBMA_PS_J_Phys_Chem_74(3)_632_Wu(1970)

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632 SOUHENG Wu Surface and Interfacial Tensions of Polymer Melts. 11. Poly( methyl methacrylate), Poly( n-butyl methacrylate) and Polystyrene by Souheng Wu Fabrics & Finishes Department, Experimental Station, E. I. du Pont de Nemours & Company, Wilmington, Delaware 19898 (Received June $8, 1969) The surface tensions of poly(methy1 methacrylate), poly(n-butyl methacrylate), and polystyrene, and the in- terfacial tensions of poly(methy1 methacrylate)-polyethylene, poly(n-butyl methacrylate)-polyethylene, poly- styrene-polyethylene, poly(methy1 methacrylate)-polystyrene, poly (n-butyl methacrylate)-poly(viny1 acetate), and poly(methy1 methacrylate)-poly(n-butyl methacrylate) systems have been measured by the pendant drop method in the temperature range of 100 to 180’. The parachor equation is found to be applicable to poly- (methyl methacrylate) and polystyrene, but not applicable to poly(n-butyl methacrylate). The equations of Fowkes and of Good and Girifalco are approximately applicable to polymer systems. However, the simplified forms of these equations are not applicable. The interfacial tensions between polymers are found to be quite high, arising mainly from the effects of the “mismatching” of the nature of the molecular forces and the chain stiffness of the polymer molecules. These two effects are included in the interaction parameter of Good and Girifalco, @ = (1 - 26) [(fidf2d) + (fl~f2p)1~z], where 6 is the fractional increment of the interfacial distance over the arithmetic mean of the intermolecular distances of the two phases,f,d is the fraction of the dis- persion-force component of the surface tension of phase i, andf,p is that of the polar-force component of phase i. The interfacial region between polymers is relatively discrete. The high interfacial tensions between polymers greatly influence various surface quantities such as contact angle, spreading coefficient, and work of adhesion. The temperature coefficient of the contact angle may be either positive or negative depending on the difference in the surface entropies of the two phases. The polymer having a lower surface tension does not necessarily spread (exhibiting zero contact angle) on the polymer having a higher surface tension. The work of adhesion between polymers can be smaller than the work of cohesion of either phase. The data provide an opportunity to examine polymer adhesion in the light of the interfacial properties of polymer systems. I. Introduction Knowledge of interfacial tension can provide informa- tion on the intermolecular forces and the interfacial structure between two phases. Although surface ten- sions of several molten p~lymersl-~ have been measured recently, the interfacial tensions between polymers have been virtually unknown. In a previous paper,l we reported the first interfacial tension measurements made on polymer systems, Le., polyethylene, polyisobutylene, and poly(viny1 acetate). The results enabled us to calculate various surface quantities such as spreading coefficient, contact angle, and work of adhesion, and
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This note was uploaded on 07/25/2011 for the course EMA 6580 taught by Professor Staff during the Spring '08 term at University of Florida.

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Paper22-Surface_Interfacial_tension_PMMA_PnBMA_PS_J_Phys_Chem_74(3)_632_Wu(1970)

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