Submitted to: Journal of Rheology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2002
Publication Date: 7/24/2002
Citation: BIRESAW, G., CARRIERE, C.J., SAMMLER, R.L. EFFECT OF TEMPERATURE AND MOLECULAR WEIGHT ON THE INTERFACIAL TENSION OF PS/PDMS BLENDS. JOURNAL OF RHEOLOGY. 2002.v.42(1).p.142-147. Interpretive Summary: Development of commercially important materials from agricultural products requires blending agricultural biopolymers with synthetic polymers. However, successful development of biomaterials requires a thorough understanding of the factors governing compatibility between agricultural biopolymers and synthetic polymers. Currently, this knowledge is almost non-existent and one approach at bridging this knowledge gap is to study well-characterized synthetic polymer blends. A study was conducted to determine the effect of temperature and molecular weight on the interfacial properties of synthetic polymer blends. The results indicate that both of these polymer properties are important in determining the interfacial tension and, hence, the compatibility of synthetic polymer blends. These findings will be applied to agricultural biopolymer/synthetic polymer blends to help accelerate the development of biomaterials from agricultural products.
Technical Abstract: The imbedded-fiber retraction (IFR) method was used to study the effect of temperature and PDMS molecular weight on the interfacial tension of PS/PDMS blends. The interfacial tension decreased with increasing temperature and analysis of the temperature dependence using a simple linear fit gave -d gamma/dT value of 0.058 +/ 0.010 dyn/cm-deg. Reported -d gamma/dT values of PS/PDMS blends are highly dependent on the molecular weights of the polymers and can have values that are <0, 0, or >0. Our interfacial tension values were independent of the molecular weight of PDMS and this was attributed to the molecular weights studied here being well above the entanglement values of both polymers. However, analysis of interfacial tension data from this work and the literature showed the following empirical relationship between apparent blend molecular weight, Mb, and interfacial tension of PS/PDMS blends with a correlation of 0.94: gamma 12 = gamma 0 + k2Mb**(-2/3), where gamma 0 = 7.3 +/ 0.3 dyn/cm; k2 = -517 +/ 41 (dyn/cm)(g/mol)**2/3.