Abstract
We examined the composition and molecular weight dependence of the glass transition temperature in detail for two types of hydrogen bonding miscible blends: poly (2-vinyl pyridine)/poly (vinyl phenol) (2VPy/VPh) and poly (4-vinyl pyridine)/poly (vinyl phenol) (4VPy/VPh). Regarding the functional form of the glass transition temperature, Tg, as a function of the weight fraction, we found a weak deviation from the Kwei equation for 2VPy/VPh blends. In contrast, such a deviation was not observed for the 4VPy/VPh blend. By relating the difference in the functional forms of Tg between the two blend systems to the difference in hydrogen bonding ability, we proposed a modified version of the Kwei equation. As for the interaction parameter, q in the Kwei equation, clear molecular weight dependence was observed for 2VPy/VPh blends: the lower the VPh molecular weight in the oligomer level, the higher the q values, suggesting the higher hydrogen bonding formability near the polymer chain ends than the middle part of a polymer chain.
Highlights
Polymer alloy is a widely used concept and still irreplaceable method to control the physical properties of polymer materials [1,2]
In the former case, the properties of each phase and the morphology and the interfacial energy often play an important role in determining their properties; [3,4] in the latter case the interaction between two components becomes important in addition to the intrinsic properties of the component polymers [5,6,7]
For miscible blends with strong attractive interaction, such as hydrogen bonds (H-bonds), the H-bond formation greatly modifies their properties compared to the blend without specific interaction [8,9,10,11]
Summary
Polymer alloy is a widely used concept and still irreplaceable method to control the physical properties of polymer materials [1,2]. Parameter q in the secondof term for polymer blends but copolymersinteraction: The parameter the second corresponds to the strength of the for inter-polymer stronger attractiveq in interaction is represented by thetolarger q value. Parameter is often utilized to quantitatively evaluate the term corresponds the strength of This the inter-polymer interaction: stronger attractive interaction is interaction strength between component polymers especially for H-bonding polymer evaluate blends. Equation (1) isk,the with the Gordon-Taylor (GT) expression [30] For the physical it as the ratio ofparameter the volume coefficients of been the pure components at Tg [30,31], and other meaning of the k, expansion two interpretations have suggested: One interpretation is tothe regard it is to it the as the ratio of the heat coefficients capacity increments ofcomponents the pure components [31,32].
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