Internal-friction spectra of poly(vinyl alcohol) with various molecular masses

• Published in: Polymer Science. Series A Vol. 57; no. 2; pp. 123 - 130
• Main Authors: Lomovskoy, V. A., Abaturova, N. A., Lomovskaya, N. Yu, Khlebnikova, O. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.03.2015; Springer Nature B.V
• Subjects: Alcohols; Chemistry; Chemistry and Materials Science; Crystal defects; Crystallinity; Dissipation; Hydration; Oscillations; Polymer Sciences; Spectra; Spectrometry; Structure and Properties; Polymer Science Series; Relaxation Transition; Loss Peak; Torsional Oscillation; Vinyl Alcohol
• ISSN: 0965-545X; 1555-6107
• DOI: 10.1134/S0965545X15020091

Dissipative effects in poly(vinyl alcohol) films with different molecular masses and degrees of hydration have been investigated with the use of relaxation spectrometry. The mechanical-loss peaks in the internal-friction spectrum reflect two relaxation transitions (α and β peaks) and one first-order phase transition (δ peak). It has been found that a decrease in the degree of hydration and an increase in the crystallinity of poly(vinyl alcohol) substantially raises the α-transition temperature. The α peak shifts to higher temperatures as the molecular mass grows. The position of the β peak in the spectrum is independent of the molecular mass, but changes with the degree of hydration. A sharp drop of the oscillation frequency in the region of the α transition and a smooth decrease in frequency in the temperature range of the β transition have been recorded. It has been found that the shear-modulus defect determined from the frequency in the region of the α transition is independent of the molecular mass and degree of hydration of poly(vinyl alcohol).