Stress relaxation and humidity dependence in sodium alginate-glycerol films. (December 2019)

• Record Type: Journal Article
• Authors: Giz, Ayşe Su; Aydelik-Ayazoglu, Sena; Catalgil-Giz, Huceste; Bayraktar, Halil; Alaca, B. Erdem
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 100(2019)
• Publication Date: 2019-12
• Subjects: Alginate -- Stress relaxation -- Glycerol -- Viscoelasticity -- Relative humidity -- Tensile stretcher; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2019.103374
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: The control of viscoelastic properties of alginate biopolymer that mimics the matrix properties of biological substrates plays an important role for the success of its biomedical applications. For this purpose stress relaxation behavior of glycerol plasticized sodium alginate films is characterized at room temperature as a function of the glycerol concentration ranging up to 40%. A series of experiments are thus conducted at relative humidity levels of 38 ± 1% and 51 ± 1%. The glycerol content is demonstrated to amplify the effect of humidity on relaxation profiles. In the case of 30% glycerol, normalized stress at the level of 65% is recorded at the end of the first 30 min at the low humidity level, whereas the corresponding value drops to 8% with increased humidity. Alginate films with no glycerol content exhibit much higher normalized stresses of 89% and 73% at low and high humidity levels, respectively. In addition, stress relaxation is observed to continue well beyond the first 30 min, especially for glycerol concentrations lower than 30%, where 9-hour parameters for a stretched exponential Kohlrausch – Williams – Watts function are reported demonstrating the importance of relaxation time for successful modeling. Graphical abstract: Image 1 Highlights: Glycerol and increased humidity contribute to stress relaxation of alginate films. Glycerol content significantly amplifies the effect of humidity. Viscoelastic modeling must consider glycerol concentration and humidity level. Modeling of long-term stress relaxation cannot rely on short-term parameters.