n-Octadecane/alginate composites of varying mannuronate/guluronate ratios

Abstract

In situ shape-stabilized n-octadecane and alginate composite is a promising system for regulating temperature in ambient atmospheres. This composite could be created by crosslinking through ion-exchange reactions in aqueous solutions, without a separate encapsulation process. This process does not require organic solvents and additional materials for the sheath to prevent leakage of molten phase change materials. The composite films were prepared with 20 wt% of n-octadecane in the alginate matrix. Mechanical properties such as tensile strength, strain, and dynamic abrasion of the composite were investigated using different alginates with varying molecular weights and fractions of mannuronate and guluronate. The composites with higher molecular weight alginates tend to have increased tensile strength and dynamic abrasion properties. The results of tensile strength were found to be from 20.56 MPa to 36.10 MPa as the molecular weight of alginate were changed from 156,558 g/mol to 616,961 g/mol. The strains of the composites increased after crosslinking and were correlated with the guluronate fraction ratio of the alginates. This study demonstrates that the fraction ratio of mannuronate and guluronate plays a role in changing the mechanical and morphological properties of the composite before and after crosslinking. Further studies will be conducted to identify more delicate changes in properties through modification of alginate matrix. The study could be guidelines for selecting alginates as matrix materials to fulfill their required functions.