Material Properties of Model Biopolymer Gel Composites - Dependence upon Particle Size and Composition

摘要

Paniculate fillers have been used extensively as reinforcing agents, for instance in the rubber industry. Such reinforcement principles are also relevant to the food industry in relation to the production of new and novel foods. The work presented here concerns the measurement of large deformation mechanical properties of gelled biopolymer systems. There have been previous reports of measurements of the mechanical properties of gelled biopolymer mixtures. In many cases these tests are performed on phase separated systems of immiscible biopolymer mixtures, where the droplets of one phase grow in the matrix as the system cools down. In these systems it is difficult to control the size of the droplets of the included phase. In order that studies could be carried out on more well defined systems, model composites were developed with inclusions of well defined dimensions, such as glass beads or Sephadex particles. The work reported here is also concerned with model systems, where the inclusions are manufactured independently before being introduced to the matrix. However, in this case the included phase droplets consist of biopolymer gels, hence allowing control of the droplet dimensions while using biopolymer inclusions of relevance to the food industry. The stress-strain relationships of the composites were analysed in compression. Compression and tensile tests were also carried out under a confocal scanning laser microscope (CLSM), with the aim of observing any events occurring within the composite. To complement these investigations of the composites, ninety degree peel tests of the relevant gels were performed to give an indication of the interfacial adhesion between the gels. These data may then be related to the stress-strain characteristics of the composites.