Fillers are used in sealant products to reduce the cost of materials, and to act as both a rheology modifier and reinforcement agent. Many materials are used as fillers and differ in both effectiveness and cost. Since the filler may be as much as 40% of the weight of a formulation, it can have a significant effect on the rheological properties of the sealant material.
This article describes how rheological experiments can be used to simulate the application of sealant coatings and to determine their in-use performance. This has considerable value in assessing the applicability and effect of particular fillers, and in optimizing formulation of the product. A number of experiments were performed on sealant samples containing stearic acid modified magnesium carbonate as a filler, and the ability of rheological testing to discern differences between samples of similar composition was shown.
A sealant has to resist fluctuations in temperature and be both cost-effective and environmentally friendly.