Final answer:
The percent polymerization shrinkage of resins is the volume reduction from liquid to solid during curing, influenced by resin type and curing conditions, with epoxy resins among those which can vary widely.
Step-by-step explanation:
The percent polymerization shrinkage of resins refers to the contraction in volume that occurs when a liquid resin is transformed into a solid polymer. This shrinking is due to the closer packing of the polymer chains as the resin cures. Various factors can influence the degree of shrinkage, including the type of resin, the degree of cross-linking, and the polymerization temperature and pressure. While certain epoxy resins may display different shrinkage percentages, a typical value you might find for polymerization shrinkage in dental composites, which are often a mix of resin and inorganic filler, could range from 2% to 5%. This is a critical consideration in applications such as dentistry, where precision and stability are necessary.
Epoxy resins, for instance, can be cured with various co-reactants, influencing not only their mechanical properties but also their shrinkage. The structure and degree of polymerization will determine the extent of volume change from liquid to solid-state. Thermoplastics and thermosets, which make up a large proportion of commercial polymers, also exhibit different behaviors upon curing, with thermosets typically undergoing a higher degree of shrinkage due to their highly cross-linked nature.