Unsaturated Polyester Resin Nanocomposites: An Overview

Unsaturated polyester resins (UPRs) including ortho, iso, bisphenolic and vinylester are the most widely used thermosetting polymeric resins in the form of coating and matrix in the industry, making up around three quarters of all thermoset resins used in the industry. The major advantages of UPRs include low cost, low viscosity, good mechanical properties and chemical resistance, lightness, low moisture absorption, curing without the formation of volatiles, and simple processing with conventional processing methods. UPRs have been used  in a wide variety of applications including composites, coatings, sealants, chemical and fuel storage tanks, and high-performance components for the construction, marine and land transportation, and electrical industries. However their high shrinkage after curing, low fire resistance and  environmental pollution due to volatile styrene have limited their use. In the past decades, the use of nanofillers in polymers to form polymer nanocomposites has attracted attention due to the ability to combine the advantages of nanofillers and polymers. In addition, the development of nanocomposites of UPRs has made these resins desirable for current and emerging applications that require high specific strength, electromagnetic shielding and improved thermal stability. However, due to the high tendency of nanoparticles to agglomerate, the main challenge in the preparation of nanocomposites is to achieve a homogeneous distribution of nanofillers in the matrix, which is the main key to achieving the desired properties. Therefore, the aim of this study is to evaluate extensive research in this field and to recognize the existing limitations related to the manufacture of these nanocomposites. For this purpose, firstly, the types of nanofillers are categorized and the mixing of nanofillers with UPRs is introduced. Then, the effect of adding nanofillers on the properties of these nanocomposites is reviewed according to the research works done in this field.