Research and development in the field of structural composites have explored various combinations of materials and methods to fulfill the load-bearing demands of industries such as automotive, aerospace, military, civil, and construction. Continuous fiber-reinforced composites based on epoxy are extensively used for primary load-bearing structural applications, owing to their unique characteristics and abilities compared to their counterparts with other polymers, thermosets in particular. With the introduction of nanotechnology and the resultant development of a new class of materials called nanomaterials, it has been observed that various properties of composites can be enhanced by the incorporation of these materials into composites. Different nanofiller materials have different effects on composite properties. This review focuses on a survey of literature published over the last two decades in which nanofillers were utilized to enhance the structural properties of epoxy-based fiber-reinforced composites. Composite modifications using carbon-based nanomaterials (fullerenes, carbon nanotubes, carbon nanofibers, graphene nanoplatelets, graphene oxide), nanosilica, nanoclay, etc. are discussed in detail. A brief summary of the use of a combination of nanofillers and attempts on the modification of reinforcement fabric is also presented.

The blending of conventionally available polymers has been extensively investigated over the past several decades and is considered as an alternative cost-effective method for the development of new polymers for specific applications. The blending of thermosets invites special attention as many of them can be used as matrices for composites for primary load-bearing applications. Cyanate ester and epoxy are two of the most popular thermoset polymers used across various industries such as aerospace, automobile, military, and civil sectors. Nevertheless, each of these resins has its limitations when used individually. Hence the blending of cyanate ester and epoxy is significant, for both commercial and academic interests. In this article, investigations on blends of cyanate ester and epoxy are reviewed based on their properties. Emphasis has been made on modifications of such blends resulting in improvements in mechanical, thermal, and other functional properties. Various applications employing these thermoset blends are discussed subsequently.

Fiber-reinforced polymer composites find extensive applications ranging from sporting goods to aircraft components. Nonetheless, the weak interlaminar properties of laminated composites impose challenges in the design of primary load-bearing structures. The incorporation of additives (e.g., particles, films, and fibers) can overcome these limitations, offering additional functionalities to composites. Interleaving in composites generally refers to the incorporation of materials at the interface between two fiber plies so as to improve various properties. Being a simple technique to integrate in the production line, interleaving is recognized as an industrially significant and commercially viable method of modifying laminated composites. In this Review, an effort to assess state-of-the-art research on interleaving is attempted. Methods, applications, and the influence of interleaves on various properties of composites are also discussed. Data from the most recent research works on interleaved composites are compiled in an attempt to aid and encourage further developments among industries and academia.

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