The Versatility of Epoxy Resin Composites

Epoxy composites are a type of polymeric material that uses an epoxy resin to create a polymer matrix that is reinforced with fibers or other fillers. For this reason, there is an increasing need to investigate and predict the deformation behavior of epoxy-based composite materials under general load conditions. The deformation mode of epoxy-based compounds is influenced by the morphology of the epoxy matrix or by the filler loading. In this way, this article discusses the chemical composition and structural properties of the epoxy polymer as a matrix in composites; the effects of the morphological properties of epoxy and fillers on deformation behavior are also discussed, focusing on an overview of the literature dealing with damage mechanisms and rupture of epoxy-based composite materials and the criteria for predicting deformation behavior under general load conditions.

Epoxy-based composites are structurally versatile materials that can meet the requirements of many applications, but have insufficient fire resistance and therefore the addition of flame retardants (FR) is often necessary. This article provides an overview of recent developments in the design and application of halogen-free flame retardant epoxy resins and their fiber-reinforced composites. It focuses on both new FRs and scientific studies on epoxy flame retardant thermosets. First, we present the different types of high-performance matrix resins, their application ranges and the selected flame retardant formulations.

Next, the intrinsically flame protected epoxy resins are introduced. Advances in the design and application of inorganic and phosphorus, nitrogen and silicon-based FRs are described. Synergistic flame retardant blends are also presented. The results of studies on the impact of fiber reinforcement on the fire behavior of epoxy-based materials are given.

In addition, the influence of FRs on material properties is described. Finally, the state of the art of science and technology is discussed, along with future challenges in the flame retardancy of epoxy-based materials. Epoxy-based composites are widely used in the manufacture of automotive components, including radiator brackets, bumper bars, fenders, bonnets, roof panels, cover caps and many other exterior and interior body components. Synthetic fiber-reinforced epoxy polymer composites are increasingly used for aircraft structures due to their superior structural performance, such as long fatigue life, high stiffness, high strength and low density (Chowdhury et al.).

Epoxies consist of a base and a curing agent that are mixed in a certain proportion. Epoxy resin can be hardened with the addition of thermoplastic polymers. Products made with epoxy resins offer improved flexural strength and increased stiffness. Polyester resins demonstrate a short set time and high shrinkage causing stress, microcracking of the resin and imprecise adhesion of the resin to the fibers (micropores).

The polyester resin subjected to rapid hardening results in an exothermic reaction that can sometimes also lead to baking. In reality, this has a negative impact on the strength of a laminate. Polymerization occurred on the limited part of the carbon black surfaces to form a polymer of network structure that resided in the carbon black particles and thus greatly improved the dispersion of carbon black in the ink, as evidenced by the verification of ink droplet propagation on substrates of glass resin and circuit boards. To ensure that the strength of the product made of polyester resin and mats corresponds to the strength (flexural strength) of the product made of epoxy resins, it will be required to double its weight.

Although fabrics mainly provide rigidity to the product, a resin also plays an important role, since it mainly influences temperature resistance, fabric permeability and other characteristics of the finished product. In applications where high electrical conductivity is required, the transition from metallic materials to epoxies may be hampered by the low electrical conductivity of the epoxy. Other types of epoxy resin can also be mixed as a mixture and other components can be added to give the required properties. However, some formulated epoxy resins may be of concern with respect to toxicity due to the inclusion of other chemicals that are of greater toxicity.

Epoxies come in liquid, solid and semi-solid forms and are usually cured by reaction with amines or anhydrides. Unfortunately, because polyester resins cost half as much, they often find applications in the manufacture of products that should actually be made of other materials (e.g., epoxies). Epoxies are thermosetting resin polymers that result from curing liquid polymers into irreversibly hardened materials. The hardener (part B) and the base resin (part A) react together in an “addition reaction”, according to a fixed ratio.

Epoxies are widely used as structural adhesives because they are useful in a wide range of applications. Volatiles and moisture emitted during curing make polyimides more difficult to work with than epoxies or EC; special formulation and processing techniques have been developed to reduce.