Curing agents are critical components of aqueous epoxy resin systems. Unfortunately, its uses and applications are restricted because of its low emulsifying yields. Epoxy resins are frequently used in electrical devices, castings, packaging, adhesive, corrosion resistance, and dip coating. In the presence of curing agents, epoxy resins become rigid and infusible. Eco-friendliness and mechanical functionality have emerged as vulcanization properties. Curing agents are used for surface modification, thermodynamic properties, functional approaches to therapeutic procedures, and recent advances in a variety of fields such as commercial and industrial levels. The curing agent has superior construction and mechanical properties when compared to the commercial one, which suggests that it has the potential for use as the architectural and industrial coatings. The thermal stability of cured products is good due to the presence of the imide group and the hydrogenated phenanthrene ring structure. Over the course of the projection period, it is anticipated that the global market for curing agents will continue to expand at a steady rate. The growth of the market is mainly driven by its expanding range in future applications such as adhesives, composites, construction, electrical, electronics, and wind energy. This review focused on the most recent advancements in curing techniques, emphasizing their thermal and mechanical properties. The review also presents a critical discussion of key aspects and bottleneck or research gap of the application of curing agents in the industrial areas.

The epoxy resin system: function and role of curing agents
    Abstract
    1 Introduction
    2 Purpose of curing
    3 Effects of curing
    4 Types of curing agents
        4.1 Aliphatic polyamines
        4.2 Modified aliphatic polyamines
        4.3 Aromatic amines
        4.4 Acid anhydrides
        4.5 Carboxylic acids
        4.6 Lewis acid and base curing agents
        4.7 Aminoplast and phenoplast resins
        4.8 Phenolic terminated resins
        4.9 Amine type curing agents
            4.9.1 Aliphatic
            4.9.2 Cycloaliphatic
            4.9.3 Aromatic
            4.9.4 Water-based
            4.9.5 Ultraviolet curing agent
            4.9.6 Photo curing agent
        4.10 Function of curing agents
    5 Epoxy curing agents
    6 Curing kinetics
    7 Curing reactivity
    8 Curing modification
    9 Curing agents in bio-based epoxy resin
    10 Mechanical properties of epoxy composites
    11 Conclusions
    Acknowledgements 
    References

• Tariq Aziz(School of Engineering, Westlake University, Hangzhou 310030, Zhejiang Province, China)
• Fazal Haq(Department of Chemistry, Gomal University, Dera Ismail Khan 29050, Pakistan)
• Arshad Farid(Gomal Center of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan, Pakistan)
• Li Cheng(College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China)
• Lai Fatt Chuah(Faculty of Maritime Studies, University Malaysia Terengganu, Terengganu, Malaysia)
• Awais Bokhari(School of Engineering, Lebanese American University, Byblos, Lebanon)
• Muhammad Mubashir(Advanced Membranes & Porous Materials Center, King Abdullah University of Science and Technology, Building 4 Level 4, Thuwal 23955‑6900, Saudi Arabia)
• Doris Ying Ying Tang(Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia)
• Pau Loke Show(Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia, Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection, Wenzhou University, Wenzhou 325035, China, Department of Chemical Engineering, Khalifa University, Shakhbout Bin Sultan St, Zone 1, Abu Dhabi, United Arab Emirates) Corresponding author