Modification of Renewable Cardanol onto Carbon Fiber for the Improved Interfacial Properties of Advanced Polymer Composites

Abstract

A facile in situ polymerization was developed for grafting renewable cardanol onto the carbon fiber (CF) surfaces to strengthen the fiber-matrix interface. CFs were chemically modified with hydroxyl groups by using an aryl diazonium reaction, and then copolymerized in situ with hexachlorocyclotriphosphazene (HCCP) and cardanol to build cardanol-modified fibers (CF-cardanol). The cardanol molecules were successfully introduced, as confirmed using Raman spectra and X-ray photoelectron spectroscopy (XPS); the cardanol molecules were found to increase the surface roughness, energy, interfacial wettability, and activity with the matrix resin. As a result, the interlaminar shear strength (ILSS) of CF-cardanol composites increased from 48.2 to 68.13 MPa. In addition, the anti-hydrothermal ageing properties of the modified composites were significantly increased. The reinforcing mechanisms of the fiber-matrix interface were also studied.Polymers 2020, 12, 45 2 of 11 important factors, such as interfacial wettability, the introduced mechanical interlocking, and the formed chemical bonding at the interface [26]. In a word, the formed chemical bonding between CFs and the matrix resin promotes the largest share of composite interface improvements.Cardanol, which is extracted from cashew nut shell liquid using a double vacuum distillation technique, is known as a significant agricultural renewable resource [27][28][29][30]. Cardanol, with a reactive phenolic moiety and an unsaturated C15 hydrocarbon chain, can easily form cross-linked structures under a thermal curing treatment, which is viewed as a robust platform for further grafting for multifunctional applications in the fields of coatings, biocomposites, curing agents, and antioxidants owing to its sustainability, low cost, large availability, and bactericidal properties [31,32]. We believe that this is the first report of a new hierarchical reinforcement that has been surface-modified with cardanol for changing the surface/interface properties. Herein, we developed a high-efficiency strategy for functionalizing CFs with renewable cardanol and studied the interfacial behaviors and the mechanisms of reinforcing, as well as toughening the interface for unsaturated polyester resin (UPR) composites. The active sites were built onto CF surfaces by using the diazonium technique, avoiding a strong acid oxidation treatment. As an agricultural renewable resource, cardanol is cost-effective, highlighting the potential of the strategy for practical applications. Moreover, the chemical bonding easily formed at the interface between CF-cardanol and UPR during the curing process, which played the most important role in enhancing the composite's interfacial properties. The preparation and characterization of CFs functionalized with cardanol and the resultant composites were fully studied, as discussed in this work.

Hybrid Electromagnetic Nanomaterials Based on Polydiphenylamine-2-carboxylic Acid

“…Modern technology demands the creation of new generation materials with a range of required properties. In recent decades, polymer nanocomposites have become a prominent area of current research promoted by rapid developments in both polymer science and nanotechnology [ 1 , 2 , 3 , 4 , 5 , 6 ]. Polymer nanocomposites have unique physicochemical properties owing to synergistic performance derived from each component.…”

Diazonium Modification of Inorganic and Organic Fillers for the Design of Robust Composites: A Review

“…Modified carbon fibers were used as a component of a composite with a polyester resin [46]. The filler was modified using 4-hydroxyl benzene diazonium salt and then copolymerized in situ with hexachlorocyclotriphosphazene and cardanol.…”

“…1 Structure of the diazonium salt where R stands for substituents while A stands for charge-balancing anion Adapted from reference [12] with permission of the Royal Society of Chemistry Fig. 2 Scheme of surface modification using diazonium salts (for simplicity, the monolayer was used in the rest of the publication Adapted from reference [12] with permission of the Royal Society of Chemistry Carbon black Phenol-formaldehyde resin Covalent [45] Carbon fiber Polyester resin Non-covalent [46] Cellulose Covalent [47] Epoxy resin Covalent [48] Carbon nanotubes Caprolactone Covalent [49] Epoxy resin Covalent [50] Polyaniline Covalent [51] [52]…”

Mussel-Inspired Co-Deposition of Polydopamine/Silica Nanoparticles onto Carbon Fiber for Improved Interfacial Strength and Hydrothermal Aging Resistance of Composites

“…Carbon fibers (CFs) have become the ideal reinforcements for advanced polymer composites, which are widely used as structural materials in engineering applications of the automotive and aerospace industries, owing to their high strength-to-weight ratio, excellent heat or chemical resistance [1][2][3][4]. It is widely accepted that fiber-matrix interface plays a key role in connecting CFs with the hot resin and ensuring efficient stress transfer, which is critical factor for overall properties of polymer composites [5][6][7].…”