Synergistic effect of MWCNTs functionalization on interfacial and mechanical properties of multi-scale UHMWPE fibre reinforced epoxy composites
Introduction
Ultra-high molecular weight polyethylene (UHMWPE) fibre reinforced composites have received great attentions due to their extraordinary properties such as light weight, high specific strengths and moduli, ease of fabrication, bio-compatibility, and bio-stability and ballistic performance arising from fibre phase. However, the non-polar and chemical inertness of UHMWPE fibres surface inherently result in poor adhesion properties with most polymers [1], [2], [3], [4]. Improved interfacial adhesion could enhance various properties of UHMWPE composites including mechanical properties and even open up new applications for this family of composite materials [5]. As mentioned, in spite of the aforementioned drawback related to UHMWPE fibre, this fibre is still increasingly used in different applications including aerospace, military, and sporting goods [6], [7], [8]. There are two general approaches to overcome the issues with adhesion and improve the interfacial properties. This is either by increasing the surface energy of the fibre through surface treatment or decreasing the surface energy of the matrix through inclusion of nano-reinforcement [8], [9], [10]. The polar functional groups have been introduced onto the fibre surface via various treatment techniques; for instance, plasma treatment, chemical etching, corona treatment, radiation-initiated graft polymerization and chemical grafting [4], [11], [12], [13], [14]. In addition to this, the polymer matrix can be modified through incorporation of different nano-reinforcements, such as graphene nanoplatelets (GnPs), carbon nanofibres (CNFs), multi-walled carbon nanotubes (MWCNTs), and nanoclay [15], [16], [17], [18], [19], [20]. theoretical and experimental results found in literature, have revealed that carbon nanotubes possess outstandingly high elastic modulus, greater than 1 TPa (the elastic modulus of diamond is 1.2 TPa) and stated strengths 10–100 times higher than the strongest steel at a fraction of the weight [21]. These modification and surface treatment approaches cause changes in surface energy, wettability, roughness, and interfacial interactions leading to enhancement of the fibre-matrix adhesion [14], [22], [23]. However, both fibre treatment and matrix modifications are usually accompanied by some undesirable problems. For example, among different fibre surface treatments, chemical grafting is known as an elegant approach to provide composite with a strong interface through chemical bonding. However, chemical grafting, particularly at high density of grafting, could deteriorate fibre properties such as tensile properties and consequently affects composite ultimate properties adversely [9], [11], [24], [25], [26], [27]. On the other hand, matrix modifications resulting in best mechanical properties do not normally occur at very low nanofiller contents. In fact incorporation of higher contents into polymer matrices often requires proper approaches including high power of ultrasonication, surface modification and use of surfactant and dispersing medium to achieve uniform dispersions and prevent nanofillers from being aggregated [28], [29], [30], [31], [32].
Despite many reports on the effect of UHMWPE fibre treatments on composites properties, there are few studies related to improvement of interfacial adhesion between UHMWPE fibre and epoxy through modifications of both fibre and epoxy matrix. In our previous study [11], compared with UHMWPE fibre/epoxy, inclusion of 1 wt% of pure CNFs alongside glycidyl methacrylate (GMA)-treated UHMWPE fibre (5 wt%) in epoxy increased tensile strength and modulus ∼52.3% and ∼26.2%, respectively. Sadeghi et al. [33] showed that the interfacial shear strength (IFSS) between epoxy and UHMWPE fibre grafted with ∼11%, ∼25%, and ∼40% GMA showed ∼126%, ∼195%, and ∼220% enhancements, correspondingly. Additionally, they exhibited that tensile strength of ∼11% GMA-grafted UHMWPE fibre-epoxy composite revealed only ∼10% enhancement, compared with untreated one. According to Jiang et al. [34], an atmospheric pressure plasma jet treatment on UHMWPE fibre could increase IFSS of UHMWPE reinforced epoxy composites by ∼330%. Li et al. [27] reported that the highest amount of improvement in IFSS (∼271%) of UHMWPE fibre/epoxy was observed for the samples reinforced with UHMWPE fibre grafted with methacrylic acid and acryl amide (UHMWPE-co-pMAA-pAM fibres). Zhang et al. [35] showed that the incorporation of ∼1 wt% nano-SiO2 during gel-spinning process could improve IFSS of UHMWPE/SiO2 composite fibres by ∼148% compared with untreated one. Zhamu et al. [36] showed that inclusion of 0.3 wt% reactive graphitic nanofibres to UHMWPE fibre/epoxy composite result in ∼34% and ∼27% increase in critical load (initial debonding load) and peak load, respectively. In addition to this, ∼116% and ∼107% increases in critical debonding energy and pull-out energy were observed, respectively. Among various nanofillers, carbon nanotubes are repeatedly used to improve properties of composites through fibre treatment or matrix modification [10], [37], [38], [39], [40].
In this work, simultaneously, both UHMWPE fibre and MWCNTs were chemically modified so that the compatibility of both fibre and matrix with MWCNTs is improved. It was hypothesized that aminated MWCNTs could react with epoxy functional groups of both GMA-treated UHMWPE fibre at interface and epoxy matrix, as well. Furthermore, as mentioned earlier, it was argued that adverse effects associated with fibre and matrix modifications could be minimized by employing simultaneous modifications but at less intensive levels. Therefore, herein, we have used a minimum amount of chemical grafting of fibre e.g., 5 wt% combined with a low loading of MWCNTs e.g., 0.2 wt% to ensure that the final properties of composites would not be affected by negative consequences of both fibre and matrix modifications. For this purpose, effect of the functional groups attached on UHMWPE fibres and MWCNTs on wettability, interfacial adhesion, mechanical properties and morphology of multi-scale epoxy composites were examined using dynamic contact angle, microbond, tensile test, and scanning electron microscopy techniques.
Section snippets
Materials
Epoxy resin and the curing agent, used in this study, were Araldite LY 5052-1 and Aradur 5052-1 grade, correspondingly (Huntsman Co., Switzerland). MWCNTs were supplied by Jiang Youg Trade Co. China with 30–50 μm length and 5–25 nm diameter. The UHMWPE fibre was Dyneema SK60 (DSM Co., Netherlands) with a fibre diameter range of 12–21 μm. Dyneema SK60 has a tensile strength of 2.7 GPa and a density of 0.97 g/cm3. Dicumyl peroxide (Merck), dibenzoyl peroxide (Merck), sodium hydroxide (98%,
Characterization of chemical modifications
According to the proposed mechanism represented in Fig. 3a, thermal decomposition of dicumyl peroxide generates unstable free radicals, which are quickly in situ-stabilized by producing of 2-aminoethanethiol radicals. These thiol end radicals were then grafted on the MWCNTs surface, leading to amino-functionalize MWCNTs. Amino-functionalization of MWCNTs was investigated by FTIR analysis (Fig. 3b). As shown in this figure, pure MWCNT exhibits some absorption peaks at 2980–2840 cm−1, 3400 cm−1,
Conclusion
In this study, epoxy matrix was reinforced with chemically modified both UHMWPE fibre and MWCNTs. Once multi-scale composites were produced, their interfacial properties including wettability, IFSS as well as mechanical properties were evaluated. The summary of findings are as follows:
- (i)
The polarity and surface energy of GMA modified UHMWPE fibres were enhanced by 85% and 52%, respectively, compared with un-treated fibre. The a-MWCNTs uniformly dispersed into epoxy matrix not only reinforced the
References (60)
- et al.
Reinforcement of bulk ultrahigh molecular weight polyethylene by fluorinated carbon nanotubes insertion followed by hot pressing and orientation stretching
Compos. Sci. Technol.
(2015) - et al.
The wear-resistance of composite depending on the interfacial interaction between thermoplastic polyurethane and fluorinated UHMWPE particles with or without oxygen
Compos. Sci. Technol.
(2015) - et al.
Chemical grafting for improved interfacial shear strength in UHMWPE/PVA-hydrogel fiber-based composites used as soft fibrous tissue replacements
Compos. Sci. Technol.
(2013) - et al.
Catechol and epoxy functionalized ultrahigh molecular weight polyethylene (UHMWPE) fibers with improved surface activity and interfacial adhesion
Compos. Sci. Technol.
(2015) - et al.
Conducting polymer/carbon particle thermoelectric composites: emerging green energy materials
Compos. Sci. Technol.
(2016) - et al.
Gel-spun fibers from magnesium hydroxide nanoparticles and UHMWPE nanocomposite: the physical and flammability properties
Compos. Part B Eng.
(2013) - et al.
Cosmic radiation shielding tests for UHMWPE fiber/nano-epoxy composites
Compos. Sci. Technol.
(2009) - et al.
Treatment of functionalized graphitic nanofibers (GNFs) and the adhesion of GNFs-reinforced-epoxy with ultra high molecular weight polyethylene fiber
Compos. Part A Appl. Sci. Manuf.
(2007) - et al.
Recent advances in fiber/matrix interphase engineering for polymer composites
Prog. Mater. Sci.
(2015) - et al.
Mechanical property characterization of carbon nanofiber/epoxy nanocomposites reinforced by GMA-grafted UHMWPE fibers
Compos. Part B Eng.
(2015)
Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting
Appl. Surf. Sci.
Ultra-high-molecular-weight polyethylene fiber reinforced dental composites: effect of fiber surface treatment on mechanical properties of the composites
Dent. Mater.
Nano-epoxy resins containing electrospun carbon nanofibers and the resulting hybrid multi-scale composites
Compos. Part B Eng.
Mechanical properties of graphene nanoplatelet/carbon fiber/epoxy hybrid composites: multiscale modeling and experiments
Carbon
Role of processing on interlaminar shear strength enhancement of epoxy/glass fiber/multi-walled carbon nanotube hybrid composites
Carbon
Improved mechanical properties of an epoxy glass–fiber composite reinforced with surface organomodified nanoclays
Compos. Part B Eng.
Advances in the science and technology of carbon nanotubes and their composites: a review
Compos. Sci. Technol.
A review of strategies for improving the degradation properties of laminated continuous-fiber/epoxy composites with carbon-based nanoreinforcements
Carbon
Enhanced interphase between epoxy matrix and carbon fiber with carbon nanotube-modified silane coating
Compos. Sci. Technol.
Radiation synthesis of a new amidoximated UHMWPE fibrous adsorbent with high adsorption selectivity for uranium over vanadium in simulated seawater
Radiat. Phys. Chem.
Surface modification of ultra high molecular weight polyethylene fibers via the sequential photoinduced graft polymerization
Appl. Surf. Sci.
Effect of surfactant treatment on thermal stability and mechanical properties of CNT/polybenzoxazine nanocomposites
Compos. Sci. Technol.
Epoxy functionalized multi-walled carbon nanotubes for improved adhesives
Carbon
Effects of surfactant treatment on mechanical and electrical properties of CNT/epoxy nanocomposites
Compos. Part A Appl. Sci. Manuf.
Effects of silane functionalization on the properties of carbon nanotube/epoxy nanocomposites
Compos. Sci. Technol.
Effects of carbon nanotube alignment on electrical and mechanical properties of epoxy nanocomposites
Compos. Part A Appl. Sci. Manuf.
Influence of ethanol pretreatment on effectiveness of atmospheric pressure plasma treatment of polyethylene fibers
Surf. Coat. Technol.
Experimental study on adhesion property of UHMWPE fiber/nano-epoxy by fiber bundle pull-out tests
Compos. Sci. Technol.
The effect of adding carbon nanotubes to glass/epoxy composites in the fibre sizing and/or the matrix
Compos. Part A Appl. Sci. Manuf.
Interfacial shear strength of a glass fiber/epoxy bonding in composites modified with carbon nanotubes
Compos. Sci. Technol.
Cited by (90)
Bio-inspired copper ion-chelated chitosan coating modified UHMWPE fibers for enhanced interfacial properties of composites
2024, International Journal of Biological MacromoleculesBiofunctionalization of natural extracts, trends in biological activity and kinetic release
2023, Advances in Colloid and Interface ScienceMulti-length scale strengthening and cytocompatibility of ultra high molecular weight polyethylene bio-composites by functionalized carbon nanotube and hydroxyapatite reinforcement
2023, Journal of the Mechanical Behavior of Biomedical MaterialsAdjusting the interfacial adhesion via surface modification to prepare high-performance fibers
2023, Nano Materials Science