The Effect of Cellulose Nanocrystal Coatings on the Glass Fiber–Epoxy Interphase (original) (raw)
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An Experimental Study on Swelling of Cellulose Nano-Fiber Films in Epoxy Resins and Water
The current breed of natural-fiber based polymer composites, because of their biobased and possibly biodegradable nature, offer an alternative as a 'green' material available for automotive and other engineering applications. However such composites suffer from the drawback of low strength and fatigue properties compared to the carbon-or glass-fiber based polymer composites. Cellulose nanofibers (CNFs) are a new type of nanofibers made purely from cellulose molecules and have very high mechanical properties compared to other natural fibers, even approaching that of inorganic reinforcing fibers. However, there remain several hurdles in the use of CNF films for the production of polymer composites through the liquid composite molding technologies. One such problem is the swelling of these films during the manufacturing of such composites. In this study, we have microscopically studied the swelling of CNF films when they come in contact with three different liquids: water, epoxy, and bio-based epoxy. It was observed that the swelling rate was very high in the beginning but decreased subsequently. The swelling process was seen to be complete within two minutes for all the three liquids. The highest and lowest swelling of CNF films were observed for water and bioepoxy, respectively.
2021
We synthesized the cellulose nanocrystals (CNCs) by using cotton as a raw material, then it was modified with 2-carboxyethyl acrylate to improve its adhesion and thermal properties. CNCs was chosen as a modifier to improve the interfacial adhesion between the reinforced nanocrystals and E-51 epoxy resin system. This gives a better modulus of elasticity, a lower coefficient of energy, and thermal expansion. Significant improvements in modulus properties, strength, transparency and thermal stability were observed with modified cellulose nanocrystals (MCNCs) compared with the standard sample. SEM, and transmission electron microscope (TEM), powder diffraction (XRD), (TGA and DTG) and Fourier transform infrared spectroscopy (FTIR) were used for the isolation of synthetic (native and modified) cellulose nanocrystals. In addition, the MCNCs adhesion properties with E-51 (Bisphenol A diglycidyl ether) epoxy resins were also investigated using the Zwick/Roell Z020 model.
Composites Part A: Applied Science and Manufacturing
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Frontiers in Bioengineering and Biotechnology, 2022
Cellulose nanocrystals (CNCs) have unparalleled advantages in the preparation of nanocomposites for various applications. However, a major challenge associated with CNCs in nanocomposite preparation is the lack of compatibility with hydrophobic polymers. The hydrophobic modification of CNCs has attracted increasing interest in the modern era standing with long challenges and being environmentally friendly. Here, we synthesized CNCs by using cotton as raw material and then modified them with 2-carboxyethyl acrylate to improve their corresponding mechanical, adhesive, contact angle, and thermal properties. Different concentrations (1–5 wt%) of CNCs were used as modifiers to improve the interfacial adhesion between the reinforced CNCs and E-51 (Bisphenol A diglycidyl ether) epoxy resin system. CNCs offered a better modulus of elasticity, a lower coefficient of energy, and thermal expansion. Compared with the standard sample, the modified CNCs (MCNCs) showed high shear stress, high toug...
Morphological and Thermal Properties of Cellulose Nanofibrils Reinforced Epoxy Nanocomposites
Drvna industrija, 2015
Epoxy resins have gained attention as important adhesives because they are structurally stable, inert to most chemicals, and highly resistant to oxidation. Different particles can be added to adhesives to improve their properties. In this study, cellulose nanofi brils (CNFs), which have superior mechanical properties, were used as the reinforcing agent. Cellulose nanofi brils were added to epoxy in quantities of 1 %, 2 % and 3 % by weight to prepare nanocomposites. Morphological characterization of the composites was done with scanning electron microscopy (SEM). Thermal properties of the nanocomposites were investigated with Thermogravimetric Analyzer (TGA/DTG) and Differential Scanning Calorimeter (DSC). SEM images showed that the cellulose nanofi brils were dispersed partially homogenous throughout the epoxy matrix for 1 % CNF. However, it was observed that the cellulose nanofi brils were aggregated (especially for 2 and 3 % CNFs) in some parts of the SEM images, and the ratios of the aggregated parts increased as the loading rate of the cellulose nanofi brils increased. The TGA curve showed that DTG and decomposition temperature of pure epoxy was higher than that of the nanocomposites. The DSC curve showed that the glass transition temperature (T g ) value of pure epoxy was found to be similar with Tg of the nanocomposites.
Surface modification of microfibrillated cellulose for epoxy composite applications
Polymer, 2008
Microfibrillated cellulose (MFC) possessing a 'web-like' morphology was successfully modified with three different coupling agents: 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and a titanate coupling agent (Lica 38). The surface modification was confirmed using infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), and contact angle measurements. These modifications changed the surface character of MFC from hydrophilic to hydrophobic. The untreated and treated MFC were successfully incorporated into an epoxy resin system using acetone as the solvent. Better and stronger adhesion between the microfibrils and the epoxy polymer matrix was observed for the treated fibers, which resulted in better mechanical properties of the composite materials.
Adhesion and Surface Issues in Cellulose and Nanocellulose
Journal of Adhesion Science and Technology, 2008
This paper provides a review of the scientific literature concerned with adhesion and surface properties of cellulose and nanocellulose. Cellulose is the most abundant chemical compound on earth and its natural affinity for self-adhesion has long been recognized. The ease of adhesion that occurs in cellulose has contributed to its use in paper and other fiber-based composite materials. Cellulose adhesion, which has received considerable attention over the past half century, occurs over a practical length scale ranging from the nanoscale to millimeters. Adhesion theories that have been examined in the bonding of cellulose fibers include: mechanical interlocking, adsorption or wetting theory, diffusion theory, and the theory of weak boundary layers. Cellulose fibers on the nanoscale are prepared in four different ways: (1) bacterial cellulose nanofibers, (2) cellulose nanofibers by electrospinning, (3) microfibrillated cellulose plant cell fibers and (4) nanorods or cellulose whiskers. Structure and properties of nanocellulose that are important include: morphology, crystalline structure, surface properties, chemical and physical properties, and properties in liquid suspension. Cellulosic nanofibers present a very high surface area which makes the adhesion properties the most important parameter to control for nanocomposite applications. In this paper, we will focus on discussion of the adhesion and surface characteristics of cellulose nanofibers that impact its properties and application in nanomaterials. Koninklijke Brill NV, Leiden, 2008
Materials & Design, 2019
This paper reports the use of cellulose microcrystals (CMCs) for improving fibre-matrix interface, mechanical, dynamic mechanical and thermal degradation behaviour of glass fibre reinforced epoxy composites. An ultrasonic treatment for 1 h was used to disperse CMCs (1-3 wt%) within an epoxy resin, which was subsequently infused through glass fabrics to develop hierarchical composites containing both macro and micro-scale reinforcements. It was observed that CMC dispersion in the epoxy resin was homogeneous at 1 wt% CMC and further increase in CMC concentrations led to linear increase in both agglomerate size and total agglomerated area. Addition of 1 wt % CMC to the composite matrix drastically changed the glass fibre-epoxy interface and led to a maximum improvement of 65% in interlaminar shear strength, 14% in tensile strength, 76% in flexural strength, 111% and 119% in fracture energy in tensile and flexural modes, 9.4% in impact strength, 13.5% in storage modulus, 21.9% in loss modulus and 13°C in the glass transition temperature of composites. Therefore, the use of CMCs could be an industrially viable, economical and eco-friendly approach of developing hierarchical glass fibre composites with considerably improved performance.
Tensile properties and wear resistance of epoxy nanocomposites reinforced with cellulose nanofibers
Polymer Bulletin, 2017
Cellulose nanofibers (CNFs) were prepared from sugarcane bagasse and used as reinforcement in epoxy nanocomposites. To obtain CNFs, the cellulose was bleached with sodium chlorite, hydrothermally hydrolyzed with 5% w/v oxalic acid under pressure of 800 psi at 100°C in a microwave reactor, and homogenized using a mechanical homogenizer. The diameters of CNFs determined from field emission scanning electron microscope (FE-SEM) vary from 8 to 86 nm. The percentage crystallinity obtained from X-ray diffractometry is 62.8%. The epoxy was mixed with the prepared CNFs and cured at room temperature for 7 days. The effects of CNFs concentrations (0, 0.5, 1.0, 3.0, 5.0 and 10.0 wt%, dry basis) on the tensile properties and scratch resistance of the nanocomposites were investigated. Young's modulus and tensile strength increased with an increasing CNFs loading up to 3 wt %. Above that concentration the tensile elongation at break increased; this was at the rate faster than the modulus decreased. The instantaneous and healing scratch depths and thus viscoelastic recovery were determined using a micro-scratch tester. The percentage recovery values are higher for the nanocomposites than for the pure epoxy.
Cellulose, 2014
Development of high-performance bionanocomposite adhesives is of high interest due to their environmentally friendly nature and superior mechanical properties in outdoor environments. Nano-crystalline cellulose (NCC) and resilin are among the most promising bio-nanofillers, providing strength and elasticity, respectively. A novel bionanocomposite comprised of NCC and resilin fused to a cellulose binding domain (Res.-CBD) is presented. As a case study, commercial epoxy adhesive was chosen as a matrix for the bio-nanocomposite adhesive. Insertion of hydrophilic NCC into hydrophobic resins, such as epoxy, is typically performed using solvent exchange, chemical modification, emulsifier addition or mixing with water-borne resins, techniques which either limit the material's application range or which are considered environmentally unfriendly. The unique approach presented here employed Res.-CBD as a surfactant-like agent supportive of the direct insertion of water-suspended NCC into an epoxy resin. The presented approach involves binding of Res.-CBD to NCC through its CBD domain and a chemical reaction between the resin epoxide groups and Res.-CBD amine moieties. The resulting bio-nano material shows a 50 % increase in the Young's modulus and a 20 % decrease in the tan(d), compared to pristine epoxy. This novel epoxy adhesive can be advantageous in applications where higher elasticity and Young's modulus are required. Keywords Nano-crystalline cellulose (NCC) Á Resilin Á Epoxy Á Bio-nanocomposites R. Verker and A. Rivkin have contributed equally to this work.