Role of cellulose nanocrystals in epoxy-based nanocomposites: mechanical properties, morphology and thermal behavior

Nascimento, Nayra Reis do; Pinheiro, Ivanei Ferreira; Alves, Guilherme Fioravanti; Mei, Lucía Helena Innocentini; Neto, José Costa de Macedo; Morales, Ana Rita

doi:10.1590/0104-1428.20210057

Cited by 10 publications

(5 citation statements)

References 51 publications

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“…Although the addition of 4.5% CNC in PLA-gelatin multilayer films significantly reduced the tensile strength and elongation, this nanocomponent was not a viable alternative to reinforce this polymeric matrix [ 22 ]. When the nature of the reinforcement material and the polymeric matrix are not the same, this low compatibility can be seen as a weakness in terms of mechanical properties, i.e., the same effect as that generated when the nanomaterials have not been uniformly dispersed in the structural matrix material [ 53 ].…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the Antimicrobial, Thermal, Mechanical, and Barrier Properties of Corn Starch–Chitosan Biodegradable Films Reinforced with Cellulose Nanocrystals

et al. 2022

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Packaging materials play an essential role in the preservation and marketing of food and other products. To improve their conservation capacity, antimicrobial agents that inhibit bacterial growth are used. Biopolymers such as starch and chitosan are a sustainable alternative for the generation of films for packaging that can also serve as a support for preservatives and antimicrobial agents. These substances can replace packaging of synthetic origin and maintain good functional properties to ensure the quality of food products. Films based on a mixture of corn starch and chitosan were developed by the casting method and the effect of incorporating cellulose nanocrystals (CNC) at different concentrations (0 to 10% w/w) was studied. The effect of the incorporation of CNC on the rheological, mechanical, thermal and barrier properties, as well as the antimicrobial activity of nanocomposite films, was evaluated. A significant modification of the functional and antimicrobial properties of the starch–chitosan films was observed with an increase in the concentration of nanomaterials. The films with CNC in a range of 0.5 to 5% presented the best performance. In line with the physicochemical characteristics which are desired in antimicrobial materials, this study can serve as a guide for the development this type of packaging for food use.

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Section: Resultsmentioning

confidence: 99%

Evaluation of the Antimicrobial, Thermal, Mechanical, and Barrier Properties of Corn Starch–Chitosan Biodegradable Films Reinforced with Cellulose Nanocrystals

et al. 2022

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“…The thermal stability for epoxy/CNF is superior for additive concentrations up to 0.75 wt.%, owing to the favorable interactions in parallel with the previously noticed increase in the T g . However, the lower thermal stability at 1.0 to 1.5 wt.% CNF has also been noticed before and attributed to the percolation threshold volume fraction causing increased thermal conductivity [ 55 ]. Alternatively, the drop in the thermal stability at high nanocellulose concentrations can be attributed to unreacted nanocellulose and epoxy after incomplete mixing.…”

Section: Resultsmentioning

confidence: 75%

“…The chemical modification also improved the micro-wear characteristics of CNC/epoxy nanocomposite coatings [ 51 ], while a general improvement in mechanical properties [ 52 ] and abrasive wear properties was reported for UV-crosslinked waterborne epoxy coatings with modified CNC [ 53 ]. In comparison, the low concentrations of up to 1 wt.% unmodified CNC also improved the mechanical strength [ 54 ], thermal behavior [ 55 ], and impact resistance [ 56 ], although proper dispersion was required and processing through solvent exchange was needed. The chemical, mechanical, physical, and thermal properties of the epoxy coatings with 0.2 to 0.7 wt.% pure CNC improved with very little aggregation [ 57 ], while further improvement with up to 2 wt.% CNC was observed after surface modification [ 58 ].…”

Section: Introductionmentioning

confidence: 99%

Nanocellulose Grades with Different Morphologies and Surface Modification as Additives for Waterborne Epoxy Coatings

Samyn,

Cosemans

2024

Polymers

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While adding different micro- and nanocellulose types into epoxy coating formulations with waterborne phenalkamine crosslinker, effects on processing conditions and coating performance were systematically investigated. The variations in viscosity, thermal and thermomechanical properties, mechanical behavior, abrasive wear, water contact angles, and coating morphologies were evaluated. The selected additives include microcrystalline cellulose (MCC) at 1 to 10 wt.% and cellulose nanocrystals (CNC), cellulose nanofibers (CNF), cellulose microfibers (CMF), and hydrophobically modified cellulose microfibers (mCMF) at 0.1 to 1.5 wt.%. The viscosity profiles are determined by the inherent additive characteristics with strong shear thinning effects for epoxy/CNF, while the epoxy/mCMF provides lower viscosity and better matrix compatibility owing to the lubrication of encapsulated wax. The crosslinking of epoxy/CNF is favored and postponed for epoxy/(CNC, CMF, mCMF), as the stronger interactions between epoxy and CNF are confirmed by an increase in the glass transition temperature and reduction in the dampening factor. The mechanical properties indicate the highest hardness and impact strength for epoxy/CNF resulting in the lowest abrasion wear rates, but ductility enhances and wear rates mostly reduce for epoxy/mCMF together with hydrophobic protection. In addition, the mechanical reinforcement owing to the specific organization of a nanocellulose network at percolation threshold concentrations of 0.75 wt.% is confirmed by microscopic analysis: the latter results in a 2.6 °C (CNF) or 1.6 °C (CNC) increase in the glass transition temperature, 50% (CNF) or 20% (CNC) increase in the E modulus, 37% (CNF) or 32% (CNC) increase in hardness, and 58% (CNF) or 33% (CNC) lower abrasive wear compared to neat epoxy, while higher concentrations up to 1.5 wt.% mCMF can be added. This research significantly demonstrates that nanocellulose is directly compatible with a waterborne phenalkamine crosslinker and actively contributes to the crosslinking of waterborne epoxy coatings, changing the intrinsic glass transition temperatures and hardness properties, to which mechanical coating performance directly relates.

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“…In the literature, several authors studied the influence of nano-reinforcements on the properties of the material. The experimental campaign of Nacimento et al [1] revealed an increase in Young's modulus and a decrease in strength of CNC/epoxy nanocomposites. Saba et al [2], studied cellulose nanofibers epoxy resin which exhibited an increase in all measured properties at 0.75% w/w content of reinforcement.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of bulk mechanical properties of a bio-based resin filled by graphene nanoplatelets and cellulose nanocrystals

Tserpes,

Lagkousi,

Tourountzi

et al. 2023

J. Phys.: Conf. Ser.

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In the present paper, a novel bio-based resin derived from epichlorohydrin was reinforced by Graphene NanoPlatelets (GNPs) and Cellulose NanoCrystals (CNCs) in different weight ratios and characterized experimentally through tension tests and fracture toughness tests on bulk specimens. The nanofillers were applied separately. The experimental results showed that the neat resin has a Young’s modulus of 3.29 GPa, a tensile strength of 45.15 MPa, a stress intensity factor of 0.61 MPa m1/2 and a critical strain energy release rate of 0.091 kJ/m2. The level of the properties reveal that the bio-based adhesive can be used for cosmetic and for some structural applications. The addition of cellulose nanocrystals in the epoxy resin didn’t improve the mechanical properties of the neat resin mainly due to the development of intense aggregation of cellulose nanocrystals. On the other hand, the addition of graphene has led to the increase of the Young’s modulus and the fracture toughness and to the decrease of the tension strength of the resin. Development of agglomerations of graphene were also present in this case. The contradictory findings on the mechanical properties of the reinforced resin gives a clear message about the need for optimizing the manufacturing process. Both nanocomposites have undergone a complete life-cycle analysis which has shown that they are far more environmentally friendly than a conventional epoxy resin.

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Role of cellulose nanocrystals in epoxy-based nanocomposites: mechanical properties, morphology and thermal behavior

Cited by 10 publications

References 51 publications

Evaluation of the Antimicrobial, Thermal, Mechanical, and Barrier Properties of Corn Starch–Chitosan Biodegradable Films Reinforced with Cellulose Nanocrystals

Evaluation of the Antimicrobial, Thermal, Mechanical, and Barrier Properties of Corn Starch–Chitosan Biodegradable Films Reinforced with Cellulose Nanocrystals

Nanocellulose Grades with Different Morphologies and Surface Modification as Additives for Waterborne Epoxy Coatings

Synthesis and characterization of bulk mechanical properties of a bio-based resin filled by graphene nanoplatelets and cellulose nanocrystals

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