Reinforcement Behavior of Chemically Unmodified Cellulose Nanofiber in Natural Rubber Nanocomposites

Abstract

We investigated the reinforcement behavior of small amounts of chemically unmodified cellulose nanofiber (CNF) in eco-friendly natural rubber (NR) nanocomposites. For this purpose, NR nanocomposites filled with 1, 3, and 5 parts per hundred rubber (phr) of cellulose nanofiber (CNF) were prepared by a latex mixing method. By using TEM, a tensile test, DMA, WAXD, a bound rubber test, and gel content measurements, the effect of CNF concentration on the structure–property relationship and reinforcing mechanism of the CNF/NR nanocomposite was revealed. Increasing the content of CNF resulted in decreased dispersibility of the nanofiber in the NR matrix. It was found that the stress upturn in the stress–strain curves was remarkably enhanced when the NR was combined with 1–3 phr CNF, and a noticeable increase in tensile strength (an approximately 122% increase in tensile strength over that of NR) was observed without sacrificing the flexibility of the NR in the NR filled with 1 phr CNF, though no acceleration in their strain-induced crystallization was observed. Since the NR chains were not inserted in the uniformly dispersed CNF bundles, the reinforcement behavior by the small content of CNF might be attributed to the shear stress transfer at the CNF/NR interface through the interfacial interaction (i.e., physical entanglement) between the nano-dispersed CNFs and the NR chains. However, at a higher CNF filling content (5 phr), the CNFs formed micron-sized aggregates in the NR matrix, which significantly induced the local stress concentration and promoted strain-induced crystallization, causing a substantially increased modulus but reduced the strain at the rupture of the NR.

High‐velocity impact behavior and quasi‐static indentation of new elastomeric nanocomposites reinforced with cellulose nanofibers and lignin powder

“…However, the fracture strain for the 6 phr sample increases dramatically. This improvement in ultimate strength and failure strain for the sample containing 6 phr is due to the good dispersion of CNFs in the rubber compound, which is achieved through the good interaction of natural rubber with CNFs 56 . CNFs in natural rubber increase nanocomposites' ultimate strength and failure strain by controlling the movement of macromolecules, especially polymer chains 57 …”

“…This improvement in ultimate strength and failure strain for the sample containing 6 phr is due to the good dispersion of CNFs in the rubber compound, which is achieved through the good interaction of natural rubber with CNFs. 56 CNFs in natural rubber increase nanocomposites' ultimate strength and failure strain by controlling the movement of macromolecules, especially polymer chains. 57 The high final strength and low final deformation are necessary for nanocomposites with a high content of CNFs because these results can be significant for protective structures.…”

Performance of Moringa Oil as an Effective Bioplasticizer on Static and Dynamic Mechanical Properties of Natural Rubber Vulcanizates

“…This is due to the variation in the plasticization efficiency of MO compared with NO, leading to a higher degree of chain entanglement in the MO plasticized NR compounds, which increased the network chain density in the system . Typically, the network chain density including naturally occurring networks (formed by interaction between the functional groups of rubber chains and nonrubber components), entanglement networks, and chemical cross-linked networks can efficiently promote strain-induced crystallization in a vulcanized natural rubber, resulting in stress upturn at lower strain in the stress–strain curve. , Moreover, the higher network chain density in the NR/MO vulcanizates also brought about an upturn of stress at a lower strain level when compared with that of the NR/NO vulcanizates.…”

Cellulosic Nanofibers Utilizing a Silicone Elastomeric Core to Form Stretchable Paper

“…Literature has shown other forms of stretchable paper in composite materials, such as works by Noguchi et al and Wongvasana et al These works discuss the fabrication of a cellulose/rubber composite nanofiber showing improved elongation at the break of the composite. [47,48] The authors mentioned tradeoffs between strength and ductility when polymers and elastomers are interfaced with each other. However, the tradeoff rule is unapplied to their material compared to their cellulose-rubber nanofiber composite.…”