Crosslinked carboxylated SBR composites reinforced with chitin nanocrystals

Abstract

This study aims to develop and characterize the nanocomposites using sulfur cross-linked carboxylated styrene-butadiene rubbers (S-xSBR) as the matrix and chitin nanocrystals (CNCs) as nanofillers. The composites' morphology and properties were examined by light transmittances, fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), dynamic mechanical analysis (DMA), thermo gravimetric analyzer (TGA), and tensile properties determination. The addition of CNCs has slight effect on transparency of the composite films. FTIR data confirm the interfacial interactions between CNCs and S-xSBR via hydrogen bonds. CNCs are uniformly dispersed in the matrix from SEM result. The addition of CNCs can significantly improve the tensile strength and modulus both in static and dynamic states. The tensile modulus and tensile strength of S-xSBR/CNCs composites with the 4 wt.% CNCs is 62.5 % and 97.6 % higher than that of pure S-xSBR. The storage modulus, glass transition temperature, and the thermal stability of the composites are higher than those of the neat S-xSBR. The mechanical properties of the composite films are water-responsive, as the swollen samples exhibit obviously decreased strength and modulus. The greatest mechanical contrast is shown in the S-xSBR/CNCs composites with 2 wt.% CNCs loading whose tensile modulus decrease from 60.4 to 6.1 MPa after swelling equilibrium. The significant reinforcement effect of CNCs on S-xSBR is attributed to the unique structure of CNCs and the interfacial interactions in the composite.

Reinforcement of poly (vinyl alcohol) films with alpha-chitin nanowhiskers

“…A possible explanation for such result might be related with the presence of the hydrogen bonding between the nanowhiskers and PVA chains reducing mobility and resulting in a material with lower elasticity but providing reinforcement to the whole film structure. Similar results were reported by different authors [34][35][36] .…”

Liquid Crystalline Behaviors of Chitin Nanocrystals and Their Reinforcing Effect on Natural Rubber

“…For example, CNCs are employed as reinforcing materials for polymer hydrogels, and CNCs act as a physical cross-linker through hydrogen bond interactions with polymer chains in the composite systems. , CNCs-incorporated polymer hydrogels not only exhibit improved mechanical properties but also show good biocompatibility. , In addition, the thermal stability and biological ability of polymer/CNCs composites can also be improved by CNCs. , For instance, poly­( l -lactide)-grafted CNCs can simultaneously improve mechanical properties, crystallinity, and cellular compatibility of poly­( l -lactide) matrix. − CNCs were also incorporated into the rubber matrix as reinforcement materials, and the results demonstrate that the processing methods and surface modification of CNCs had a significant effect on the properties of composites. − Previously, we used the CNCs as nanofiller to reinforce carboxylated styrene–butadiene rubber (x-SBR) through solution mixing. A significant improvement of the mechanical performance and water-triggered modulus changes of x-SBR was achieved by CNCs. , However, the processing–structure–performance relationships of the rubber/CNCs composites are not fully understood as their counterparts of cellulose nanocrystals. − Also, CNCs were added to chitosan to increase the mechanical behavior and cell adhesion properties. − CNCs-reinforced polymer composites combine the comprehensive advantages including high strength, lightweight, light color, biodegradability, and biocompatibility. However, the critical factors determining the performance of composites are agglomerates and lack of interfacial interactions, which weaken the load transfer from the polymer matrix to the CNCs.…”

“…A significant improvement of the mechanical performance and water-triggered modulus changes of x-SBR was achieved by CNCs. 20,21 However, the processing−structure−performance relationships of the rubber/CNCs composites are not fully understood as their counterparts of cellulose nanocrystals. 22−24 Also, CNCs were added to chitosan to increase the mechanical behavior and cell adhesion properties.…”

Elastomer Reinforced with Regenerated Chitin from Alkaline/Urea Aqueous System

“…Chitin, a structural and natural polymer that can be found in the exoskeleton of crustacean, cuticle of insects, and cell wall of fungi, is, next to cellulose, the most bountiful biopolymer on Earth. , Apart from its application in drug delivery, tissue engineering, environmental pollutants remediation, and optoelectronics, chitin is also attracting a great deal of attention as a green reinforcing agent in both synthetic and natural polymeric matrices. , However, compared to cellulose, the attempts to apply chitin in elastomer composites is relatively scarce. Most researchers focused on the use of chitin nanocrystals as a reinforcing phase in elastomer composites. − In these previous reports, the chitin nanocrystals were first suspended in water, and the chitin suspension was mixed with polymer latex/solution to achieve a fine dispersion within the polymeric matrix. As expected, chitin nanocrystal shows a prominent reinforcing effect toward the elastomer due to its rigid attribute.…”