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There is a growing drive in replacing conventional non-renewable fibres such as glass and carbon reinforced composites with more sustainable and renewable reinforcements such as flax, hemp, jute in biobased composites in key industry sectors such as automotive, marine, building and construction motivated by lower carbon footprint and sustainability. Despite this drive, flammability characteristics of these sustainable biobased composites are not fully understood. Through an up-to-date review, this article meticulously discusses the theme of bio-based and eco-friendly flame retardants (FRs), delving into their intricate mechanisms, flammability testing methodologies, and emerging research trends. It underscores the pivotal necessity of developing tailor-made eco-friendly FRs customised for a diverse range of materials to bolster fire safety in sustainable material applications. Furthermore, it illuminates the limitations associated with prevalent methods for assessing flammability and advocates for advancements in dynamic testing and multi-scale analyses to more accurately simulate real-world fire scenarios. This review also highlights the key characteristics of natural plant fibres and their composites critical for the development of sustainable and fire safe materials for key applications areas. Additionally, it highlights the diverse spectrum of strategies employed in the realm of flame-retardant materials research, emphasizing a pronounced shift towards eco-friendly alternatives, innovative coatings, and the ongoing exploration of synthetic biopolymers, nanocomposites, and fibres in the pursuit of heightened fire safety. Amidst the inherent challenges, this comprehensive review unequivocally underscores the pivotal role of interdisciplinary research collaboration in driving forward fire safety within the domain of sustainable materials. [ABSTRACT FROM AUTHOR]

In this work, thermal analysis of olive/bamboo fiber‐based epoxy hybrid composites was carried out. Three types of olive fibers, which are olive tree small branch (OTS), olive tree big branch (OTB), and olive tree leaves (OTL), along with bamboo fibers (B), were used to fabricate the composites. Thermal properties of hybrid composites were examined by the thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), and thermomechanical analyzer (TMA). It was found that the thermal stability improved with the incorporation of hybrid fibers in epoxy composites compared to pure fiber composites. Hybrid composite (OTS‐B) exhibited a lower residue (15.82%) whereas hybrid composites (OTB‐B and OTS‐B) show 54.65% and 54.53% weight loss at the maximum decomposition temperature. DMA results showed that the storage modulus and loss modulus reduced with hybrid fiber composites while the damping factor (tan delta) was increased. The storage modulus values of the pure composite sample (B) exhibited a higher increased (3150 MPa). In contrast, the pure composite sample (B) exhibited the highest loss modulus (337 MPa). From TMA analysis, OTL‐B hybrid composite presented a higher Tg and lower coefficient of thermal expansion. We concluded that finding from this work will strengthen attracting interpretation of utilization of two different fibers to fabricate hybrid composites for various lightweight purposes in a wide‐ranging choice of industrial applications such as biomedical tools, automobile, and construction fields. Additionally, a novel method can be used to develop hybrid biocomposites materials, which have potential applications in biomaterials and engineering areas. [ABSTRACT FROM AUTHOR]

The addition of short fibers has been experimentally observed to slow the stress relaxation of viscoelastic polymers, producing a change in the relaxation time constant. Our recent study attributed this effect of fibers on stress relaxation behavior to the interfacial shear stress transfer at the fiber-matrix interface. This model explained the effect of fiber addition on stress relaxation without the need to postulate structural changes at the interface. In our previous study, we developed an analytical model for the effect of fully aligned short fibers, and the model predictions were successfully compared to finite element simulations. However, in most industrial applications of short-fiber composites, fibers are not aligned, and hence it is necessary to examine the time dependence of viscoelastic polymers containing randomly oriented short fibers. In this study, we propose an analytical model to predict the stress relaxation behavior of short-fiber composites where the fibers are randomly oriented. The model predictions were compared to results obtained from Monte Carlo finite element simulations, and good agreement between the two was observed. The analytical model provides an excellent tool to accurately predict the stress relaxation behavior of randomly oriented short-fiber composites. [ABSTRACT FROM AUTHOR]

ABSTRACT This study focuses on the performance characteristics of wood/short carbon fiber hybrid biopolyamide11 (PA11) composites. The composites were produced by melt-compounding of the fibers with the polyamide via extrusion and injection molding. The results showed that mechanical properties, such as tensile and flexural strength and modulus of the wood fiber composites were significantly higher than the PA11 and hybridization with carbon fiber further enhanced the performance properties, as well as the thermal resistance of the composites. Compared to wood fiber composites (30% wood fiber), hybridization with carbon fiber (10% wood fiber and 20% carbon fiber) increased the tensile and flexural modulus by 168% and 142%, respectively. Izod impact strength of the hybrid composites exhibited a good improvement compared to wood fiber composites. Thermal properties and resistance to water absorption of the composites were improved by hybridization with carbon fiber. In overall, the study indicated that the developed hybrid composites are promising candidates for high performance applications, where high stiffness and thermal resistance are required. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43595. [ABSTRACT FROM AUTHOR]

Natural fibers can be attractive reinforcing materials in thermosetting polymers due to their low density and high specific mechanical properties. Although the research effort in this area has grown substantially over the last 20 years, manufacturing technologies to make use of short natural fibers in high volume fraction composites; are still limited. Natural fibers, after retting and preprocessing, are discontinuous and easily form entangled bundles. Dispersion and mixing these short fibers with resin to manufacture high quality, high volume fraction composites presents a significant challenge. In this paper, a novel pneumatic design for dispersion of natural fibers in their original discontinuous form is described. In this design, compressed air is used to create vacuum to feed and convey fibres while breaking down fibre clumps and dispersing them in an aerosolized resin stream. Model composite materials, made using proof-of-concept prototype equipment, were imaged with both optical and X-ray tomography to evaluate fibre and resin dispersion. The images indicated that the system was capable of providing an intimate mixture of resin and detangled fibres for two different resin viscosities. The new pneumatic process could serve as the basis of a system to produce well-dispersed high-volume fraction composites containing discontinuous natural fibres drawn directly from a loosely packed source. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, the skin of the beavertail cactus, Opuntia Basilaris, was used for the isolation of cellulose nanofibers using a chemo-mechanical technique. It was shown that the skins had a relatively high cellulose content, whereas their lignin content was low. Fourier transform infrared spectroscopy and X-ray diffraction proved that the isolation of cellulose nanofibers from the amorphous components of the skins was performed successfully. The cactus skins were also shown to have a high content of calcium oxalate crystals. Morphological observations proved that the isolated cellulose fibers had diameters in the range of 10-50 nm. It was shown that the addition of nanofibers increased the modulus and strength of the polyvinyl alcohol matrix significantly, whereas the elongation at break decreased. Thermogravimetric analysis proved that: (i) isolated nanofibers had higher thermal stabilities than the cactus skins, and (ii) inclusion of nanofibers increased the stability of polyvinyl alcohol noticeably. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42499. [ABSTRACT FROM AUTHOR]

ABSTRACT The current work focuses on enhancing the mechanical and thermal properties of sisal fiber reinforced composites that were previously used in developing interior automotive trims. In order to extend their use in other structural applications, two hybrid biocomposites with the combination of sisal (SF) and glass fiber (GF)-SF20/GF10 and SF10/GF20 were blended with polypropylene via extrusion and injection molding process. Critical material properties such as density, fogging, acoustic, mechanical, thermal, and rheological properties were evaluated and results were analyzed using ANOVA. Hybridization of SF and GF enhanced flexural strength and thermal properties of the biocomposites by 33 and 19%, respectively, while no significant change in acoustic, impact and rheological properties were observed. The properties of the hybrid biocomposites were compared with the material specification of a battery tray and it was found that these hybrid biocomposites could be better alternative materials in structural applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42452. [ABSTRACT FROM AUTHOR]

In a rapidly urbanizing global society, the issue of solid waste management has become even more challenging in recent times. Manufacturing of paper, an integral part of human civilization, generates a substantial amount of effluent sludge, which invariably needs extra monetary resources to dispose-off in millions of tons annually around the world. Currently, most of the widely practiced disposal options, landfilling and incineration, invariably pose serious environmental risks to immediate neighborhoods as well as to society at large. Recent stricter environmental legislations and general public awareness have been forcing paper producers to follow a sustainable approach in dealing with residual biomass generated at their facilities. At the same time, reducing waste at source and recycling have become an integral part of waste management of some responsible companies and governments of the industrialized world have also taken a number of initiatives in this regard. This review presents a holistic overview on current practices in dealing with paper sludge and their environmental and economic implications. Also presented is a comprehensive discussion on emerging biorefinery trends leading to value-added utilization of primary, secondary and mixed biosolids originating from effluent treatments plants, especially from paper mill operations. [ABSTRACT FROM AUTHOR]

Abstract: Objective: This paper investigates the potential and limitations of using relatively low volume fractions of cellulose nanofibre as reinforcement in cement pastes. Materials and methods: General use limestone (GUL) cement and cellulose nanofibre gel suspension were used in the preparation of cement paste. Mixture conductivity, hydration, flexural strength, energy absorption and fibre dispersion in hardened cement matrix were evaluated. Results: Cellulose nanofibre reduced the conductivity and the early age hydration of mixtures. However, at 28days, the cumulative heat of hydration and the degree of hydration of cement pastes containing cellulose nanofibre were higher than those of the unreinforced reference mixture. Optimum mechanical properties were observed for paste containing 0.1% nanofibre. The decrease in mechanical properties at higher nanofibre content is as a result of fibre agglomeration. In comparison to the reference paste, the flexural strength and energy absorption of 0.1% nanofibre paste increased by approximately 106% and 184%, respectively. [Copyright &y& Elsevier]

The effects of cellulose nanofiber (CNF) on the non-isothermal crystallization behaviors of poly(lactic acid) (PLA) at atmospheric pressure and at various CO 2 pressures were investigated using a regular differential scanning calorimeter (DSC) and a high-pressure DSC at different cooling rates of 1, 2, 3, and 5 °C/min. The POM images revealed that the CNFs acted as crystal nucleating agents, increasing the number of crystals and decreasing the crystal sizes. The non-isothermal crystallization showed that PLA’s crystallization rate increased with cooling rates and the incorporation of CNFs accelerated the overall crystallization kinetics by providing more nuclei, thereby decreasing the crystallization half-time. The degree of crystallinity was not proportional to the CO 2 pressure. The highest crystallinity was obtained at a higher pressure with increased cooling rates. The activation energy analysis showed that the incorporation of CNFs restricted the movement of PLA molecular chains, thereby hindering crystallization. By comparing the Avrami analysis, Mo analysis, and activation energy results, it was speculated that heterogeneous crystal nucleation with the presence of CNFs might be the dominant factor in determining the overall non-isothermal crystallization rate of the PLA/CNF composites. Wide angle X-ray diffraction (WAXD) diffractograms showed that CNFs and CO 2 pressure had no influence on the crystalline structure of PLA. The effects of CNF content, CO 2 pressure, and cooling rate on T c , T m , and T g were also investigated. [ABSTRACT FROM AUTHOR]