Mode I and II interlaminar fracture toughness of nanoclay-reinforced epoxy/GF composites

Of prime importance in fiber reinforced composites is the interfacial strength between glass fiber reinforcement and matrix. A potential benefit of nanoclays (NC) is to improve the matrix-reinforcement stress transfer due to their positive interactions with glass. Double cantilever beam (DCB) and end-notch flexural (ENF) tests were performed to evaluate the interfacial fracture toughness (Gc) in mode I and II, respectively, of GF composites with a NC/epoxy matrix. Results show no benefit of NC on mode I thoughness while a significant 20%+ improvement on mode II was obtained. Given the non-optimal chemistry of the epoxy/GF laminate used, this result is encouraging.Pour les composites renforc\ue9s avec des fibres, la r\ue9sistance interfaciale entre le renfort en fibre de verre et la matrice est de la plus haute importance. Le meilleur transfert de contrainte matrice/renfort en raison de leurs interactions positives avec le verre constitue un b\ue9n\ue9fice potentiel des nanoargiles. On a r\ue9alis\ue9 des essais de flexion ENF (end-notch flexural) et des essais avec deux poutres en porte \ue0 faux pour \ue9valuer la t\ue9nacit\ue9 interfaciale (Gc) en mode I et II, respectivement, de composites GF avec une matrice nanoargile/\ue9poxy. Les r\ue9sultats ne montrent aucun b\ue9n\ue9fice de la nanoargile en mode I, alors qu\u2019une am\ue9lioration significative de plus de 20 % a \ue9t\ue9 observ\ue9e en mode II. \uc9tant donn\ue9 la chimie non optimale du stratifi\ue9 \ue9poxy/GF utilis\ue9, ce r\ue9sultat est encourageant.Peer reviewed: YesNRC publication: Ye

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions

The Role of Interface in Fabrication of Clay-Polyolefin (PO) Nanocomposites: Computation and Reality

The effect of interfacial interaction between the nano-particles and the polymer matrix plays a determined role in the fabrication of polymer nanocomposites. For layered structure nano-particles like nanoclays, depending on the level of such interaction, the dispersion of the nanoclays can vary from micro-size (micro-composite) to nano-size (nano-composite, both intercalated and exfoliated structure). This article focuses on the effect of the interaction between the nanoclay and polypropylene matrix on the dispersion of the obtained nanocomposites. Both computation (molecular modeling) and experiments have been conducted on various systems (with different modifications of clay surface) in order to get a better understanding about this complex issue. The results have provided different useful highlights for the fabrication of polyolefin nanocomposites.Peer reviewed: NoNRC publication: Ye

Biomaterial value proposition of triticale

Cereal starch and straw are particularly good candidates for the manufacturing of environmentally friendly polymer materials, especially as replacements, either fully or partially, for traditional synthetic plastic products because of their renewal ability, biodegradability, and low cost. However, the use of cereal starch for the development of bio-based plastics has generated a competition with the human food supply and also created lots of concerns. The use of triticale starch for such purpose can ease those competition and concerns. In this chapter, the development of triticale starch and straw for plastic products and their potential applications are presented. For starch, the most promising venue that can bring rapidly triticale starch into plastic market is as direct use to replace partially traditional plastics and is mainly focused in this chapter. In this case, starch is plasticized and gelatinized (so-called thermoplastic starch or TPS) prior to replace conventional plastics. TPS are also blended with other plastics at a molten stage to produce homogenous blends. All these steps can be performed in one step using conventional plastic processing equipment in order to reduce energy consumption and production cost. The triticale starch morphology, the blending and processing ability into plastic products, and the formulation and the properties of the obtained triticale TPS-based plastic products, such as crystallization structure, morphology, rheological behavior, mechanical properties, and biodegradability are quite comparable to those of other TPS-based plastics made from other starch sources. Thus, it confirms the benefits of TPS-based plastics made from triticale are equivalent with those of other food-grade TPS-based plastics. The straw was processed using different ways to produce either fibers or particles at different sizes prior to incorporating them in commodity plastics. While the starch-based plastics are focused for short-term uses due to the biodegradable nature of starch, the straw-reinforced plastics are aimed for more durable applications with good recycling ability. Different formulations have been developed for both hydrophobic and hydrophilic plastic systems. The processing ability, the performance, and the recycling ability of the triticale straw-reinforced plastics have been proven to be comparable with those of the virgin plastics with significant cost reduction. Finally, the potential of triticale plastic products made from different plastic systems and fabricated by different processes is also envisaged for various industrial applications. This development has registered new value-added products into triticale industrial product portfolio thus enhancing the value proposition for triticale. The massive volume consumption of plastic products can rapidly and significantly increase the net usages of biomass resources based on triticale thus reinforcing the sustainable development in the agricultural and manufacturing sectors in Canada.Peer reviewed: YesNRC publication: Ye

Novel polylactide/triticale straw biocomposites : processing, formulation, and properties

This article aims to the development of polylactide (PLA)/ triticale straw biocomposites with focus on the relationship between triticale straw content, additive presence, processing, and final properties. Prior to melt compounding, the triticale straw used in this study was chopped using the paper process to produce triticale particles that were further pelletized to assure a consistent feed rate into the extrusion line. PLA/triticale straw biocomposites were obtained for different triticale contents from 10 up to 40%vol, without and with maleic anhydride grafted polylactide (PLA-g-MA) as a coupling agent. As a supplementary additive, a PLA-specific branching agentwas used in some selected formulations to minimize the reduction in PLA\u2019s molecular weight. The biocomposites were characterized in terms of rheology, thermal properties, morphology, mechanical properties (tensile, flexural, and impact), and recyclability. The PLAg- MA increased the tensile strength of biocomposites by 10%, whereas boosted the tensile modulus about 2.5 times at 40%vol triticale content. For the same formulation, the flexural strength was raised by 15% and flexural modulus was doubled. However, a combination of PLAg- MA and branching agent proved to be the best approach to enhance PLA/triticale straw mechanical properties. When 20%vol of triticale was used as reinforcement, the presence of branching agent increased the flexural strength about 25%. The results demonstrate that the triticale straw processed in this way could offer a similar reinforcement capability as the cellulosic fibers based on the agricultural and forestry resources and can be easily recycled without losing its mechanical properties. It has a good potential in the biocomposites field with promising applications in construction, common goods, and transportation industries.Peer reviewed: YesNRC publication: Ye

Fire resistance cellulosic fibers for biocomposites

NRC publication: Ye

Selective compatibilization for stiffer, high impact tpo/clay nanocomposites

Peer reviewed: YesNRC publication: Ye

PVC formulation with renewable biomass lignin

NRC publication: Ye

PP-Based Nanocomposites with Various Intercalant Types and Intercalant Coverages

In this article, nanocomposites based on polypropylene containing montmorillonite, modified with two different intercalants (primary and quaternary amine), at three different coverage levels have been investigated. The specimens were prepared in a mini-extruder machine with a counter-rotating configuration. The effectiveness of intercalant type and clay coverage level on the dispersion was analyzed by different means, including Xray diffraction analysis, field emission gun scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. The flexural performance of the specimens was also examined.Peer reviewed: YesNRC publication: Ye