Tensile testing of cellulose based natural fibers for structural composite applications

A series of tensile tests were conducted on a Lloyd LRX tensile testing machine for numerous natural fibers deemed potential candidates for development in composite applications. The tensile tests were conducted on the fibers jute, kenaf, flax, abaca, sisal, hemp, and coir for samples exposed to moisture conditions of (1) room temperature and humidity, (2) 65% moisture content, (3) 90% moisture content, and (4) soaked fiber. These seven fibers were then tested for the four conditions and the mechanical properties of tensile strength, tensile strain to failure, and Young's modulus were calculated for the results. These results were then compared and verified with those from the literature, with some of the fibers showing distinctly promising potential. Additionally, a study on the effect of alkalization using 3% NaOH solution was carried out on flax, kenaf, abaca, and sisal to observe impact that this common fiber pre-treatment process has on fiber mechanical properties. The result of the investigation indicated that over treatment of natural fibers using NaOH could have a negative effect on the base fiber properties. It is consequently apparent that a treatment time of less than 10 min is sufficient to remove hemicelluloses and to give the optimum effect

Механические свойства и проницаемость термопластичных крахмальных композитов, армированных нановолокнами целлюлозы, для применения в качестве упаковки

In this study, a facile, ecofriendly nanocomposite based on glycerol-plasticized thermoplastic potato starch (TPS) containing 0-4 wt.% cellulose nanofiber (CNF) from pineapple leaf was prepared by the solution casting technique. The nanocomposite films showed better mechanical properties compared to neat film. The tensile properties were fit with theoretical predictions. Tensile strength increased with CNF loading and reached up to 4.682 MPa (TPS+3 wt.% CNF) from 1.58 MPa (neat TPS), an improvement of ~196% over the neat polymer. The addition of cellulose nanofiber improved the barrier properties of films by creating a tortuous path for penetrant molecules. Gas transport behavior of CNF-based TPS nanocomposite films was explored using O2 gas. A 56% decrease (relative to neat TPS) in oxygen permeability of the nanocomposite membranes was achieved by adding only 3 wt.% CNF. The oxygen permeability data were fit with two theoretical modelsОписан легкий, экологически чистый нанокомпозит на основе пластифицированного глицерином термопластичного картофельного крахмала (ТКК), содержащий 0-4 мас.% целлюлозного нановолокна (ЦН) из листьев ананаса, полученный методом испарения из раствора. Нанокомпозитные пленки имели улучшенные механические свойства по сравнению с исходной пленкой из крахмала. Свойства на растяжение соответствовали теоретическим предсказаниям. Предел прочности на растяжение композитных пленок повышался при увеличении содержания ЦН с 1,58 МПа (чистый ТКК) до 4,682 МПа (ТКК + 3 мас.% ЦН); это улучшение составило ~ 196 % по сравнению с чистым полимером. Добавление целлюлозного нановолокна улучшало барьерные свойства пленок за счет извилистого пути для проникающих молекул. Газотранспортное поведение нанокомпозитных пленок ТКК-ЦН было исследовано с использованием газообразного кислорода. Ведением всего 3 % ЦН было достигнуто 56%-ное уменьшение кислородной газопроницаемости композитных пленок по сравнению с чистым ТКК. Данные по кислородной проницаемости соответствовали двум теоретичеким моделя

Woodflour as Reinforcement of Polypropylene

The effect of the filler content and size, as well as accelerated aging on the mechanical properties of polypropylene composites reinforced with woodflour (WF/PP) were evaluated. The composites were prepared by the extrusion of polypropylene with woodflour (Pinus elliotti) based on following ratios: 15, 25 and 40 wt% with two different granulometries. The specimens were injection molded according to ASTM standards. The composite properties did not show significant differences as a function of the filler granulometry. We also observed that by increasing the filler content, both the mechanical properties and the melt flow index (MFI) decreased, and the elasticity modulus, hardness and density increased. Concerning the accelerated aging, the composite presented a reduction in tensile properties. The results showed that the composite properties are extremely favorable when compared to other commercial systems reinforced by inorganic fillers