Extraction and characterization of fiber from the flower stalk of Sansevieria cylindrica.

A number of natural fibers are being proposed for use in composite materials, especially those extracted from local plants, especially those able to grow spontaneously as they are cost-efficient and have unexplored potential. Sansevieria cylindrica, within the Asparagaceae (previously Agavacae) family, has recently been considered for application in polymer and rubber matrix composites. However, its characterization and even the sorting out of technical fiber from the stem remains scarce, with little available data, as is often the case when the fabrication of textiles is not involved. In this study, Sansevieria cylindrica fibers were separated down to the dimensions of a filament at an 8-15 micron diameter from the stem of the plant, then characterized physically and chemically, using Fourier transform infrared spectroscopy (FTIR), morphologically by scanning electron microscopy (SEM), as well as their thermal degradation, by thermogravimetric analysis (TGA). Their crystallinity surface roughness was measured by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The results indicate over 70% cellulose fibers content with a very high crystallinity (92%) and small crystallite size (1.45 nm), which suggests a low water absorption, with thermal degradation peaking at 294°C. Despite this, due to the significant porosity of the cellular structure, the density of 1.06 g cm-3 is quite low for a mainly cellulose fiber. Roughness measurements indicate that the porosities and foamy structure result in a highly negative skewness (-3.953), in the presence of deep valleys, which may contribute to an effective relation with a covering resin.

Phenol formaldehyde resin modified by cellulose and lignin nanomaterials: Review and recent progress.

In recent years, growing consideration of the concepts of ecological sustainability, environmentally friendly, recyclability, non-toxicity and biodegradability towards a green environment, have led scientists to focus on the utilization of natural fibers as green reinforcing agents for improving thermal, physical, and mechanical characteristics of composites. In this way, cellulose and lignin (nano) materials are receiving global attention due to their unique and potentially useful features, containing abundance, renewability, low cost, excellent physical-mechanical properties, environmental friendliness, and low weight. Therefore, this research, addressed a survey of the literature on extending the performance of phenol-formaldehyde (phenolic) composites reinforced by cellulose and lignin nano materials that were explored in the last decade. Physical, mechanical behavior and thermal stability of the phenolic composites were comprehensively examined. Indeed, different types of phenolic composites modified with nanocellulose and nanolignin have been made using various advanced synthesis processes. The results were unanimous and highlighted the remarkable effect of nanocellulose and nanolignin on improving the overall performance of the fabricated composites.

Effects of the Face/Core Layer Ratio on the Mechanical Properties of 3D Printed Wood/Polylactic Acid (PLA) Green Biocomposite Panels with a Gyroid Core.

Gyroid structured green biocomposites with different thickness face layers (0.5, 1, 2 and 2.5 mm) were additively manufactured from wood/ polylactic acid (PLA) filaments using a 3D printer. The mechanical properties of the composite panels, bending properties, compressive strength (parallel to the surface), Brinell hardness, and face screw withdrawal resistance, were determined. The surface layer thickness significantly affects the mechanical properties of the composite materials. As the surface layer thickness was increased from 0.5 to 2.5 mm, all the mechanical properties significantly improved. In particular, the Brinell hardness and face screw withdrawal resistance of the specimens improved sharply when the skin thickness was higher than 2 mm. The bending strength, bending modulus, compressive strength (parallel to the surface), Brinell hardness, and face screw withdrawal resistance of the specimens with a skin of 0.5 mm were found to be 8.10, 847.5, 3.52, 2.12 and 445 N, respectively, while they were found to be 65.8, 11.82, 2492.2, 14.62, 26 and 1475 N for the specimens with a 2.5 mm skin. Based on the findings from the present study, gyroid structured composites with a thickness of 2 mm or higher are recommended due to their better mechanical properties as compared to the composites with skins that are thinner.

Preparation and characterization of polyhydroxybutyrate-co-valerate (PHBV) as green composites using nano reinforcements.

This article presents the preparation and characterization of polyhydroxybutyrate-co-valerate (PHBV) nanocomposite films containing cellulose nanocrystals (CNC) and aluminum oxide nanoparticles (Al2O3) as reinforcements. The effects of adding nanoparticles on the mechanical properties, such as tensile strength and elongation, were studied using dynamic-mechanical analysis (DMA) such as modulus and tan δ. Also, morphology and thermal features were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. For this purpose, first, CNC and Al2O3 with a ratio of 0, 1, 3 and 5 wt% was added to a biopolymer, then a combination of these two with the ratio of 3:3 and 5:5 was added to the PHBV matrix, separately; and finally, the various nanocomposite films were prepared by the solvent casting method. After adding nanoparticles, the tensile strength and thermal stability of the PHBV/CNC films increased and the elongation decreased. SEM observations showed that large amounts of nanoparticles (3 wt%) are strongly agglomerated in the biopolymer matrix. This led to a decrease of mechanical properties in the composites with nanoparticles of more than 3% by weight. DSC results showed that the glass transition temperature (Tg) increased slightly with the incorporation of nano participles to PHBV. The enthalpy of fusion (ΔHfus) increased from 33.8 J/g for neat PHBV film to 48.1, 50 and 45.8 J/g for PHBV films containing 1, 3, and 5 wt% CNC, respectively. These results are consistent with the conclusions of DMA. The improvement of physical and mechanical properties of the composites confirmed that CNC has a better effect than aluminum oxide nanoparticles as a nano reinforcement.

All-cellulose composite films with cellulose matrix and Napier grass cellulose fibril fillers.

Diverse move has been attempted to use biomass as a filler for the production of biodegradable all-cellulose composites. In this study, cellulose fibrils (CFs) extracted from native African Napier grass (NG) fibres were used as fillers in cellulose matrix and made all-cellulose composites. Napier Grass Cellulose fibrils (NGCFs) loading was varied from 5 to 25 wt% in cellulose matrix in random orientation and the all cellulose composites were made by regeneration process. These composites were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, thermogravimetric analysis, optical microscopy, and tensile testing. The FTIR spectra indicated not only the presence of minute amounts of hemicelluloses and lignin in the filler but also the possible interaction between the matrix and NGCFs. The crystallinity of the all-cellulose composites was found to be lower than that of the cellulose matrix. The thermal stability of the all-cellulose composites was found to be higher than that of the cellulose matrix and increased with NGCFs filler content. The tensile strength of the all-cellulose composites though was lower than that of the cellulose matrix but still was higher than for commodity polymers. The all-cellulose composites can be considered for wrapping and mulching applications.

Evaluation of the physical, mechanical properties and formaldehyde emission of particleboard manufactured from waste stone pine (Pinus pinea L.) cones.

The objective of this study was to investigate some physical/mechanical properties and formaldehyde emission of particleboard containing particles of waste stone pine cone at various usage ratios using urea-formaldehyde resin. Some physical (thickness swelling, water absorption), mechanical (modulus of elasticity, modulus of rupture, internal bond strength) properties and formaldehyde emission of particleboards were evaluated. The addition of cone particle improved water resistance of the panels and greatly reduced their formaldehyde emissions. However, flexural properties and internal bond strength decreased with increasing cone particle content in the panel. The cone of the stone pine can be considered as an alternative to wood material in the manufacture of particleboard used in indoor environment due to lower thickness swelling, water absorption and formaldehyde emission.

Utilization of waste tire rubber in manufacture of oriented strandboard.

Some physical and mechanical properties of oriented strandboards (OSBs) containing waste tire rubber at various addition levels based on the oven-dry strand weight, using the same method as that used in the manufacture of OSB. Two resin types, phenol-formaldehyde (PF) and polyisocyanate, were used in the experiments. The manufacturing parameters were: a specific gravity of 0.65 and waste tire rubber content (10/90, 20/80 and 30/70 by wt.% of waste tire rubber/wood strand). Average internal bond values of PF-bonded OSB panels with rubber chips were between 17.6% and 48.5% lower than the average of the control samples while polyisocyanate bonded OSBs were 16.5-50.6%. However, water resistance and mechanical properties of OSBs made using polyisocyanate resin were found to comply with general-purpose OSB minimum property requirements of EN 300 Type 1 (1997) values for use in dry conditions at the lowest tire rubber loading level (10%) based on the oven-dry panel weight. The tire rubber improved water resistance of the OSB panel due to its almost hydrophobic property. Based on the findings obtained from this study, we concluded that waste tire rubber could be used for general-purpose OSB manufacturing up to 10% ratio based on the oven-dry panel weight.