Leaf fibres from Phormium tenax (harakeke, New Zealand flax) were treated with 1 wt.% aqueous NaOH at 30 °C to remove all of the acetyl groups, accounting for most of a 7% mass loss. Increasing the treatment time to 4 h showed no detectable increase in mass loss, but increasing the NaOH concentration to 5% doubled the mass loss by removing some of the xylans. Changes in fibre morphology were interpreted in terms of swelling of cell walls into lumens, followed by shrinkage on drying without reopening the lumens. Deacetylation retarded the rate of water uptake in unidirectional epoxy composites, but showed no detectable influence on the equilibrium moisture content, flexural modulus or strength. The results suggest that high levels of natural acetylation are not a useful feature of leaf fibres, at least in the context of reinforcement for epoxy composites.

Epoxy composites reinforced with deacetylated Phormium tenax leaf fibres

This article addresses the processing and ageing properties of jute fiber reinforced polypropylene (PP) composites. The composite has been manufactured by a continuous extrusion process and results in free flowing composite granules, comprising up to 50 weight percent (wt %) jute fiber in PP. These granules have similar shape and diameter as commercially available PP granules. Rheological analysis shows that viscosity of the compounds follows the same shear rate dependency as PP and is on the same level as glass-PP compounds. The mechanical properties show very little variation and exhibit strength and stiffness values at the upper range of competing natural fiber reinforced compounds for injection molding. The mechanical performance reduces gradually upon prolonged thermal loading and immersion in water. The low water diffusion coefficient of the 50 wt % jute-PP composites indicates that the fibers are not forming a continuous network throughout the polymer. The jute fibers exhibit a stabilizing effect against ultra violet irradiation (UV) on PP polymer and, as a consequence, the mechanical properties of jute-PP composites hardly decrease during an accelerated UV ageing test. Bacteria, fungi, and garden mold grow easily on the compound material, but only have a limited effect on mechanical properties. The resistance to growth of bacteria on the materials surface can be increased using a biostabilizer.

Jute fiber reinforced polypropylene produced by continuous extrusion compounding, part 1: Processing and ageing properties

Effect of volume fraction of ramie cloth on physical and mechanical properties of ramie cloth/UP resin composite

Thermal degradation of PVC and acacia wood flour (with and without silane treatment) composites was studied by using TGA in nitrogen atmosphere. The wood flour was varied from 10 to 30 % within the PVC matrix. Thermal stability of the composites increased with increase in percentage of wood flour at higher temperature. The thermal stability of the silane treated microcellular composites (SPVC) was found to be greater than that of the untreated (UPVC) one. It was also strengthened by the higher activation energy of the silane treated composites for 30 % (SPVC30) and 10 wt% (SPVC10) filler loading (210 and 187 kJ mol−1) in comparison to that of UPVCs (185 and 161 kJ mol−1) respectively. The isothermal degradation and thermodynamic parameters were also studied and found that the isothermal stability with time, entropy change (ΔS) and enthalpy change (ΔH) increased with increase in wt% of UPVCs and SPVCs . The values of ΔH were recorded as 534 and 452 kJ mol−1 for SPVC30 and SPVC10, which were highest among all the composites. It proved the better thermal stability of silane treated over the untreated microcellular composites. The values of Gibb’s free energy (ΔG) decreased as the filler content increased from 10 to 30 wt% filler loading, which supports the above said statements.

Thermal decomposition kinetics of silane treated wood: PVC microcellular composites

Henequen fiber was air-stabilized, carbonized, and steam-activated to obtain high surface area activated henequen fiber (AHF). Thermal behavior of henequen fibers has been studied by TGA. The structural morphology and characteristics were observed by SEM and BET surface area measurement. The yield of AHF from natural henequen was in the range of
20~25 wt%. Mesopores (2~2.5 nm) were developed on the AHF as the activation temperature was raised up to 700oC, and the band of mesopore size distribution moved to 15~30 nm when the activation were carried out at 900oC for 30 min. The specific surface area and the total pore volume were about 1394 m2/g and 1.30 cm3/g, respectively at this activation conditions.

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Preparation and Characterization of Activated Henequen Fiber

This work deals the effect of acetylated and
non-acetylated sisal fiber 011 thermal degradation of
polypropylene. Applying the R-G method at constant conversion
levels of 0.1, 0.3, 0.5, 0.7 and 0.9 to thermograms of the
”PP/untreated sisal fiber” blend, E, values of 99, 213, 224,
187, and 145 kJ/mol were obtained, whereas they were 99, 299,
255, 205, 154 kJ/mol for the “PP/treated sisal fiber” blend. On
the other hand, with the R-G method at constant temperature,
activation energies within the range of 156-417 kJ/mol were
obtained for the “PP/treated sisal fiber” blend and within the
range of 126-344 kJ/mol for the “PP/untreated sisal fiber”
blend. Additionally, the method establishes as dominant the
following decomposition mechanisms: three-dimension limiting
surface reaction between both phases, diffusion in two and three
dimeiisions and first-order random nucleation and nuclei
growth.

J. Guevara

Papers

Thermal stability of PP with acetylated sisal fiber: Romero García kinetic method