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Lignocellulosic Fibers (lignocellulosic + fiber)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Effect of Lignin on the Heat and Light Resistance of Lignocellulosic Fibers

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2007
Narendra Reddy
Abstract The existence of lignin in lignocellulosic fibers increases the loss in breaking tenacity and elongation of fibers when they are exposed to heat and light. Delignification by sulfonation helps to remove some of the lignin from the fibers without affecting the breaking tenacity. The delignified fibers have higher resistance to heat and light exposure compared to the raw fibers. The effect of lignin on the heat and light resistance of kenaf and cornhusk fibers with three different lignin contents was studied in comparison to cotton at various periods of heat and light exposure. The changes in the breaking tenacity, breaking elongation and yellowness of the samples were studied. [source]

The influence of fiber surface modification on the mechanical properties of coir-polyester composites

POLYMER COMPOSITES, Issue 4 2001
J. Rout
Coir, an important lignocellulosic fiber, can be incorporated in polymers like unsaturated polyester in different ways for achieving desired properties and texture. But its high level of moisture absorption, poor wettability and insufficient adhesion between untreated fiber and the polymer matrix lead to debonding with age. In order to improve the above qualities, adequate surface modification is required. In our present work, fiber surface modification was effected through dewaxing, alkali (5%) treatment, aqueous graft copolymerization of methyl methacrylate (MMA) onto 5% alkali treated coir for different extents using CuSO4 , NaIO4 combination as an initiator system and cyanoexhylation with a view to improve the mechanical performance of coir-polyester composites. Mechanical properties like tensile strength (PS), flexural strength (ES) and impact strength (IS) of the composites as a function of fiber loading and fiber surface modification have been evaluated. Composites containing z5 wt% of fiber (untreated) improved tensile and flexural strength by 30% and 27% respectively in comparison to neat polyester. The work of fracture (impact strength) of the composite with 25 wt% fiber content was found to be 967 J/m. The elongation at break of the composites exhibits an increase with the introduction of fiber, All types of surface modification result In improved mechanical properties of the composites. Significant improvement in mechanical strength was also observed for composites prepared from 5% PMMA grafted fiber. [source]

Effect of Lignin on the Heat and Light Resistance of Lignocellulosic Fibers

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2007
Narendra Reddy
Abstract The existence of lignin in lignocellulosic fibers increases the loss in breaking tenacity and elongation of fibers when they are exposed to heat and light. Delignification by sulfonation helps to remove some of the lignin from the fibers without affecting the breaking tenacity. The delignified fibers have higher resistance to heat and light exposure compared to the raw fibers. The effect of lignin on the heat and light resistance of kenaf and cornhusk fibers with three different lignin contents was studied in comparison to cotton at various periods of heat and light exposure. The changes in the breaking tenacity, breaking elongation and yellowness of the samples were studied. [source]

Unmodified and Modified Surface Sisal Fibers as Reinforcement of Phenolic and Lignophenolic Matrices Composites: Thermal Analyses of Fibers and Composites

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2006
Jane Maria Faulstich de Paiva
Abstract Summary: The study and development of polymeric composite materials, especially using lignocellulosic fibers, have received increasing attention. This is interesting from the environmental and economical viewpoints as lignocellulosic fibers are obtained from renewable resources. This work aims to contribute to reduce the dependency on materials from nonrenewable sources, by utilizing natural fibers (sisal) as reinforcing agents and lignin (a polyphenolic macromolecule obtained from lignocellulosic materials) to partially substitute phenol in a phenol-formaldehyde resin. Besides, it was intended to evaluate how modifications applied on sisal fibers influence their properties and those of the composites reinforced with them, mainly thermal properties. Sisal fibers were modified by either (i) mercerization (NaOH 10%), (ii) esterification (succinic anhydride), or (iii) ionized air treatment (discharge current of 5 mA). Composites were made by mould compression, of various sisal fibers in combination with either phenol-formaldehyde or lignin-phenol-formaldehyde resins. Sisal fibers and composites were characterized by thermogravimetry (TG) and DSC to establish their thermal stability. Scanning electron microscopy (SEM) was used to investigate the morphology of unmodified and modified surface sisal fibers as well as the fractured composites surface. Dynamic mechanical thermoanalysis (DMTA) was used to examine the influence of temperature on the composite mechanical properties. The results obtained for sisal fiber-reinforced phenolic and lignophenolic composites showed that the use of lignin as a partial substitute of phenol in phenolic resins in applications different from the traditional ones, as for instance in other than adhesives is feasible. Micrograph of the impact fracture surface of phenolic composite reinforced with mercerized sisal fiber (500 X). [source]

Mechanical behavior of cold plasma,treated sisal and high-density polyethylene composites

POLYMER COMPOSITES, Issue 3 2003
Adriana R. Martin
Sisal fibers and finely powdered high-density polyethylene were surface functionalized with dichlorosilane on a RF(radio frequency)-plasma reactor. Composites made from sisal and high-density polyethylene were compounded using a thermokinetic mixer. The discharged mass was cooled, granulated, and injected molded into composite specimens for testing. The mechanical behaviors (tensile, impact and thermal dynamical mechanical properties) of composites made from cold plasma-treated and untreated components are compared and discussed. The best mechanical performance was generally obtained for composites where only the inert thermoplastic matrix was plasma-functionalized. Plasma treatment of lignocellulosic fibers seems to induce decomposition processes of the surface layers structures exposed to the plasma that generally does not contribute to significant improvement on the mechanical behavior of the composite. [source]

Flammability and fire resistance of composites reinforced by natural fibers

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2008
Ryszard Koz, owski
Abstract Natural fiber-reinforced composites are more and more frequently applied to building industry and transportation. Therefore, the knowledge of their behavior during fire is of high importance. Flammability is one of very important parameters that often limits the application of composites to a given area. It is well-known that addition of lignocellulosic fibers to polymer changes mechanical properties of the product obtained. However, little information is available on their fire performance. The purpose of this review was to obtain fire performance data for several types of composites reinforced by lignocellulosic fibers. Copyright © 2008 John Wiley & Sons, Ltd. [source]