SISAL

About: SISAL is a research topic. Over the lifetime, 1878 publications have been published within this topic receiving 55528 citations.

Micromechanical analysis of hybrid composites reinforced with unidirectional natural fibres, silica microparticles and maleic anhydride

Abstract: The work describes the analytical and experimental characterisation of a class of polymeric composites made from epoxy matrix reinforced with unidirectional natural sisal and banana fibres with silica microparticles and maleic anhydride fabricated by manual moulding. The analytical models, ROM rule of mixtures and Halpin-Tsai approach, have been used in conjunction with a Design of Experiments (DOE) analysis from tensile tests carried out on 24 different composites architectures. The following experimental factors were analyzed in this work: type of fibres (sisal and banana fibres), volume fraction of fibres (30% and 50%) and modified matrix phase by adding silica microparticles (0%wt, 20%wt and 33%wt) and maleic anhydride (0%wt and 2%wt). The ROM approach has shown a general good agreement with the experimental data for composites manufactured with 30%vol of natural fibres, which can be attributed to the strong adhesion found between the phases. On the opposite, the semi empirical model proposed by Halpin and Tsai has shown greater fidelity with composites manufactured from 50%vol of natural fibres, which exhibit a weak interfacial bonding. The addition of microsilica and maleic anhydride in the system did not enhance the adhesion between the phases as expected.

Effect of dynamical converging channels on fiber organization and damage during vane extrusion of sisal fiber‐reinforced polypropylene composites

Abstract: It is well known that converging channel can generate elongational deformation field. In this study, novel dynamical converging channels were successfully incorporated into plant fiber-reinforced thermoplastics composites processing. A dynamical elongational deformation field (DEDF) generated by these channels was studied. The fiber organization and damage in the DEDF has been investigated in terms of its relationship to changes in rotating speed of the channels. A vane extruder based on these channels was used to prepare sisal fiber-reinforced polypropylene composites. By investigating rapidly cooled samples in the vane extruder, sisal fiber in the center part of these channels has an orientation with an angle to the discharging direction. Rotating speed increases from 30 to 90 r/min result in 30.99–42.7% decreases in average fiber length. The issues of fiber distribution and voids formation have been related to the mechanical properties of the composites, particularly tensile strength and modulus. Increased rotating speeds from 30 to 90 r/min results in tensile strength and modulus increases of about 21.3% and 11.6%, respectively. The majority of this change is caused by decreased voids formation with the increases of speed, which is in agreement with scanning electron microscopy of the composites. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers

Some aspects of acetylation of untreated and mercerized sisal cellulose

Abstract: We report here on some aspects of the acetylation in LiCl/N,N-dimethylacetamide, DMAc, of untreated and mercerized sisal cellulose, hereafter designated as sisal and M-sisal, respectively. Fiber mercerization by NaOH solution has resulted in the following changes: 29.9% decrease in the index of crystallinity; 16.2% decrease in the degree of polymerization and 9.3% increase in α-cellulose content. A light scattering study of solutions of sisal, M-sisal, microcrystalline and cotton celluloses in LiCl/DMAc has shown that they are present as aggregates, with (an apparent) average aggregation numbers of 5.2, 3.2, 9.8, and 35.3, respectively. The presence of these aggregates affects the accessibility of cellulose during its functionalization. A study of the evolution of the degree of substitution, DS, of cellulose acetate as a function of reaction time showed an increase up to 5 h, followed by a decrease at 7 h. Possible reasons for this decrease are discussed. As expected, M-sisal gave a higher DS that its untreated counterpart.

Studies on mechanical properties of sisal fiber/phenol formaldehyde resin in-situ composites

Abstract: Phenol formaldehyde resin (PF) reinforced with short sisal fibers (SF) were obtained by two methods, direct-mixing and polymerization filling. Impact and bending properties of resulting composites were compared. Under the same compression molding conditions, polymerization filled composites showed better mechanical properties than those of direct-mixed composites. The influences of fiber modifications on the mechanical properties of SF/PF in-situ (polymerization filled) composites have been investigated. Treated-SF-reinforced composites have better mechanical properties than those of untreated-SF-reinforced composites. The effects of SF on water absorption tendencies of SF/PF composites have also been studied. In addition, sisal/glass (SF/GF) hybrid PF composites of alkali-treated SF were prepared. Scanning electron microscopic studies were carried out to study the fiber-matrix adhesion. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Lignocellulosic fiber breakage in a molten polymer. Part 1. Qualitative analysis using rheo-optical observations

Abstract: Understanding how lignocellulosic fibers break during compounding and shaping processes (e.g. extrusion, injection) is of the greatest importance for mastering fiber size evolution and thus predicting composite mechanical properties. In this first paper of a series devoted to this topic, rheo-optical experiments were used for a direct observation of fibers’ behavior when sheared in a molten thermoplastic matrix. Fibers from four vegetal species were studied: hemp, flax, sisal and miscanthus. While possessing different morphological, composition and mechanical characteristics, these fibers also display different preponderant breakage mechanisms. We were able to distinguish fibers breakage (i) in a fragile way (flax and sisal), (ii) by fatigue, i.e. cumulated strain (hemp), or (iii) by peeling (miscanthus). Each fiber type is qualitatively classified according to these categories and correlations with lignin and hemicellulose contents are discussed.