SISAL

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

Adding value to the Brazilian sisal: acid hydrolysis of its pulp seeking production of sugars and materials

Abstract: The present work is inserted into the broad context of the upgrading of lignocellulosic fibers. Sisal was chosen in the present study because more than 50% of the world’s sisal is cultivated in Brazil, it has a short life cycle and its fiber has a high cellulose content. Specifically, in the present study, the subject addressed was the hydrolysis of the sisal pulp, using sulfuric acid as the catalyst. To assess the influence of parameters such as the concentration of the sulfuric acid and the temperature during this process, the pulp was hydrolyzed with various concentrations of sulfuric acid (30–50%) at 70 °C and with 30% acid (v/v) at various temperatures (60–100 °C). During hydrolysis, aliquots were withdrawn from the reaction media, and the solid (non-hydrolyzed pulp) was separated from the liquid (liquor) by filtering each aliquot. The sugar composition of the liquor was analyzed by HPLC, and the non-hydrolyzed pulps were characterized by viscometry (average molar mass), and X-ray diffraction (crystallinity). The results support the following conclusions: acid hydrolysis using 30% H2SO4 at 100 °C can produce sisal microcrystalline cellulose and the conditions that led to the largest glucose yield and lowest decomposition rate were 50% H2SO4 at 70 °C. In summary, the study of sisal pulp hydrolysis using concentrated acid showed that certain conditions are suitable for high recovery of xylose and good yield of glucose. Moreover, the unreacted cellulose can be targeted for different applications in bio-based materials. A kinetic study based on the glucose yield was performed for all reaction conditions using the kinetic model proposed by Saeman. The results showed that the model adjusted to all 30–35% H2SO4 reactions but not to greater concentrations of sulfuric acid. The present study is part of an ongoing research program, and the results reported here will be used as a comparison against the results obtained when using treated sisal pulp as the starting material.

Sisal fibers treated with NaOH and benzophenonetetracarboxylic dianhydride as reinforcement of phenolic matrix

Abstract: In this work, composites based on a phenolic matrix and untreated- and treated sisal fibers were prepared. The treated sisal fibers used were those reacted with NaOH 2% solution and esterified using benzophenonetetracarboxylic dianhydride (BTDA). These treated fibers were modified with the objective of improving the adhesion of the fiber-matrix interface, which in turn influences the properties of the composites. BTDA was chosen as the esterifying agent to take advantage of the possibility of introducing the polar and aromatic groups that are also present in the matrix structure into the surface of the fiber, which could then intensify the interactions occurring in the fiber-matrix interface. The fibers were then analyzed by SEM and FTIR to ascertain their chemical composition. The results showed that the fibers had been successfully modified. The composites (reinforced with 15%, w/w of 3.0 cm length sisal fiber randomly distributed) were characterized by SEM, impact strength, and water absorption capacity. In the tests conducted, the response of the composites was affected both by properties of the matrix and the fibers, besides the interfacial properties of the fiber-matrix. Overall, the results showed that the fiber treatment resulted in a composite that was less hygroscopic although with somewhat lower impact strength, when compared with the composite reinforced with untreated sisal fibers.

The use of sisal and henequen fibres as reinforcements in composites

Abstract: Firstly, a brief overview of sisal fibres, including global sources and availability, chemical compositions, key properties, extraction and quality control is given. Their multi-scale structures and dimensional parameters are revealed by micro-observation, and their mechanical properties are measured a by single fibre tensile test. Several theoretical models are proposed and the results are compared with experimental values. Secondly, manufacturing techniques of sisal fibre-reinforced thermoplastics and thermosets are introduced. Effects of fibre surface treatments and moisture absorption on the interfacial shear strength, interlaminar shear strength and interlaminar fracture toughness are investigated. Mechanical properties, moisture absorption behaviour, and effects of moisture absorption and UV light radiation are revealed. Finally, current applications and further research aspects are proposed.

Soil fertility decline and fallow effects in ferralsols and acrisols of sisal plantations in Tanzania

Abstract: Soil fertility decline and fallow effects were studied in Ferralsol-Acrisol catenas of plantations of sisal (Agave sisalana) in north-east Tanzania. The fertility of Ferralsols that had been subject to continuous sisal cultivation in the absence of fertilizers was extremely low but that of Ferralsols that had been under 18 years of bush fallow or under secondary forest was slightly better. Acrisols that had been under continuous sisal cultivation were less depleted than the Ferralsols because of greater intrinsic fertility. A comparison of soil analytical data from the 1950s and 1960s with recent data from the same sisal fields showed that the topsoil pH of the Ferralsols had decreased by 1.5 (r2 = 0.807) and that of the Acrisols by 1.2 (r2 = 0.494) under continuous sisal cultivation. Thus there had been a serious decline in soil fertility under sisal cultivation, and this decline was not adequately reversed by fallowing.

Mechanical Properties of Phenol Formaldehyde Hybrid Composites Reinforced with Natural Cellulose Fibers

Abstract: This paper reports on the preparation and mechanical properties of hybrid polymer composites involving areca fine fibers (AFFs), sisal fibers (SFs), and roselle fibers (RFs) as reinforcing agents in a phenol formaldehyde (PF) resin-based polymer matrix. For comparative study, an AFF/glass fiber-reinforced PF hybrid composite and AFF/PF composite were also prepared. Hybrid composites were fabricated using a hand lay-up technique, where the weight fraction of fibers was kept at 40 wt% at a ratio of 1:1. Tensile and flexural properties of randomly oriented intimately mixed hybrid polymer composites were evaluated. The results revealed that the mechanical properties of the AFF/PF composite increased by a considerable amount when hybridized with the sisal fibers. Scanning electron microscopy (SEM) was used to analyze the fractured surface of the composite specimens after mechanical testing.