Showing papers on "SISAL published in 1994"

Stress relaxation in short sisal-fiber-reinforced natural rubber composites

Abstract: Stress relaxation behavior of chemically treated short sisal fiber-reinforced natural rubber composite was studied. The effect of bonding agent, strain level, fiber loading, fiber orientation, and temperature has been studied in detail. The existence of a single relaxation pattern in the unfilled stock and a two-stage relaxation mechanism for the fiber-filled composite is reported. The relaxation process is influenced by the bonding agent, which indicated that the process involved fiber-rubber interface. The rate of stress relaxation increased with fiber loading, whereas it decreased with aging. © 1994 John Wiley & Sons, Inc.

Mechanical and viscoelastic properties of short fiber reinforced natural rubber composites: effects of interfacial adhesion, fiber loading, and orientation

Abstract: The effect of a two-component dry bonding system consisting of resorcinol and hexamethylene tetramine on the mechanical and viscoelastic properties of short sisal fiber reinforced natural rubber composites has been studied. The studies were conducted with chemically treated and untreated short sisal fibers. Treated fibers impart better mechanical properties to the composites. By mixing with short fibers, the dynamic storage modulus (E') of natural rubber composites was improved. The effects of fiber-matrix adhesion on the mechanical and viscoelastic properties of the composites were investigated. The storage moduli and mechanical loss increased continuously with an increase in fiber loading but decreased with an increase of temperature. The influence of the fiber orientation on the mechanical and viscoelastic properties is discussed.

Reinforced biodegradable polymer

Abstract: Natural fibres, such as in particular sisal or ramie fibres, are used to reinforce a substantially biodegradable polymer in order to prevent it from at least partially losing its biodegradability when it is reinforced with additives such as fibres and the like.

A biomaterial-based carbon fiber

Abstract: An attempt to convert natural sisal fiber into low cost carbon fibrous materials was made. The pretreatment, pyrolysis and carbonization processes of raw sisal fiber as well as structure and properties of the resultant product were investigated. It was found that the sisal-based carbon fiber with moderate mechanical performance can be manufactured under the conditions applied. In addition, the application of the obtained sisal-based carbon fiber serving as functional material is presented. Es wurde versucht, Sisalfasern zu kostengunstigen Kohlefasern zu carbonisieren. Vorbehandlung, Pyrolyse- und Carbonisierungsvorgang sowie Struktur und Eigenschaften der gebildeten Produkte wurden untersucht. Anwendungsmoglichkeiten fur die aus Sisal hergestellten Kohlefasern mit masigen mechanischen Eigenschaften werden vorgeschlagen.

Nutrient depletion in Ferralsols under hybrid sisal cultivation in Tanzania

Abstract: . Sisal production in Tanzania has declined sharply in the past two decades because of a decrease in the area grown and a decrease in yields. As sisal is cultivated without manuring, depletion of soil fertility is considered one of the main causes of the declining yields. This paper presents a balance of the macronutrients N, P, K, Ca and Mg for sisal grown in a plantation in NE Tanzania on deep, red clay soils (Ferralsols). Annual fibre yields declined from 2.5 t/ha in the 1960s to about 1 t/ha in the 1980s. Hybrid sisal is a demanding crop and in ten years, with a total fibre yield of 11 t/ha, about 260 kg of N, 40 kg of P, 385 kg of K, 890 kg of Ca and 330 kg of Mg are removed in the harvested leaves. A comparison of soils after two and three 10-yr cycles of sisal production showed that in the third cycle the pH decreased by 0.5 units and that exchangeable bases were decreased by fifty per cent or more. The amounts of K, Ca and Mg removed from the soil were similar to those in leaves. However, soil analyses could not detect changes in total N and available P, possibly because of the large amount of total N in the soil and the lack of precision in the N and P analyses. In the Ferralsols, potassium is likely to become deficient first, followed by magnesium and calcium. The soil has little available P, and an increase in soil acidity may decrease it further and also create aluminium and manganese toxicities. In order to maintain sisal production, fertilization with P, K, Ca and Mg is necessary, and to improve yields N must also be applied.

Fire behaviour of sisal short fibers reinforced gypsum

Abstract: The fire behavior of sisal fibers reinforced gypsum in laboratory tests is described. Specially designed testing equipment that is easily available has been implemented in this work to analyze the fire behavior of fibers under load and their composite fire performance.

Extracting parallelism in Fortran by translation to a single assignment intermediate form

Abstract: The paper presents MUSTANG, a system for translating Fortran to single assignment form in an effort to automatically extract parallelism. Specifically, a sequential Fortran source program is translated into IF1, a machine-independent dataflow graph description language that is the intermediate form for the SISAL language. During this translation, Parafrase 2 is used to detect opportunities for parallelization which are then explicitly introduced into the IF1 program. The resulting IF1 program is then processed by the Optimizing SISAL Compiler which produces parallel executables on multiple target platforms. The execution results of several Livermore Loops are presented and compared against Fortran and SISAL implementations on two different platforms. The results show that the translation is an efficient method for exploiting parallelism from the sequential Fortran source code. >