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Short Fibers (short + fiber)

Distribution by Scientific Domains

Polymers and Materials Science	83%

Selected Abstracts

Innovative Catalysts for Oxidative Dehydrogenation in the Gas Phase , Metallic Short Fibers and Coated Glass Fabrics,

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2005
R. Brüning
Abstract The catalytic activity of metallic short fibers with chosen alloy components and textures was investigated in the oxidative dehydrogenation (ODH) of propane to yield propene, and of isopropanol to yield acetone. The short fibers were synthesized using a melt extraction process and the properties of the fibers were intensely characterized. A correlation between the structure and the catalytic activity of the material was established. Optical microscopic, DSC, XRD, REM and EDX methods were used to characterize the fibers. Selective results of the dependency of the temperature on the propane conversion are presented in this work. A yield of more than 35,% propene is obtained at a propane conversion of 50,%. The ODH of isopropanol to acetone occurred with attractive yields of over 80,%. The results demonstrate the high innovative potential of the metal fiber materials. The use of coated glass fabrics as catalysts for the ODH and total oxidation of propane were also part of this investigation. [source]

Short fibers as reinforcement of rubber compounds

POLYMER COMPOSITES, Issue 4 2002
M. A. López Manchado
The effect of aramid, glass and cellulose short fibers on the processing behavior, crosslinking density and mechanical properties of natural rubber (NR), ethylene-propylene-diene terpolymer rubber (EPDM) and styrene-butadiene rubber (SBR) has been investigated. Two fiber percentages (10 and 20 phr) were added to the rubber. The results have shown that the above-mentioned fibers, especially aramid fibers, are effective reinforcing agents for these rubbers, giving rise to a significant increase in mechanical properties, such as tensile modulus and strength, and tear and abrasion resistance. Moreover, a significant decrease in the time to reach 97% of curing, t,c (97) is observed, which indicates that the fibers tend to increase the vulcanization rate, regardless of the rubber used. Fibers give also rise to an increase in crosslinking, especially the aramid fibers. [source]

A Solvent Free Graft Copolymerization of Maleic Anhydride onto Cellulose Acetate Butyrate Bioplastic by Reactive Extrusion

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2006
Arief C. Wibowo
Abstract Summary: Interfacial adhesion between fibers and matrix is a crucial factor for effective stress transfer from matrix to fiber; especially in short fiber reinforced composite systems. The use of a chemical compatibilizer is an efficient means to achieve such adhesion. Maleic anhydride-grafted-cellulose acetate butyrate (CAB-g-MA) is one such compatibilizer which can be used in biocomposite fabrication, and this has been synthesized in our laboratory by utilizing a twin-screw reactive extrusion process in the presence of a free radical initiator (2,5-dimethyl-2,5-di(tert -butylperoxy)hexane). The unique feature of this process is its solvent-free approach for grafting of maleic anhydride onto CAB, without hydroxyl group protection. CAB-g-MA was characterized using FTIR as well as by a non-aqueous titration method. The effects of initiator and monomer concentrations and various processing conditions on the graft content were also investigated. The preliminary results show that by adding approximately 10 wt.-% of CAB-g-MA into a plasticized cellulose acetate butyrate (TEB)-industrial hemp fiber biocomposites system, an improvement in tensile strength (20%) and in tensile modulus (45%) were obtained. These results are promising in that they pave the way for future studies involving the use of CAB-g-MA as a suitable compatibilizer for cellulose ester-natural fiber biocomposites. [source]

Effects of temperature and strain rate on the tensile behavior of short fiber reinforced polyamide-6

POLYMER COMPOSITES, Issue 5 2002
Zhen Wang
Tensile behavior of extruded short E-glass fiber reinforced polyamide-6 composite sheet has been determined at different temperatures (21.5°C, 50°C, 75°C, 100°C) and different strain rates (0.05/min, 0.5/min, 5/min). Experimental results show that this composite is a strain rate and temperature dependent material. Both elastic modulus and tensile strength of the composite increased with strain rate and decreased with temperature. Experimental results also show that strain rate sensitivity and temperature sensitivity of this composite change at a temperature between 25°C and 50°C as a result of the glass transition of the polyamide-6 matrix. Based on the experimental stress-strain curves, a two-parameter strain rate and temperature dependent constitutive model has been established to describe the tensile behavior of short fiber reinforced polyamide-6 composite. The parameters in this model are a stress exponent n and a stress coefficient ,*. It is shown that the stress exponent n, which controls the strain rate strengthening effect and the strain hardening effect of the composite, is not only strain rate independent but also temperature independent. The stress exponent ,*, on the other hand, varies with both strain rate and temperature. [source]

Preparation of rubber composites from ground tire rubber reinforced with waste-tire fiber through mechanical milling

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007
Xin-Xing Zhang
Abstract Composites made from ground tire rubber (GTR) and waste fiber produced in tire reclamation were prepared by mechanical milling. The effects of the fiber content, pan milling, and fiber orientation on the mechanical properties of the composites were investigated. The results showed that the stress-induced mechanochemical devulcanization of waste rubber and the reinforcement of devulcanized waste rubber with waste-tire fibers could be achieved through comilling. For a comilled system, the tensile strength and elongation at break of revulcanized GTR/fiber composites reached maximum values of 9.6 MPa and 215.9%, respectively, with 5 wt % fiber. Compared with those of a composite prepared in a conventional mixing manner, the mechanical properties were greatly improved by comilling. Oxygen-containing groups on the surface of GTR particles, which were produced during pan milling, increased interfacial interactions between GTR and waste fibers. The fiber-filled composites showed anisotropy in the stress,strain properties because of preferential orientation of the short fibers along the roll-milling direction (longitudinal), and the adhesion between the fiber and rubber matrix was improved by the comilling of the fiber with waste rubber. The proposed process provides an economical and ecologically sound method for tire-rubber recycling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4087,4094, 2007 [source]

GC-MS and 13C NMR Investigation of Lead Zirconate Titanate Precursor Sols for Fiber Preparation

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2007
Mei Zhang
Different macroscopic properties of PZT fibers have been obtained when using acetic acid and methacrylic acid to modify the PZT precursor. In order to clarify the role of the acids the molecular structure of the acidified PZT precursors was investigated and compared by gas chromatography-mass spectrometry, Fourier transform infrared, 13C nuclear magnetic resonance (NMR) spectroscopy (solution and solid state 13C NMR) and the reason for obtaining long PZT fibers is discussed. The results indicate that when methacrylic acid was used, long gel and ceramic fibers have been obtained because strongly co-ordinating carboxylate groups of methacrylic acid were formed. Linear chains, like those of methacrylic acid propyl ester and methacrylic acetate, have been formed in the PZT precursor sols. In addition, after heat treatment the polymer decomposed quickly so that pure perovskite could be obtained at low temperature in the PZT fibers. When acetic acid was used short fibers were obtained. Acetic acid may act as chelate agent to form oxo acetate in the precursors; this oxo acetate nature also resulted in PZT fibers drawing. However, the longest gel and ceramic fibers have been prepared from precursors with methacrylic acid. [source]

Creep behavior of biocomposites based on sisal fiber reinforced cellulose derivatives/starch blends

POLYMER COMPOSITES, Issue 3 2004
Vera A. Alvarez
Biodegradable composites based on cellulose derivatives/starch blends reinforced with sisal short fibers were fabricated by injection molding. Results of short-term flexural creep tests are reported to investigate the time-dependence behavior of the composites. Fiber content and temperature effects are also considered, taking into account various methods and equations. At short times, a creep power law is employed. A master curve with the Arrhenius model is used to determine the creep resistance at longer times and different temperatures. Good fitting of the experimental results with the four-parameter model is reported, leading to a relationship between the observed creep behavior and the composite morphology. The addition of sisal fibers to the polymeric matrix promotes a significant improvement of the composite creep resistance. Polym. Compos. 25:280,288, 2004. © 2004 Society of Plastics Engineers. [source]

Short fibers as reinforcement of rubber compounds

On predicting elastic moduli and natural frequencies of multi-phase composites with randomly distributed short fibers

POLYMER COMPOSITES, Issue 1 2000
Lu-Ping Chao
This study presents a formulation to determine the overall stiffness of an n -phase short fiber composite to include the inclusions' aspect ratio ranging from less than one to greater than one. The Mori-Tanaka theory is initially employed to investigate the overall stress-strain relation of a multi-phase short-fiber-reinforced composite material, particularly whether or not the fibers and the matrix are isotropic, cubic, or transversely isotropic material. The effective stiffness tensor of a multi-phase composite is then denoted as a function of the matrix's elastic moduli, the n -phases' inclusions' elastic moduli, the n -phases' inclusions' Eshelby tensor, and the n -phases' inclusions' volume fractions. Utilizing the equivalent inclusion method allows us to model inclusions of n -phases that consist of fictitious eigenstrains. In addition, the corresponding Eshelby tensors' values for ellipsoidal inclusion embedded in the isotropic matrix with the variation of aspect ratio are presented. Numerical results of the proposed formulation in solving a two-phase composite closely correspond to the Halpin-Tsai Equation. Results presented herein provide valuable information on the appropriate manufacturing requirements of multi-phase composite materials or the design and optimization of multi-phase composite structures. [source]

Morphology development of PC/PE blends during compounding in a twin-screw extruder

POLYMER ENGINEERING & SCIENCE, Issue 1 2007
Bo Yin
The morphological development of a polycarbonate/polyethylene (PC/PE) blend in a twin-screw extruder was studied using a scanning electron microscope (SEM). The effects of extrusion temperature, viscosity ratio (the ratio of the viscosity of the dispersed phase to that of the matrix), and the screw configuration on the morphology of the PC/PE blend during the extrusion were discussed in detail. It was found that the morphology of the dispersed particles and the interfacial adhesion between the dispersed phase and matrix were both influenced by the extrusion temperature. The dispersed phase had a spheroidal shape and a small size during the high temperature processing, and an irregular shape and a large size when it was processed at low temperature. The PC phase with a lower viscosity was easier to disperse and also to coalesce. Therefore, the deformation of the low-viscosity dispersed phase during the processing was more intense than that of the high-viscosity dispersed phase. By comparing the effects of the different screw configurations on the morphology development of the PC/PE blend, it was found that the melting and breaking up of the dispersed phase were mainly affected in the initial blending stages by the number of the kneading blocks. While a kneading block with a 90 degree staggering angle was used, the size of the dispersed particles decreased and the long fibers were shortened, the large particles were drawn by the additional kneading zone. Finally, all of these structures were completely changed to the short fibers. POLYM. ENG. SCI., 47:14,25, 2007. © 2006 Society of Plastics Engineers [source]