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Mechanical Properties of Polymers and Composites
14 Dec 1993-
TL;DR: In this article, the authors discuss various mechanical properties of fiber-filled composites, such as elastic moduli, creep and stress relaxation, and other mechanical properties such as stress-strain behavior and strength.
Abstract: Mechanical Tests and Polymer Transitions * Elastic Moduli * Creep and Stress Relaxation * Dynamical Mechanical Properties * Stress-Strain Behaviour and Strength * Other mechanical Properties * Particulate-Filled Polymers * Fiber- Filled Composites and Other Composites.
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01 Jan 2001
TL;DR: In this paper, the authors investigated the dynamic mechanical properties in the radial and tangential directions of Pinus sylvestris and found that the tangential direction had on average a higher peak temperature than the radial direction for a loss factor peak around −80˚ C.
Abstract: Wood is a complex cellular structure with different properties in the radial and tangential direction. Many researchers have measured dynamic properties in the longitudinal direction and a few in the radial direction but very little data can be found in the literature on dynamic mechanical properties in the tangential direction. The purpose of the work presented in this paper was to investigate the dynamic mechanical behaviour in the radial and tangential directions of wood (Pinus sylvestris). Testing was done in tension at 1 Hz with a Dynamic Mechanical Thermal Analyser. Properties in radial and tangential direction were different. The radial direction showed a higher elastic modulus and lower loss factor levels at temperatures between −120 ◦ C and 80 ◦ C. The tangential direction had on average a higher peak temperature than the radial direction for a loss factor peak around −80 ◦ C. It is the opposite of synthetic composites where the stiffer direction has a higher peak temperature. A loss factor peak at around 0 ◦ C was seen, most significantly in the tangential direction. This peak has scarcely been reported in the literature before. The distance between annual rings did not significantly affect the dynamic behaviour in the tangential direction. C � 2001 Kluwer Academic Publishers
32 citations
TL;DR: In this article, a novel composite material is described, where tension, applied to polymeric fibres, is released prior to molding them into a matrix and compressive stresses imparted by the viscoelastically strained fibres improve mechanical properties.
Abstract: A novel composite material is described, where tension, applied to polymeric fibres, is released prior to moulding them into a matrix. On matrix solidification, compressive stresses imparted by the viscoelastically strained fibres improve mechanical properties. Previous studies showed that these viscoelastically prestressed composites had improved impact and tensile properties compared with control (unstressed) counterparts. In the current study, three-point bend tests on composites using nylon 6,6 fibre reinforcement in epoxy and polyester resins have demonstrated that the viscoelastic prestressing effect increases flexural stiffness. From deflections at 5 s and 900 s, using a freely suspended load on large span/thickness ratio ( L / h ) samples, the flexural modulus was increased by ∼50% relative to control counterparts. Stiffness-increasing mechanisms relating to pre-tensioned fibre and matrix prestress effects are discussed. For small L / h samples (using controlled rate deflection up to ∼5 s), the flexural modulus and resulting increase from viscoelastic prestressing were lower. This is attributed to shear effects and possibly fibre–matrix load transfer mechanisms. By exploiting time–temperature superposition, all samples were aged to the equivalent of 100 years at 20 °C and subsequent bend tests revealed no significant change in the modulus increase resulting from viscoelastic prestressing.
32 citations
TL;DR: In this paper, the results of using unbleached sugar cane bagasse nanofibres (average diameter 26.5 nm; aspect ratio 247 assuming a dry fibre density of 1,500 kg/m3) to improve the physico-chemical properties of starch-based films were reported.
Abstract: This paper reports on the results of using unbleached sugar cane bagasse nanofibres (average diameter 26.5 nm; aspect ratio 247 assuming a dry fibre density of 1,500 kg/m3) to improve the physico-chemical properties of starch-based films. The addition of bagasse nanofibres (2.5 to 20 wt%) to modified potato starch (i.e. soluble starch) reduced the moisture uptake by up to 17 % at 58 % relative humidity. The film’s tensile strength and Young’s modulus increased by up to 100 % (3.1 to 6.2 MPa) and 300 % (66.3 to 198.3 MPa) respectively with 10 and 20 wt% fibre addition. However, the strain at yield dropped by 50 % for the film containing 10 wt% fibre. Models for composite materials were used to account for the strong interactions between the nanofibres and the starch matrix. The storage and loss moduli as well as the glass transition temperature (Tg) obtained from dynamic mechanical thermal analysis, were increased with the starch-nanofibre films indicating decreased starch chain mobility due to the interacting effect of the nanofibres. Evidence of the existence of strong interactions between the starch matrix and the nanofibres was revealed from detailed Fourier transform infra-red and scanning electron microscopic evaluation.
32 citations
Cites background or methods from "Mechanical Properties of Polymers a..."
...7 (Nielson and Landel 1994) Ecomposite Ematrix ¼ 1þ A B vf 1 B w vf ð7Þ where Ecomposite and Ematrix are the Young’s modulus of the fibre-filled composite and the unfilled starchmatrix film respectively and vf the film nanofibre volume fraction....
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...w is based on the fibre packing factor and vf (Nielson and Landel 1994)....
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...9 The ratio of the elongation at break (ecomposite/ematrix) versus nanofibre volume fractions (circles) and a generalized elongation ratio model (dashed line) (Nielson and Landel 1994) Cellulose (2014) 21:2695–2712 2707...
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...A is a constant based on the fibre aspect ratio while B is a constant based on the ratio of the Young’s modulus of the fibre and starch-matrix as well as A. w is based on the fibre packing factor and vf (Nielson and Landel 1994)....
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...The index m is a constant that was varied until the model was fitted to the data (Nielson and Landel 1994)....
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TL;DR: In this paper, a new protic ionic liquid N-butylguanidinium tetrafluoroborate (BG-BF4) has been synthesized by single-step method.
32 citations
TL;DR: In this paper, the effects of applying titanate and silane coupling agents to wet ground muscovite mica in nylon-6 composites are described, and the effect of coupling agents on the dielectric strength, heat distortion temperature, and morphology are also investigated.
Abstract: The effects of applying titanate (TYZOR® TPT) and silane (DYNASYLAN VTMO) coupling agents to wet ground muscovite mica in nylon-6 composites are described. Nylon-6 composites of 5–40 wt % filler loadings were compounded using an APV Baker twin-screw extruder. Mica (25 wt %) brought about an increase in the Young's modulus, flexural strength, and flexural modulus but did not produce significant variations in tensile and impact strength. Hence different coupling agents were employed. It was observed that titanate coupling agent improved the tensile strength and the Young's modulus of the composites much while the impact properties were enhanced by the silane coupling agent. An attempt was made to use ϵ-caprolactum in improving the interfacial adhesion of the filler and the matrix. It was observed that ϵ-caprolactum improved the flexural modulus of the composites most. The effect of coupling agents on the dielectric strength, heat distortion temperature, and morphology were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4074–4081, 2006
31 citations