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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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TL;DR: In this article, the authors investigated adhesion and demolding force in UV-NIL for different compositions of a model UV-curable resist system containing a base (either tripropyleneglycol diacrylate with shorter oligomer length or polypropylenedilene diacylate with longer oligomer lengths), a cross-linking agent (trimethylolpropane triacrylated) and a photoinitiator (Irgacure 651) and found that the decrease in elastic modulus results in a decreased adhesion force
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TL;DR: In this article, the authors reported the preparation and characterization of fluoroelastomer/multi-walled nanotube hybrid nanocomposites prepared by conventional rubber mixing using a two-roll mill.
Abstract: The present article reports the preparation and characterization of fluoroelastomer/multi-walled nanotube hybrid nanocomposites prepared by conventional rubber mixing using a two-roll mill. The morphology of the resulting hybrid nanocomposites were characterized by X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopies (TEM). SEM photographs showed the formation of completely exfoliated and uniformly dispersed nanotubes in the polymer matrix during the high shear mixing process. Magnetic force microscopy (MFM) has been used to further study the topography of the composites which also showed complete exfoliation. The effect of increasing MWNT loadings on the mechanical properties like tensile strength, modulus, elongation at break, hardness, and tear resistance has also been studied. The fracture surface of the composite has been studied by SEM. A ‘ hatched pattern’’ has been observed. The thermal stability of the composites has been studied by TGA and increase in decomposition temperature with increase in MWNT loadings has been observed which was attributed to the antioxidant nature of nanotubes. POLYM. COMPOS., 30:121–130, 2009. a 2008 Society of Plastics Engineers
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TL;DR: In this article, an algorithm to predict long-term laminate properties of fiber reinforced composites is presented, where the classical laminate plate theory is extended to include time-related response of composite materials for membrane and bending load.
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Journal Article•
TL;DR: In this article, the phase separation behavior of wheat flour was studied for three wheat cultivars when influ- without disturbing the composite system, and the influence of factors such as mixing time, ascorbic acid, defatting, and lecithin, which are known to affect both the baking behavior and the Theological behavior at small deformations was investigated.
Abstract: Cereal Chem. 73(l):25-31 Separation by ultracentrifugation provides a simple tool for studies of with increased mixing time, while the separation of spring wheats was the aqueous phases of wheat flour dough. A separation into liquid, gel, not influenced. The general effect of adding ascorbic acid to dough or gluten and starch, phases was maintained. More or less unseparated using defatted flour was improved separation. Lecithin impaired separadough was also found at the bottom of the test tube. In the present study, tion. An advantage of this technique is that the phases could be studied the separation behavior was studied for three wheat cultivars when influ- without disturbing the composite system. This resulted in valuable inenced of factors known to affect the baking behavior. The separation formation for the interpretation of rheological measurements on dough. properties differ among cultivars. Increased mixing time caused an It was possible to relate effects on the modulus to either gluten strength, approximately linear increase for incorporation of water into the gluten the liquid phase, or interactions between starch and gluten. phase. For winter wheat, the amount of unseparated dough decreased One of the unique features of wheat flour is the phase separation of two continuous aqueous phases when the flour is mixed into a dough. The bicontinuous phases are the gluten phase (water-swollen protein) and the liquid phase (containing the dispersed starch granules and soluble components) (Eliasson and Larsson 1993). In a previous study, in which ultracentrifugation was used to illustrate the phase separation of dough, it was observed that the separation of dough occurred when the water content was high enough to enable a gluten phase to separate (Larsson and Eliasson 1996). The rheological behavior at small deformations was correlated with the phase separation behavior over a wide range of water contents. However, it was not possible to establish a simple relationship between the rheological behavior and the amount or properties of the separated phases when cultivars were compared. In the present study, the influence of factors such as mixing time, ascorbic acid, defatting, and lecithin, which are known to affect both the baking behavior, and the Theological behavior at small deformations has been investigated. These factors, which may modify the properties of either or both of the bicontinuous phases, are compared for three wheat cultivars. Results from rheological measurements on dough at small deformations may appear conflicting. For example, for an increasing flour protein content, both an increase (Abdelrahman and Spies 1986) and a decrease (Hibbered 1970) in the modulus have been observed. Also, for increasing mixing time, different studies have shown both an increase (Bohlin and Carlsson 1980) and a decrease (Mani et al 1992) in the modulus measured at small deformations. The present technique demonstrates that an effect on the rheological behavior at small deformations, such as stress relaxation, may be attributed to different properties of the two aqueous phases present in dough.
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TL;DR: In this article, a twin-screw compounder was used to homogenize polypropylene/CaCO3 composites and six different fillers were used in a wide range of average particle sizes between 0.08 and 12 μm.
Abstract: Polypropylene/CaCO3 composites were homogenized in a twin-screw compounder and then injection molded into tensile bars. Six different fillers were used in a wide range of average particle sizes between 0.08 and 12 μm. Tensile and flexural properties were measured by standard techniques, while impact resistance was determined by instrumented impact testing. Structure was characterized by light and electron microscopy, while failure initiation and propagation was studied with in situ high-voltage electron microscopy. The results showed that aggregation of particulate fillers occurs when their particle size is smaller than a critical value. This critical size depends on component properties and processing conditions. Strength and impact resistance usually decrease with increasing number of aggregates. The presence of aggregation can be detected by the use of a simple semiempirical model. Comparison of samples prepared by two different technologies showed that twin-screw extrusion and injection moldi...
47 citations