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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 paper, the effects of electron irradiation on the molecular motion of epoxy resins and a composite reinforced by carbon fiber were studied, and the results indicated that this relaxation is related to the local motion of chains subjected to an internal stress produced during curing.
34 citations
TL;DR: An innovative bioplastic system, composed of carbon dioxide-derived poly(propylene carbonate) (PPC) and nature-originated cellulose acetate (CA), was developed, and the extract from oregano waste was incorporated into the bioplastics as a low-cost and effective antioxidant resource.
Abstract: Active packaging materials, biodegradable and from renewable resources, are the most promising substitutes of nonbiodegradable, petroleum-based plastics, toward green and sustainable packaging solutions. In this study, an innovative bioplastic system, composed of carbon dioxide-derived poly(propylene carbonate) (PPC) and nature-originated cellulose acetate (CA), was developed. The extract from oregano waste was incorporated into the bioplastics as a low-cost and effective antioxidant resource. Thin, freestanding, and flexible PPC.CA bioplastic films were obtained by a simple, easily scalable solvent casting technique. The pristine films, without the oregano extract, featured good transparency and high water vapor barrier ability, along with suitable mechanical and thermal properties that are comparable to commercial plastics used for packaging. Interestingly, the incorporation of oregano waste extract added to the bioplastics high UV protection and high antioxidant activity, suitable features for active food packaging applications, without compromising the intriguing properties of the pristine films. The biocomposite films were not only biocompatible but also started biodegrading after just 1 week in seawater. The reported biocomposites are foreseen as promising candidates for several packaging applications, but in particular for sustainable active food packaging.
34 citations
TL;DR: In this article, the rheological properties of a series of lightly crosslinked carboxy copolymers in aqueous solutions have been evaluated in steady shear and dynamic oscillatory modes.
Abstract: The rheological properties of a series of lightly crosslinked carboxy copolymers in aqueous solutions have been evaluated in steady shear and dynamic oscillatory modes. Viscosity profiles and the behavior of storage modulus are related to the chemical composition of the copolymers and their crosslinking density. A maximum in viscosity and in storage modulus which depends on the type of crosslinking agent used is explained by a combination of a chain entanglement mechanism and a closely-packed spheres model. The recovery of viscosity and storage modulus after shearing is very fast and is related to the very fast rearrangement of the microgel structure as a function of time.
34 citations
TL;DR: In this article, the thermal expansion behavior of epoxy matrix particulate composites prepared with different volumetric filler contents (ϕ) up to 25% was studied using a very simple optical dilatometer developed in our laboratory.
Abstract: The thermal expansion behavior of epoxy matrix particulate composites prepared with different volumetric filler contents (ϕ) up to 25 vol.% was studied. Using a very simple absolute optical dilatometer developed in our laboratory, the coefficients of thermal expansion (CTE) for pure epoxy resin matrix and the composites in the glassy and rubbery states (293 K ≤ T ≤ 493 K) were obtained. For the matrix, the CTE obtained in the two states are in good agreement with those reported. For composites the results are discussed into the frame of different approaches using well-known mechanical models. In the glassy state, the CTE behavior could be well described by the upper bound of the Hashin–Shtrikman model. In the rubbery state it was necessary to evaluate the contribution of the average volume of nanoholes in the epoxy matrix as a consequence of the addition of particles. To this aim, using positron annihilation lifetime spectroscopy, the dependence of the average volume of nanoholes with ϕ was measured.
34 citations
TL;DR: In this article, surface modified silica nanoparticles were added to poly(ethylene 2,6-naphthalate) (PEN) to investigate their effect on the mechanical properties on the PEN nanocomposite material.
Abstract: We added surface-modified silica nanoparticles to poly(ethylene 2,6-naphthalate) (PEN) to investigate their effect on the mechanical properties on the PEN nanocomposite material The torque and total torque values of the composites decreased in the silica nanoparticle composites The tensile modulus of the composites reinforced with unmodified silica nanoparticles increased upon increasing the silica content, while the tensile strength and elongation decreased accordingly In contrast, stearic acid-modified, silica nanoparticle reinforced PEN composites exhibited an increase in elongation and a decrease in tensile modulus upon addition of the silica nanoparticles because the stearic acid that had adsorbed onto the surface of the silica nanoparticle in multilayers could act as a plasticizer during melt compounding Stearic acid modification had a small effect on the crystallization behavior of the composites We calculated theoretical values of the tensile modulus using the Einstein, Kerner, and Nielsen equations and compared these values with the experimental data obtained from the composites The parameters calculated using the Nielsen equation and the Nicolais- Narkis model revealed that the interfacial adhesion between silica nanoparticles and the PEN matrix could be improved
34 citations