Search results for "tensile"
showing 10 items of 453 documents
Modeling the nonlinear deformation of flax-fiber-reinforced polymer matrix laminates in active loading
2015
In an attempt to fully utilize the mechanical properties of bast fibers in polymer-matrix composites, unidirectional (UD) or quasi-UD flax-fiber-reinforced composites are being developed and characterized. Their response in tension is markedly nonlinear both in on- and off-axis loading. A semiempirical tensor-linear model is applied to describe such deformation nonlinearity in active combined loading. The deformation model of UD ply, combined with an elementary laminate theory, is used to predict the stress–strain curves of laminated composites in tension. Reasonable accuracy of prediction is demonstrated for fiber-dominated layups.
Effects of filler type and mixing method on the physical properties of a reinforced semirigid liquid crystal polymer
1996
Semirigid liquid crystalline polymers (LCPs) show some advantages with respect to rigid LCP: in particular lower processing temperatures, better compatibility with flexible thermoplastics, but also some disadvantages. Thermal resistance of rigid LCPs is much better and the maximum working temperature is, in general, very high. The thermomechanical properties can be improved by adding inorganic fillers. In this work processing, mechanical and thermomechanical properties of a filled semirigid liquid crystal copolyester are reported. Several inorganic fillers have been used in order to put in evidence the influence of shape and dimensions of the particles on the properties of the filled materi…
Processing and characterization of blends of fluoroelastomers with semirigid liquid crystal polymers
1996
Fluoroelastomers (FEs) usually have working temperatures above 150°C and a great resistance to aggressive agents such as oils, fuels, aliphatic and aromatic solvents, steam, moderate acid, and basic environments. Liquid crystal polymers (LCPs) can be effective processing aids and reinforcing agents for elastomers. These characteristics are very attractive to lower melt viscosity and to stiffen and strengthen the final product through a simple blending. Among the LCPs, the semirigid LCPs seem the most appealing for blending with flexible thermoplastics (FTs) because their processing temperatures can be arranged to be in the same processing temperature range of FTs and because the presence of…
Kenaf-filled biodegradable composites: rheological and mechanical behaviour
2012
Biodegradable polymer composites, typically based on biodegradable polymer matrices and natural-organic fillers, are gaining rising interest and importance over the last few years. Several natural-organic fillers can be used but the most widespread so far is wood, in the form of fibres or flour. Alternative cellulosic fillers can ensure advantages in terms of resource utilization and properties of the final composite. In this work, Mater-Bi® based biodegradable composites were prepared with two kinds of wood flour, and directly compared with alternative composites containing kenaf fibres. The use of kenaf fibres allowed improved elastic modulus, tensile strength and interaction with the pol…
Biopolymer interactions affect the functional properties of edible films based on agar, cassava starch and arabinoxylan blends
2009
Abstract Edible films based on the binary combination of agar (AG), cassava starch (CAS) and arabinoxylan (AX) were studied with regard to their microstructure, moisture barrier and mechanical properties. Though the films appear macroscopically homogeneous, electron microscopy observations reveal a phase separation and dispersion, respectively, in AG–CAS and AG–AX blend film structures, whereas the structure of CAS–AX blend films seems homogeneous. In case high moisture (84% and 99% RH), neither the combination of AG and CAS nor the addition of AX into CAS can improve film moisture barrier properties, except at a lower RH (57%). Conversely, water vapor permeability (WVP) of AG based film is…
Mechanical performance of thermoplastic matrix natural-fibre composites
2008
Publisher Summary Natural-Fibre Composites (NFCs) are being considered as high-tech materials meant to replace conventional composites in high-performance applications. There are a number of advantages that natural fibres can offer compared with synthetic materials. Thermoplastic natural-fibre composites can be classified by the polymer used as a matrix as well as by the type of the fibre reinforcing the polymer. Currently, the main areas of application of thermoplastic NFCs are packaging, transportation and building industries. The packaging industry requires materials that possess specific properties, but that can also be easily discarded after use. This chapter discusses the mechanical p…
Evaluation of interfacial shear strength by tensile tests of impregnated flax fiber yarns
2011
Adhesion of flax fibers and polymer matrix as well as mutual bonding of elementary fibers in a technical fiber are among the principal factors governing the mechanical response of flax fiber-reinforced polymer–matrix composites. A method for evaluation of adhesion is proposed based on tension tests of impregnated fiber yarns, with subsequent characterization by optical microscopy of length distribution of fibers pulled out of the yarn fracture surfaces. An elementary probabilistic model is derived relating aspect ratio distribution of the pulled-out fibers to the fiber tensile strength distribution and the effective interfacial shear strength (IFSS). The method was applied to flax fiber/vi…
Rapeseed oil-based rigid polyisocyanurate foams modified with nanoparticles of various type
2014
Polyisocyanurate foams have been developed using a polyol system partially derived from rapeseed oil (RO). The effect of nanofillers with iso-dimensional geometry (zinc oxide), nanofibers (carbon nanotubes), and nanoplatelets (organically modified montmorillonite) on stiffness and strength of the foams has been studied. It was demonstrated that the tensile properties of the filled foams are enhanced by roughly the same proportion as the stiffness and strength of monolithic filled polymers.
Melt Strength and Extensibility of High-Density Polyethylene
1984
The extensional flow of polymer melts has been extensively studied because of its importance in many technological processing operations and, from a more fundamental point of view, because the tensile properties of the polymer melts cannot be correlated directly with shear viscosity behavior.1–5
Effect of the orientation and rheological behaviour of biodegradable polymer nanocomposites
2014
Abstract The recent increasing interest towards biodegradable polymers has favoured the investigation on these systems, showing also their limits. On the other hand, the success achieved by nanocomposites has fostered the search for new systems where the polymer matrix is biodegradable. The final properties can depend on a number of factors, including the biodegradable polymer used as well as the nanosized filler, their mutual compatibility, the filler dispersion and the processing conditions. In this work, nanocomposites based on a starch-derived matrix and three different lamellar silicates were prepared, and the effects of the elongational flow on the dispersion, the improvement of inter…