Search results for "Modulus"

Molecular modifications—Mechanical behaviour relationships for gamma irradiated LLDPE/PA6 blends

1994

Abstract The molecular modifications, due to γ radiation under vacuum, of linear low density polyethylene/polyamide 6 blends are presented and related to their mechanical behaviour. Solubility and melt viscosity tests indicate that in blends the polyethylene component undergoes mainly crosslinking phenomena, whereas the main effect on polyamide is chain branching. According to these molecular modifications, the most relevant effect is the increase of the tensile modulus for the polyethylene rich blends and the increase of the impact strength for the polyamide rich blends.

Effects of organoclay on morphology and properties of nanocomposites based on LDPE/PA-6 blends without and with SEBS-g-MA compatibilizer

2009

LDPE/PA-6 blends (75/25 wt/wt) were added with SEBS-g-MA (S) and/or an organoclay (20A) using different compounding sequences and the morphology and the properties of the blends or composites were investigated. An XRD study of the nanocomposites with pure polymers showed that 20A is intercalated by LDPE or PA-6 chains, whereas it is exfoliated by S if the clay concentration does not exceed 10 wt%. The SEM investigation showed that both S and 20A behave as efficient emulsifying agents for the LDPE/PA-6 blends. However, their effect on the mechanical properties was found to be opposite: S enhanced toughness but lowered the stiffness, whereas 20A improved the elastic modulus but impaired the i…

Mechanical properties of injection-molded binary blends of polyethylene with small additions of a liquid-crystalline polymer

2011

The results of the investigation of the mechanical properties of polyethylene (PE) blends with small (<3 wt %) additions of thermotropic liquid-crystalline polymers (LCPs) are reported. PE/LCP compositions with various LCP weight contents were obtained by thermoplastic mixing in a two-stage process. Short-term and long-term mechanical behavior of various PE/LCP compositions were analyzed. Data on the influence of LCP addition on the tensile elastic modulus [or Young's modulus (E)], stress at yield (σY), stress at break (σB), strain at yield, strain at break, and deformation at long-term (1000-h) tensile creep were obtained. The experimental results of the investigation show that even small …

Mechanical properties and XRD of Nafion modified by 2-hydroxyethylammonium ionic liquids

2013

In this work, the Nafion 112 membrane impregnated with 2-hydroxyethylammonium carboxylate ionic liquids have been investigated. The used ionic liquids were 2-hydroxyethylammonium formate [HEA]F, acetate [HEA]A and lactate [HEA]L. Prepared composite membranes Nafion/ionic liquid are characterized by mechanical testing, such as tensile test and creep test. It is found that ionic liquids decrease elastic modulus and creep compliance, but do not have significant effect on the tensile strength. Also, composite membranes were studied by wide angle X-ray diffraction. All ionic liquids shift the peak maximum to the lower angle. In this work, only biodegradable ionic liquids were used for composite …

Linear ViscoElastic (LVE) Behaviour of Pure Bitumen via Fractional Model

2012

AbstractBy fitting experimental data from static creep/recovery carried out on pure bitumen, it is shown that the fractional model proposed enables the description of both creep and recovery behaviour with fewer parameters than those needed by other models in the literature. In particular, the model is fitted to experimental data of complex modulus |G*| and phase angle δ° obtained from Dynamic Mechanical Analysis. Lastly, it is demonstrated that when the fractional model is used, complex modulus isotherms for a range of frequencies can be created simply starting from isochronals at f = 1Hz.

Il modulo elastico statico e dinamico del calcestruzzo

2012

Estimates for the Differences of Certain Positive Linear Operators

2020

The present paper deals with estimates for differences of certain positive linear operators defined on bounded or unbounded intervals. Our approach involves Baskakov type operators, the kth order Kantorovich modification of the Baskakov operators, the discrete operators associated with Baskakov operators, Meyer&ndash

The importance of fracture-healing on the deformation of fluid-filled layered systems

2014

International audience; Understanding the fracturingehealingerefracturing cycle is a fundamental part of studying the deformation dynamics and the permeability evolution of rock systems. Previous studies, however, have not examined the influence of healing i.e. fracture-closure through vein formation and the mechanical properties of the " healed " fractures (veins) on the rock deformation. We present results from a two-dimensional coupled hydro-mechanical model which simulates large time and spatial scale dynamic fracturing and healing of a porous medium under the influence of gravity, tectonic stretching and elevated fluid pressures. Our results show that healing decreases the local porosi…

Mechanics of invagination and folding: Hybridized instabilities when one soft tissue grows on another

2015

We address the folding induced by differential growth in soft layered solids via an elementary model that consists of a soft growing neo-Hookean elastic layer adhered to a deep elastic substrate. As the layer/substrate modulus ratio is varied from above unity towards zero we find a first transition from supercritical smooth folding followed by cusping of the valleys to direct subcritical cusped folding, then another to supercritical cusped folding. Beyond threshold the high amplitude fold spacing converges to about four layer thicknesses for many modulus ratios. In three dimensions the instability gives rise to a wide variety of morphologies, including almost degenerate zigzag and triple-ju…

Modular Small Diameter Vascular Grafts with Bioactive Functionalities.

2015

We report the fabrication of a novel type of artificial small diameter blood vessels, termed biomimetic tissue-engineered blood vessels (bTEBV), with a modular composition. They are composed of a hydrogel scaffold consisting of two negatively charged natural polymers, alginate and a modified chitosan, N,O-carboxymethyl chitosan (N,O-CMC). Into this biologically inert scaffold two biofunctionally active biopolymers are embedded, inorganic polyphosphate (polyP) and silica, as well as gelatin which exposes the cell recognition signal, Arg-Gly-Asp (RGD). These materials can be hardened by exposure to Ca(2+) through formation of Ca(2+) bridges between the polyanions, alginate, N,O-CMC, and polyP…