Search results for "Modulus"

EFFECT OF MOISTURE ON THE BULK PROPERTIES OF SALTED POLY(CAPROAMIDE).

1980

The glass-transition temperature (Tg) and the elastic modulus of nylon-6 and its mixtures with 4% w/w LiCl and with 2% LiCl+3% LiBr were investigated. In one set of experiments care was taken to avoid absorption of moisture during the measurements. In another set of experiments, samples were exposed to atmospheric humidity for different lengths of time. Both unoriented and oriented specimens were investigated. The presence of 4% LiCl almost doubles the amount of moisture absorbed at equilibrium by nylon-6. The Tg was found to be greatly affected by the moisture content and by salt type. When strict precautions to exclude moisture are taken, the addition of 4% LiCl raises the Tg of nylon-6 b…

Enhancing the mechanical performance of polymer based nanocomposites by plasma-modification of nanoparticles

2012

Abstract The possibility of enhancing the mechanical performance of two different polymer-based nanocomposites using polyamide 6 (PA6) and poly[ethylene-co-(vinyl acetate)] (EVA) as matrices was investigated. The nanofillers used were, respectively, either carbon nanotubes (CNTs) or an organically modified montmorillonite (Cloisite 15A), both previously modified by plasma treatment to introduce polar moieties. The nanofillers were fully characterized by Raman spectroscopy, XPS, FT-IR and XRD, demonstrating their effective modification with oxygenated groups. The nanocomposites were prepared by melt processing in order to obtain films and fibres. The mechanical tests carried out on the nanoc…

EVA Copolymer Based Nanocomposites

2002

Nanocomposites are a new class of polymer material with an ultrafine phase dispersion of the order of a few nanometers that shows very interesting properties often very different from those of conventional filled polymers. In this work the mechanical and optical properties of Poly-[ethylene-co-(vinyl acetate)] (EVA copolymer) based nanocomposites have been investigated to evaluate its possible use in several applications. For example, films for covering greenhouse effect. Mechanical properties, and the rigidity in particular, are, on the contrary, quite low. Nanocomposites should avoid this shortcoming if optical properties and processability are not unfavorably effected. EVA copolymer base…

Ethylene-vinyl Acetate Thermoplastic Copolymers Filled with Multiwall Carbon Nanotubes: Effect of Hydrothermal Ageing on Mechanical, Thermal, and Ele…

2013

A range of properties of two commercial thermoplastic ethylene-vinyl acetate (EVA) copolymers, Elvax 420 and Elvax 450, neat and as melt-mixed composite filled with 15 wt.-% of multi-wall carbon nanotubes (MWCNTs), are studied in the “as produced” state and after hydrothermal ageing. Addition of MWCNTs into the neat copolymers introduces the functionality of electrical conductivity and significantly improves their mechanical properties, while thermal characteristics are slightly affected by the presence of carbon nanotubes. A remarkable increase of the elastic modulus (150%) and stress at failure (50%) in stress–strain experiments as well as creep resistance (40%) of the nanocomposites in c…

Numerical–Analytical Model for Nanotube‐Reinforced Nanocomposites

2013

Structure and elastic properties of smectic liquid crystalline elastomer films

2001

Mechanical measurements, x-ray investigations, and optical microscopy are employed to characterize the interplay of chemical composition, network topology, and elastic response of smectic liquid crystalline elastomers (LCEs) in various mesophases. Macroscopically ordered elastomer films of submicrometer thicknesses were prepared by cross linking freely suspended smectic polymer films. The cross-linked material preserves the mesomorphism and phase transitions of the precursor polymer. The elastic response of the smectic LCE is entropic, and the corresponding elastic moduli are of the order of MPa. In the tilted ferroelectric smectic-C* phase, the network structure plays an important role. Du…

Phase behavior and elastic properties of a slightly crosslinked liquid crystalline main-chain polymer

1990

A liquid crystalline main-chain polymer was slightly crosslinked by a reaction withα, ω-difunctionalized oligo-siloxanes. Crosslinking does not disturb the liquid crystalline phases, which are identified by x-ray measurements as smecticB and smecticA phases. Measurements of the elastic properties of the crosslinked sample show rubber-like elasticity, even in the liquid crystalline phases. A difference of 7 K was found between cooling and heating for the smecticA/isotropic transition from DSC and mechanical measurements.

Characterization and Processability of Blends of Polylactide Acid with a New Biodegradable Medium-Chain-Length Polyhydroxyalkanoate

2015

In this work the processability and the mechanical performance of polylactide acid (PLA) based blends with a sample of a new biodegradable medium-chain-length poly (hydroxyalkanoate) (PHA) were investigated. The two polymers are incompatible with scarce adhesion and with the dispersed PHA particles size increasing with the PHA content. Rheological tests in shear flow indicate that adding PHA improves the processability of the matrix by increasing the content of this second component in the blend, as observed also for the torque curves, due to the very low viscosity of this new sample of PHA. The processability is only slightly worsened in non-isothermal elongational flow as the melt strengt…

Effect of the elongational flow on morphology and properties of polypropylene/graphene nanoplatelets nanocomposites

2018

Abstract In this work the effect of the presence of graphene nanoplatelets (GnP) on the morphology and mechanical properties of polypropylene/GnP nanocomposites has been investigated when these polymer systems are subjected to non-isothermal elongational flow in a melt spinning operation. The presence of the GnP magnifies the effect of the elongational flow. Indeed, the elastic modulus and the tensile strength of nanocomposites increases with the orientation more than that observed for the pure matrix. Moreover, the elongation at break increases at low values of the draw ratio for the nanocomposites, while, the matrix shows the expected decrease in deformability. These effects have been cor…

Mechanical, structural and magnetic properties of polypropylene/iron ferrite magnetic nanocomposites

2012

In this research, composites of polypropylene (PP) and a relatively small concentrations of iron ferrite (Fe3O4) nanopowder equal to 2, 5 and 10 wt.% have been made. An methacrylate monomer 2,2'-bis-(4-(2-methylprop-2-enoyloxy)phenyl)- propane (BAD) was added at a small amount (3 wt.%) to part of the composites during the thermoplastic mixing. The BAD has been used as a compatibilizing agent on the phase interaction between the filler and the matrix of polypropylene. It has been found that composites have adjustable mechanical, structural and magnetic properties dependent on the content of magnetic filler. Increase of concentration of ferrite particles affects a notable increase of elastic …