Authors:M. Evora, L. Machado, V. Lourenço, O. Gonçalez, H. Wiebeck, and L. de Andrade e Silva
The aim of this work is to study the ionizing radiation effects on thermal properties of there cycled polyamide-6. This polymer
was irradiated with an electron beam of 1.5 MeV with different doses. The thermal properties of the samples were determined
by TG, DSC and DMA measurements. It was observed that the irradiated samples of recycled polyamide-6undergo a crosslinking
Polyamide-6-block-polybutadiene copolymers have been prepared by the anionic polymerization of ɛ-caprolactam in presence of
α,ω-dihydroxy terminated polybutadiene. TG, Hi-Res™ TGA, DSC, TMDSC and DMA techniques have been applied. The suitability
of the methods used to determine the content, thermal stabilities and glass transition temperatures of the components constituting
the block copolymer is discussed.
Equilibrium melting temperatures and crystallization parameters of polyamide 6/polyurethane blends were investigated. Thermal
properties of the crystalline phase of blends obtained from polyamide 6 and polyurethane containing 40 wt% of hard segments,
are only limited influenced by the overall blend compositon. Because from separate measurements single glass transitions for
all samples were estimated, so in the investigated case the blending process may occur mainly between amorphous fraction of
polyamide 6 and the polyurethane or, what is more probable, the polyurethane phase is dispersed in the continuous polyamide
matrix, although some interactions exist.
The temperature dependence investigated by means of DMTA of dynamic storage modulusE′, dynamic loss modulus E″ and loss tangent tgδ of blends obtained from polyamide 6 and poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (Biopol D600G)
indicated, that the dynamic mechanical properties of the blends containing up to 40% Biopol D600G are governed by the properties
of polyamide 6. First at the 50% Biopol D600G content in the blend the transitions of the Biopol phase become visible and
dominant. The shifts of the loss modulus maxima of the blends might indicate some interactions between the blend components
in the amorphous phase.
Blends obtained from polyamide 6 and polyester or polyether polyurethanes were investigated by means of DMTA. The blends were
prepared by compounding in a twin-screw Brabender —Plasticorder. Changes in composition did not influence the glass temperature
of the amorphous fraction of the polyamide, but also no distinct transition for separated polyurethane soft segment was visible.
Therefore the blends seem to be multiphase systems, where the elastomeric polyurethane phase is dispersed in a continuous
polyamide phase. From changes in the β relaxation region of the polyamide better miscibility of polyester polyurethanes comparing
to polyether polyurethanes was explained by hydrogen bonding in the common amorphous phase.
Authors:M. Stankowski, Anna Kropidłowska, Maria Gazda, and J. Haponiuk
A series of polyamide 6 nanocomposites (NC) and PA6/TPU/clay nanocomposite blends (NCB) were prepared from commercial polyamide
6, synthesized thermoplastic polyurethanes and two types of organically modified montmorillonites - Cloisite® 10A and Cloisite®
20A. The thermal behavior was examined by non-isothermal thermogravimetry (TG, DTG), differential scanning calorimetry (DSC)
and dynamic-mechanical thermal analysis (DMTA). It has been proved that the thermal stability and tensile properties of these
new systems were greater when the organoclay was present within the polymer matrix. What more these properties depend on both
the OMMT loading and the type of the gallery cations of organically modified montmorillonites.
Authors:A. Leite, L. Maia, R. Paz, E. Araújo, and H. Lira
The aim of this work was to obtain membranes from polyamide 6/montmorillonite clay nanocomposites through the phase inversion
technique. The nanocomposites and membranes from polyamide 6/montmorillonite clay were characterized by X-ray diffraction
(XRD), Scanning Electron Microscopy (SEM), Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). Microporous
and asymmetric membranes were successfully obtained from nanocomposites and the results showed that the salts were incorporated
by intercalation between the organoclay layers and, apparently that the nanocomposites and membranes were thermally more stable
than the pure polyamide.
Authors:A. Manich, J. Maíllo, D. Cayuela, J. Carilla, M. Ussman, and J. Gacén
Polyamide 6.6 multifilament yarns are converted to crimped fibres by texturing in order to simulate the properties of natural
staple fibre yarns for textile applications. Texturing is carried out by mechanical stresses (turbulences or twisting) in
different atmospheres which affect crystallinity and thermal stability of yarns. Two polyamide yarns with the same linear
density but consisting of filaments of different fineness were textured by the air-jet and the false-twist procedures. The
influence of texturing conditions and filament fineness on crystallinity and thermomechanical behaviour and dimensional stability
were studied by TMA and DSC. The air-jet texturing procedure leads to a slight increase in crystallinity of yarns whereas
the false-twist texturing procedure was more effective especially when thicker filaments were textured. The inflection point
of the shrinkage curve before melting was a good estimator of the effective temperature of yarn texturing.