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The non-isothermal equation was extended to describe non-isothermal cold crystallization kinetics of oriented polymers. The validity of the equation was examined by using a DSC crystallization curve of oriented poly(ethylene terephthalate) (PET) fibers with a constant heating rate. The double cold crystallization peaks appeared in the DSC curve. The relative degrees of crystallinity at different temperatures...
The mobility of small molecules in a glassy polymer is largely determined by the amount of free volume present in the material. The amount of free volume can be altered by changing the physical state of the polymer. Plastic deformation under compression reduces this amount, whereas the application of a tensile stress increases it. Furthermore, orientation of a polymer introduces an anisotropy in the...
Polyamides (PA) PA66, 610 and 612 were adsorbed as thin films on functionalized substrates. The conformational changes after adsorption are studied. New conformations due to the rotation of diamine/diacid planes were evidenced by infrared reflection absorption spectroscopy (IRRAS) and polarization modulation IRRAS (PM-IRRAS). The study of some infrared vibrators, which have a well defined transition...
The effect of platelet type nanoparticles and processing conditions; mold temperature and injection speed, on the development of local microstructure in injection molded nylon 6 parts was investigated. The molded parts exhibit two crystal forms (α and γ) of nylon 6 in varying proportions from skin to core. The γ crystals preferentially grow near the surface regions and α crystal fraction increases...
Rheo-optical Fourier-transform infrared (FTIR) spectroscopy is based on the simultaneous acquisition of stress–strain data and FTIR spectra on-line to the mechanical treatment of polymers and is frequently applied for the characterization of transient structural changes during deformation and stress-relaxation. In the present communication, this technique has been employed in order to investigate...
Orientation of amorphous, miscible poly(vinyl phenol) (PVPh)-poly(ethylene terephthalate) (PET) blends is studied using experimental and modelling techniques. Up to 50wt% PVPh, the blends are semi-crystalline and were therefore not studied. At 60wt% PVPh, no crystallisation was observed using either differential scanning calorimetry or X-ray diffraction. For the 60wt% PVPh blend, FTIR dichroism determination...
Oriented films of nylon 11/poly(vinylidene fluoride) (PVDF) blend were prepared by uniaxially stretching the melt-mixed blends. The drawn films of fixed length were heat-treated at 170 °C for 5 min to melt the PVDF component, followed by quenching in ice water or isothermal crystallization at various temperatures. The crystal forms and orientation textures of the obtained samples were studied using...
Deformation of polyethylene terephthalate, PET, was simulated using atomistic molecular dynamics using a Parrinello-Rahman constant-stress constant-temperature algorithm under periodic boundary conditions. The evolution in trans and gauche populations is in good agreement with experimental data reported in the literature: In the isotropic model, approximately 15% trans angles are found, and the trans...
Poly(6-[4-(4-cyanophenylazo)phenoxy]x-methylene methacrylate) (P x , x is 2 or 6) were synthesized and used to study the texture of side-chain liquid crystalline polymers (SCLCPs) after photoinduced orientation. With increasing temperature of irradiated P 2 film up to 125 o C, just above its T g , 123 o C, a banded texture was observed for SCLCPs under polarized...
The differential scanning calorimeter heating curves of uniaxially oriented poly(ethylene terephthalate) (PET) fibers with three peaks were analyzed by using a newly proposed equation. The diffusion-controlled crystallization theory is suitable for describing cold crystallization of uniaxially oriented PET fibers. A crystallization model was proposed based on the kinetic parameters obtained. The model...
We present an experimental investigation of the effect of clay orientation, as produced by melt extrusion, on the tensile modulus of compatibilized and uncompatibilized syndiotactic polypropylene nanoclay composites. The orientation of the clay tactoids in extruded tape samples was quantified using 2D X-ray diffraction data. It was found that in the case of the tapes made from compatibilized nanocomposites...
Drawn PVC fibres were investigated using birefringence, DSC and TMA techniques, and their tenacity was measured. An increase in fibre draw ratio (DR) for heat set samples produced an increase in tenacity, birefringence and X-ray intensity. The linearity of a tenacity/birefringence plot suggested that tenacity was a good indicator of molecular orientation. An ‘undrawn’ filament was substantially amorphous...
The three-dimensional orientation change during thermally induced structural change was monitored in a ‘real-time’ mode with polarized FTIR–ATR spectroscopy using a double-edged parallelogram crystal in a temperature-controlled ATR set-up. Upon cold-crystallization of stretched PTT sample, the growth of crystalline phase along the stretching direction was much faster than those along the perpendicular...
An elongational flow field is imposed on a solution of block copolymers consisting of semirigid macromolecules with rigid, rodlike sequences of units in combination with random coil (flexible) units. The problem is formulated according to the lattice treatment of Matheson and Flory. In this formulation, the system consists of rigid blocks whose lengths and locations are fixed by the structure within...
Composites of HDPE and glass or mica particles with different aspect ratios and surface modifications were prepared. The aspect ratio of the mica platelets was evaluated by image analysis of SEM micrographs. Test specimens, in which the platelet faces are oriented either parallel or perpendicular to the specimen flat surface, were prepared and the orientation of the particles was assessed by X-ray...
Improvement of gas-barrier properties of poly(ethylene terephthalate) (PET) by blending with an aromatic polyamide, either poly(m-xylylene adipamide) (MXD6) or a copolyamide based on MXD6 in which 12mol% adipamide was replaced with isophthalamide (MXD6-12I), was studied. Incorporating a small amount of sodium 5-sulfoisophthalate into the PET matrix compatibilized the blends and reduced the polyamide...
In this article, tensile properties have been discussed in terms of phase morphology, crystallinity and molecular orientation in the HDPE/iPP blends, prepared via dynamic packing injection molding, with aid of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) as well as two dimensional X-ray scattering (2D WAXS). For the un-oriented blends, the tensile properties (tensile...
Polypropylene/linear low-density polyethylene (PP/LLDPE) multilayer and blends blown films are investigated in terms of crystalline morphology and orientation. The crystalline structures were probed using microscopy, infrared trichroism and X-ray pole figures. Two different PPs were used, one was a homopolymer and the other was a copolymer. Similar orientation characteristics were observed for both...
To characterize and understand carbon nanotube (CNT) orientation state in thermoset composite processing, we surface treated multi-walled carbon nanotubes (MWNT) and suspended them in vinyl ester resin. The surface treatment prevented clustering of the nanotubes and maintained homogeneously separate nanotubes in the suspension ensuring good dispersion quality. The suspension was subjected to shear...
Morphology and orientation of cellulose in the vessels of vascular bundles of wheat straw were studied. The results indicated that cellulose acts as the framework in the vascular bundles and cellulose chains are high in orientation. In the thickening part of the vessels, cellulose exists in the form of cellulose crystalline lamellae but not cellulose microfibrils. The crystalline lamellae are perpendicular...
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