Poly(ethylene terephthalate) (PET) based nanocomposites containing 3 wt % of different nanoparticles (MontMorilloniTe-MMT; titanium dioxide-TiO 2 ; and silica dioxide-SiO 2 ) were prepared via two independent procedures: mechanical mixing with subsequent direct injection molding (DIM) and mechanical mixing, followed by extrusion blending and injection molding (EIM). The contributions of nanofillers with respect to pure PET were evaluated. The incorporation of nanofillers reduces the intrinsic viscosity of the polymer matrix when processed by DIM and EIM. SAXS results showed that: MMT layers were intercalated for both processing procedures, but slightly higher for EIM; a better dispersion with smaller agglomerates size is achieved for TiO 2 and SiO 2 nanoparticles for EIM than for DIM. According to the results of DSC analysis, all fillers behave as nucleating agents for PET except SiO 2 that acts as inhibitor in case of DIM procedure. The mechanical behavior was assessed in tensile testing. The mechanical test revealed that the addition of nanoparticles have a slight influence on the elastic modulus and yield stress, but a drastic negative influence on the deformation capabilities of the moldings. The measured optical properties of the moldings gloss and haze are also strongly affected by the presence of nanoparticles.

This study investigates the influence of various nanofillers of different shapes and sizes on the properties of PET nanocomposites. PET was reinforced with 0.3 wt.% of different nanoreinforcements, namely: (i) 1D platelet-like shape of organo-modified layered silicates (montmorillonite) (platelet size approx. 1 x 200 nm) with average agglomerate size of: (a) 30 μm and (b) 8 μm; (ii) 3D spherical shape particles of titanium oxide with an average size of 21 nm and (iii) 3D spherical shape silica with an average particle size of 12 nm. PET nanocomposites were prepared by melt blending in an asymmetric batch minimixer followed by compression moulding process. The effect of nanofillers upon thermal, mechanical and structural properties in comparison to the neat PET are discussed.

This work investigates the solid state uniaxial stretching of neat polyethylene therephthalate, PET, and its montmorillonite, MMT, nanocomposites (0.3 wt % of MMT particles with different initial agglomerate sizes) showing intercalated and tactoid morphologies, followed by in situ WAXS and SAXS experiments under an X-ray synchrotron source. The distinct nanocomposite morphologies were assessed by WAXS and transmission electron microscopy. The in situ WAXS experiments during stretching evaluated the evolution of phase's mass fractions and the average level of molecular orientation upon uniaxial deformation, and the in situ SAXS experiments assessed the evolution of craze-like structures and void sizes. Multiscale structure evolution models are proposed and compared for neat PET and its nanocomposites. Main global mechanisms are identical although with distinct evolutions of phase mass fractions. Also craze-like/voids structures evolve with distinct sizes. Intercalated MMT morphology induces an earlier formation of periodical mesophase, a retarded widening of craze-like structures and the smallest void sizes.V C 2012 Wiley Periodicals, Inc. J.Appl. Polym. Sci. 128: 2884-2895, 2013

Background: The application of radiofrequency (RF) has been successfully used in the treatment of chronic pain conditions, including facet arthropathy, sacroiliac joint pain, groin pain, radicular pain, cervicogenic headaches, and phantom limb pain. Due to the neurodestructive effect of continuous RF ablation and possible deafferentation sequelae, only pulsed radiofrequency (PRF) has been applied to peripheral sensory nerves. There are no previous reports of successful PRF application to the sural nerve. Objectives: To report on the successful use of PRF to the sural nerve for the treatment of ankle pain. To discuss current theories on the mechanism by which PRF produces pain relief. Methods: The report presented here describes the case of a 39-year old patient who sustained injury to her ankle. The patient was complaining of pain in the distribution of the sural nerve, which was confirmed by electrodiagnostic studies. The pain did not respond to oral and topical analgesics. The patient had short-term relief with a sural block with bupivacaine and triamcinolone. The patient then underwent PRF application to the right sural nerve for 240 seconds at 45 volts. Results: The patient reported complete relief. There was no pain recurrence 5 months after the procedure. Limitations: This report describes a single case report. Conclusions: It is conceivable that PRF may provide long-term pain relief in cases of sural nerve injury. The exact mechanism of the antinociceptive effect is still unknown. Possible mechanisms include changes in molecular structure by the electric field, early gene expression, stimulation of descending inhibitory pathways, and transient inhibition of excitatory transmission. Key words: chronic ankle pain, sural neuropathy, radiofrequency, pulsed radiofrequency application

ABSTRACT:In this article, we present an investigation of the structural development of poly(ethylene terephthalate) (PET) during uniaxial stretching above the glass-transition temperature; this followed a statistical design of experiment approach to determine the influence of the stretching variables on the structural development. Amorphous PET was submitted to a stretching program with variations in the stretching temperature (T st ), stretching rate (_ e st ), and stretching ratio (k st ). Stretched samples were rapidly quenched and characterized by wideangle X-ray scattering, optical birefringence, and differential scanning calorimetry. The relevance and influence of the stretching variables on the obtained parameters (phase fraction, phase orientation, and thermal parameters) were analyzed.

This work reports an in situ wide-angle Xray scattering (WAXS) study of the structural evolution of PET with distinct initial morphologies during step uniaxial stretching in the solid state. Two types of samples were analyzed under synchrotron X-ray radiation, namely quasi-amorphous (QA) and semicrystalline (SC) (with 2D and 3D order). Results show that initially different QA morphologies evolve following the same stages: (i) stage I (before neck), at almost constant orientation level the amorphous phase evolves into mesophase; (ii) stage II (neck formation), there is a rapid increase of polymer orientation and the appearance of a periodical mesophase from the highly oriented mesophase; (iii) stage III (necking propagation), there is a leveling off of the average polymer orientation together with partial conversion of the periodical mesophase and mesophase into highly oriented amorphous. The behaviors of the two SC morphologies are completely distinct. A 2D order crystalline morphology evolves with stretching likewise the QA through three stages: (i) at early stages of deformation the polymer orientation remains unchanged while the amorphous phase amount increases slightly, stage I; (ii) in stage II, a fast increase of polymer orientation is accompanied by large formation of mesophase; and (iii) in stage III there is the level off of polymer orientation as the chains approach their finite extensibility and the 3D crystalline order is achieved. Evolution of SC sample with 3D crystalline order mainly features constant orientation increase together with mesophase increment. Structure deformation models are suggested.

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