Effect of nanoclay type on dyeability of polyethylene terephthalate/clay nanocomposites

Influence of Carbon Micro- and Nano-Fillers on the Viscoelastic Properties of Polyethylene Terephthalate

In this research study, three carbon fillers of varying dimensionality in the form of graphite (3D), graphite nano-platelets (2D), and multiwall carbon nanotubes (1D) were incorporated into a matrix of poly (ethylene terephthalate), forming carbon-reinforced polymer composites. Melt compounding was followed by compression moulding and then a quenching process for some of the samples to inhibit crystallization. The samples were analysed using dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM), considering the dimensionality and loading of the carbon fillers. The dynamic mechanical analysis revealed a similar decline of storage moduli for all composites during the glassy to rubbery transition. However, storage moduli values at room temperature increased with higher loading of nano-fillers but only to a certain level; followed by a reduction attributed to the formation of agglomerates of nanotubes and/or rolled up of nano-platelets, as observed by SEM. Much greater reinforcement was observed for the carbon nanotubes compared to the graphite and or the graphite nano-platelets. The quenched PET samples showed significant changes in their dynamic mechanical properties due to both filler addition and to cold crystallization during the DMTA heating cycle. The magnitude of changes due to filler dimensionality was found to follow the order: 1D > 2D > 3D, this carbon filler with lower dimensionality have a more significant effect on the viscoelastic properties of polymer composite materials.

Influence of polyethylene terephthalate/ polyamide (PET/PA) bilayer structure on physical and strength-related properties of superpressure angioplasty balloons

BACKGROUND

Percutaneous transluminal coronary angioplasty (PTCA), including balloon angioplasty, is a standard clinical invasive treatment for coronary artery disease. The coronary lesion with calcification is difficult to dilate and the prevention of balloon failure is especially important.

OBJECTIVE

A novel superpressure balloon was fabricated with bilayered structure of polyethylene terephthalate (PET) and PA12 (polyamide).

METHODS

The structures of bilayer balloon were adjusted to achieve overall excellent performance. Physicochemical, thermal and mechanical properties of bilayer balloons were characterized by X-ray diffraction, differential scanning calorimeter, hydraulic tester and theoretical simulation.

RESULTS

Compared with pure PA12 and PET balloons, PA12 outer layer: PET inner layer balloon with layer ratio of 3:7 shows the highest burst stress and relatively low compliance due to an increase in crystallinity and orientation.

CONCLUSIONS

The produced bilayer balloon proved to possess a small folding dimension thanks to its ultrathin bilayer structure, which is good for crossing cramped vessels. We believe these optimally fabricated bilayer balloons are proved to provide attractive opportunities for preparation, performance enhancement, and practical applications of super-pressure balloon catheters and cryoablation balloons, that will significantly promote the development of percutaneous transluminal coronary angioplasty for clinical applications.

Effect of Lemon Waste Natural Dye and Essential Oil Loaded into Laminar Nanoclays on Thermomechanical and Color Properties of Polyester Based Bionanocomposites

In this work, polyester-based nanocomposites added with laminar nanoclays (calcined hydrotalcite, HT, and montmorillonite, MMT) loaded with lemon waste natural dye (LD) and essential oil (LEO) were prepared and characterized. The optimal conditions to synthetize the hybrid materials were obtained by using statistically designed experiments. The maximum LD adsorption with HT was found using 5 wt% of surfactant (sodium dodecyl sulfate), 5 wt% of mordant (aluminum potassium sulfate dodecahydrate) and 50% (v/v) ethanol. For MMT, 10 wt% of surfactant (cetylpyridinium bromide), 5 wt% of mordant, 1 wt% of (3-aminopropyl) triethoxysilane and 100% distilled water were used. LEO adsorption at 300 wt% was maximized with MMT, 10 wt% of surfactant and 50 °C following an evaporation/adsorption process. The obtained hybrid nanofillers were incorporated in a polyester-based matrix (INZEA) at different loadings (3, 5, and 7 wt%) and the obtained samples were characterized in terms of thermal stability, tensile behavior, and color properties. HT_LEM-based samples showed a bright yellow color compared to MMT_LEM ones. The presence of lemon hybrid pigments in INZEA-based systems produced a remarkable variation in CIELAB color space values, which was more visible with increasing the nanofillers ratio. A limited mechanical enhancement and reduced thermal stability was observed with the nanopigments addition, suggesting a limited extent of intercalation/exfoliation of MMT and HT in the polymer matrix. MMT_LEM pigments showed higher thermal stability than HT_LEM ones. A significant increase in Young's modulus of nanocomposites loaded with hybrid LEO was observed compared to the biopolymer matrix. The LEO inclusion into the nanoclays efficiently improved its thermal stability, especially for MMT.

PET Fibers Modified with Cloisite Nanoclay

The alternative method of reducing the flammability of polyethylene terephthalate (PET) fibers, analogous to dyeing of PET fibers with dispersed dyes in a high-temperature bath, was proposed. A commercial organophilic montmorillonite Cloisite^®15A (C15A) was applied as a flame retardant. The aim of the presented work was to evaluate the effectiveness of the introduced modifier and the improvement of the flame-retardant properties of PET fibers by limiting oxygen index (LOI) and thermogravimetric analysis (TGA) measurements. Evolved gas analysis (EGA) by spectrometric method (FTIR) during coupled thermogravimetric analysis (TGA) was applied in order to confirm no increase in the toxicity of volatile degradation products released from burning modified fibers. The nanocomposite nature of modified fibers was confirmed based on the structural parameters of the fibers determined using wide-angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) X-ray diffraction methods.

High-Throughput Fabrication Method for Producing a Silver-Nanoparticles-Doped Nanoclay Polymer Composite with Novel Synergistic Antibacterial Effects at the Material Interface

In this study, we report a high-throughput fabrication method at industrial pilot scale to produce a silver-nanoparticles-doped nanoclay-polylactic acid composite with a novel synergistic antibacterial effect. The obtained nanocomposite has a significantly lower affinity for bacterial adhesion, allowing the loading amount of silver nanoparticles to be tremendously reduced while maintaining satisfactory antibacterial efficacy at the material interface. This is a great advantage for many antibacterial applications in which cost is a consideration. Furthermore, unlike previously reported methods that require additional chemical reduction processes to produce the silver-nanoparticles-doped nanoclay, an in situ preparation method was developed in which silver nanoparticles were created simultaneously during the composite fabrication process by thermal reduction. This is the first report to show that altered material surface submicron structures created with the loading of nanoclay enables the creation of a nanocomposite with significantly lower affinity for bacterial adhesion. This study provides a promising scalable approach to produce antibacterial polymeric products with minimal changes to industry standard equipment, fabrication processes, or raw material input cost.

AFM probing of polymer/nanofiller interfacial adhesion and its correlation with bulk mechanical properties in a poly(ethylene terephthalate) nanocomposite

The interfacial adhesion between polymer and nanofiller plays an important role in affecting the properties of nanocomposites. The detailed relationship between interfacial adhesion and bulk properties, however, is unclear. In this work, we developed an atomic force microscopy (AFM)-based abrasive scanning methodology, as applied to model laminate systems, to probe the strength of interfacial adhesion relevant to poly(ethylene terephthalate) (PET)/graphene or clay nanocomposites. Graphite and mica substrates covered with ∼2 nm thick PET films were abrasively sheared by an AFM tip as a model measurement of interfacial strength between matrix PET and dispersed graphene and clay, respectively. During several abrasive raster-scan cycles, PET was shear-displaced from the scanned region. At temperatures below the PET glass transition, PET on graphite exhibited abrupt delamination (i.e., full adhesive failure), whereas PET on mica did not; rather, it exhibited a degree of cohesive failure within the shear-displaced layer. Moreover, 100-fold higher force scanning procedures were required to abrade through an ultimate "precursor" layer of PET only ∼0.2-0.5 nm thick, which must be largely disentangled from the matrix polymer. Thus, the adhesive interface of relevance to the strength of clay-filler nanocomposites is between matrix polymer and strongly bound polymer. At 90 °C, above the bulk PET glass transition temperature, the PET film exhibited cohesive failure on both graphite and mica. Our results suggest that there is little difference in the strength of the relevant interfacial adhesion in the two nanocomposites within the rubbery dynamic regime. Further, the bulk mechanical properties of melt mixed PET/graphene and PET/clay nanocomposites were evaluated by dynamic mechanical analysis. The glassy dynamic storage modulus of the PET/clay nanocomposite was higher than that of PET/graphene, correlating with the differences in interfacial adhesion probed by AFM.