Curing Kinetics Analysis of Dgeba-Mda System

Thermoset polymers and thermoset based composites are normally polymerized and performed in a step process. This work studies the kinetics behavior of a commercial epoxy system used as matrices of medium and high performance composite materials. The characterization study was performed by differential scanning calorimetry (DSC) and spectroscopic analysis

Furfuryl Alcohol-Based Resin as Matrix for High Performance Composites:

The polymerisation of a furfuryl alcohol-based resin, used as matrix for glass-fiber-reinforced composite materials, was studied by differential scanning calorimetry (DSC), and an empirical kinetic model of the complex reactive process was developed. The kinetic investigation led to the determination of kinetic constants, activation energies, and reaction orders for the adopted kinetic model

Preparation and Characterization of Nanocomposite Films

The incorporation of nanosized inorganic particles into a polymeric matrix represents the most important problem in the nanocomposite fabrication. Success in manufacturing materials for optical devices can be achived only if the particle aggregation is avoided. This paper describes the preparation of a polymeric nanocomposite containing a well-dispersed red pigment synthesized using nanosized titania particles

A Method for Simple and Precise Measurements of Kinetics of Reactions between SiC and Molten Al

Reinforced aluminum is generally fabricated by liquid metal infiltration. The reinforcement degradation produced by molten matrix is the major problem to be considered. The relationship between conversion and thermal exposure time is an important information. In the present paper a method for measuring the conversion by weight determinations is proposed

Wear effects in retrieved acetabular UHMW-PE cups

There is an increasing awareness of the clinical problems associated with ultra-high-molecular-weight polyethylene (UHMW-PE) wear and failure in orthopaedics. This disadvantage is certainly promoted from the various oxidation process that can occur during prosthesis life. Scanning electron microscopy, IR-spectroscopy, and X-ray-photoelectron spectroscopy were employed to investigate the mechanism of polymer degradation. In particular, comparison among the spectra of starting and retrieved UHMW-PE components shows that the polymer oxidizes mainly in vivo. The data indicate that hydroxyl radicals are likely to be a major factor in degradation of the surface of this polymer, these groups are produced in vivo during the implantation time. Several other chemical groups, produced in the different steps of the prosthesis life, are contained in the material

Nanocomposites Based on Metal and Metal Sulfide Clusters Embedded in Polystyrene

Transition-metal alkane-thiolates (i.e., organic salts with formula Me(SR)x, where R is a linear aliphatic hydrocarbon group, –CnH2n+1) undergo a thermolysis reaction at moderately low temperatures (close to 200 °C), which produces metal atoms or metal sulfide species and an organic by-product, disulfide (RSSR) or thioether (RSR) molecules, respectively. Alkane-thiolates are non-polar chemical compounds that dissolve in most techno-polymers and the resulting solid solutions can be annealed to generate polymer-embedded metal or metal sulfide clusters. Here, the preparation of silver and gold clusters embedded into amorphous polystyrene by thermolysis of a dodecyl-thiolate precursor is described in detail. However, this chemical approach is quite universal and a large variety of polymer-embedded metals or metal sulfides could be similarly prepared

Potential contact and intraocular lenses based on hydrophilic/hydrophobic sulfonated syndiotactic polystyrene membranes

Abstract Crystalline films of syndiotactic polystyrene (s-PS), a commercially available thermoplastic polymer, having a highly hydrophilic amorphous phase, were achieved by using a mild solid-state sulfonation procedure. Despite the used mild process conditions, an easy and uniform sulfonation of the phenyl rings of the amorphous phase is obtained. The crystallinity of the polymer was not affect by the sulfonation degree (S), at least at S less than 20%, and the obtained polymer films show the nanoporous crystalline form of s-PS. As widely reported in literature, the nanoporous nature of the polymer crystalline phase gives to these materials the ability to absorb and release organic molecules of appropriate size and polarity. This property, coupled to transparency, makes these materials potentially useful intraocular lens (IOLs) and contact lens applications. Sulfonation procedure and sulfonated film samples characterization by using wide-angle X-ray diffraction (WAXD), Fourier-transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopy techniques and water sorption tests were reported. Furthermore, the biocompatibility study demonstrated no cytotoxicity and appropriate cell interaction properties for the specific applications

Nanocomposite synthesis by thermolysis of (Ag(hfac)(COD)) in amorphous polystyrene

AbstractLightfast color filters (intensively and brightly colored) can be easily produced by dying optical plastics with the surface plasmon resonance (SPR) of metal nanoparticles such as silver and gold. Here, color filters based on silver nanoparticles embedded in amorphous polystyrene have been prepared by dissolving and thermally decomposing (1,5-cyclooctadiene)(hexafluoro-acetylacetonate)silver(I) in amorphous polystyrene. The metal precursor quickly decomposes (10 s, at 180°C), leading to silver atoms that clusterize and produce a non-aggregated dispersion of silver particles in the polymer matrix. The intensity of the yellow coloration due to the SPR of nanoscopic silver can be widely tuned simply by varying the cluster numerical density in the polymer matrix that depends on the silver precursor concentration. The obtained nanocomposite films have been characterized by X-ray power diffraction, transmission electron microscopy, and UV-Vis spectroscopy