The effect of pigments on the stability of silicone/montmorillonite prosthetic nanocomposites

Abstract

The purpose of this investigation was to evaluate the protection provided to silicone by pigments, such as dry earth pigments. In addition, the effect of nanostructured and organically modified montmorillonite fillers on the overall behavior of reinforced systems was explored. To obtain relevant data and, furthermore, to reveal possible mechanisms of structural changes that could influence silicone stability, pure and reinforced silicon elastomers were mixed with various colorants and studied for their stability to accelerating aging, during the exposure to UV radiation and humidity. A number of tests were run such as, Attenuated Total Reflectance, Fourier Transform Infrared Spectroscopy (ATR-FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Tensile measurements. Swelling in toluene and color tests were also carried out. The experimental results showed that the UV aging of silicone elastomers results in chain scission and cross-linking rather than formation of oxygen containing groups. The main conclusion of this work is montmorillonite acts as a significant reinforcement and protects silicone against degradation during exposure to UV irradiation.

Behavior of UV‐cured print inks on LDPE and PBAT/TPS blend substrates during curing, postcuring, and accelerated degradation

“…Additionally, the exothermic peak height tends to be correlated with the concentration of free radicals that increases the exothermic reaction energy. The observed reduction is directly associated with the different interactions that may happen between light and the pigments, and is generally associated with a reduced absorption of photons by the reactive species of the photoinitiator. For instance, samples containing black pigment (carbon black) had the lowest heat flow values [Figure (a)].…”

“…Similar values for the polymerization rates (around 3.0 × 10 −4 s −1 ) observed in this work were reported by Kuo et al The behavior of the yellow‐pigmented samples was similar to that of the black‐pigmented samples during photo‐DSC tests (Figure ). According to Vasilakos and Tarantili, the low values for heat flow of the yellow samples are due to the great interaction between UV light and the yellow chromaticity.…”

Analysis of nanoindentation creep of polydimethylsiloxane

“…Water in the bottom of the test chamber is heated in order to fill the chamber with hot vapour and create 100% humidity at 50uC. 19 The specific set-up of the accelerated aging procedure performed in this work is as follows (i) 8 h UV radiation with a power of 0?76 W m 22 nm 21 at 60¡2?5uC (ii) 4 h water condensate at 50¡2?5uC. 20…”

Shape programming of polymeric based electrothermal actuator (ETA) via artificially induced stress relaxation

“…Such result reveals that the 2 hours under 80 °C curing time for sample fabrication was sufficient. According to literature, PDMS has a Tg close to −125 °C 44–48 while incorporation of nanoparticles has either little or no effect on the Tg. For example, Panou et al .…”