The effect of layered silicates on the crosslinking reaction of silanol‐terminated polysiloxane

Abstract

The effect of incorporation of clay nanoparticles on the vulcanization reaction of silanol-terminated polysiloxane was studied. Three different types of commercial clays were investigated as reinforcement, namely: Cloisite 20 A (organically modified with nonpolar aliphatic chains), Cloisite 30B (modified with aliphatic chains containing hydroxyl-end groups) and Nanofil 116, an unmodified montmorillonite as a reference. Nanoclays were found to increase the rate of curing, assessed by viscosity measurements, in all the examined systems and the acceleration rate is proportional to the content of the additive. Moreover, an increase of the area of peaks corresponding to the formation of SiAOASi bonds (900-1200 cm 21) was recorded by FTIR spectroscopy for pure and reinforced poly(dimethylsiloxane) (PDMS). Temperature modulated differential scanning calorimetry was also used for accurately monitoring the curing reaction of organoclay/PDMS hybrids, through the heat capacity and the enthalpy of cold crystallization measurements. For pure PDMS low reaction rate was observed during the first 200 min, followed by fast acceleration. A linear increase of the reaction rate as a function of time was observed for the organoclay/PDMS hybrids. POLYM. ENG. SCI., 55:957-965, 2015.

Preparation and characterization of room temperature vulcanized silicone rubber using α-amine ketoximesilanes as auto-catalyzed cross-linkers

“…Longer tack free time was observed by increasing the crosslinker content in the examined cross-linked PDMS, which might be due to the restriction of the elastomeric chain mobility thus preventing acceleration. 24 The differences in tack free time of cross-linked PDMS by using MOS versus a-amine ketoximesilanes appear to be inuenced by their cross-linking mechanism, which is discussed by DFT calculation.…”

Rheological behavior and network dynamics of silica filled vinyl-terminated polydimethylsiloxane suspensions

“…This is accompanied with a decrease in G′ with increasing strain‐amplitude. On the other hand, strain‐thickening behavior (increase of dynamic moduli at a particular strain) is prominent in the fumed silica filled PDMS suspensions, as discussed earlier, which is absent in the CaCO 3 filled PDMS suspensions . Such observations may be due to enhanced interaction between fumed silica and PDMS compared to the interaction between CaCO 3 and PDMS.…”

“…The appearance of a pronounced peak of G ″ in the low strain regime has been attributed to strain‐induced agglomeration of fumed silica particles. Reportedly in case of CaCO 3 filled PDMS suspension, there is no indication of strain‐induced agglomeration . Therefore, G ″ can be considered to be subsequently controlled by the breakdown‐reformation dynamics of filler network.…”

“…Poly‐dimethyl‐siloxane (PDMS) is one of the most versatile materials due to its unique properties such as excellent thermal stability, low chemical reactivity, excellent dielectric properties, low temperature flexibility, low surface energy, high gas permeability, transparency, high hydrophobicity, and biocompatibility . Due to these attractive properties, PDMS is used in a large number of biomedical and temperature sensitive applications . However, due to poor mechanical properties of PDMS above its glass transition temperature, many potential applications are hindered.…”

Preparation by solution mixing and characterization of condensation type poly(dimethyl siloxane)/graphene nanoplatelets composites

“…In particular, the 0.2 and 1 phr systems showed a notably faster viscosity increase rate. The aforementioned observation reveals that, due to the high aspect ratio and efficient dispersion of GN nanoparticles, even a small amount of filler can interact with the unvulcanized polymer matrix and according to Vasilakos et al, 23 probably have a strong effect on the viscosity and rheological properties of its mixture with PDMS.…”