Polymer/montmorillonite nanocomposites with improved thermal properties

Abstract

The results of recent research indicate that the introduction of layered silicatemontmorillonite -into polymer matrix results in increase of thermal stability of a number of polymer nanocomposites. Due to characteristic structure of layers in polymer matrix and nanoscopic dimensions of filler particles, several effects have been observed that can explain the changes in thermal properties. The level of surface activity may be directly influenced by the mechanical interfacial adhesion or thermal stability of organic compound used to modify montmorillonite. Thus, increasing the thermal stability of montmorillonite and resultant nanocomposites is one of the key points in the successful technical application of polymer/clay nanocomposites on the industrial scale. Basing on most recent research, this work presents a detailed examination of factors influencing thermal stability, including the role of chemical constitution of organic modifier, composition and structure of nanocomposites, and mechanisms of improvement of thermal stability in polymer/montmorillonite nanocomposites.

Avaliação da morfologia e propriedades termo-mecânicas em nanocompósitos de PVC

“…Porém, alguns cátions metálicos presentes entre as camadas da OMMT podem catalisar a reação de desidrocloração das cadeias do PVC [16] . Além disso, os cátions orgânicos do modificador alquil amônio podem atuar como ácidos de Lewis e acelerar a liberação dos íons cloreto, removendo-os da cadeia do PVC, através da absorção na forma de um sal hidroclorídrico de amina orgânica.…”

Thermal stability, flammability and fire hazard of butadiene-acrylonitrile rubber nanocomposites

“…The maximal rate of the thermal decomposition of the OLS takes place at about 240°C ( Fig. 1) and proceeds according to the Hofmann's degradation mechanism [4,8]. The initial step includes the formation and desorption of olefin and amine, leaving acidic proton on the surface of the MMT at the site of the ammonium cation (Reactions 1, 2).…”

“…A growing interest is focused on inorganic nanofillers, i.e. nanosilica, and natural layered silicates such as kaolinite, halloysite, illite, endelite, smectite and the most commercially important montmorillonite belonging to the group of 2:1 phylosilicates [3,4].…”

“…of rubber appropriately dispersed in the polymeric matrix, creates a considerably larger surface of polymer-filler interaction than that of conventional fillers. As a result, the oscillation amplitude of polymeric chain segments is reduced and consequently the temperatures of degradation and destruction of the filled polymer are increased [4].…”

Thermal properties of nanocomposites based on polyethylene and n-heptaquinolinum modified montmorillonite

“…Increased thermal resistance of polymers is obtained as a result of the formation of surface carbonation structure i.e., a mechanically resistant barrier layer which hinders the formation and emission of gases during combustion and at the same time provides thermal insulation for the polymer. Nanofillers considerably limit heat transmission within a polymer and therefore confine open flame preventing the smouldering material from dripping [8,9].…”