Structure‐properties relationship in resol/montmorillonite nanocomposites

Abstract

Polymer/layered silicate nanocomposites were prepared, adding modified, and nonmodified montmorillonites to a resol resin. It was observed that the composites exhibited an intercalated disordered structure by means of X-ray diffraction (XRD) and transmission electronic microscopy. The crosslinking density of the resol network was greatly influenced by the presence and type of clay that was added to the resin. The composites filled with the modified montmorillonites showed a lower glass transition temperature value as well as a higher degradation peak at $ 4008C, which is characteristic of the degradation of methylene bridges, indicating a decrease in the crosslinking density of the resol network when modified clays are added. Resol/ unmodified montmorillonite composites exhibited different behavior comparing to the other composites and the resol. A higher thermal resistance was observed in the fragmentation zone and a different tan d response was seen in the DMA analysis. These differences in the behavior of the composites could be because of the interaction between the resol prepolymer and the clay modifiers and as a result of their chemical compatibility. The hardness and elastic modulus of the resol were improved with the addition of clays. However, higher values were obtained for the composite made with the more dispersed montmorillonite.

Influence of Clay Modification on the Properties of Resol Nanocomposites

“…The results obtained in the present work could be compared with the ones published previously [25] where resol nanocomposites were also studied. The main difference between both works was the way of curing the polymer.…”

“…[6] In recent years, thermosetting polymer/clay nanocomposites have attracted more attention. Epoxy [7][8][9][10][11][12][13][14] polyurethane, [15] unsaturated polyesters [16] and phenolic resins [17][18][19][20][21][22][23][24][25] are the common matrices studied so far. The studies about phenolic resins nanocomposites were made on both novolacs and resols.…”

“…The disadvantage of using resols as matrix is their crosslinked structure that makes the entrance of the chains into the clay galleries difficult and consequently the intercalation or exfoliation of the montmorillonite. In a previous work, [25] we obtained resollayered silicate nanocomposites curing by means of acid addition. It was found that the composites made by the addition of organically modified montmorillonite showed a better dispersion of the clay in the polymer matrix than those with unmodified montmorillonite.…”

Morphology and Thermal Stability of Novolac Phenolic Resin/Clay Nanocomposites Prepared via Solution High‐Shear Mixing

“…[4][5] Choi et al [6] investigated melt intercalation and curing behavior of a Novolac phenolic resin incorporating layered silicates such as pristine montmorillonite (PM), dodecylammonium-modified montmorillonite (C12M), octadecylammonium-modified montmorillonite (C18M), and benzyldimethyloctadecylammonium-modified fluorohectorite (C18BH), where hexamethylenetetramine (HMTA) was used as the curing agent. Manfredi et al [7] used sonication to mix resole phenolic resin/5 wt.-% organoclay (Cloisite 10A or Cloisite 30B) nanocomposites and their unmodified Cloisite Na þ analogs. Wang et al [8] synthesized the Novolac/layered silicate nanocomposites by condensing phenol/formaldehyde using an acid-modified montmorillonite catalyst.…”

Synthesis and properties of epoxy-phenolic clay nanocomposites

“…Epoxy/clay has been one of the most studied systems, where merely intercalated or exfoliated structures were obtained [6,8,10]. On the other hand exfoliation has been reported for several polymer matrixes, such as polyimide [4,7], polyaniline [19], nylon [20] and phenolic [21,22]. However, there is no reported research on EpoxyPhenolic/clay system.…”