Effects of production parameters on the structure of resol type phenolic resin/layered silicate nanocomposites

Polymer/layered silicate nanocomposites belong to one of the most promising group of materials of the past few decades and most probably for the near future. Following the pioneering works of Toyota Research Group in the 1980s, the interest on these materials increased rapidly and research is now being carried out world wide, using all kinds of polymers as base material. In this present study, the aim was to investigate the effects of several different production parameters; on the morphology of resol type phenol formaldehyde based layered silicate nanocomposites produced by mixing and casting. For this purpose; two different liquid resol type phenolic resins (PF76 and PF76TD), two different curing methods (heat cure route and acid cure route), two different montmorillonite clays (unmodified Cloisite Na+ and modified Rheospan), two different clay sources (Wyoming-USA and Tokat-Turkey), and five different clay amounts (0.5%, 1%, 1.5%, 3%, 10%) were used. XRD, SEM, TEM analyses and mechanical tests indicated that resol type phenolic resins lead to better structures when they were modified with ethylene glycol and cured by the use of an acidic curing agent. It was also observed that use of modified clay with no more than 1.5 wt% in the phenolic matrix lead to certain degree of exfoliation consequently better structure and higher mechanical performance.