Synthesis of resole‐type phenolic beads from phenol and formaldehyde by suspension polymerization technique

The phenolic beads (PB) in macrosize range were obtained by mixing phenol and formaldehyde in the presence of basic catalyst by suspension polymerization. In this reaction, the triethylamine (TEA), poly(vinyl alcohol), and hexamethylenetetramine (HMTA) were used as initiator, stabilizer, and crosslinking agent, respectively. The resulting PB within size range 0.1–2.0 mm was obtained in this polymerization reaction, carried out at temperature 96°C ± 1°C with agitation rate 475 rpm for 4 h. The effects of different variables such as, formaldehyde to phenol ratio ( F / P ) by mole, initiator concentration, concentration of crosslinking agent, and temperature on the particle sizes of PB and its formation were investigated. The particle size and its distribution were shown to be dependent on the F / P ratio, initiator concentration, and temperature. The average particle size of PB increased with increasing F / P ratio by mole in the reaction mixture. The average particle size of PB decreased with increasing TEA concentration. The particle size distribution of PB became narrow in size range 0.9–1.3 mm with 86% of yield of 1.0% by weight. As far as the crosslinking is concerned, the uncured phenolic resin was formed in the reaction solution when the reaction was performed in the absence of HMTA at 96°C ± 1°C for 4 h. The amount cured PB formed increased with increase in the concentration of HMTA. The surface morphology, shape and size of PB were studied using scanning electron microscopy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009