Effect of resin pH on creep behaviour of cured phenol formaldehyde resins

Abstract

Seven different types of phenol formaldehyde (PF) resins samples with five different pH values were used in order to investigate the effects of resin pH on the creep behaviour of cured PF resins. The results suggest that the effect of resin pH value on the creep behaviour of PF resins is significant. Alkali presence increases the hygroscopicity and enhances time dependent creep of PF resins due to the plasticisation of adhesive. The PF resins with a high pH have great potential to develop delayed elastic creep. The acidified resins also develop greater creep rate. Resols reacted under acidic conditions may form linear linkages. These structural changes in cured resins will increase the flexibility of these resins, and thus, enhance the creep rate and therefore improve stress relaxation in glue lines.

Keywords

phenol formaldehyde resin / pH value / creep behaviour

References

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