Thermal Degradation of Modified Phenol-Formaldehyde Resin with Sodium Silicate

Phenol formaldehyde (PF) is thermosetting polymer that is widely used in many applications, including as an adhesive in wood industry.Modification using sodium silicate has been successfully improving the curing temperature and bonding strength. But, it’s important to studies phenol formaldehyde thermal stability, since its main application were using high temperature. In this work, the thermal stability of modified phenol formaldehyde was studied using thermogravimetric analysis (TG/DTA) at heating rate of 10oC/min to understand the step of the degradation process. In addition, the ash content was determined at 1000oC in order to compare the thermal stability of the PF resin samples. The amount of sodium silicate was varied in the range of 0% to 25% (w/w) in terms of sodium silicate to phenol. The experimental results indicate that modified PF resin has improved thermal stability in comparison with conventional PF resin. The thermogravimetric curves showed four stage of the phenol formaldehyde thermal decomposition. The presence of sodium silicate can increase the crosslink density that improves the thermal stability at temperature lower than 700oC. However, at temperature higher than 700oC the Si-O bonding were easier to break than the methylene and methylene ether bond that lead to faster decomposition in phenol formaldehyde for higher sodium silicate concentration