Thermal degradation of melamine‐formaldehyde resins

Thermal degradation of three melamine‐formaldehyde resins in air at temperatures from 150° to 350° has been studied by thermogravimetric and infra‐red analysis. Weight loss is markedly dependent on particle size and, for a given temperature and time, appears to increase with decreasing melamine/formaldehyde ratio. This suggests that degradation involves methylene and/or methylene ether bridges and possibly methylol groups. Below about 250° only these groups appear to be involved and fairly high initial rates of weight loss are followed by decreased rates of loss. At 250° an increased rate of loss follows the initial rate. This is accompanied by a decrease in infra‐red absorption associated with the triazine ring and one of the products of decomposition is melamine. Above 250° breakdown of methylene and/or methylene ether bridges and loss of melamine occur together from the start of heating.