Condensation polymerisation formaldehyde resin

The polymers can be categorised as formaldehyde containing and formaldehyde free and as thermoset or thermoplastic resins. Typical formaldehyde containing resins are melamine formaldehyde sulfonamide resins, where the sulfonamide is ortho and para toluenesulfonamide. The sulfonamide, which is a solvent for the dye, undergoes a condensation polymerisation with formaldehyde and melamine, the latter acting as a cross-linking agent. Non-formaldehyde, thermoplastic resins are usually polyamides and polyesters. 

Linseed oil fatty amides were reacted with melamine or tartaric acid to obtain melamine or tartaric acid-modified poly (ester amide). This was cured at room temperature by poly(styrene co-maleic anhydride) or butyl-ated melamine formaldehyde in different weight percentages (30-80%) to obtain a highly thermostable surface coating material. Similarly, piperazine-modified fatty amide was prepared from A,A-bis(2-hydroxyethyl) linseed oil fatty amide and piperazine by condensation polymerisation. The poly(ester amide) resin was cured with butylated melamine-formaldehyde... 

Step-growth condensation copolymerisations give rise to additional experimental difficulties, with respect to the former reactions studied, due to the continuous release of e.g. water. Indeed, the evaporation of water produced by the reaction may obscure the detection of the cure process and prohibit a reliable quantification of the reaction heat and the reaction conversion. To illustrate how condensation polymerisations can be studied by MTDSC, the post-cure condensation reactions of melamine-formaldehyde (MF) resins will be discussed [91]. 

Phenolics Phenol and resorcinol formaldehyde adhesives cure by condensation polymerisation with the elimination of water, and therefore require high curing pressures. They are normally available as two-component systems consisting of a paste resin and a liquid hardener. Traditional uses include wood bonding and plywood fabrication, but nowadays phenolics, especially modified phenolics, are also used in structural bonding of metals and plastics. 

As far as calix[4]pyrrole-based materials are concerned, particular emphasis should be placed on the production of chelating resins. Those obtained by the condensation reaction of calix[4]pyrrole and formaldehyde in the presence of formic acid offer potential for their use as extracting agents for fluoride removal from water. Their advantage relies on the fact that a single-step procedure is required for polymerisation. However, research in this area is in a preliminary stage. Much work needs to be done to establish the full capacity of these materials to take up fluoride from water, the kinetics of the process, and the optimum experimental conditions for fluoride extraction. Although, their ability to extract fluoride reaches a value of 88% from solutions of tetra-n-butylammonium fluoride... 

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