Features of the foaming of acrylamide-acrylic acid copolymers

Achievements and prospects for the synthesis of poly(meth)acrylimide foams. Stage of the thermal imidisation of polymer precursors

“…In such technologies, the stage of moulding polymeric half-finished materials from powders or granules (with additives of foaming and other agents), the stage of intramolecular imidisation, the stage of intermolecular imidisation (strong cross linking of macromolecules) and foaming can be separated. 40 Technologies of this type can expand the area of application of P(M)AI and, most importantly, will dramatically reduce their cost by increasing the productivity of the stage of obtaining polymer precursors.…”

“…Thermal imidisation with simultaneous foaming of AAm-AA copolymers (mole ratio of 1:2) was studied. 40 The release of ammonia as a result of intermolecular imidisation (Figure 11) was not observed, probably, due to the rapid involvement of ammonia in the transformations according to Figure 6. The rate of consumption of amide groups as a result of the intra- and intermolecular imidisations of the copolymer is well described by the general equation…”

“…Examples are P(M)AI foams obtained by heat treatment (170–200°C) of copolymers AAm-MAA, AAm-AA, 66,92 AAm-maleic anhydride, of the terpolymer AAm-AA-maleic anhydride. 91 Dyatlov et al 39,40 investigated the thermal imidisation of AAm-AA copolymer (mole ratio of 1:2) in the presence and in the absence of foaming agents. Heating the copolymer at different temperatures without a foaming agent made it possible to distinguish between intra- and intermolecular imidisation reactions since the products of these reactions differ in glass transition temperatures.…”

“…It was repeatedly noted 20,84 that the patterns of thermal imidisation are sufficiently close for different copolymers of the type (meth)acrylonitrile–(meth)acrylic acid. Therefore, it can be assumed that the revealed patterns 39,40,97 can be extended to the most important industrial thermal imidisation of MAN-MAA copolymers.…”

“…They also contain the glutarimide ring as a main fragment (Figure 1). PAIs can be obtained by the polymerisation of diacrylimides (but these monomers, similar to dimethacrylimides, are not promising for practical use); intramolecular thermal imidisation of copolymers of acrylonitrile (AN) and acrylic acid (AA) 39,40 or intramolecular thermal imidisation of copolymers of α-cyanacrylic acid. 40 We therefore decided to use a common name ‘poly(meth)acrylimides’ (P(M)AIs) when discussing imide polymers.…”