Thermogravimetric study of polyacrylamide with evolved gas analysis

Abstract

SYNOPSISDried samples of polyacrylamide in an He atmosphere have been subjected to thermogravimetric analysis in the 30-600°C range, and the evolved gases were monitored by FTIR. Water, ammonia, and small quantities of carbon dioxide are released in the first stages of decomposition (22O-34O0C), where the polymer chains remain intact and the reaction occurs on the pendant amide groups. In the second stage of decomposition ( 340-440°C), the majority of the weight loss occurs, and main chain breakdown occurs, releasing carbon dioxide, water, nitrile compounds, and imides. Trapping of the gases in this stage and analysis by GC-FTIR and GC-MS reveals the presence of more than 20 decomposition products, and confirms that a large proportion of these can be assigned to glutarimide and its substituted analogs. Imidization and dehydration reactions on the amide groups, as well as free radical breakdown of the main chains, with inter-and intramolecular hydrogen transfer, can account for many of the products of the decomposition. 0 1993 John Wiley & Sons, Inc.ature, thermal stability, and mechanism of decomposition.2-'2 PAM is amorphous with a glass transition temperature ( T,) of 184°C.6 When heated thermogravimetrically at rates of 5-20°C min-' , undried samples of this polymer decompose in at least three stages. The first stage (20-220°C) corresponds to loss of bound H20, and the second (220-340°C) to loss of NH3 by imidization (intra-and intermolecular) and H 2 0 by dehydration. The third region ( >34OoC) represents substantial weight loss, and is normally attributed to main chain breakdown.Evolved gas analysis can yield substantial insight into the mechanism of thermal decomposition. Maurer and Harvey' used thermogravimetry-mass spectrometry (TG-MS) on PAM to identify NH3, H20, and COZ as gases that evolve during decomposition. Leung, Axelson, and Van Dyke2 used MS to determine the presence of several evolved gases ( NH3, H20, CO,, N2, and CO) when samples of PAM were heated isothermally at various elevated temperatures. Toth et a1.l' used TG-MS to identify H20, NH3, CO, C02, HCN, and some low molecular 1807

Swelling, thermal and mechanical properties of NIPAM-based terpolymeric hydrogel

“…In this temperature range, firstly pendant group (amide and hydroxyl ethyl groups) degradation takes place followed by the degradation of main chain back bone and release of different gaseous molecules. Similar type of result was found by Van Dyke et al for TGA data of poly(acrylamide) homopolymer [19].…”

Synthesis and characterization of pH-responsive carboxymethyl chitosan-g-polyacrylic acid hydrogels

“…In the last stage of decomposition, the main chain breakdown takes place, releasing carbon dioxide, water, nitrile compounds, and imides [22,23]. Figure 3b shows endo.…”

Deposition of polymeric perfluored thin films in proton ionic membranes by plasma processes

“…2. This kind of bond supplies vibrations at the band of 2240-2400 cm À1 [14]. It was possible to verify that the fluorine-containing plasma treatment modified the surface chemical structure, probably improving the hydrophobic characteristics of the material.…”