Polyacrylamide decomposition

The major mode of polyacrylamide decomposition at elevated temperature (in the absence of oxygen) is hydrolysis (319,320). Thus, the concentration of divalent metal ions has an effect on viscosity retention at high temperature. Chelating and sequestering agents have been used to reduce the adverse effect of... 

The polymerization of acrylamide in aqueous solutions in the presence of alkaline agents leads to the ob-tainment of partially hydrolyzed polyacrylamide. The polymerization process under the action of free radicals R (formed on the initiator decomposition) in the presence of OH ion formed on the dissociation of an alkali addition (NaOH, KOH, LiOH), and catalyzing the hydrolysis can be described by a simplified scheme (with Me = Na, K, Li) ... 

Cross-hnked polyacrylamides are a group of hydrophihc solid supports introduced primarily for preparation of biopolymers (Fig. 4). Unhke PS resins, polyacrylamides have excellent swelling capacity in both protic (water, alcohols) and aprotic (dichloromethane, dimethylformamide) solvents [88]. These beads are stable towards bases, acids, and weak reducing and oxidizing agents [89]. Predictably, conditions under which amide bonds are cleaved (i.e., sodium in liquid ammonia) [90] lead to rapid decomposition of the polymer. 

Fortunately, the imide has a characteristic peak in the UV which facilitates the monitoring of its formation and decomposition. Figure 2 shows that this takes Qplace with polyacrylamide in 0.2N NaOH solution at 25°C. No such imide intermediate was observed in... 

RF RIC RMM RSD S/N SDM SD SDS-PAGE spectrometry radiofrequency reconstructed ion chromatogram relative molecular mass relative standard deviation signal-to-noise ratio selected-decomposition monitoring standard deviation sodium dodecyl sulfate-polyacrylamide gel electrophoresis... 

Acrylic Polymers. Burrows et al. [95] showed by the Integral Procedural Decomposition Temperature (IPDT) method that for main group metal ions -the stabilizing effect in regard to polyacrylamide is inversely proportional to the radius of the metal ion reemphasizing that the strength of the complex between the ion and the polymer is of importance in deciding the stability. 

TG-IR has also been used to examine the thermally induced decomposition products of polyvinyl chloride (PVC), polyacrylamide, tetrafluoroethylene-propylene, styrene-... 

Modified polyacrylamide amido catalyst of H202 decomposition 1008... 

Ammonia gas m/e 17) is evolved in the first decomposition temperature range for polyacrylamide. Other peaks corresponding to m/e 18, 28, 32, 40, 42, 44, 54 and 58 indicate the possibility that water, carbon monoxide, nitrogen, carbon dioxide and CONH and other species may be released at this temperature. The evolution of ammonia supports the theory that imidisation between neighbouring amide groups in polyacrylamide constitutes one of the major decomposition reactions in this region. 

Unfortunately, these agents are extremely toxic, so that they cannot be used in every case. In the same paper, the resistance of polyacrylamide to bacterial degradation was reported. In order to combine the stability of the all carbon vinyl-chain with the bulkiness (chain extension) and the intermolecular interactions known from biopolymers, a group of the vinyl-saccharides have been synthesized. Another kind of biological aging is found in in enzymatic decomposition reactions, e.g., the cracking of starch to a-g1ucose with a-amylose. 

Arnold C (1979) Stability of high-temperature polymers. J Polym Sci Macromol Rev 14 265-378 Beyler CL, Hirschler MM (1995) Thermal decomposition of polymers. In DiNenno PJ (ed) The SFPE handbook of fire protection engineering (Chaps. 1-7), 2nd edn. NFPA, Quincy, MA, pp 110-131 Bhuiyan AL (1984) Some aspects of the thermal stability action of the structure in aliphatic polyamides and polyacrylamides. Polymer 25 1699-1710... 

Tutas M, Saglam M, Yuksel M, Guler C. Investigation of the thermal decomposition kinetics of polyacrylamide using adynamic TG technique. Thermochim Acta. 1987 111 121-6. Kitahara Y, Okuyama K, Ozawa K, Suga T, Takahashi S, Fujii T. Thermal decomposition of acrylamide from polyacrylamide time-resolved pyrolysis with ion-attachment mass spectrometry. J Therm Anal Calorim. 2012 110 423-9. 

The fluorination of polyacrylamide produced a fluorocarbon polymer with distinctly different physical properties and structure from the parent. There are significant number of molecular units of the proposed structure as evidenced by the carbonyl and nitrogen-fluorine stretches observed in the infrared spectra. It is likely that some of the amide groups have been destructively fluorinated to CF3 groups. This phenomenon has been reported by Attaway, Groth and Bigelow. However, no visible decomposition has occurred in the product which has a very white appearance. 

Infrared spectroscopy and thermogravimetry have been used in polymer analysis for many years. By coupling the effluent of thermogravimetry to an infrared gas cell, TG/IR (sometimes known as evolved gas analysis) has been used to examine the thermally induced decomposition products a variety of polymers including of poly(vinyl chloride) (7), polyacrylamide (2), tetrafluoroethylene-propylene (3) and ethylene-vinyl acetate (4) copolymers, as well as styrene-butadiene composite (5). 

In most cases, the thermal decompositions lead to a coevolution of several materials, particularly when the backbone of the polymer is broken apart. Because of the mbcture of products generated, identification of the constituents could only be made through the use of spectral subtraction or when small molecules with simple infrared spectra, such as carbon monoxide, carbon dioxide, and hydrogen chloride were generated. In the study on polyacrylamide (2), the effluent was trapped in a gas collection tube immersed in liquid nitrogen and then separated and analyzed by GC/FT-IR and gas chromatography/mass spectrometry. 

Polymer stability is very important, and the decomposition temperatures of commodity plastics are often investigated by TG. The mechanism of decomposition varies between different pol)uners, as does the temperature at which this occurs. For example, polyethylene and pol)q)ropylene degrade completely in a single step between 150 and 450°C, but pol)rvinyl chloride (PVC) shows two steps, the first with a loss of 60%, by about 400°C. Cellulose and polyacrylamide both show several steps. 

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