Pyrolysis Of Copolymers Research Articles

Recent Advances in Porous Carbon Materials as Electrodes for Supercapacitors.

Porous carbon materials have demonstrated exceptional performance in various energy and environment-related applications. Recently, research on supercapacitors has been steadily increasing, and porous carbon materials have emerged as the most significant electrode material for supercapacitors. Nonetheless, the high cost and potential for environmental pollution associated with the preparation process of porous carbon materials remain significant issues. This paper presents an overview of common methods for preparing porous carbon materials, including the carbon-activation method, hard-templating method, soft-templating method, sacrificial-templating method, and self-templating method. Additionally, we also review several emerging methods for the preparation of porous carbon materials, such as copolymer pyrolysis, carbohydrate self-activation, and laser scribing. We then categorise porous carbons based on their pore sizes and the presence or absence of heteroatom doping. Finally, we provide an overview of recent applications of porous carbon materials as electrodes for supercapacitors.

AlBr3 impact on the thermal degradation of P(S-co-MMA): a study performed by contemporary techniques

Pyrolysis of copolymer, [P(S-co-MMA)], in the presence of AlBr3 was inspected in an inert atmosphere. Five different proportions (copolymer/additive) were chosen. Films were cast from common solvent. It was noticed that copolymer showed more stability on the basis of T 0, however, regions of stability were also observed for the blends. Copolymer showed T 0 at 260 °C, whereas blends started degrading around 70 °C. T max was the same for the copolymer and the blends. Low-temperature decompositions of blends were attributed to the generation of free radicals (Br•) and the zones of stabilizations were assigned to the formation of a “complex type” structure between Al and the carbonyl oxygens of MMA units. Degradation products were collected and identified employing Py-GC–MS technique. Intermediates (solid) at different temperatures (300, 350 and 400 °C) were examined through FTIR spectroscopy. In the light of gathered data, a degradation mechanism was proposed. New products were encountered, viz., bromobenzene, ‘brominated’ anhydride ring, etc., which established the chemical interactions between the constituents of the blends, i.e., copolymer and additive. Anhydride rings were absent when poly (methyl methacrylate) was pyrolyzed in the presence of AlBr3. Oligomers of styrene were not found hinting at the involvement of additive in “targeting” the degrading styrene units. The blends indicate 2–7% residue of original mass; the additive exhibits 9% while the copolymer does not leave residue at the completion of the TG run. The presence of char in the residues of blends suggests that the additive imparts stability to the copolymer. Horizontal burning rate was lowest (6 times less than that of neat copolymer) for [P(S-co-MMA):AlBr3, 87.5:12.5%], thereby revealing the efficiency of the additive as thermal stabilizer. The highest activation energy was calculated for the copolymer (169.46 kJ/mol) and the range of this parameter for the blends was found from 52.72 to 27.14 kJ/mol.

A novel type of nanoporous carbon material supporting high dispersion of rhodium nanoparticles

Nanoporous carbon (NC) was prepared by the controlled pyrolysis of copolymer of vinylidene chloride and acrylonitrite. These organicinorganic hybrid polymers were synthesized by suspending polymerization. After gradually controlled pyrolysis at 180–300 °C under nitrogen stream, the resulting material was carbonized at 1000 °C for 3h under argon stream. In this way, nanoporous carbon was obtained, which has uniform pore size in the range of 0.8–1.6nm and specific surface area of 900–1000 m2 g-1. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Rhodium particles kept in a highly dispersed state over it were prepared and characterized by XPS and transmission electron microscopy (TEM). The expected high catalytic activity of the final material for methanol carbonylation was observed experimentally.

Thermal degradation mechanism of methacrylonitrile-styrene copolymers on flash pyrolysis

The thermal degradation mechanisms of random copolymers of methacrylonitrile (MAN) and styrene (St) have been investigated by pyrolysis gas chromatography in the temperature range of 358 to 920‡C using a Curie point pyrolyzer (JHP-2) and comparing results with the results from TG/DTA-FTIR apparatus (SII-6200, JASCO-320). The amount of St monomer from decomposition of the copolymer is higher than that from P(St) alone; whilst that of MAN monomer from copolymer is lower than that from P(MAN). This phenomenon reflects the boundary effect in the pyrolysis of copolymer. The thermal degradation mechanisms of copolymers are discussed in terms of the competition between the depolymerization and the back biting reaction on the basis of bond dissociation energies of C-C and C-H bonds in the copolymer chain.

Isomeric structure of styrene-acrylonitrile and styrene-methylcrylate copolymer pyrolysis products

Gas chromatographic retention indices of pyrolysis products of styrene-acrylonitrile and styrene-methylacrylate copolymers were measured on two columns prepared with different stationary phases. A retention index against retention index diagram proved to be useful to define the composition of product molecules, as the points of homologous series form straight lines. We identified the isomeric structure of dimers and trimers consisting of two kind of monomer units by comparing their retention indices. This comparison was based on the determination of the retention index increments of cyano, methoxy-carbonyl and phenyl groups bounded to primary, secondary or olefinic carbon atom. The isomeric structures of styrene-acrylonitrile dimers and trimers were confirmed by mass spectroscopy.