In the context of atmospheric chemistry, two reactions radical-molecule of hydrogen abstraction have been studied. These are the OH' and NO3: radical (oxidizers agents in the troposphere) with formaldehyde in gas-phase. The calculations were carried out using the PM3 and <>. Ab initio methods of the UHF type. The results have allowed us to estimate the corresponding times of tropospheric permanency and the implications of these reactions in the removal of forrnaldehyde and similars from the low atmosphere.

In the context of atmospheric chemistry, two reactions radical-molecule of hydrogen abstraction have been studied. These are the OH' and NO3: radical (oxidizers agents in the troposphere) with formaldehyde in gas-phase. The calculations were carried out using the PM3 and <>. Ab initio methods of the UHF type. The results have allowed us to estimate the corresponding times of tropospheric permanency and the implications of these reactions in the removal of forrnaldehyde and similars from the low atmosphere.

Diverse structures have been studied involved in the initial stages of polymerization and of copolymerization with different positions of the bridges divinilbenceno (DVB) between two styrene polymers chains. The energy of the optimized geometries and vibrational frequencies calculated with methods HF and PM3 have shown that the conformation sindiotactic present the minimum of energy in relation to their similar isotactic and atactic. In the resin of exchange cationics the structures with minima of energy correspond those with bridges in intermediate positions in front of those of near or far away bridges.

Diverse structures have been studied involved in the initial stages of polymerization and of copolymerization with different positions of the bridges divinilbenceno (DVB) between two styrene polymers chains. The energy of the optimized geometries and vibrational frequencies calculated with methods HF and PM3 have shown that the conformation sindiotactic present the minimum of energy in relation to their similar isotactic and atactic. In the resin of exchange cationics the structures with minima of energy correspond those with bridges in intermediate positions in front of those of near or far away bridges.

Residual commercial polystyrene samples (PScr) have been undergone to thermal decomposition processes between 433 hand 673 K (160 at 400 °C). The analyses of the distilled have confirmed that PS has been transformed into styrene with a yield from 45 to 60%. The monomer obtained has been polymerized in suspension using benzoyl peroxide like initiator and divinylbenzene (DVB) in proportions of 2, 6 and 10%. The obtained microspheres of copolymer (PS-DVB) have been sulfonated. After characterization, the results showed that 6% of DVB, presents similar characteristic than the commercial strongly acid cationic exchange resin Sybron Chemicals Inc. Ionac ® C-249.

Muestras de poliestireno comercial residual (PScr) se han sometido a procesos de descomposición térmica entre 433 a 673 K (160 a 400 °C). Los análisis del destilado han confirmado que el PS ha sido transformado a estireno con un rendimiento entre el 45 al 60%. El monómero obtenido se ha polimerizado en suspensión usando peróxido de benzoilo como iniciador y divinilbenceno (DVB) en proporciones de 2, 6 y 10%. Las microesferas obtenidas del copolímero (PS-DVB) han sido sulfonadas. El resultado, después de la caracterización, fue aquel del 6% de DVB presenta características similares a las de la resina comercial de intercambio catiónico fuertemente ácida Sybron Chemicals Inc. Ionac ® C-249.