Radiolysis of aqueous formaldehyde relevant to cometary environments

Using controlled radiolysis of melamine to reinforce melamine‐urea‐formaldehyde resin impregnated wood

“…Simultaneously, the radiolysis of formaldehyde further reduces the content of free formaldehyde with the increase of irradiation dose (Figure 13). [17] Furthermore, this effect is more profound when the original formaldehyde emission of specimens is high (2.80 mg/L), confirming that EB is of great importance to the treatment of wood-based panels with high formaldehyde emission. According to GB/T 9846.3-2004 standard, MUF impregnated wood can be upgraded from E2 grade (1.5 mg/L<E2 ≤ 5.0 mg/L) to E1 grade (0.5 mg/L<E1 ≤ 1.5 mg/L) with EB irradiation dose greater than 20 kGy, then can be applied indoors directly.…”

“…The radiolysis of formaldehyde after EB irradiation [17] Besides, the variation of formaldehyde emission under low original formaldehyde emission level (0.29 mg/L) is not obvious. One possible reason is the reversibility of the addition reaction of urea and formaldehyde (hydroxymethyl reaction), which means that under conventional reaction conditions, free formaldehyde will always be present in urea-formaldehyde resin if no other substances are involved in the reaction.…”

“…[32] Additionally, other researchers have claimed that the major products of radiolysis of formaldehyde were speculated to be formic acid and methanol, which would result in the pH value decreasing abruptly as the irradiation dose increased. [17] The acidification of organic solutions caused by irradiation, which has been published by many researchers, presents a trend where the higher the irradiation dose was, the more obvious the acidification resulted. [33][34][35][36] As a consequence, the above conditions have a positive effect on the curing.…”

Computational study of radiation chemical processing in comet nuclei

“…Furthermore, it has been suggested that the dark surfaces of cometary nuclei could be attributed to radiation effects (Cruikshank, 1989). The formation of polymers from irradiated ices is well established by laboratory experiments (Moore et al, 1983;Dragani6 et al, 1985;Khare et al, 1989;Navarro-Gonzfilez et al, 1991;Strazzulla, et al, 1991;Castillo-Rojas, et al, 1992;Negrdn-Mendoza et al, 1992). Figure 5 shows schematically the differences between new and evolved comets.…”

“…The radiolysis of the volatile fraction of comets by cosmic rays and the decay of internal radionuclides leads to a variety of radicals and radical-ions, such as "COEH, "CHEOH, "CHO, "CO~, "CO], "CH = NH, -'C = NH, "CH = N-OH, -'C = N-OH, "NH2 and "CH3 (Table V). Their reactions were not included in our computer model because there is no data available regarding their specific mode (Moore et al, 1983;Dragani6 et aL, 1985;Khare et aL, 1989;Moore et al, 1991;Castillo-Rojas, et al, 1992;Negr6n-Mendoza et al, 1992).…”