Hydrogen catalysis of alkyl radical decay in single crystalline polyethylene

Although hydrogen gas is about tenfold more soluble in hot-filtered mats of polyethylene (PE) single crystals (SC) than in bulk linear PE, we found that no hydrogen solubility at all could be measured in freeze-dried SC. Despite this, hydrogen gas still exerts a catalytic effect on alkyl radical decay on both the fast and slow first-order decay reactions in the freeze-dried samples. Above 40°C the first-order decay constants of the slowly decaying component decrease with increasing fold period.     

Kinetics of free-radical decay reactions in polymeric solids

Kinetic equations for the decay of the free radicals in polymeric solids are given for the following assumptions on which they are based: (1) two simultaneous first-order but physically separated decay reactions; (2) two simultaneous noninteracting second-order decay reactions; (3) combined simultaneous but intermingled first- and second-order decay reactions; (4) the same but for independent, i.e., not intermingled, first- and second-order decay reactions; (5) a second-order decay reaction in the presence of some free radicals that do not decay; and (6) a first-order decay reaction in the presence of some free radicals that do not decay. In all of the above physical systems the total concentration only can be measured. Hence the above kinetic equations refer to the change of the total concentration with time. It is found that the data for the decay of the free radicals in irradiated isotactic polypropylene and 61% styrene-39% butadiene block copolymer agree best with the equations for the second-order decay in the presence of a fraction of nondecaying free radicals.     

Electrospray mass spectroscopy of macromolecule degradation in the electrospray

As previously shown, by electrospraying dilute polystyrene (PS) solutions gas phase macroions can be produced. Degradation of the PS in the electrospray was tested by collecting the electrosprayed PS and measuring its number-average molecular weight osmotically. About 10% degradation was observed when using negative voltages, but the degradation was considerably reduced when the electrospray occurred in the presence of SF₆ gas. No degradation was apparent in the case of positive sprays. A quantitative analysis of the results was made difficult by a small less of PS in the nitrogen gas stream and by diffusion of lighter ions to the vertical wall of the spray chamber. The latter effect did not occur at the highest spray voltage used, ?24 kV.     

Observation of X(3872)→J/ψγ and search for X(3872)→ψ'γ in B decays

We report a study of B→(J/ψγ)K and B→(ψ'γ)K decay modes using 772×10? B ?B events collected at the Υ(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. We observe X(3872)→J/ψγ and report the first evidence for χ(c2)→J/ψγ in B→(X_{c ?cγ)K decays, while in a search for X(3872)→ψ'γ no significant signal is found. We measure the branching fractions, B(B(±)→X(3872)K(±))B(X(3872)→J/ψγ)=(1.78(-0.44)(+0.48)±0.12)×10(-6), B(B(±)→χ(c2)K(±))=(1.11(-0.34)(+0.36)±0.09)×10(-5), B(B(±)→X(3872)K(±))B(X(3872)→ψ'γ)<3.45×10? (upper limit at 90% C.L.), and also provide upper limits for other searches.