Photostabilization of polyvinyl chloride by some new thiadiazole derivatives

(5-Amino-1,3,4-thiadiazole-2-yl)phenol and it derivatives have been synthesized and characterized by spectral methods lik (FT-IR, UV-Vis, and 1H NMR) and elemental analysis beside the measurements of their physical properties. All the prepared compounds were used as photo stabilizer with polyvinyl chloride. The rate of photo degradation and photo stabilization for PVC films were monitored with irradiation time by measuring the carbonyl (Ico) index values. In addition, the effect of concentrations additives on the rate of photo degradation and photo stabilization process was also studied. We found that the rates were increased with increasing of additives concentrations. Besides, the effect of film thickness is studied and the results showed that the increasing of film thickness will decrease the rate of photo degradation as the following sequences: [5] > [2] > [1] > [3] > [4] > PVC. Degree of deterioration (α), average number of cuts per single polymer chain (s), were calculated for PVC films as a control and that which contains the additives. According to the experimental results obtained several mechanisms were suggested depending on the structure of the additive. Among then UV absorption and radical scavenger for photo stabilizer additive mechanisms were suggested

NATO explores APS standardisation

Work is proceeding within NATO toward establishing STANAG 4686, which would define the performance levels of armoured vehicles' active protection systems. This would be in addition to the existing, well-established standardisation agreements embodied in STANAG 4569 on the levels of ballistic protection of armoured vehicles and the threat of blast mines to them. The new STANAG has been ratified recently in principle and the first three of its eight volumes are now being ratified but details of it all remain to be released. In the meantime, Czech magazine ATM has reported that tests have already been carried out in the Czech Republic according to STANAG 4686 with the Czech Explosively Formed Axe (EFA) active protection system. The tests were conducted against RPG-7 rocket-propelled grenades and, in keeping with STANAG 4686, took into account not only the failure of the grenades to defeat their targets but also how little, if any, collateral damage the active protection system caused. So far, only the EFA's developers have agreed to have their system tested in accordance with STANAG 4686. However, its tests represent a significant contribution to the efforts of the NATO working group to finalise the new standard. The chairman of the working party has been Ricolt Boeschoten of the Netherlands' TNO research organisation and he, together with a group of international observers, attended the Czech tests