Discriminative detection of laser-accelerated multi-MeV carbon ions utilizing solid state nuclear track detectors

A new diagnosis method for the discriminative detection of laser-accelerated multi-MeV carbon ions from background oxygen ions utilizing solid-state nuclear track detectors (SSNTDs) is proposed. The idea is to combine two kinds of SSNTDs having different track registration sensitivities: Bisphenol A polycarbonate detects carbon and the heavier ions, and polyethylene terephthalate detects oxygen and the heavier ions. The method is calibrated with mono-energetic carbon and oxygen ion beams from the heavy ion accelerator. Based on the calibration data, the method is applied to identify carbon ions accelerated from multilayered graphene targets irradiated by a high-power laser, where the generation of high-energy high-purity carbon ions is expected. It is found that 93 ± 1% of the accelerated heavy ions with energies larger than 14 MeV are carbons. The results thus obtained support that carbon-rich heavy ion acceleration is achieved.

Consistent modelling of material weight loss and gas release due to pyrolysis and conducting benchmark tests of the model—A case for glovebox panel materials such as polymethyl methacrylate

It is necessary to consider how a glove box’s confinement function will be lost when evaluating the amount of radioactive material leaking from a nuclear facility during a fire. In this study, we build a model that consistently explains the weight loss of glove box materials because of heat input from a flame and accompanying generation of the pyrolysis gas. The weight loss suggests thinning of the glove box housing, and the generation of pyrolysis gas suggests the possibility of fire spreading. The target was polymethyl methacrylate (PMMA), used as the glove box panel. Thermal gravimetric tests on PMMA determined the parameters to be substituted in the Arrhenius equation for predicting the weight loss in pyrolysis. The pyrolysis process of PMMA was divided into 3 stages with activation energies of 62 kJ/mol, 250 kJ/mol, and 265 kJ/mol. Furthermore, quantifying the gas composition revealed that the composition of the pyrolysis gas released from PMMA can be approximated as 100% methyl methacrylate. This result suggests that the released amount of methyl methacrylate can be estimated by the Arrhenius equation. To investigate the validity of such estimation, a sealed vessel test was performed. In this test, we observed increase of the number of gas molecules during the pyrolysis as internal pressure change of the vessel. The number of gas molecules was similar to that estimated from the Arrhenius equation, and indicated the validity of our method. Moreover, we also performed the same tests on bisphenol-A-polycarbonate (PC) for comparison. In case of PC, the number of gas molecules obtained in the vessel test was higher than the estimated value.

Condensation polymers: synthesis, properties, and applications

With the widening of the application fields of polycondensation polymers, many types of modifiers have been used to modify the molecular structure of polycondensation polymers. In recent years, more and more researchers have focused on the study of the molecular structure modification of polycondensation polymers and gradually ignored the research on the synthesis methods and properties of polycondensation polymers. This review covers the synthesis strategies of four common polycondensation polymers in the market, including polyamide (PA), polycarbonate (PC), polyester (PET), and phenolic resin. Two general synthesis routes of PET starting from dimethyl terephthalate and terephthalic acid were suggested; the synthesis strategies of PA-66 and PA-6 were discussed; the synthesis methods of aromatic PC from bisphenol A polycarbonate by phosgene or transesterification were summarized; the general synthesis methods of thermoplastic phenolic resin and thermosetting phenolic resin were discussed. In addition, some new synthesis methods and modification methods of these polycondensation polymers were reviewed. Besides, the properties, application, and market value of these polycondensation polymers were summarized. It is hoped that it will be helpful for the new synthesis of polycondensation polymers.

Evaluation of the Mechanical Behavior of Bisphenol-A Polycarbonate after Thermal Degradation

This work investigates the mechanical behavior of a PCLIGHT type of polycarbonate (PC). PC samples display interesting results after thermal degradation at different temperatures. Samples of PC in sheet form were exposed for a period of 5 hours at temperatures of 50, 100, 150 e 200°C. After, thermogravimetric test, flexural, impact and tensile tests were performed. The results show that the samples treated at 200oC have their mechanical performance affected. This indicates that the temperature acts on the PC embrittlement behavior. Thus, it can be inferred that temperatures above 150oC can negatively influence the mechanical behavior of the polycarbonate indicating that this material should not be used in association with high temperatures.