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Radiation protective materials are widely applied to avoid occupational hazards from either particle emissions or high-energy electromagnetic waves. Herein, we present a boron imidazolate framework (BIF) as a novel neutron shielding additive with high neutron capture cross-section elements B/Li and H. The BIF1-based epoxy resin matrix (Ep-BIF1) possesses high thermal stability and excellent resistance capacity. The neutron radiation shielding property was characterized using an Am–Be source, in which the thermal neutron shielding efficiency of Ep-BIF1 is notably higher than that of Ep-B4C with equal boron concentration, showing potential applications as an advanced efficient neutron radiation shielding composite. [ABSTRACT FROM AUTHOR]

The role of inter-pulse delay on plasma dynamics and spectral emission in dual-pulse fiber-delivery plasma has been investigated using fast imaging, optical emission spectroscopy, and laser shadowgraphy. The detection on the return spectrum in dual-pulse fiber-optic laser-induced breakdown spectroscopy showed that the self-reversal and self-absorption were reduced as the inter-pulse delay increased from 50 to 1000 ns. Using scanning electron microscopy, the ablation depth showed a changing trend of increasing first and then decreasing, and a maximum of ∼2.8 μm was achieved at 250-ns inter-pulse delay. Experimental results confirmed that the improvement was due to the reduction of the plasma thickness from 1.161 mm to 0.964 mm, and the calculation of electronic excitation temperature along the photon collection path showed that the excited atom densities became more spread, which both contributed to the self-absorption reduction. At a long inter-pulse delay, the plasma trailing edge would gradually separate from the target surface with a little further expansion distance of the leading edge, resulting in the reduction of plasma thickness after a time delay of several hundred nanoseconds. The heating of the peripheral cold particles by the second-generation plasma in the later expansion led to the rapid reduction of the peak temperature. Also, the early expansion trajectory of the second-generation plasma was tracked by laser shadowgraphy, which started to appear at an inter-pulse delay of 100 ns, and the average expansion velocity reached its maximum of ∼3.8 km/s. [ABSTRACT FROM AUTHOR]

The paper deals with the influence of the spatial confinement on the evolution of laser bubbles and shock waves by means of the shadowgraphy technique. Due to the constraint of walls, the bubble center shrinks faster than the bubble edge and collapses before the edge of the bubble, splitting into left and right small bubbles that continue to shrink down. The result validates that the Bjerknes force has little effect on bubble evolution at the expansion stage but a great influence on it at the collapse stage. We study the evolution of laser bubbles with different Al-plate intervals for displaying a gradual transition from constrained conditions to unconstrained conditions. In addition, we describe the dynamics of the first bubble at the expansion stage using the Rayleigh-Plesset equation. The pressure and temperature inside laser bubbles are calculated in the meanwhile. [ABSTRACT FROM AUTHOR]

• The interfacial compatibility between silicone rubber (SR) and high-density polyethylene (HDPE) was increased by electron beam irradiation. • The addition of SR will significantly reduce the heat release rate of HDPE/magnesium hydroxide (MH) composites. • The addition of SR will significantly increase the amount of carbon layer after the complete combustion of the HDPE/MH composite. • The maximum expansion height of carbon layer formed after complete combustion can reach 2.2 cm. In this study, silicone rubber (SR) was introduced into high-density polyethylene/magnesium hydroxide (HDPE/MH) composites by melt blending, and the electron beam irradiation was used to prepare the irradiation crosslinked flame retardant HDPE composites. The changes of properties of the samples were investigated by melt index test (MI), mechanical property test, thermal stability test (TG/DTG), oxygen index test (LOI) and cone calorimetry (CCT). MI test results indicated that SR can increase the internal lubricity of HDPE composites. The morphology results showed that the SR can promote the interfacial compatibility between MH and HDPE. The test results of mechanical properties further revealed that the addition of SR can effectively improve the continuity between MH and HDPE, which was evidenced by the 240 % increasing of the elongation at break. TGA test results showed that with the continuous increase of SR, the mass loss rate (LR) decreased rapidly, and the residue content increased. When the addition of SR reached 7.5 phr, the LOI was promoted by 27.4 %. CCT results indicated that the addition of SR can effectively inhibit the heat release rate (HRR) and total heat release (THR), but had little effect on the total smoke release (TSP). When 10 phr of SR were added, the content of residue can reach up to 37 %, and the expansion height can reach to 2.2 cm. Conclusively, the SR contributed to significantly synergistic flame retardant property to HDPE composites. [ABSTRACT FROM AUTHOR]

Radiation protective materials are widely applied to avoid occupational hazards from either particle emissions or high-energy electromagnetic waves. Herein, we present a boron imidazolate framework (BIF) as a novel neutron shielding additive with high neutron capture cross-section elements B/Li and H. The BIF1-based epoxy resin matrix (Ep-BIF1) possesses high thermal stability and excellent resistance capacity. The neutron radiation shielding property was characterized using an Am-Be source, in which the thermal neutron shielding efficiency of Ep-BIF1 is notably higher than that of Ep-B 4 C with equal boron concentration, showing potential applications as an advanced efficient neutron radiation shielding composite.