The design of lightweight neutrons shields has been restricted for quite some time to the use of the epoxy thermosets as the main building blocks. Meanwhile, the recent developments in the field of polymers suggest otherwise. Indeed, benzoxazine resins have taken the lead over the traditional thermosets in many exigent applications. Therefore, in a vision to introduce newer matrices with better performances and to further expand the applications of the benzoxazine resins into the nuclear field, the neutron shielding efficiency along with the thermal and thermomechanical performances of the neat benzoxazine polymer and its subsequent B4C-reinforced composites were investigated. The neutron shielding measurements were performed using an optimized experimental setup at NUR research reactor, Algiers. The neat benzoxazine polymer displayed almost similar thermal neutrons screening performances than the epoxy with a macroscopic cross-section (Σ) of a 0.724 cm− 1 equivalent to a mean free path (λ) of 0.957 cm. The effect of the particle amount was also studied to maximize the shielding ability of the developed materials. For instance, the benzoxazine composite containing 20 wt.% of B4C displayed the outstanding screening ratio of about 96% for a sample thickness of 13 mm. Finally, the remarkable findings were put into context by providing multifaceted comparisons with the available shielding materials.
By following the rules of green chemistry, a novel composite is developed from a renewable and ecofriendly resource, namely the vanillin. The latter was used as a phenolic precursor for the microwave synthesis of a bio-based benzoxazine resin (Va-BZ). Afterwards, high performance green composites were developed by reinforcing the Va-BZ with various amounts of chopped silane surface modified basalt fibers (BFs). The chemical structure of the Va-BZ monomers was confirmed by 1H NMR and FTIR spectroscopy. The grafting of the silane moiety on the BFs surface was assessed by FTIR and TGA analyses. The autocatalytic ring opening polymerization of the Va-BZ monomers was confirmed by DSC analysis. The mechanical performances of the developed green composites were studied by flexural and tensile investigations. The findings suggested that the maximum amount of 20 wt. BFs afforded the best results, with flexural and tensile strengths of 447 and 460 MPa, respectively. The SEM was used to study the fractured tensile surfaces and elucidated the toughening mechanism. Meanwhile, the TGA showed that the introduction of the BFs markedly improved the thermal stability of the benzoxazine matrix. Finally, the gamma rays shielding effectiveness was studied and revealed the highly benefic role of the BFs. For instance, a 1 cm thick Va-BZ polymer only showed a 6% gamma rays screening ratio, the latter was improved to 18.4% for the composite made of 20 wt.% of treated BFs. Overall, this study confirmed that greener approaches can also result in high performance composite satisfying the needs of exigent applications.
The design of lightweight neutron shields has been restricted for quite some time to the use of epoxy thermosets as the main building blocks. Meanwhile, the recent developments in the field of polymers suggest otherwise. Indeed, the phthalonitrile (PN) resins have taken the lead over traditional thermosets in many demanding applications. Therefore, in a vision to introduce newer matrices with better performances and to further expand the applications of the PN resins into the nuclear field, the neutron shielding efficiency along with the thermal resistance performances of the neat PN polymer and its subsequent silane surface-modified B4C-reinforced composites were investigated. The neutron shielding measurements were performed using an optimized experimental setup at the NUR research reactor in Algiers. The neat PN polymer displayed better thermal neutron screening performances than the epoxy and benzoxazine, with a macroscopic cross-section (Σ) of a 1.936 cm−1, equivalent to a mean free path (λ) of 0.358 cm. The effect of the particle amount was also studied to maximize the shielding ability of the developed materials. For instance, the PN composite containing 20 wt. % of B4C displayed an outstanding screening ratio of about 99.8% for a sample thickness of 13 mm. Finally, the remarkable findings were put into context by providing multifaceted comparisons with the available shielding materials.
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