Boron-enriched polymer films cut thermal neutron shielding thickness by 99 percent

A set of flexible polymer films loaded with boric acid reduced the material thickness needed to halve thermal neutron intensity from 31.85 centimeters to 0.219 centimeters, a 99 percent reduction, according to a study published in the Journal of Materials Science on 22 October 2026. Dalal Abdullah Aloraini and Aly Saeed fabricated polyvinyl alcohol composites containing 0, 25, and 50 weight percent boric acid and systematically evaluated their neutron and gamma ray shielding performance. The films were produced through a solvent casting approach, yielding homogeneous composites with good dopant dispersion across the entire series.

The work responds to a need the authors describe directly: the increasing reliance on nuclear technologies in energy production, medicine, and industry has intensified the urgent demand for efficient radiation shielding materials that provide high protection while meeting modern requirements for lightweight, flexible, and sustainable design. Within this framework, polymer-based shields have gained considerable attention as promising alternatives to conventional materials. The present study reports the design and systematic evaluation of boric acid reinforced polyvinyl alcohol composites as lightweight neutron shielding materials, tested in film form at three distinct boric acid loadings.

Structural characterization of the films confirmed the absence of crystalline boric acid phases and revealed the formation of strong borate ester linkages, denoted B-O-C, together with B-OH groups. According to the authors, these features indicate crosslinking interactions within the polymer network. The measurements show that the boron-containing additive is incorporated into the polymer structure rather than remaining as separate crystalline boric acid, and that the resulting composites are chemically integrated systems in which the boron species are bound into the polyvinyl alcohol matrix.

Thermal analysis demonstrated a pronounced enhancement in thermal stability as boric acid content increased. The glass transition temperature rose from 77 degrees Celsius for the pristine PVA-B0 film to 94 degrees Celsius for the PVA-B50 composite containing 50 weight percent boric acid. The char yield at 600 degrees Celsius increased from 6.30 percent to 9.42 percent across the same series. Both changes accompanied the increasing boric acid loading in the fabricated films, and they were recorded under the controlled heating conditions of the laboratory thermal analysis.

The largest improvements appeared in thermal neutron shielding. The macroscopic thermal neutron absorption cross section increased from 0.022 per centimeter for PVA-B0 to 1.862 per centimeter for PVA-B25 and 3.165 per centimeter for PVA-B50. Correspondingly, the half value layer, the thickness of material required to reduce the thermal neutron intensity by half, fell from 31.85 centimeters for the pristine polymer to 0.219 centimeters for the most heavily loaded composite, which the authors report as a 99 percent reduction. These values were measured for the three fabricated compositions and define the shielding performance of the films as prepared.

Fast neutron attenuation also improved with boric acid incorporation, although by a smaller margin. The removal cross section for fast neutrons increased from 0.082 per centimeter for the pristine polymer to 0.103 per centimeter for PVA-B25 and 0.117 per centimeter for PVA-B50, while the corresponding half value layer decreased from 8.45 to 5.92 centimeters. The study describes the materials as hydrogen- and boron-enriched polymer composites, and the reported gains in both thermal and fast neutron attenuation were obtained across the same film series under the same evaluation program.

Gamma ray attenuation exhibited a limited but measurable improvement across the composite series. According to the authors, this confirms the complementary shielding role of the composites within multilayer protection systems rather than establishing them as primary gamma attenuators. The study explicitly emphasizes the necessity of extending future research toward the development of complementary gamma ray shielding materials in order to achieve comprehensive radiation protection alongside the neutron shielding capability demonstrated here.

Taken together, the reported results highlight the effectiveness of the developed boron-containing polyvinyl alcohol composites for neutron shielding in laboratory evaluation. The findings are limited to the three film compositions fabricated and characterized in the study, spanning 0 to 50 weight percent boric acid, and the authors frame further work on gamma ray shielding as a necessary next step toward comprehensive radiation protection for the nuclear energy, medical, and industrial applications that motivate the research.

Subject of Research: Boric acid reinforced polyvinyl alcohol composites for lightweight neutron shielding and gamma ray attenuation

Article Title: Ultra-lightweight hydrogen- and boron-enriched polymer composites for superior efficient fast and thermal neutron shielding and gamma ray attenuation

Article References: Aloraini, D. A., & Saeed, A. (2026). Ultra-lightweight hydrogen- and boron-enriched polymer composites for superior efficient fast and thermal neutron shielding and gamma ray attenuation. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13922-2

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13922-2

Keywords: neutron shielding, boric acid, polyvinyl alcohol, polymer composites, radiation protection, materials science, Ultra-lightweight, hydrogen-, boron-enriched, polymer, composites, superior