This work presents the development of novel gypsum board composites for advanced thermal energy storage (TES) and electromagnetic interference (EMI) shielding applications. Activated carbon (AC) derived from spent coffee with a high surface area (SBET = 1372 m2/g) was used as a shape stabilizer, while the commercial paraffin, RT18HC, was used as organic encapsulant phase change material (PCM). The AC showed a remarkable encapsulation efficiency as a shape stabilizer for PCM, with ~120.9 wt% (RT18HC), while the melting enthalpy (ΔHm) of the shape-stabilized PCM was 117.3 J/g. The performance of this PCM/carbon nanocomposite as a thermal energy storage material was examined by incorporating it into building components, such as gypsum wallboards. The microstructure of these advanced panels, their density, and their dispersion of additives were examined using X-ray microtomography. Their thermal-regulated performance was measured through a self-designed room model with a similar homemade environmental chamber that was able to create a uniform temperature environment, surrounding the test room during heating and cooling. The measurements showed that the advanced panels reduce temperature fluctuations and the indoor temperature of the room model, in comparison with normal gypsum panels, by a range of 2–5%. The investigated gypsum board composite samples showed efficient electromagnetic shielding performance in a frequency range of 3.5–7.0 GHz, reaching an EMI value of ~12.5 dB, which is adequate and required for commercial applications, when filled with PCMs.
Bioactive glasses in the CaO–MgO–Na2O–P2O5–SiO2–CaF2 system are highly promising materials for bone and dental restorative applications. Furthermore, if thermally treated, they can crystallize into diopside–fluorapatite–wollastonite glass-ceramics (GCs), which exhibit appealing properties in terms of mechanical behaviour and overall bone-regenerative potential. In this review, we describe and critically discuss the genesis, development, properties and applications of bioactive glass “1d” and its relevant GC derivative products, which can be considered a good example of success cases in this class of SiO2/CaO-based biocompatible materials. Bioactive glass 1d can be produced by melt-quenching in the form of powder or monolithic pieces, and was also used to prepare injectable pastes and three-dimensional porous scaffolds. Over the past 15 years, it was investigated by the authors of this article in a number of in vitro, in vivo (with animals) and clinical studies, proving to be a great option for hard tissue engineering applications.
15 May 2021 in Journal of Materials Science: Materials in Electronics
The present study demonstrated the fabrication of a sustainable, high-performance composite by upcycling waste denim fabric within a cyanoacrylate matrix reinforced with B₄C micro-particles (4, 7, and 10 wt%). XRD and SEM analyses confirmed the successful integration of the ceramic filler and effective fiber encapsulation, with particle agglom-eration identified at 10 wt% loading. The 7 wt% B₄C composition achieved optimum static mechanical performance, with a tensile strength of ~21.5 MPa and Young's modulus of 1.5 GPa — improvements of ~26% and ~88% over the unreinforced matrix — while at 10 wt%, both properties declined below the unreinforced baseline due to agglomeration-induced stress concentration. Under dynamic impact loading, the peak transmitted force increased monotonically from 0.34 kN to 1.31 kN with B₄C content yet remained well below in-ternational impact protection standard thresholds across all compositions. This divergence between static and dynamic responses reveals that impact resistance is governed by particle hardness and packing density, whereas tensile performance depends critically on dispersion quality and fiber–matrix adhesion. Surface wettability analysis showed a marked increase in hydrophobicity, with the water contact angle rising from 105 ± 4° to 133 ± 4° upon B₄C incorporation, consistent with a Cassie–Baxter wetting regime. These results position B₄C-reinforced waste denim–cyanoacrylate composites as a promising, cost-effective, and eco-friendly material platform for potential next-generation Personal Protective Equipment (PPE) applications.
The present study demonstrated the fabrication of a sustainable, high-performance composite by upcycling waste denim fabric within a cyanoacrylate matrix reinforced with B4C micro-particles (4, 7, and 10 wt%). XRD and SEM analyses confirmed the successful integration of the ceramic filler and effective fiber encapsulation, with particle agglomeration identified at 10 wt% loading. The 7 wt% B4C composition exhibited the highest static mechanical performance, with a tensile strength of ~20.3 ± 1.3 MPa and Young’s modulus of 1.17 GPa—improvements of ~22.8% and ~41% over the unreinforced denim–cyanoacrylate composite—while at 10 wt% B4C the ultimate tensile strength declined below the unreinforced baseline and the Young’s modulus reverted to a comparable value, likely reflecting agglomeration-induced stress concentration as a major contributing factor. Under dynamic impact loading, the peak contact force increased monotonically from 0.34 kN to 1.31 kN with increasing B4C content yet remained well below the thresholds specified by international impact protection standard thresholds across all compositions. This divergence between static and dynamic responses indicates that the increase in contact force with B4C content reflects progressive stiffening and more direct load transfer rather than improved energy attenuation, whereas tensile performance depends critically on dispersion quality and fiber–matrix adhesion. Surface wettability analysis showed a marked increase in hydrophobicity, with the water contact angle rising from 105 ± 4° to 133 ± 4° (for the DSGB-7 wt% composite), consistent with a Cassie–Baxter wetting regime. These preliminary results suggest that B4C-reinforced waste denim–cyanoacrylate composites merit further investigation as candidate materials platform for protective textile applications, pending validation through larger-scale, standardized testing.
The crystallization behavior of the bioactive silicate glass “1d” was analyzed using non-isothermal conditions through differential scanning calorimetry (DSC). The plots carried out at different heating rates showed only one crystallization peak. The activation energy for crystallization was calculated through the equations proposed in the Kissinger and Matusita–Sakka models. The Johnson–Mehl–Avrami coefficient (n) was estimated by applying Ozawa and Augis–Bennet methods, resulting in a two-dimensional crystal growth. Crystalline phases which developed during high-temperature treatment were analyzed by X-ray diffraction and scanning electron microscopy. The activation energy for viscous flow was estimated to be 513 kJ/mol, which is lower than the activation energy for crystallization (539 kJ/mol). The Malek test highlighted that the crystallization process was more complex than a simple nucleation-growth mechanism. The sinterability parameter and Hruby coefficient showed the high stability of 1d glass against crystallization, which makes this bioactive material highly appealing for producing well-sintered products of biomedical interest, such as bioactive porous scaffolds for bone regeneration.