Structural characterization of fillers of inorganic materials in bismaleimide resins

Because of its dimensional stability, minimal shrinkage, chemical and fire resistance, good mechanical qualities and high resistance to a variety of solvents, acids and water, bismaleimide (BMI) thermosetting polymers are mostly employed in aerospace applications. Corrosion prevention has also been accomplished using BMI coating. The addition of inorganic materials like metal oxides can influence the properties of BMI as an inorganic–organic composite. Ferric chloride–bismaleimide (FeCl3–BMI) and titania–bismaleimide (TiO2–BMI) composites were synthesized. Fillers of inorganic compounds like MnO2, Ni (NO3)2·6H2O and Al2(SO4)3 were synthesized as well. The structural and crystalline configuration as well as physicochemical changes were thoroughly studied by XRD and Fourier transform infrared spectroscopy (FTIR).

Binary Polyamide-Imide Fibrous Superelastic Aerogels for Fire-Retardant and High-Temperature Air Filtration

Fibrous air filtration materials are highly desirable for particle removal from high-temperature emission sources. However, the existing commercial filter materials suffer from either low filtration efficiency or high pressure drop, due to the difficulty in achieving small fiber diameter and high porosity simultaneously. Herein, we report a facile strategy to fabricate mechanical robust fibrous aerogels by using dual-scale sized PAI/BMI filaments and fibers, which are derived from wet spinning and electrospinning technologies, respectively. The creativity of this design is that PAI/BMI filaments can serve as the enhancing skeleton and PAI/BMI fibers can assemble into high-porosity interconnected networks, enabling the improvement of both mechanical property and air filtration performance. The resultant dual-scale sized PAI/PBMI fibrous aerogels show a compressive stress of 8.36 MPa, a high filtration efficiency of 90.78% (particle diameter of 2.5 μm); for particle diameter over 5 μm, they have 99.99% ultra-high filtration efficiency, a low pressure drop of 20 Pa, and high QF of 0.12 Pa^-1, as well as thermostable and fire-retardant properties (thermal decomposition temperature up to 342.7 °C). The successive fabrication of this material is of great significance for the govern of industrial dust.

Flexible layered cotton cellulose-based nanofibrous membranes for piezoelectric energy harvesting and self-powered sensing

Cellulose has attracted an increasing attention for piezoelectric energy harvesting. However, the limited piezoelectricity of natural cellulose constraints the applications. Therefore, we demonstrate the development of piezoelectric nanogenerators based on robust, durable layered membranes composed of cotton cellulose interfaced maleic-anhydride-grafted polyvinylidene fluoride (PVDF-g-MA) nanofibers. Exploiting polydopamine@BaTiO₃ (pBT) nanoparticles as interlayer bridges, interlocked layer-layer interfaces that covalently bind component layers are constructed by a facile and scalable approach. As-obtained membranes exhibit significantly improved piezoelectricity with a maximum piezoelectric coefficient of 27.2 pC/N, power density of 1.72 μW/cm², and stability over 8000 cycles. Substantial enhancement in piezoelectricity over pristine cellulose is ascribed to the synergy of components and the localized stress concentration induced by pBT nanoparticles. The self-powered device could also be used to detect human physiological motions in different forms. Such cellulose-based membranes can be up-scaled to fabricate ecofriendly, flexible and durable energy harvesters and self-powered wearable sensors.