1,721,095 research outputs found
Functionalization Of Graphene And Reduced Graphene Oxide In Different Matrices
No full textGraphene (G) presents a huge variety of intriguing properties, as extraordinary electronic transport characteristics.
G, thanks to its low chemical reactivity, can also be used as an active support for catalytic nanoparticles. Some possible
graphene application could be: its employment in active material in electronic devices such as sensors [1], batteries [2],
supercapacitors, hydrogen storage systems or as fillers to produce multifunctional nanocomposite polymeric materials [3].
In more detail we would like to examine: different approach of reduction and functionalization of in situ reduced graphene
oxide obtaining an enhancement of thermal conductivity and an resistivity decrease [4]. Surface modification and
functionalization of rGO to improve its dispersion in organic solvent and also polymeric matrix [5]
Biobased Vitrimeric Epoxy Networks
Full text linkThe scientific strategies reported in the literature for developing biobased epoxy vitrimers are summarized. Biomass resources such as lignin, cellulose, or different vegetable oils can be exploited as biobased building blocks for epoxy thermosets as an alternative to the bisphenol-A-based ones. Biorenewable resources have been synthesized introducing dynamic covalent bonds in the cross-linked networks. This combination allows to achieve cross-linked biobased epoxy networks with thermoset-like properties at a temperature of use, but showing (re)processability, recyclability, and self-healing properties above a well-defined temperature named topology freezing transition temperature (Tv).Here, all the scientific strategies reported in the literature for developing biobased epoxy vitrimers are summarized. The strategy for achieving sustainable and recyclable epoxy thermosets is exploiting monomers from biorenewable resources by introducing dynamic covalent bonds in the cross-linked networks. This combination allows to achieve cross-linked biobased epoxy networks with thermoset-like properties at a temperature of use, but showing (re)processability, recyclability, and self-healing properties.imag
Radical photoinduced cationic frontal polymerization in porous media
Full text linkTwo different interpenetrating phase composites were produced using a radical photoinduced cationic frontal polymerization process. The composites were based on polyurethane (PU) and aluminium open-cell foams impregnated with a formulation of a cycloaliphatic epoxy with different concentrations of a cationic photoinitiator and a thermal initiator. The influence of both types of initiators on the frontal polymerization features was systematically evaluated for the PU foam. It was found to occur only when the concentration of both initiators was greater than 0.5 wt%, leading to full conversion of the epoxy in the whole volume of the 15 mm thick composite samples within less than 100 s. The maximum temperature reached by the propagation front was in the range 275–305 °C depending on the type of formulation, leading to pores in the epoxy phase and extensive degradation of the PU phase. In the case of the opaque aluminium foam, an additional layer of pure resin was required on the UV-exposed surface, which corresponded to a critical mass of a few grams to ensure sufficient heat generation and trigger the front propagation. © 2020 Society of Chemical Industry
Light induced grafting-from strategies as powerfull tool for surface modification
No full textChemical-induced grafting processes can be performed either a grafting-to method, where preformed polymer chains are grafted on the surface previously activated, or alternatively, the polymer chains can be grown from the surface via a grafting-from method. The last one can be considered a bottom-up approach in which polymers are generated directly on the surface starting from their precursors. As a preliminary process the substrate is functionalized with specific groups that can initiate a polymerization reaction. While the polymerization can be initiated by a thermal initiator or directly by radicals formed by high energy treatment of the surface, light induced triggering of the grafting reaction has recently found increasing interest. With this review, by placing emphasis on the initiating system, we aim to show the significant feasibility of photografting-from method to properly functionalize any type of surface
Composite Propellant Manufacturing Process Based on Deposition and Light-Activated Polymerization for Solid Rocket Motors
No full textSample Condensation in Online Continual Learning
No full textOnline Continual learning is a challenging learning scenario where the model must learn from a non-stationary stream of data where each sample is seen only once. The main challenge is to incrementally learn while avoiding catastrophic forgetting, namely the problem of forgetting previously acquired knowledge while learning from new data. A popular solution in these scenario is to use a small memory to retain old data and rehearse them over time. Unfortunately, due to the limited memory size, the quality of the memory will deteriorate over time. In this paper we propose OLCGM, a novel replay-based continual learning strategy that uses knowledge condensation techniques to continuously compress the memory and achieve a better use of its limited size. The sample condensation step compresses old samples, instead of removing them like other replay strategies. As a result, the experiments show that, whenever the memory budget is limited compared to the complexity of the data, OLCGM improves the final accuracy compared to state-of-the-art replay strategies
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