1,721,187 research outputs found
Applicazioni di sistemi ibridi da sol–gel
No full textAtti del XXVIII Convegno Scuola AIM Mario Farina su “Materiali polimerici ibridi e nanostrutturati” – 30 Aprile – 4 Maggio 2007, Gargnano (BS
Verniciatura di substrati plastici
No full textAtti del XXXI Convegno Scuola AIM Mario Farina su “Rivestimenti polimerici - Materiali, tecnologie e proprietà” - 17-20 Maggio 2010, Gargnano (BS
Materiale composito formato da un biofiller e da una matrice termoplastica e procedimento per realizzare un articolo con un tale materiale composito
No full textA comprehensive overview of conventional and bio-based fillers for rubber formulations sustainability
Full text linkIn recent years, there has been a significant increase in literature regarding the development of sustainable rubber composites. This is due to the widespread use of rubber and the need to transition towards a circular economy, which addresses environmental concerns such as global warming and pollution. Extensive research has been conducted to replace conventional fillers like silica and petroleum-based fillers in rubber composites with eco-friendly and sustainable alternatives, namely bio-based fillers. These biofillers present diverse fundamental characteristics, making them promising substitutes for carbon black or inorganic mineral-based fillers, reducing reliance on petroleum. They possess biodegradable properties, resulting in a reduced environmental footprint, as well as lower density and cost compared to conventional counterparts. Furthermore, their unique properties, such as high specific strength and stiffness, render them well-suited for various rubber applications. The performance of reinforced rubber composites is influenced by factors including the matrix polymer, as well as the source, size, shape, chemical composition, and volume fraction of fillers. Rubber composites incorporating biofillers offer the dual advantages of economic efficiency and environmental sustainability. This article provides a comprehensive review of recent research in rubber composite development, with a specific focus on utilizing various fillers. Additionally, it examines the characterization of both conventional and bio-based fillers and their effects on the behaviour and performance of rubber composites, including morphology, thermal properties, and mechanical properties
REACTION PATHWAY IN VAPOR-PHASE HYDROGENATION OF MALEIC-ANHYDRIDE AND ITS ESTERS TO GAMMA-BUTYROLACTONE
No full textThe catalytic reactivity of maleic anhydride (MA), succinic anhydride (SA) and their dimethyl esters (dimethyl maleate and dimethyl succinate) in the vapour phase hydrogenation to gamma-butyrolacetone (GBL) was investigated. In order to obtain general data, both a multicomponent catalyst (CAT 1: Cu/Zn/Mg/Cr 40:5:5:50, atomic ratio %), obtained by reduction of a nonstoichiometric spinel-type precursor, and a commercial catalyst (CAT 2: Cu/Mn/Ba/Cr = 44:8:1:47, atomic ratio %) were used. The MA/GBL solution exhibited the highest GBL production, while the SA/GBL solution was converted only partially due to a competitive adsorption of GBL on the active sites, as evidenced by the similar reactivities observed with pure anhydrides. The best carbon balances were observed with the esters, probably the result of lowest light hydrocarbon synthesis and tar formation. With all the feedstocks, the activity of CAT 2 is higher than that of CAT 1, which, however, gives the best yield in GBL due its lower activity in the overhydrogenation and hydrogenolysis reaction. It was found that n-butanol (BuOH) and butyric acid (BuA) derived mainly from GBL. On this basis, the reactivities of the main products observed were investigated separately, confirming the stability of tetrahydrofuran (THF), which reacted only at high temperature with low conversions to ethanol. On the other hand, GBL gave rise to overhydrogenation and/or hydrogenolysis, with high conversion (mainly with CAT 2), confirming its key role in both reactions. Furthermore, the formation in the catalytic tests with BuA and BuOH of n-butanal, notwithstanding the high H-2/organic ratio, implies that it is the main intermediate in the hydrogenolysis reactions. A new reaction scheme is proposed, pointing out the key role of GBL as the ''intersection'' of two possible reaction pathways, giving rise to THF or overhydrogenation and hydrogenolysis products, respectively
In Situ Synthesis of Rubber Nanocomposites
No full textThe preparation and characterization of rubber based nanocomposites prepared by in situ generation of inorganic oxides by means of the hydrolytic sol– gel process are reviewed in the present chapter. The sol–gel approach has been applied to several rubber matrices to prepare reinforced vulcanized and unvul- canized rubbers. Several synthetic procedures are presented while the most investigated filler is silica obtained by hydrolysis and condensation of tetraeth- oxysilane. The effects of the different preparation conditions and of the filler content are generally discussed in terms of morphology (investigated by electron microscopy and small angle X-ray scattering) and mechanical properties (modulus, strength and extensibility). The mechanical properties of the in situ filled nano- composites are generally better than those of the corresponding materials prepared with the conventional mechanical mixing of preformed particulates and elasto- mers. This enhancement is generally attributed to a lower tendency to filler–filler aggregation due to a lower particle surface interaction resulting from the ‘bottom- up approach’ of the sol–gel process applied to the preparation of organic–inorganic hybrid materials
Composizione di resine foto-polimerizzabili, metodo di fabbricazione di un manufatto impiegante la stessa e manufatto cosi’ ottenuto
No full text
Non-hydrolytic sol–gel synthesis and reactive suspension method: an innovative approach to obtain magnetite–epoxy nanocomposite materials
No full textInnovative magnetite–epoxy nanocomposites were prepared starting from magnetite nanoparticles suspended in alcoholic or amino reactive solvents, synthesized by non-hydrolytic sol–gel process from iron (III) acetylacetonate. The obtained suspensions, also synthesized using microwave heating, were mixed with an epoxy monomer (bisphenol A diglycidyl ether, DGEBA), and the formulations were subsequently cured. The thermally activated ring-opening polymerization produced a three-dimensional network in which the suspending medium was covalently linked to the epoxy network according to the chain or step polymerization mechanisms during the cross-linking reaction. This synthetic strategy allowed to obtain nanocomposites in which the nanoparticles play an active role in the polymeric structure, affecting the structural (mechanical and thermal) and functional (magnetic) properties of the final system. The presence of magnetite nanoparticles in the composite resulted in distinct reinforcing effects, acting as rigid filler and/or as cross-linking point, depending on the different chemical environment at the nanoparticle–polymer interphase
Preservation of wood structure using stabilized alkaline bleaching agents: a novel and mild approach to enhance whitening for lignin-rich wood template
Full text linkPreservation and enhancement of wood properties have become increasingly important due to the growing demand for sustainable materials in the construction and manufacturing industries. This study focuses on bleaching processes as an alternative to conventional delignification, aiming to retain a significant amount of lignin while achieving the desired whiteness of the wood template. In particular, stabilized alkaline hydrogen peroxide is investigated as a bleaching agent under mild conditions. The treatment preserves more than 90% of the native mass in both balsa and birch, ensuring that most of the wood’s structural components are maintained. This results in a high wood volume fraction, corresponding to reduced porosity and a structure closely resembling that of unbleached wood. Fourier Transform Infrared spectroscopy (FTIR) semi-quantitative analysis further confirms that the relative lignin content is retained, ranging between 70 and 80% depending on the species. Unlike conventional approaches that often degrade the wood structure and require long treatment times at high temperatures, the proposed process is performed at room temperature under mild conditions and completed in less than 2–4 h, thus reducing energy demand and avoiding harmful byproducts. Overall, this work provides a bleaching strategy that combines efficiency, structural integrity, and sustainability, offering bleached wood templates suitable for further characterization and advanced applications
- …
