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DAVIDE MORSELLI

DIPENDENTE ALTRA UNIVERSITA presso: Dipartimento di Ingegneria "Enzo Ferrari"


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Pubblicazioni

2014 - EPDM rubber reinforced with titania generated by nonhydrolytic sol-gel process [Articolo su rivista]
Paderni, Katia; Morselli, Davide; Bondioli, Federica; Luyt, Adriaan S.; Mokhothu, Thabang H.; Messori, Massimo
abstract

EPDM rubber was reinforced with titania in situ generated by using a nonhydrolytic sol-gel (NHSG) process starting from TiCl4 as titania precursor and tert-butanol as oxygen donor. Titania particles in anatase form and with average diameter of 6 nm were synthesized via NHSG route and then the same procedure was adopted in presence of EPDM rubber to obtain composites containing up to 30 wt% of filler. Extraction and equilibrium swelling tests suggested an interfering effect of the NHSG reaction on the vulcanization process of the rubber resulting to a crosslink density which decreased in the presence of titania. Quasistatic and dynamic-mechanical characterizations indicated that the presence of titania as rigid filler in both the unvulcanized and vulcanized EPDM matrix led to a significant increase in stiffness and stress at break. The experimental values of modulus were systematically higher than the values predicted by classical equations suggesting an additional stiffening contribution deriving from the molecular interaction between the rubber and the filler.


2014 - Epoxy resins reinforced with TiO2 generated by non-hydrolytic sol-gel process [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; Marco, Sangermano; Ignazio, Roppolo; Messori, Massimo
abstract

Innovative epoxy-titania nanocomposites were prepared starting from titania nanoparticles suspended in benzyl alcohol (BzOH) generated by nonhydrolytic sol–gel process from TiCl4. The obtained suspensions were mixed with an epoxy resin (bisphenol A diglycidyl ether, DGEBA) and the formulations were cured in the presence of ytterbium(III) trifluoromethanesulfonate as cationic initiator. The thermally activated cationic ring-opening polymerization produced a three-dimensional network in which the suspend- ing medium BzOH was covalently linked to the epoxy network according to the “activated monomer” mechanism during the propa- gation step. The presence of titania nanoparticles resulted in a reinforcing and stiffening effect due to both their hydrodynamic effect and, most important, a significantly higher cross-linking density of the composite material with respect to the unfilled epoxy resin.


2013 - Preparation and characterization of EPDM rubber modified within situgenerated silica [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; Adriaan S., Luyt; Thabang H., Mokhothu; Messori, Massimo
abstract

This article is concerned with the preparation of a filled elastomer by means the nonconventional bottom-up approach to polymer composites, alternatively with the conventional mechanical compounding of preformed filler particles with rubber. EPDM rubber was modified with in situ generated silica particles prepared by means of a sol–gel process adopting a solution process. The used synthetic procedure permitted the preparation of highly filled rubbers (up to 40 wt % of silica) with silica particle dimensions ranging from 0.2 to 2 um. Equilibrium swelling and extraction tests indicated a hindering effect of the presence of in situ generated silica on the vulcanization process which reduced the cross linking degree of the rubber matrix. Both tensile tests and dynamic–mechanical analysis showed a significant improvement in the mechanical properties due to the presence of the reinforcing filler, with an enhancement more significant than that expected from a simple hydrodynamic reinforcing mechanism.


2012 - Gomma EPDM rinforzata con silice generata in-situ [Relazione in Atti di Convegno]
Morselli, Davide; Bondioli, Federica; Messori, Massimo
abstract

gomma EPDM è stata rinforzata generando silice in situ mediante tecnica sol-gel. Il processo in soluzione adottato ha permesso l’ottenimento di campioni a elevata quantità di filler (fino a un 30% in peso). Sia il test a trazione che il comportamento dinamico meccanico hanno dimostrato un netto miglioramento delle proprietà meccaniche dovuto alla presenza del filler rigido in grado di rinforzare la matrice gommosa. Dalle prove a trazione è stato trovato un modulo elastico iniziale significativamente incrementato se confrontato a quello teorico calcolato dall’equazione di Smallwood-Guth-Einstein considerando un semplice meccanismo di rinforzo idrodinamico.


2012 - Photo-cured epoxy networks reinforced with TiO2 in-situ generated by means of non-hydrolytic sol-gel process [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; M., Sangermano; Messori, Massimo
abstract

Suspensions of titania nanoparticles in benzyl alcohol were synthesised from TiCl4 by means of non- hydrolytic sol-gel (NHSG) process. The stable suspensions were mixed with an aliphatic epoxy resin and subsequently photo-polymerised in the presence of a cationic photo-initiator to produce transparent composite films. The presence of titania didn’t influence significantly the polymerisation rate, while a progressive decrease in the maximum value of epoxy groups conversion was observed by increasing the titania content. Gel content analysis demonstrated that all organic species (benzyl alcohol and corresponding by-products) were covalently linked to the epoxy network, suggesting that both ‘active chain end’ and ‘activated monomer’ mechanisms were active during the propagation step in the cationic ring- opening polymerisation. The presence of titania increased significantly both glass transition temperature and modulus (in the rubbery region) confirming the reinforcing and stiffening effect due to both the presence of inorganic nanofillers and, most importantly, a higher cross-linking density of the composite material with respect to the pristine epoxy matrix. Nano-indentation and scratch tests also showed a systematic increase of hardness and scratch resistance by increasing the filler content.


2012 - Poly(methyl methacrylate)–TiO2 nanocomposites obtained by non-hydrolytic sol–gel synthesis: the innovative tert-butyl alcohol route [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; M., Fiorini; Messori, Massimo
abstract

The present article concerns the preparation of poly(methyl methacrylate)/titania nanocomposites by a non-conventional bottom-up approach, as alternative to the conventional mechanical compounding of preformed filler particles. Poly(methyl methacrylate) (PMMA) was modi- fied with in situ generation of titania nanoparticles by means of the so-called non-hydrolytic sol–gel (NHSG) process in the presence of tert-butyl alcohol (tBuOH) as oxygen donor and polymer solvent. The results showed that the synthetic procedure used permitted the preparation of the highly filled PMMA (up to 20 phr of titania in anatase form) with titania actual content values very close to the nominal ones and with enhanced filler dispersion and homogeneous distribution within the polymeric matrix, avoiding the typical rheological problems related to distributive and dispersive mixing of conventional compounding methods. The presence of titania nanoparticles led to increases in glass transition temperature and E' modulus in the rubbery region for all the prepared samples with respect to the pristine PMMA. Finally, the nano-composites showed an interesting photo-catalytic activity towards organic molecules. The findings led us to conclude that the NHSG process was successfully employed to produce anatase titania in the presence of tBuOH and PMMA. The proposed process seems to offer a very promising method to produce polymer nanocomposites with good filler dispersion and homogeneous distribution and with interesting functional properties such as photo-catalytic activity.


2012 - Resine epossidiche rinforzate con titania generata in situ mediante processo dol-gel non idrolitico [Relazione in Atti di Convegno]
Morselli, Davide; Bondioli, Federica; M., Sangermano; Messori, Massimo
abstract

Sospensioni di nanoparticelle di titania in alcol benzilico sono state preparate mediante processo sol-gel non-idrolitico e miscelate a una resina epossidica alifatica. Le formulazioni ottenute sono poi state foto-polimerizzate in presenza di un foto-iniziatore cationico per produrre film nanocompositi. La presenza di titania non ha variato significativamente la velocità di foto-polimerizzazione, mentre è stata osservata una riduzione della conversione massima di gruppi epossido all'aumentare del contenuto di titania. Attraverso l'analisi del contenuto di gel è stato evidenziato che tutte le specie organiche presenti (alcol benzilico e relativi sottoprodotti) sono covalentemente legati al reticolo epossidico indicando che entrambi i meccanismi 'active chain end' e 'activated monomer' sono attivi nella fase di propagazione della polimerizzazione cationica per apertura di anello. La presenza di titania ha portato a significativi aumenti sia della temperatura di transizione vetrosa che del modulo e questo effetto di rinforzo è stato attribuito, oltre che all'atteso effetto idrodinamico legato alla presenza di particelle rigide, anche a una maggiore densità di reticolazione nel materiale composito rispetto alla resina epossidica pura.


2011 - Poly(methyl methacrylate)-TiO2 nanocomposite obtained by non-hydrolytic sol–gel synthesis [Articolo su rivista]
Morselli, Davide; Messori, Massimo; Bondioli, Federica
abstract

Poly(methyl methacrylate) (PMMA)/titanium dioxide (TiO2) nanocomposites were prepared by means of in situ generation of TiO2 through a non-hydrolytic sol–gel process (NHSG), starting from titanium chloride, as titania precursor, benzyl alcohol, as oxygen donor, and commer- cial PMMA. TiO2 nanoparticles (average size of 30 nm) were obtained in the anatase and amorphous forms. The in situ generation led to a very homogeneous distribution of particulate fillers within the polymeric matrix avoiding the problems related to distributive and dispersive mixing of conventional compounding methods (top down approach). A slight increase of glass transition temperature was observed for all prepared composites with respect to the pristine PMMA. The NHSG process did not affect the molecular weight of the polymers indicating the absence of any degradation reaction for PMMA. The presence of titania in the anatase phase increases the photodegradation of the PMMA matrix due to UV irradiation.