Non-hydrolytic sol–gel synthesis of polypropylene/TiO2 composites by reactive extrusion

Abstract

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Tuning Polymer/TiO2 Nanocomposites Morphology by In Situ Non-Hydrolytic Sol-Gel Syntheses in Viscous Polymer Medium: Influence of the Polymer Nature and Oxygen Donor

“…However, in the PP-Ti(O i Pr) 4 -Ac 2 O composite pattern, the absence of signals other than those of the polypropylene ones evidenced that the in situ synthesized TiO 2 was in an amorphous state. These observations are consistent with previous results obtained for in situ hydrolytic sol-gel synthesis of TiO 2 in molten polypropylene [ 9 , 19 ] and also with our first study dedicated to the in situ NHSG synthesis of TiO 2 in polypropylene [ 13 ].…”

“…The in situ non-hydrolytic sol-gel synthesis of TiO 2 from Ti(O i Pr) 4 and Ac 2 O was already described in our previous work [ 13 ]. The affinity between acetic anhydride and polypropylene or polystyrene matrices was investigated by the determination of their solubility parameters δ by the Fedors’ method, which requires only the knowledge of the compound structural formula [ 17 ].…”

“…The mean formula of the Ti domain is therefore Ti(O) 1.58 (OR) 0.84 which implies a condensation degree of 79%. The condensation degree calculation was already detailed in a previous publication [ 13 ] For the PS-Ti(O i Pr) 4 -Ac 2 O nanocomposite, the deconvolution of the O(1s) signal ( Figure 3 b) allowed to determine that 11% of O atoms were involved in –Ti–O–Ti bonds and 89% were involved in -Ti–O–C or –Ti–O–H bonds, giving a condensation degree of 20%.…”

“…Titanium isopropoxide and the oxygen donor (acetic anhydride (Ac 2 O), benzoic anhydride (BzA) or acetophenone (Aph) respectively) in stoichiometric proportions (2 eq of oxygen donor relative to titanium isopropoxide) were added to the molten polypropylene or viscous polystyrene in a Haake ® (Germany) internal mixer equipped with two rotors R600 running in a counter rotating way. For the use of acetic anhydride as oxygen donor, reactants (Ti(O i Pr) 4 and anhydride) were pre-mixed as previously described [ 13 ]. The rotor speed was fixed at 50 rpm.…”

“…Indeed, the sol-gel chemistry is a method of “chimie douce” [ 12 ] which involves a temperature range compatible with the classical melt process of most commodity polymers. To illustrate, in a previous work, we have already described the synthesis of a TiO 2 filler into molten polypropylene via a non-hydrolytic sol-gel route [ 13 ]. PP/TiO 2 composites were prepared in an extruder at 200–240 °C.…”