PREPARAZIONE DEI BIONANOCOMPOSITI TRAMITE SOLUTION CASTING

La procedura di preparazione consiste essenzialmente nella miscelazione di una soluzione del copolimero con una dispersione di nanowhiskers, entrambe in cloroformio. Una certa quantità di copolimero è stata disciolta all’interno di un volume di cloroformio e mantenuta sotto agitazione tramite ancoretta magnetica. Contemporaneamente, una quantità di CNWs (0.25 , 0.5, 1, 2 % ww rispetto al peso di copolimero) è stata disciolta in un volume opportuno di cloroformio e sottoposta alla procedura di dispersione; agitazione meccanica a 21.000 rpm per 15 minuti mediante Ultra- TURAX e due cicli di sonicazione, con sonicatore a punta, per 2 minuti intervallati da 30 secondi di pausa.

CopR7030 7 x10-3 3 x 10-3

4 x 10-6

101 La dispersione di CNWs così ottenuta è stata aggiunta alla soluzione del copolimero. La nuova miscela è stata successivamente sottoposta ad agitazione con TURAX per altri 15 minuti seguita da un’ultima sonicazione di 2 minuti. Il contenuto è stato infine versato in dischi di petri in teflon per permettere l’evaporazione del solvente e così la formazione del film di composito.

Sono stati preparati due gruppi di film a spessore differente; 100-200 µm e 1- 1.5 mm destinati alle prove di degradazione idrolitica i primi e meccaniche di trazione i secondi. In tabella 8 sono riportate le quantità usate per la preparazione delle due tipologie di compositi.

Tabella 8 Campioni di bionanocompositi preparati per prove di degradazione idrolitica e meccaniche

utilizzo Copolimero

(g)

CNWs (mg) % ww

CNWs

Cloroformio (ml) Spessore film (mm) CopR CNWs Degradazione idrolitica 1g 0 0 10 10 0.15 2.5 0.25 0.13 5.0 0.5 0.20 10.0 1 0.17 20.0 2 0.14 Prove meccaniche 4.6 0 0 40 30 1.34 11.5 0.25 1.39 23.0 0.5 1.50 46.0 1 1.48 92.0 2 1.46

102

5

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