A plasticizer index to universally correlate the normalized work of fracture and elastic modulus of plasticized cellulose triacetates.

Cellulose triacetate (CTA) plasticization with 25 wt% glycerin (GLY), triethyl citrate (TEC) or dioctyl phthalate (DOP) enhanced its crystalline content as much as 55%, while only 10% crystalline content increase noticed using poly (ethylene glycol) (PEG). In addition, GLY and PEG did not cause any sensible Tg depression regarding CTA, whereas DOP and TEC decreased it as much as 46°C and 16°C, respectively. Furthermore, the work of fracture (WoF) of CTA was deteriorated by PEG, did not change using GLY and magnified as much as 6.5 and 15 times by TEC and DOP, respectively. The elastic modulus (EM) of the plasticized CTAs, however, were 1.07, 1.06, 0.42 and 0.3 GPa using GLY, PEG, TEC and DOP, respectively. Finally, the normalized WoF and EM of the plasticized CTAs by their Tg depression (ΔTg) and crystalline content (Xc) showed a universal correlation with a plasticizer index containing its molar volume, concentration and polymer/plasticizer Painter-Coleman interaction parameter.