The effects of different plasticizers (triacetin and triethyl citrate) on polyvinyl alcohol
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Date
2018-05
Authors
Siti Aina Najian Muhammad Zuber
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Abstract
This work aims to investigate the applicability to two different natural based
plasticizers as alternative plasticizers in different types of Polyvinyl Alcohol (PVA). Two
natural based plasticizers were chosen which are triacetin and Triethyl citrate as new
alternative plasticizers in PVA of different hydrolysis degree (88 and 99%) but similar
molecular weight and the effectiveness in term of miscibility, thermal, tensile and
morphological properties were studied. The PVA and plasticizer were mixed by solvent
blending method and the solution of PVA compound was casted to produce plasticized
PVA film. At a fix amount of plasticizer, Differential scanning calorimetry (DSC) analysis
showed that the presence of Triacetin caused reduction of glass transition temperature
(Tg) and melting temperature (Tm) of both types of PVA with higher changes in 88%
hydrolysis degree but with Triethyl citrate, the film showed insignificant changes of Tg
and slight reduction of Tm in both types of PVA suggesting higher effectiveness of the
former system. Morphology of the blends indicated phase separation of the system of
PVA with Triethyl citrate thus responsible for the less effectiveness of Triethyl citrate as
plasticizer of PVA. Meanwhile, thermal properties of PVA of 88% hydrolysis with different
amount of Triacetin indicated that Tg continuously decreased with increasing plasticizer
up to 15 wt% but then did not significantly different with 20wt% Triacetin. Tensile strength
and modulus indicated slight reduction of value with increasing triacetin up to 10 wt%
before sudden jump to up to around 32 MPa and 80MPa, respectively but continuous
increased of elongation at break with triacetin loading. Morphological study showed
significant change of morphology with rough surface in the presence of 15wt% Triacetin
suggesting that the optimum loading of the plasticizer in PVA.