HYDROGELS MICRO COMPOSITES BASED ON POLYVINYL ALCOHOL / BENTONIT

Abstract

HIDROGEL MIKROKOMPOSIT BERBASIS POLIVINILALKOHOL / BENTONIT. Hidrogel mikrokomposit untuk keperluan biomedis disintesis dari PoliVinil Alkohol (PVA) berderajat hidrolisis 98% hingga 99% dan penguat bentonit menggunakan teknik freeze and thawing dengan 3 siklus. Bentonit yang digunakan bertipe sodium, terlebih dahulu dikecilkan ukurannya dengan planetary ball mill sehingga memiliki diameter sebesar 305 nm. Dalam percobaan ini komposisi bentonit divariasikan pada nilai 2,5% w, 5% w, 10% w dan 15% w. Hidrogel dianalisis terhadap sifat-sifat umumnya seperti fraksi gel, derajat pembengkakan setimbang Equilibrium Degree of Swelling (EDS), kandungan air setimbang Equilibrium Water Content (EWC) dan laju transmisi uap air. Struktur kimianya dianalisis menggunakan Spektrofotometer Fourier Transform InfraRed (FT-IR) dan morfologinya dengan menggunakan Scanning Electron Microscope (SEM) dan X-Ray Diffractometer (XRD). Sifat termalnya diuji menggunakan Differential Scanning Calorimetry (DSC) dan sifat mekaniknya dengan uji tarik. Komposisi bentonit dari 0% w hingga 15% w dalam sistem mikrokomposit ini memberikan pengaruh terhadap penurunan daya absorpsi dari 67,79% hingga 52,17% dan meningkatkan fraksi gel dari 78,43% hingga 94,48%. Kekuatan hidrogel meningkat dilihat pada kuat tariknya naik dari 2,18 MPa hingga 3,48 MPa. Laju transmisi uap air menurun seiring penambahan komposisi bentonit dari 53,07 g/m2h hingga 34,42 g/m2h. Titik leleh nanokomposit relatif tidak berubah, yaitu berkisar 230°C hingga 235°C, tetapi Tg mengalami kenaikan akibat penambahan bentonit, yakni 127,8°C pada 0% berat bentonit menjadi 147,2°C pada 5% berat bentonit.

ABSTRACT

HYDROGELS MICRO COMPOSITES BASED ON POLYVINYL ALCOHOL/BENTONITE. Hydrogels micro composite for biomedical application has been synthesized from polyvinyl alcohol (PVA) with degree of hydrolyzed 98-99% and bentonite as reinforcement using freeze and thawing technique with 3 cycles. Sodium bentonite used has been sized to 305 nm in average using planetary ball mill. Variation of bentonite composition used in the synthesis are 2.5%, 5%, 10% and 15% w. The hydrogel had been analyzed for its common properties such as gel fraction, Equilibrium Degree of Swelling (EDS), Equilibrium Water Content (EWC) and Water Vapor Transmission Rate (WVTR). While its chemical structure was identified using Fourier Transform-Infra Red (FT-IR) Spectrophotometer and its morphology was characterised using Scanning Electron Microscope (SEM) and X-Ray Diffractometer (XRD). Additionally, its thermal properties were analyzed using Differential Scanning Calorimetry (DSC), and its mechanical properties were tested by tensile machine. Effect of bentonite composition from 0 %w to 15 %w in hydrogel micro composite is decreasing the water absorption capacity from 67.79% to 52.17% and increasing the gel fraction from 78.43% to 94.48%. As more bentonite added, the composite strength increases by increase in tensile stress from 2.18 MPa to 3.48 MPa, while the water vapor transmission rate decreases from 53.07 g/m2h to 34.42 g/m2h. The hydrogel micro composite melting point does not change with the bentonite addition, i.e. in the range of 230-235°C, but its glass transition temperature (Tg) increases from 127.8°C for 0% w to 147.2°C for 5% w.