Isotherm Adsorbsi Uap Air Komposit Poli(asam laktat) - Grafit

Fadilah Fadilah, Mujtahid Kaavessina, Sperisa Distantina, Dwi Ardiana Setyawhardani, Endang Kwartiningsih, Aida Nur Ramadhani, Isa Fakhruddin, Amaldo Firjarahadi Tane

Abstract

ABSTRAK.Poli asam laktat adalah polimer hidrofobik yang termasuk dalam kelas biomaterial yang bersifat biodegradable. Poli asam laktat berpotensi untuk dijadikan komposit polimer konduktif (conductive polymer composite - CPC) yang dipergunakan sebagai bahan semikonduktor dengan cara mencampurkan grafit kepadanya. Perilaku adsorpsi uap air perlu dipelajari untuk mengetahui stabilitas komposit dan ditunjukkan melalui kurva isotherm adsorpsi uap air. Tujuan dari penelitian ini adalah mempelajari isotherm adsorpsi uap air komposit poli asam laktat/grafit pada berbagai komposisi grafit. Pengamatan terhadap isotherm adsorpsi uap air dilakukan dengan metode gravimetri pada berbagai kondisi kelembaban relatif. Hasil yang diperoleh menunjukkan bahwa kurva isotherm mengikuti tipe II menurut kasifikasi Brunauer, yaitu kurva berbentuk sigmoidal.  Semakin tinggi kondisi kelembaban relatif, semakin besar kandungan air kesetimbangan. Peningkatan kandungan air kesetimbangan secara tajam terjadi pada kondisi kelembaban di atas 75%.  Semakin tinggi komposisi grafit, semakin besar kandungan uap air kesetimbangan. Data kesetimbangan dicocokkan dengan model kesetimbangan sorpsi uap air yaitu model Guggenhiem-Anderson-deBoer (GAB), model Peleg, dan model Oswin. Model GAB memberikan gambaran isotherm yang terbaik.

Kata kunci:

adsorpsi uap air, kesetimbangan, komposit, poli asam laktat/grafit, pemodelan 

 

ABSTRACT. Poly(lactic acid)/PLA is a hydrophobic polymer that belongs to the class of biodegradable biomaterial. PLA can be used as material in the manufacture of conductive polymer composite (CPC), which is used as a semiconductor material by mixing graphite into it. The water vapor adsorption behavior needs to be studied to determine the stability of the composite. This research aims to investigate the water vapor adsorption isotherm in poly(lactic acid)/graphite composites on various graphite compositions. The gravimetric method carried observations on the water vapor adsorption isotherm at various relative humidity conditions. The results obtained indicate that the isotherm curve follows type II according to the Brunauer classification. The higher the relative humidity, the greater the equilibrium water content. A sharp increase in the equilibrium water content occurs at humidity conditions above 75%. The higher the graphite composition, the greater the equilibrium moisture content. The Guggenhiem-Anderson-deBoer (GAB), Peleg, and Oswin sorption models were used to fit the experimental data. The GAB model best described the isotherms of the composites.

Keywords:

composite, equilibrium, modeling, poly(lactic acid)/ graphite, water vapor adsorption


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