CANSU ULKER TURAN^1,*, YUKSEL GUVENILIR¹

Journal of Polymer Materials, Vol.38, No.3-4, pp. 271-280, 2021, DOI:10.32381/JPM.2021.38.3-4.8

Abstract Rice husk ash is a side-product of rice production; thus, it is a cheap, abundant, and renewable material, and utilized as an enzyme carrier to immobilize Candida antarctica lipase B. In this study, Candida antarctica lipase B immobilized onto rice husk ashes was used to catalyze ring opening polymerization of 16-membered lactone, ω-pentadecalactone. In order to determine the best polymerization conditions for highest molar mass polymer, reactions were proceeded at various temperatures and time periods. The best reaction conditions were obtained as 80°C and 6 hours (M_n = 34255 g mol^-1). Molecular structure of this polymer sample was confirmed via… More >

Cansu Ulker^*, Zeynep Gok, Yuksel Guvenilir

Journal of Renewable Materials, Vol.7, No.4, pp. 335-343, 2019, DOI:10.32604/jrm.2019.03819

Abstract Novozyme 435, which is the commercially available immobilized form of Candida antarctica lipase B, has been successfully conducted ring opening polymerization of lactones in organic solvents. In this paper, it was aimed to introduce an alternative biocatalyst for Novozyme 435. Candida antarctica lipase B immobilized onto rice husk ashes via physical adsorption (with a specific activity of 4.4 U/mg) was prepared in previous studies and used as a biocatalyst for poly(δ-valerolactone) synthesis in the present work. Polymerization reactions were proceeded at various reaction temperatures and periods via both two immobilized enzyme preparations. The resulting products were characterized spectroscopically and thermally.… More >

Yasemin Kaptan, M.Sc.^1,*, Yüksel Avcıbaşı-Güvenilir¹

Journal of Renewable Materials, Vol.6, No.6, pp. 619-629, 2018, DOI:10.32604/JRM.2018.00142

Abstract Surface-modified rice husk ash was used as an inorganic support material for immobilization of Candida antarctica lipase B. (3-aminopropyl) trimethoxysilane was used for surface modification. Immobilization of CALB was performed via both physical adsorption and cross-linking. PCL synthesis was carried out by using these immobilized enzymes, free enzyme and Novozyme 435®. Molecular weight distribution of polymer samples was obtained by gel permeation chromatography (GPC) and chain structures of the polymer samples were observed by hydrogen nuclear magnetic resonance (1H-NMR). The highest monomer conversion is generally obtained by using cross-linked enzyme, around 90%. PDI values for all polymer samples were approximately… More >

Cansu Ulker*, Yuksel Guvenilir

Journal of Renewable Materials, Vol.6, No.6, pp. 591-598, 2018, DOI:10.7569/JRM.2017.634189

Abstract As an alternative biodegradable aliphatic polyester, poly(w-pentadecalactone-co-ε-caprolactone) copolymer was synthesized via enzymatic ring-opening polymerization. A new biocatalyst, Candida antarctica lipase B, immobilized onto rice husk ash was used for catalysis. Reactions were carried out at various temperatures and periods for varied copolymer compositions in order to obtain the highest molecular weight copolymer. The best reaction parameters were found to be 80 °C and 6 hours and molecular weights increased proportionally with the amount of w-pentadecalactone (w-PDL). The molecular structure of copolymer with 75% weight ratio of w-PDL (Mn = 19720 g/mol) was characterized by proton and carbon nuclear magnetic resonance… More >