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Faik Tugut, Mehmet Turgut and Dursun Saraydin

Abstract

The study aimed to evaluate the effects of adding different concentrations of 2 hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate (HEA), ethyl methacrylate (EA) and isobutyl methacrylate (IBMA) monomers on the structural, thermal and mechanical properties of a fiber reinforced heat-polymerized acrylic resin. For each test, 126 acrylic resin specimens were fabricated and divided into 6 groups with 7 specimens each. One group was the control group, the other one is a fiber reinforced group and others were the test groups, which were formed according to the different concentrations of monomers. 6 mm length, and the weight ratio of 3% short glass fibers are added to acrylic powder polymerized by heating. The 2%, 5%, 10%, at 20 % ratios of different comonomers added to a monomer of MMA are composed of copolymer structures. Flexural strength was assessed with a three-point bending test using a universal testing machine. Impact strength testing was conducted using an impact test machine by the Charpy method. The analysis of the connection between acrylic resin and fiber by SEM and structural changes in the acrylic resin was investigated by FTIR spectroscopy. Data analyses using analysis of Kruskal-Wallis and Mann-Whitney U tests (α=0.05) significant difference tests showed that adding 2%, 5% HEMA and IBMA monomers significantly increased the flexural and impact strength compared to the control, only fiber and others group (P< 0.05). It is observed that the process of adding low concentration of HEMA and IBMA monomers improved certain mechanical properties of fiber reinforced with polymethylmethacrylate.

Open access

Ceylan Hepokur, Hesna Nursevin Öztop and Dursun Saraydin

Abstract

In this study, molecular imprinted polymers for highly selective recognition of cholic acid, which is a bile acid, were prepared. Acrylamide, methacrylic acid, methacrylamide were chosen as monomer for the production of molecularly imprinted polymers. Functional monomers were polymerized with various crosslinkers; ethylene glycol dimethacrylate (EGDMA), 1,4-butanediol diacrylate (BUT), trimethylpropane triacrylate (TMT) with target molecule (MIP-EGDMA, MIP-BUT and MIP TMT) and various MIPs were prepared. The cholic acid was removed from MIP with a suitable method. NIP polymers were synthesized without cholic acid (NIPEGDMA, NIP-BUT and NIP-TMT). For the characterization of synthesized polymers FTIR, DSC, TGA, SEM analyses were used. The parameters that affect the adsorption of target species on polymers such as temperature, pH, and concentration were evaluated. The selectivity and reusability studies were also investigated.

It is concluded that MIPs showed better adsorption capacity than NIPs for all solvents for cholic acid. The adsorption sequencing is MIP-TMT > MIP-BUT > MIP EGDMA. The maximum adsorption achieved with ethyl alcohol. The adsorption of cholic acid varies with chancing pH for all produced MIPs and NIPs. It is concluded that the adsorption of cholic acid is not affected by the temperature. The adsorption of cholic acid is followed as L type from Giles adsorption isotherms. The thermodynamic parameters are proved the physical nature of adsorption process. The studies conducted with deoxycholic acid, taurocholic acid that is homolog to cholic acid showed that produced MIPs are highly selective for cholic acid.

Open access

Hesna Nursevin Öztop, Fatma Banu Çatmaz and Dursun Saraydin

Abstract

Poly (methacrylamide / maleic acid) PM/MA and poly (methacrylamide) PM hydrogels were prepared aiming to be used as a support for invertase. Spectrophotometric, thermal analysis methods, swelling and diffusion experiments were used for the characterization of hydrogels. The swelling of PM/MA was higher than that of PM in water. The diffusion of water within the hydrogel was found to be non-Fickian. Invertase was immobilized onto PM and PM/MA (samples named PM-I and PM/MA-I respectively). The optimum pH values were found to be; 6.0, 5.0 and 5.5 for free invertase, PM-I and PM/MA-I respectively. The optimum temperature values were found to be 30 °C, 35 °C and 40 °C for free invertase, PM-I and PM/MA-I respectively. The Michaelis constant (Km) and maximum velocity of the enzymes (Vmax) were Km: 11,75 mM, Vmax: 1,95 μmol min−1 for free invertase, Km: 67,24 mM, Vmax: 60,6 μmol min−1 for PM-I and Km: 74,55 mM, Vmax: 18,12 μmol min−1 for PM/MA-I. PM/MA-I showed excellent thermal, operational and storage stability.