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    The changes on some chemical properties of artificially aged garment leathers [Modificarile unor proprietati chimice ale pieilor pentru confectii îmbatrânite artificial]
    (2010) Isik N.O.; Karavana H.A.
    Aging is a process of reversible and/or irreversible structural change of material, which depends on structural characteristics and environmental factors. Heat, humidity, UV radiation, chemical effects and their causes in visible and invisible damages which lead to structural deteriorations and decreases in fastness are some factors that aging in leathers and leather products depends on. In this research, chromium (VI) and formaldehyde contents which resulted after artificial aging procedure in chrome, vegetable and semi-vegetable tanned garment leathers, caused by the chemical decomposition, have been investigated. Temperature, temperature/humidity and temperature/UV radiation have been chosen as aging factors. According to the findings, in finished garment leather samples, chromium (VI) and formaldehyde contents were higher than acceptable limits and aging conditions effective on level of increase have been investigated through ISO 17228 (2005) artificial aging procedure depending on temperature, humidity and UV radiation.
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    Determination of abrasion resistance of automobile upholstery leathers [Determinarea rezistentei la abraziune a pieilor pentru tapiteria automobilelor]
    (2011) Isik N.O.; Cireli I.; Koizhaiganova M.
    In recent years, as a result of increasing customer demands such as natural appearance and handle, comfort, luxury and prestige, parallel to technologic improvements in automotive industry, a new trend for using leather in coating and upholstering the interior elements of autos has raised. Leathers and leather goods used in automotive sector are in the leather article group with high performance expectations. However; there has been no consensus about criteria for performance characteristics of automobile upholstery leathers, thereby, each car manufacturer wants to buy leathers according to their own requirements. It is inevitable phenomena that in progressing time material aging would cause lacking in performance and at the same time the diverse effects (but in most cases negatively) in properties and the setbacks in comfort. In particular, proceeding possible chemical decomposition depending on interior conditions of a car is of importance enabling both the lacking of material properties and decreasing the comfort of driving as well as health risks of drivers. In this study, one of the expected performance characteristics of automobile upholstery leathers-the abrasion resistance was determined by Taber Abraser.
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    Effects of Chromium VI Stress on Photosynthesis, Chlorophyll Integrity, Cell Viability, and Proline Accumulation in Lichen Ramalina farinacea1
    (2010) Unal D.; Isik N.O.; Sukatar A.
    In order to contribute to understanding of the response to metal stress, Ramalina farinacea (L.) Ach. was treated with different concentrations of chromium (VI) (5, 15, and 30 mM of K2CrO4) for 1, 3, and 24 h, and alterations in the photosystem II photosynthetic quantum yield, pigment content, integrity of chlorophyll, cell viability, and proline accumulation were investigated. Significant alterations of the photosynthetic quantum yield (Fv/Fm) ratio were observed in response to the increase in chromium concentration. The Fv/Fm ratio decreased in R. farinacea following 24-h treatment with 30 mM Cr6+ solution. In present study, in both control and other plant groups treated with 5 mM Cr6+, the Chl a/b ratio was approximately within the range of 2.0-3.5. However, this ratio significantly decreased for the samples treated with 15 (exposure period of 24 h) and 30 mM; (exposure periods of 3 and 24 h) Cr6+. We also showed that cell viability of samples treated with 15 and 30 mM Cr6+ significantly decreased. Accumulation of metal resulted in proline accumulation in R. farinacea thalli; however, when photodestructive effects on photosystem II occurred, proline intracellular concentration declined. On the basis of these results, we suggest that proline accumulation might not be the stress marker during heavy metal stress. © 2010 Pleiades Publishing, Ltd.
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    The effects of different tanning agents on some properties of medical sheepskins
    (2010) Bitlisli B.O.; Karavana H.A.; Basaran B.; Isik N.O.
    In this research washing and perspiration fastnesses of medical sheepskins produced with different combinations of aluminium triformiade, basic chromium sulphate, polyaldehyde, synthetic and vegetal tanning agents were investigated. It was found that differences of the softness values between the process recipes were statistically significant (P<0.05). It was determined that softness characteristics of leathers after washing and perspiration treatment had improved depending on usage rate of chromium and polyaldehyde. It was also detected that lighter leathers could produced by using more chromium and area loss of leathers after washing and perspiration treatment was minimum level by increasing usage rate of polyaldehyde. Differences of the colour coordinate values between the procedures were found statistically significant (P<0.05). It was determined that colour characteristics of leathers changed depending on tanning agents and leathers had been lighter colour when the ratio of aluminium increases.
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    The effects of different tanning agents on some properties of medical sheepskins [Efectele diverşilor agenti de tabacire asupra unor proprietati ale pieilor de ovine pentru uz medical]
    (2010) Bitlisli B.O.; Karavana H.A.; Basaran B.; Isik N.O.
    In this research washing and perspiration fastnesses of medical sheepskins produced with different combinations of aluminium triformate, basic chromium sulphate, polyaldehyde, synthetic and vegetal tanning agents were investigated. It was found that differences of the softness values between the process recipes were statistically significant (P<0.05). It was determined that softness characteristics of leathers after washing and perspiration treatment had improved depending on usage rate of chromium and polyaldehyde. It was also detected that lighter leathers could be produced by using more chromium and area loss of leathers after washing and perspiration treatment was minimum level by increasing usage rate of polyaldehyde. Differences of the colour coordinate values between the procedures were found statistically significant (P<0.05). It was determined that colour characteristics of leathers changed depending on tanning agents and leathers are lighter when the ratio of aluminium increases.