Ali Yorgancioglu

Comparison of different tanning agents on the stabilization of collagen via differential scanning calorimetry

Leather is composed of a three-dimensional weave of collagen fiber bundles. Collagen is a fibrous protein well organized in the formation of skin as building blocks. Leather production involves serial operations where the tanning plays the major role in improving the durability of leather products by stabilizing the triple helical structure of collagen matrix. In the leather-making industry, different tanning agents are used to produce different kind of leather goods. These tanning agents have varied efficiency on the stabilization of collagen. In this study, thermal stability of the leathers tanned with most commonly used tanning agents was evaluated by conventional shrinking test (CST) and differential scanning calorimetry (DSC) methods. The results showed that the thermal stability of leathers varied by the type of tanning agent which were in accordance with theoretical approaches. A distinct correlation was also observed between CST and DSC results of the tanned leathers.

A novel approach in leather finishing: Surface modification with flock fibers

In recent years, finishing has begun introducing an extraordinary touch and appearance to the surface of leathers by surface modification. Because some superficial anomalies cannot be recovered by conventional finishing procedures, those can only be drawn on by coating techniques. Coating aims at obtaining an alluring product, which must both recover the surface anomalies and be compatible with the leather characteristics. This study is for valorization of leathers with inferior quality, which contain surface defects, thereby being aimed at improvement of the surface characteristics. The product should have ease of use, as well as giving a fashionable look and touch to flocked fibrous surfaces, whether applied to synthetic leather types or Alcantara. For covered and patterned fibrous surfaces, the experimentations of different flock formulations with different binder types were executed, superficial characteristics were imaged with optoanalytical techniques and the fiber adhesion onto the surface was examined by abrasion tests. The research results showed that polyurethane binder had acceptable qualities for bags, footwear, garments and accessories and yielded superior binding characteristics compared to acrylic binder.

Farklı Proses Aşamasındaki Derilerin Diferansiyel Taramalı Kalorimetre ile Termal Davranışlarının Belirlenmesi ve Analiz Koşullarının Değerlendirilmesi

Calismada farkli proses asamasindaki derilerin termal davranislari cesitli kosullar altinda diferansiyel taramali kalorimetre (DSC) ile incelenmis ve derilerin hidrotermal stabilitesinin DSC ile tespit edilebilirligi arastirilmistir. Bu amacla oncelikle ham deri, pikle, tabaklanmis ve mamul haldeki derilerin hidrotermal stabilitesi, buzulme sicakligi standart testi ile analiz edilerek belirlenmistir. Ardindan ayni deri ornekleri farkli kosullandirma parametreleri kullanilarak kuru ve yas formda DSC metodu ile analiz edilmistir. Elde edilen veriler; 24 saat kosullandirilmis ve basinca dayanikli kaplar icerisinde, sulu ortamda, 25-150 oC araliginda analiz edilen deri orneklerinin en iyi sonuclari verdigini gostermistir. Ayni zamanda mevcut kosullardaki DSC termogramlarindan elde edilen verilerin, derilerin standart metot ile elde edilen buzulme sicakligi (Ts) degerleri ile paralellik gosterdigi tespit edilmistir.

Synthesis and characterization of functional acrylic copolymers via RAFT mini-emulsion polymerization

Copolymers bearing reactive functional groups with controlled molecular weights are of importance since they can be used in many fields such as composites, coatings, membranes, catalysis, biology, optoelectronics, pharmaceuticals, etc. In the present study low molecular weight copolymers based on butyl acrylate (BA) and methyl methacrylate (MMA) in combination with reactive functional monomers of vinyl trietoxysilane (VTES), 3-trimetoxysilylpropyl methacrylate (TMSPMA) and glycidyl methacrylate (GMA) were synthesized via RAFT mini-emulsion technique using 2-cyano 2-propyldodecyldithiocarbonate as CTA agent. The results showed that the average molecular weights of copolymers were close to the theoretical values. On the other hand, PDI values were found to be higher than conventional RAFT polymers. The particle sizes of the latexes were small with very homogenous distributions and good stability. FTIR, H-NMR and TGA results verified the success of copolymer syntheses.

Ozonation as an Environmentally Friendly Method to Decolorize the Leather Products

ABSTRACT In this study, ozonation as an environmentally friendly bleaching method was studied for decolorization of leather products. The effect of ozonation time (3, 5, 10, 15 and 30 min) and water pick-up value (WPV) (0%, 20%, 40%, 60%, 80% and 100%) were investigated on decolorization effect. For this aim, the color measurement and tensile strength tests were performed, and also structural changes were determined by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) after ozonation process. The results of color measurements showed that 30 min for ozonation and 60% WPV were optimum parameters to obtain maximum decolorization effect. SEM images of the ozonated leathers showed some deformations on the collagen fibers and resulted with the slightly decreases in tensile strength of the products. On the other hand, decreases in the tensile strength values were not statistically important levels.