Hasan Özgünay

Bitkisel Tabaklanmış Saraciyelik Derilerde Yağlayıcı Polimerlerin Kullanılabilirliği

The demand on the production of leathers with natural look and touch has shown an increase in recent years. Therefore, the usage of vegetable tannins in leather production has also increased accordingly. However, the leathers tanned or heavily retanned with vegetable tannins show high hydrophilic character. Besides, a light finishing is usually preferred to be applied on leathers in order to obtain the natural look and touch which hinders the resistance of leathers to external factors (water, humidity, light etc.). Lubricating acrylic syntans are well-known auxiliaries in leather industry with their fatliquoring and filling effect in retannage as well as their water-repellent properties. In this research, different percentages of a lubricating acrylic polymer was used in retanning process of vegetable tanned leathers and its effect on water absorption and vapour permeability properties of the leathers were investigated. The results showed that the water absorption properties of the leathers processed with lubricating acrylic syntans were lower than the blank samples. The increase in syntan quantities resulted in decreased water absorption values of the leathers. The water vapour permeability of the samples was also found to be increased with the offer of lubricating acrylic syntans.

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.

Usage of Starch in Leather Making

In recent years, various industries begin to head towards cleaner production due to increasingly restrictive regulations. Therefore, production from natural and renewable sources has become more important. Starch is a remarkable raw material because it is abundant, inexpensive and biodegradable natural polymer. The use of natural starch has remained limited, to be usually for food purposes, until recent decades. However, the usage of starch has increased significantly over the last few decades; via modification some of the properties of the starch and it has found wide range of applications in many industries such as plastics, agriculture, pharmaceutics, adhesive, textile, paper and food. In recent years, several studies have taken part in literature on possible use of modified starches also in leather industry – especially in tanning and retanning processes to ensure cleaner production. And it seems that starch products that modified with various methods in accordance their field of use will find more interest and use in leather making. For this reason in the present paper it is aimed to make an overview on the structure of starch as a renewable and natural resource and its potential applications in leather making.