M.S. Theses
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Browsing M.S. Theses by Subject "Adhesives."
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Item Modification of biopolyelectrolytes for bioadhesive applications(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2012., 2012.) Çömert, Fatih.; Kayıtmazer, A. Başak.Biomimetic research on the development of bioadhesives mimicing the adhesive proteins secreted by blue mussels have become very popular in the recent years. The most important feature of the adhesive proteins is that they can stick to any type of surfaces in dry or wet environment. Furthermore, these proteins can preserve their bulk adhesive properties over time in the presence of water in which most adhesives fail to manage. 3,4-dihydroxy-L-phenylalanine (L-DOPA) is an aminoacid found in the adhesive proteins of marine mussels. L-DOPA is the most abundant molecule at the interface of adhesion and the catechol group of DOPA is believed to be the key funtional group in mussel attachment. There have been numerous studies on catechol functionalization of polymers to mimic the adhesive feature of mussel adhesive proteins. However, the advantage of our method is that the polymers were modified by forming strong amide bond, which is more stable against hydrolysis, using catechol containing molecules. In this study, the catechol modification of two biopolyelectrolytes; hyaluronic acid (HA) and chitosan (CHI) with L-DOPA-Methyl ester and 3,4-dihydroxyhydrocinnamic acid (DOHA), respectively, was achieved via carbodiimization of active esters. The modification was confirmed with 1H-NMR analysis, UV spectroscopy and gelation with periodate. The degrees of modification (% by mole) of polymers were calculated by UV-Vis spectroscopy. Potentiometric titrations were also carried out to investigate the effect of modification on pKa of biopolymers. Higher pKa values of modified polymers than that of unmodified ones also confirmed the modification.Item Synthesis of novel pressure sensitive adhesives for label applications(Thesis (M.S.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2012., 2012.) Eren, Şükrü.; Acar, Ali Ersin.In the label adhesives industry, the accepted pressure sensitive adhesives (PSA) are acrylic based water dispersions. These acrylic polymer emulsions have excellent ultraviolet (UV) and chemical resistance. However, their adhesion values alone are not enough for market requirements. Due to this, producers compound these acrylic polymers with tackifier resin dispersions especially for paper labels. In this study, it is aimed to produce label adhesive using a new approach. The goal is to develop a new one-pot polymerization process for the filmic label market. In one pot system, the purpose is to synthesize ready dispersions for label adhesives by adding the tackifier resin during the polymerization to the acrylic monomer. By doing so, it is hoped to eliminate high cost dispersing machines and high level of surfactants used in the dispersion process of the tackifier resin. Elimination of the surfactant coming from the tackifier resin dispersion is a potential solution for the whitening problem of the filmic labels. Another advantage is to save energy from the high cost dispersing process.