Researcher:
Eynur, Tuğba

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Master Student

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Tuğba

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Eynur

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Eynur, Tuğba

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2008 - 200932010 - 20111

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Researcher Of Publications: search.filters.isAuthorOfPublication.a7acaa2b-d14a-471a-ba6e-8636096ada22

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    POLY 598-contribution of soft segment entanglements on the tensile properties of silicone-urea copolymers with low hard segment contents
    (American Chemical Society (ACS), 2009) Wilkes, Garth; Department of Chemistry; N/A; Department of Chemistry; Department of Chemistry; Yılgör, Emel; Eynur, Tuğba; Bakan, Murat; Yılgör, İskender; Researcher; Master Student; Undergraduate Student; Faculty Member; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; 40527; N/A; N/A; 24181
    Novel, segmented thermoplastic silicone–urea (TPSU) copolymers based on rather high molecular weight aminopropyl terminated polydimethylsiloxane (PDMS) soft segments ( 10,800 and 31,500 g/mol), a cycloaliphatic diisocyanate (HMDI) and various diamine chain extenders were synthesized. Copolymers with very low urea hard segment contents of 1.43–14.4% by weight were prepared. In spite of very low hard segment contents, solution cast films showed very good microphase separation and displayed reasonable mechanical properties. Tensile strengths of TPSU copolymers showed a linear dependence on their urea hard segment contents, regardless of the structure of the diamine chain extender used. The modulus of silicone–urea copolymers is dependent on the urea concentration, but not on the extender type or PDMS molecular weight. When silicone–urea copolymers with identical urea hard segment contents were compared, copolymers based on PDMS-31,500 showed higher elongation at break values and ultimate tensile strengths than those based on PDMS-10,800. Since the critical entanglement molecular weight (Me) of PDMS is about 24,500 g/mol, these results suggest there is a significant contribution from soft segment chain entanglement effects in the PDMS-31,500 system regarding the tensile properties and failure mechanisms of the silicone–urea copolymers. 
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    Influence of soft segment molecular weight on the mechanical hysteresis and set behavior of silicone-urea copolymers with low hard segment contents
    (Elsevier Sci Ltd, 2011) Bilgin, Sevilay; Wilkes, Garth L.; Department of Chemistry; N/A; Department of Chemistry; Yılgör, İskender; Eynur, Tuğba; Yılgör, Emel; Faculty Member; Master Student; Researcher; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; 24181; N/A; N/A
    Effect of polydimethylsiloxane (PDMS) soft segment molecular weight (M-n = 3200, 10,800 and 31,500 g/mol) and urea hard segment content (2.0-11.4% by weight) on the hysteresis and permanent set behavior of segmented silicone-urea (TPSU) copolymers were investigated. In spite of very low hard segment contents, all copolymers formed self-supporting films and displayed good mechanical properties. When the mechanical hysteresis and set behavior of the silicone-urea copolymers with similar hard segment contents (around 7.5% by weight) but based on PDMS-3K, PDMS-11K and PDMS-32K were compared, it was very clear that as the PDMS molecular weight increased, hysteresis and instantaneous set values decreased significantly. Copolymers based on the same silicone soft segment (PDMS-11K or PDMS-32K) but with different hard segment contents showed a linear increase in hysteresis and a slight decrease in the instantaneous set as a function of hard segment content. Constant initial stress creep experiments also showed lower creep as the PDMS segment molecular weight increased for copolymers with similar urea contents. Since the critical entanglement molecular weight (M-e) of PDMS is stated to be 24,500 g/mol, our results tend to suggest important contribution of chain entanglements on the hysteresis and instantaneous set of these silicone-urea copolymers.
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    Contribution of soft segment entanglement on the tensile properties of silicone–urea copolymers with low hard segment contents
    (Elsevier Sci Ltd, 2009) Wilkes, Garth L.; Department of Chemistry; N/A; Department of Chemistry; Yılgör, İskender; Eynur, Tuğba; Yılgör, Emel; Faculty Member; Master Student; Researcher; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; 24181; N/A; N/A
    Novel, segmented thermoplastic silicone-urea (TPSU) copolymers based on rather high molecular weight aminopropyl terminated polydimethylsiloxane (PDMS) soft segments ( 10,800 and 31,500 g/mol), a cycloaliphatic diisocyanate (HMDI) and various diamine chain extenders were synthesized. Copolymers with very low urea hard segment contents of 1.43-14.4% by weight were prepared. In spite of very low hard segment contents, solution cast films showed very good microphase separation and displayed reasonable mechanical properties. Tensile strengths of TPSU copolymers showed a linear dependence on their urea hard segment contents, regardless of the structure of the diamine chain extender used. The modulus of silicone-urea copolymers is dependent on the urea concentration, but not on the extender type or PDMS molecular weight. When silicone-urea copolymers with identical urea hard segment contents were compared, copolymers based on PDMS-31,500 showed higher elongation at break values and ultimate tensile strengths than those based on PDMS-10,800. Since the critical entanglement molecular weight (M(e)) of PDMS is about 24,500 g/mol, these results suggest there is a significant contribution from soft segment chain entanglement effects in the PDMS-31,500 system regarding the tensile properties and failure mechanisms of the silicone-urea copolymers.
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    Poly 622-effect of reaction procedure on the degree of branching and polymer properties in highly branched polyureas obtained by A2+B3 polymerization
    (Amer Chemical Soc, 2008) N/A; N/A; Department of Chemistry; Department of Chemistry; Bilgin, Sevilay; Eynur, Tuğba; Yılgör, Emel; Yılgör, İskender; PhD Student; Master Student; Researcher; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; 24181
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