Copolymerization of isoprene with polar vinyl monomers: Reactivity ratios, characterization and thermal properties

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• 作者：David Contreras-Ló ; pez^a ; Enrique Saldí ; var-Guerra^a ; ^{esaldivar@ciqa.mx} ; Gabriel Luna-Bá ; rcenas^b
• 关键词：Isoprene ; Maleic anhydride ; Glycidyl methacrylate ; Polar monomer ; Reactivity ratios ; Copolymer
• 刊名：European Polymer Journal
• 出版年：2013
• 出版时间：July, 2013
• 年：2013
• 卷：49
• 期：7
• 页码：1760-1772
• 全文大小：1670 K

文摘

Reactivity ratios for the copolymers isoprene (IP)-co-maleic anhydride (MAH) and isoprene (IP)-co-glycidyl methacrylate (GMA) are reported. Copolymers were prepared by free radical polymerization using benzoyl peroxide (BPO) as initiator at 70 ¡ãC. These copolymers were characterized by FTIR and ¹H NMR. The monomer compositions in the copolymer were determined by ¹H NMR and the reactivity ratios (r_i) were calculated applying diverse linear methods, namely Finemann-Ross (FR), Inverted Finemann-Ross (IFR), Kelen-T¨¹d?s (KT), Extended Kelen-T¨¹d?s (EKT) and the nonlinear method of Tidwell-Mortimer (TM). By using the latter procedure, the values of the reactivity ratios were estimated as 0.119 and 0.248 for the system IP (1) and GMA (2) respectively; whereas for the IP and MAH system were 0.057 and 0.078 respectively. These values suggest the formation of nearly-alternating copolymers in both systems. Molecular weights were determined by gel permeation chromatography (GPC). Glass transition temperatures (T_g) of the copolymers were obtained by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Good agreement is obtained between experimental T_g values and the model of Couchman. T_g increases when the concentration of polar monomer in the copolymer increases.