Calucci Lucia, Pizzanelli Silvia, Mandoli Alessandro, Birczyński Artur, Lalowicz Zdzisław T, De Monte Cristina, Ricci Lucia, Bronco Simona
Istituto di Chimica dei Composti OrganoMetallici, Consiglio Nazionale delle Ricerche-CNR, Via G. Moruzzi 1, 56124 Pisa, Italy.
Centro per l'Integrazione della Strumentazione Scientifica dell'Università di Pisa (CISUP), Lungarno Pacinotti 43/44, 56126 Pisa, Italy.
Polymers (Basel). 2021 Aug 11;13(16):2686. doi: 10.3390/polym13162686.
Polyvinyl butyral (PVB) is an amorphous polymer employed in many technological applications. In order to highlight the relationships between macroscopic properties and dynamics at a microscopic level, motions of the main-chain and of the propyl side-chains were investigated between - 288 °C and + 55 °C, with indicating the glass transition temperature. To this aim, a combination of solid state Nuclear Magnetic Resonance (NMR) methods was applied to two purposely synthesized PVB isotopomers: one fully protonated and the other perdeuterated on the side-chains. H time domain NMR and H field cycling NMR relaxometry experiments, performed across and above , revealed that the dynamics of the main-chain corresponds to the α-relaxation associated to the glass transition, which was previously characterized by dielectric spectroscopy. A faster secondary relaxation was observed for the first time and ascribed to side-chains. The geometry and rate of motions of the different groups in the side-chains were characterized below by H NMR spectroscopy.
聚乙烯醇缩丁醛（PVB）是一种应用于许多技术领域的无定形聚合物。为了突出宏观性质与微观层面动力学之间的关系，研究了在-288°C至+55°C之间主链和丙基侧链的运动情况，其中Tg表示玻璃化转变温度。为此，将固态核磁共振（NMR）方法组合应用于两种特意合成的PVB同位素异构体：一种是完全质子化的，另一种是侧链全氘代的。在Tg上下进行的1H时域NMR和1H场循环NMR弛豫测量实验表明，主链的动力学对应于与玻璃化转变相关的α弛豫，这一点先前已通过介电谱进行了表征。首次观察到更快的次级弛豫，并将其归因于侧链。通过1H NMR光谱对低于Tg温度下侧链中不同基团的运动几何结构和速率进行了表征。
