Multiscale Chain Dynamic Study Of Plasticized Polyvinyl Butyral Under Service Conditions

Due to its excellent properties,polyvinyl butyral(PVB)is widely used in industry,especially in safety glass.However,the workability of pure P VB resin is poor,so most industrial PVB products require the addition of 25 wt%plasticizer(trisooxylate).The addition of plasticizer not only greatly improves the workability of PVB,but also has a significant impact on its dynamic structure,transforming PVB from a singlecomponent single-phase system to a multi-component polyphase system.The structure of PVB determines its properties,and the excellent performance of plasticized PVB comes from its complex dynamic structure.To achieve precise regulation of PVB properties,it is necessary to study the plasticize level chain dynamics of PVB molecular.In order to study the chain dynamics of a plasticized PVB system and its changes in the constrained state,this paper carried out a detailed study on the plasticized PVB system using various solid-state nuclear magnetic technologies.The aim was to obtain detailed chain dynamics information at the molecular level and to preliminarily establish the relationship between the structure and dynamics of the plasticized PVB system and its service performance.The specific research contents and results are as follows:(1)The relaxation dynamics information of the multi-scale heterogeneous chains of plasticized PVB was accurately obtained to reveal the selective plasticizing law of different spatial components of PVB.Deuterium nuclear magnetic resonance(2H NMR)and two-dimensional solid-state nuclear magnetic resonance(2D 1H-13C WISE NMR)showed that,except for the rigid zone formed by vinyl alcohol(VA)enrichment and the flexible zone formed by butyraldehyde(VB)enrichment,there were significant kinetic differences in each phase.The heterogeneous chain dynamics of plasticized PVB were quantitatively studied by the Torchia 13C T1 relaxation experiment.The rigid phase of plasticized PVB contained 78%VA units,19%VB units,and 3%plasticizers,while the flexible phase contained 14%VA units and 79%VB units and 7%plasticizers.The 14%VA units and physical entanglement in the flexible phase are the main reasons for the non-uniform chain dynamics.At the same time,based on the selective resolution of solid nuclear magnetic chemical sites,we found that the plasticizer had different plasticizing effects on VB units of different spatial configurations:the internal elimination structure made VB units more susceptible to plasticization.(2)Non-destructive testing was carried out to investigate the PVB chain relaxation dynamics in laminated glass,in order to reveal the effect of temperature on the nonuniform chain relaxation dynamics of plasticized PVB under real service conditions.The plasticized PVB and the chain dynamics information of the plasticizer under service conditions were systematically studied using a variety of low-field NMR related techniques.Additionally,the morphology information of the plasticized PVB at room temperature was obtained.The chain dynamics of plasticized PVB in the servicelimited state were studied using Magic-Sandwich Echo(MSE)nuclear magnetic technology,which revealed that the chain dynamics of plasticized PVB in laminated glass were slower.Based on Carr-Purcell-Meiboom-Gill(CPMG)nuclear magnetic technology,the chain dynamics of the plasticizer under service conditions were also studied.Finally,the phase morphology and size of the plasticized PVB at room temperature were accurately determined using spin diffusion nuclear magnetic technology.