Su Junfeng, Wang Yingyuan, Yang Peng, Han Shan, Han Ningxu, Li Wei
Tianjin Key Laboratory of Advanced Fibers and Energy Storage, Tianjin Polytechnic University, Tianjin 300387, China.
Department of Polymer Materials, School of Material Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China.
Materials (Basel). 2016 Nov 17;9(11):932. doi: 10.3390/ma9110932.
Microencapsulated rejuvenator has been attracted much attention for self-healing bitumen. The diffusion coefficient is one of the key parameters to estimate the feasibility of rejuvenator to age bitumen. The objective of this research was to evaluate diffusion behaviors of microencapsulated rejuvenator in aged bitumen by a FTIR-ATR method. Various microcapsule samples were mixed in bitumen to form thin films. The core material of microcapsules used as rejuvenator was diphenylsilane (DPS), its fairly specific absorption band at 843 cm was selected as a marker band to calculate the diffusion coefficient (D). The microstructure parameters, including contents, mean size and mean shell thickness of microcapsules, were considered to understand the diffusion behaviors under different temperatures (20, 30, 40 and 50 °C) in bitumen. The results showed that a larger mean size of microcapsules did not greatly affect the D values under the same temperature. In contrast, a higher mean shell thickness decreased the D values because of the decrement of damage probability of microcapsules under the same content. With the same microcapsule sample in bitumen, the D values presented a trend of linear increase when the content of microcapsules was increased. All these results indicated that the microstructure affected the diffusion behaviors based on the concentration of released rejuvenator. A preliminary model of diffusion behaviors of microencapsulated rejuvenator in bitumen was given based on the Arrhenius equation considering the microstructure of microcapsules, the amount of released rejuvenator and the age degree of bitumen. This model may be a guide to the construction and application of self-healing bitumen using microcapsules.
微胶囊化再生剂因可实现沥青的自修复而备受关注。扩散系数是评估再生剂对老化沥青作用可行性的关键参数之一。本研究的目的是通过傅里叶变换红外衰减全反射（FTIR-ATR）方法评估微胶囊化再生剂在老化沥青中的扩散行为。将各种微胶囊样品与沥青混合制成薄膜。用作再生剂的微胶囊核心材料为二苯基硅烷（DPS），选择其在843 cm处相当独特的吸收带作为标记带以计算扩散系数（D）。考虑微胶囊的含量、平均粒径和平均壳厚度等微观结构参数，以了解在不同温度（20、30、40和50℃）下在沥青中的扩散行为。结果表明，在相同温度下，较大的微胶囊平均粒径对D值影响不大。相反，较高的平均壳厚度会降低D值，这是因为在相同含量下微胶囊的破损概率降低。对于沥青中相同的微胶囊样品，当微胶囊含量增加时，D值呈现线性增加趋势。所有这些结果表明，微观结构基于释放的再生剂浓度影响扩散行为。基于阿伦尼乌斯方程，考虑微胶囊的微观结构、释放的再生剂数量和沥青的老化程度，给出了微胶囊化再生剂在沥青中扩散行为的初步模型。该模型可为使用微胶囊的自修复沥青的构建和应用提供指导。
