Tan Chen, Tirri Teija, Wilen Carl-Eric
Center of Excellence for Functional Materials (FUNMAT), Faculty of Science and Engineering, Laboratory of Polymer Technology, Åbo Akademi University, Biskopsgatan 8, 20500 Turku, Finland.
Polymers (Basel). 2017 May 21;9(5):184. doi: 10.3390/polym9050184.
In this work, a number of chain extended moisture-curable urethane prepolymers were synthesized in order to develop isocyanate terminated urethane prepolymer formulations that would simultaneously display both high adhesive strength and low viscosity. Proton nuclear magnetic resonance spectroscopy (¹H-NMR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and Brookfield viscometry were utilized for characterizing the prepared urethane prepolymers. In addition, the adhesion strength of the cured prepolymers was determined by tensile shear strength test according to the DIN EN (Deutsches Institut für Normung, the German Institute for Standardization) 1465 standard. Especially, the role of different types of linear (butanediol, pentanediol) and branched chain extenders (dipropyleneglycol (di-PPG), tripropyleneglycol (tri-PPG) and the influence of their dosage on the degree of microphase separation between hard segments (HS) and soft segments (SS) in urethane prepolymers were studied. Furthermore, the benefits of utilizing either a one-step versus a two-step polymerization process were investigated. The results revealed that the extent of phase separation of different urethane prepolymers was dependent on the extent of hydrogen bonding interactions which was extensively studied by attenuated total reflectance infrared spectroscopy (ATR-FTIR). The incorporation of branched chain extenders (di-PPG and tri-PPG) did not result in notable phase separation between hard segments and soft segments, while linear chain extenders (pentanediol and butanediol) readily promoted phase separation. The degree of phase separation was particularly pronounced for butanediol, and when the linear chain extender ratio was higher than or equal to 0.74. Compared with a two-stage process, one-stage process produced more randomly distributed polymer chains with highly dispersed hard segments. Thus, urethane prepolymers exhibiting strong adhesive strength with simultaneously low viscosity were successfully developed by systematic adjustment of structural parameters.
在本研究中，合成了多种扩链的湿固化聚氨酯预聚物，以开发具有异氰酸酯端基的聚氨酯预聚物配方，使其同时具有高粘接强度和低粘度。利用质子核磁共振光谱（¹H-NMR）、尺寸排阻色谱（SEC）、差示扫描量热法（DSC）和布鲁克菲尔德粘度测定法对制备的聚氨酯预聚物进行表征。此外，根据DIN EN（德国标准化协会）1465标准，通过拉伸剪切强度试验测定固化预聚物的粘接强度。特别地，研究了不同类型的线性（丁二醇、戊二醇）和支化扩链剂（二丙二醇（di-PPG）、三丙二醇（tri-PPG））的作用及其用量对聚氨酯预聚物中硬段（HS）和软段（SS）之间微相分离程度的影响。此外，还研究了采用一步法与两步法聚合工艺的优势。结果表明，不同聚氨酯预聚物的相分离程度取决于氢键相互作用的程度，衰减全反射红外光谱（ATR-FTIR）对其进行了广泛研究。支化扩链剂（di-PPG和tri-PPG）的加入并未导致硬段和软段之间明显的相分离，而线性扩链剂（戊二醇和丁二醇）则容易促进相分离。丁二醇的相分离程度尤为明显，且当线性扩链剂比例高于或等于0.74时。与两步法相比，一步法产生的聚合物链分布更随机，硬段高度分散。因此，通过系统调整结构参数，成功开发出了具有高粘接强度和低粘度的聚氨酯预聚物。
