Novel CO2-based low-molecular weight poly (propylene carbonate) diol (PPCD) for two-component polyurethane adhesive

The subject of this study was the application of a novel CO2-based low-molecular weight poly (propylene carbonate) diol (PPCD) in the field of adhesive. Two-component polyurethane adhesive (PPCD-PU) was prepared with PPCD and polymethylene polyphenyl polyisocyanate (PAPI) as raw materials, propylene carbonate diol (PCD-EDA) as extender. The effects of the molecular weight, carbonate linkage content of PPCD and content of PCD-EDA on the properties of PPCD-PU were also investigated. The results showed that the novel CO2-based low-molecular weight poly (propylene carbonate) diol had higher carbonate linkage content (35%). The PPCD-PU synthesized by the PPCD had good adhesion performance, and the lap shear strength reached to 15 MPa. The addition of PCD-EDA not only improved the bonding properties of the adhesive, but also made PPCD-PU adhesive achieved higher lap shear strength in a shorter curing time. When the amount of PCD-EDA was 20 wt.%, the lap shear strength increased to 17 MPa, and the lap shear strength increased significantly from 3.7 to 10.6 MPa after curing at 80 degrees C for 30 min. Water absorption rate of PPCD-PU film was about 1.7%, and the lap shear strength was almost unchanged after 24 h of immersion in water. The temperature of 5%-weight loss of PPCD-PU was 284 degrees C, and the glass transition temperature was 79.3 degrees C. All the polyurethane adhesives obtained performed good heat and water resistance.