Hangyan Ji,Yu Wang,Yuxiang Bai,Xiaoxiao Li,Lizhong Qiu,Zhengyu Jin
The production of γ-cyclodextrin usually includes the utilization of organic complexants. However, the non-complexant production of γ-cyclodextrin is always being explored due to the defects of organic complexants. However, in non-complexant production, the separation of γ-cyclodextrin from α- and β-cyclodextrin is still a challenge. Here, the selective hydrolysis ability of a cyclodextrinase designated PpCD (cyclodextrinase from Palaeococcus pacificus ) on α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin was proved. The k cat /K m values of PpCD for α-cyclodextrin and β-cyclodextrin were roughly 12-fold and 5-fold higher than that of γ-cyclodextrin. It was proved that PpCD had selective hydrolysis ability and its γ-cyclodextrin purification performance was apparent on various simulated cyclodextrin mixtures with reported proportions derived from different CGTases. Besides, the hydrolysis temperature was optimized and it could be seen that 85°C was appropriate for the production of γ-cyclodextrin. In addition, the production of γ-cyclodextrin was achieved by using PpCD in the γ-CGTase reaction products.
Trimethylolpropane (TMP) as a cross-linker and KH-602, a siloxane coupling agent, were precisely grafted onto the branched chains of PPCD waterborne polyurethanes using molecular structure design. A series of waterborne polyurethanes (WPUs) were synthesized by selecting polycarbon dioxide-based polyol (PPCD) and isocyanate (IPDI) as soft and hard segments. The effects of changes in the content of TMP and KH-602 on the performance of the WPU coatings were investigated by analyzing the adhesion, mechanical, and thermal properties. The results showed that the thermal stability of the polyurethane coatings was significantly improved, and the decomposition temperature increased from 190.3 °C to 274 °C at a weight loss of 5 %. In addition, the water contact angle increased from 63.4° to 75.5° with the increase in polysiloxane content in the coating. This increase in hydrophobicity was accompanied by a significant increase in bond strength, with peel strength increasing 2.44-fold from 1.19 to 2.91 N/mm. This innovative formulation has excellent heat resistance and adhesion properties and therefore has potential for a wide range of applications in waterborne polyurethane coatings.
Wang Chaozhi,Li Hualin,Huang Zhenhong,Ding Zhu,He Zonglin,Liu Baohua,Ai Jiaoyan,Song Lina
The subject of this study was the application of a novel CO 2 -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 CO 2 -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 °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 °C, and the glass transition temperature was 79.3 °C. All the polyurethane adhesives obtained performed good heat and water resistance.
危险品化学品经营许可证（带存储）