Surface modification of zinc oxide and its application in polypropylene with excellent fire performance and ultra-violet resistance.

Despite the advantages of easy moulding and excellent mechanical properties, there are still some shortcomings with polypropylene (PP) such as high flammability and poor ultra-violet (UV) resistance. In this work, modified zinc oxide (mZnO) was prepared by reacting zinc oxide nanoparticles (ZnO) with polysiloxanes, and the effect of mZnO on the effectiveness of intumescent flame-retardant and on the UV aging resistance of polypropylene were investigated. By introducing 16 wt% (intumescent flame-retardant /mZnO) and 0.3 wt% maleic anhydride-grafted PP (MAH-g-PP), the limiting oxygen index increased to 32.7 %, and passed UL-94V-0 rating. In comparison to the controls, the peak heat release rate and the peak smoke release rate were 88.5 % and 80 % lower, respectively. In addition, PP samples showed improved mechanical properties, with a 5 % increase in tensile properties compared to the pure PP sample. After 100 h of UV irradiation, the surface of the samples was relatively flat and smooth, and the carbonyl index decreased from 81.1 of neat PP to 26.7. PP composites with 100 h aging treatment still had excellent flame retardancy and mechanical properties. The results showed that mZnO was effective in improving the flame retardancy, mechanical properties and light aging tolerance of PP. This study provides a novel approach to fabricate long-life flame-retardant PP composites with low additive content.

The Effect of Off-Pump Coronary Artery Bypass Grafting in Patients on Aspirin Therapy until Surgery Day.

Coronary artery bypass grafting (CABG) is widely used to treat coronary artery disease, and intraoperative and postoperative bleeding is one of the major factors affecting the efficacy and mortality of CABG. To overcome the adverse effects of extracorporeal circulation (CPB), nonextracorporeal coronary artery bypass grafting (OPCABG) has become the main modality of CABG but is still prone to thromboembolic events. Whether antiplatelet agents should be clinically applied before CABG, especially OPCABG, remains controversial. Aspirin is currently the most important perioperative oral antiplatelet agent for coronary artery bypass graft surgery. In this study, we evaluated the effect of continuing aspirin therapy before OPCABG and observed perioperative performance and physiological indicators to find evidence for continuing aspirin therapy before surgery in China. The study showed that preoperative aspirin application had a positive effect on enhancing early postoperative platelet inhibition without increasing the incidence of adverse effects such as cardiovascular events. This provides an important clinical reference for whether antiplatelet agents should be applied before CABG, especially OPCABG.