苯乙烯-丙烯腈共聚物对聚氯乙烯加工性能及抗紫外老化行为的影响

通过苯乙烯-丙烯腈共聚物(SAN)共混改性聚氯乙烯(PVC),制备了PVC/SAN共混材料。利用转矩流变、色差分析、表面形貌分析、元素分析等方法研究了PVC/SAN共混材料的加工性能和抗紫外老化性能。结果表明,SAN的加入可促进PVC的塑化,改善其加工性能;同时SAN具有较强的紫外光吸收能力,能抑制PVC脱氯化氢,显著降低紫外老化时PVC颜色变暗、变红和变黄的速率;此外SAN的引入使PVC/SAN共混材料表面平整、致密,可以有效阻止紫外光和氧气深入到材料内部造成严重的破坏,从而显著提高PVC的抗紫外老化性能。     

MOF基的光解水制氢催化剂研究进展

随着能源枯竭和环境污染问题日益严重,人们不得不将目光转向更加清洁环保的氢能源。光解水制氢技术是一种获取氢能源经济且清洁的理想方式,通过光催化手段将太阳能转化为化学能也是一种很有前景的技术手段。然而如何选取高效、经济的光催化剂是制氢最关键的环节。金属-有机框架(Metal-organic frameworks, MOFs)由于比表面积大、孔尺寸可调节、结构易于修饰及活性位点丰富等特点,使其成为光解水制氢理想的光催化剂候选材料。国内外学者就MOFs光解水制氢开展了大量的研究,并且取得了丰硕的成果。本论文综述了MOF基材料作为催化剂在光解水制氢领域的研究进展,总结了MOFs作为催化剂的优点和局限性,并对MOFs及其相关材料在光催化水解制氢领域的发展前景提出展望,以期对未来研究提供参考。     

Nanocrystalline Cellulose– and Graphene Oxide–reinforced Polyvinyl Alcohol Films: Synthesis,Characterization, and Origin of Beneficial Co-filling Effects

Applied Composite Materials - The increased demand for durable yet flexible and stretchable membranes has inspired the investigation of polymer nanocomposite films, such as those based on polyvinyl...     

柑桔精油中d-苧烯的转化研究

本课题以冷榨、高速离心分离、己烷低温浓缩的方法从柑桔皮渣中成功地提取了柑桔精油 ,产率达 8.81克 /千克柑桔皮。并探讨了以粉碎———绝氧陈化———紫外线激活的方法 ,让柑桔皮中的自体酵素发酵催化 ,将柑桔精油中的d-烯转化成含氧萜烯类 ,降低了精油中碳氢萜类 ,相对提高了含氧萜烯类含量 ,从而明显地提高了柑桔精油的产量和香气品质。     

超声波降解对丙烯基塑性体性能的影响

利用自制的超声波辐照装置,对一种新型丙烯基塑性体(简称DP)熔体进行超声波降解,研究了超声波降解对DP结晶性能、力学性能和流变性能的影响。与等规聚丙烯相比,DP的结晶性能差,屈服拉伸强度低,但断裂伸长率明显提高。在超声波辐照下,DP熔体发生力化学降解,无规断链主要集中在高相对分子质量部分,相对分子质量分布变宽,大分子结构中出现羰基。超声波降解产生的低相对分子质量链段活动能力和极性增强,可在较高温度下结晶。另外,超声波降解也会导致DP的屈服拉伸强度下降,表观黏度降低。     

Ultrasonic improvement of rheological behavior of polystyrene

The effects of ultrasonic oscillation on die pressure, productivity of extrusion, melt viscosity, and melt oscillating flow of polystyrene (PS) as well as their mechanism were studied in a special ultrasonic oscillations extrusion system developed in our lab. The experimental results show that in the presence of ultrasonic oscillations, the PS melt oscillating flow or surface distortion of PS extrudate is inhibited or disappears. The surface appearance of PS extrudate gets greatly improved. The die pressure, melt viscosity, flow activation energy, and consistency efficiency of PS decreased and the productivity of PS extrudate increased in the presence of ultrasonic oscillation. The shear sensitivity of PS melt viscosity is decreased because of the increase of its power law index in the presence of ultrasonic oscillation. Introduction of ultrasonic oscillation into PS melt can greatly improve the processibility of PS. Their possible mechanism is also proposed in this article. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2451–2460, 2002     

Effect of ultrasonic oscillations on weld line strength of PS,PMMA, and their blends

The effect of ultrasonic oscillations on the weld line strength of amorphous polystyrene (PS), polymethyl methacrylate (PMMA), and PS/PMMA (20/80, 50/50, 80/20) blends at various temperatures was investigated. By facilitating the molecular diffusion across the weld line, the introduction of ultrasonic oscillations could evidently improve the weld line strength of PS, PMMA, and their blends. The different effects on the weld line strength of PS/PMMA (20/80, 50/50, 80/20) blends were investigated. The ultrasonic oscillations could greatly increase the weld line strength of PS/PMMA (80/20) by ～ 70%, but was less efficient to PS/PMMA (50/50, 20/80) blends, due to the great difference of weld line morphologies of these blends. The dispersed phase of PS/PMMA (80/20) in the weld line was spherical while two different morphologies in the weld line of PS/PMMA (50/50) were observed. And the stripe‐like morphology of PS perpendicular to the flow direction in the weld line of PS/PMMA (20/80) is responsible for the little effect of ultrasonic oscillations. The fractured surfaces of PS, PMMA, and PS/PMMA (80/20) with weld line became much rougher due to the introduction of ultrasonic oscillations. The morphology study of PS/PMMA (80/20) showed that the spherical dispersed phase of PS/PMMA at the skin turned smaller under ultrasonic oscillations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2990–2997, 2006     

Mechanically Strong and Ductile Polypropylene/Poly(ethylene-co-octene) Blends Prepared Through Multistretched Extrusion: Morphological Evolution,Toughening, and Reinforcing Mechanism

In this paper, polypropylene matrix with densely stacked shish-kebab crystalline structure and dispersed poly(ethylene-co-octene) phase with micro/nanofibers were formed simultaneously in polypropylene/poly(ethylene-co-octene) blends through multistretched extrusion. The as-obtained highly oriented and densely stacked shish-kebab crystalline structure can provide blends with greatly enhanced tensile yield strength. The as-formed poly(ethylene-co-octene) micro/nanofibers can toughen polypropylene matrix effectively through deflecting the crack, which is different from the toughening mechanism in polypropylene/poly(ethylene-co-octene) blends filled with spherical poly(ethylene-co-octene) particles. Compared with that of conventional polypropylene/poly(ethylene-co-octene) blends, the tensile yield strength of multistretched blends increased approximately 300%, while the notched impact strength declined slightly.     

“山竹”台风对广州市滨江园林树木的 影响——以临江大道及带状公园为例

临江大道及其带状公园是广州市沿江道路绿化和滨江绿地，是该城市园林景观的重要组成部分。由于2018年第22号“山竹”台风的影响，临江大道园林树木受损严重。基于临江大道行道树安全检测评估，综合“山竹”台风灾后临江大道及带状公园的树木受损情况进行了分析，结果发现不同的树种其抗风性差异较大；对6种重要的不同树种倒伏进行Logistic回归分析，发现相关的种树之间的倒伏差异极显著。从树木安全评估角度去探讨滨江园林树木受损、树种选择与种植情况，为华南地区城市滨江园林树木养护和修复提供参考和借鉴。     

广州南沙地区整体城市设计和重要节点城市设计

南沙地区整体城市设计和重要节点城市设计既尊重《南沙地区发展规划》“自上而下”的要求，又在分析南沙地区资源潜力的前提下，“自下而上”对相关规划提出了基于空间形态的调整意见，尤其是“创建南沙中心城”和“塑造宜人尺度滨海城市”的构思对南沙的未来发展有重要意义。