有机改性金红石型纳米TiO_2对聚乙醇酸抗光老化性能的研究

用硅烷偶联剂(A-172)对金红石型纳米TiO_2进行有机表面改性,采用红外光谱(FTIR)、透射电镜(TEM)对改性结果进行了表征。红外光谱表明,A-172以化学键的方式结合在纳米TiO_2表面;透射电镜照片表明,改性后的纳米TiO_2表现出较强疏水性。将改性后的纳米TiO_2作为紫外线屏蔽剂添加到聚乙醇酸(PGA)中,分别制备了TiO_2质量分数为0.5%、1%、1.5%和2%的复合材料,并采用氙灯气候试验机对纯PGA和PGA/纳米TiO_2复合材料进行加速老化对比试验。实验结果表明,改性后的纳米TiO_2在PGA材料中具有良好的分散性,使PGA具有更宽的紫外吸收范围和更强的紫外吸收峰,其中,当添加质量分数为1.5%时改性效果最佳,经过800h加速老化后,复合材料黄色指数只增加4.1,拉伸强度和缺口冲击强度保持率为56.34%和65.15%,分别比纯PGA提高了42.29%和37.21%,重均分子量和数均分子量保持率也分别提高了33.64%和33.99%。

Distribution characteristics of size-fractionated chlorophyll a, primary production and new production in the Laizhou Bay, July 1997

The distributions of chlorophyll a concentration, primary production and new productionwere observed in the Laizhou Bay of the Bohai Sea in both spring and neap tides during July 1997. The results showed that there were marked features of spatial zonation in the surveyed area, due to the differences between the geographic environment and the hydrological conditions. Chlorophyll a, primary production and new production were all higher in spring tides than that in neap tides in the Laizhou Bay. The highest values of these parameters were encountered in the central regions of the bay. At most stations, chlorophyll a concentrations at the bottom were higher than that at the surface. The results of size-fractionated chlorophyll a and primary production showed that contributions of nanocombining pi-coplankton ( <20 μm) to total chlorophyll a and primary production were dominant in phytoplankton community biomass and production of the Laizhou Bay. The environmental factors, primary production and new production in the Laizhou Bay are compared with other sea areas.

两类聚酯吸氧材料的制备及性能

制备了1,4-丁烯二醇/顺丁烯二酸酐和端羟基聚丁二烯(HTPB)/顺丁烯二酸酐酯化物吸氧剂,讨论了反应时间及醇酐比对吸氧剂酯化率的影响,并且将1,4-丁烯二醇/顺酐、HTPB/顺酐吸氧剂接枝共聚到PET中得到改性吸氧材料。考察了两种吸氧材料的物理性能和吸氧性能,以及影响吸氧性能的双键保留率,催化剂用量、醇酐比。实验表明,顺酐与1,4-丁烯二醇、HTPB反应的最佳酯化时间分别为2 h和3 h,含1,4-丁烯二醇/顺酐和HTPB/顺酐的吸氧材料最大数均分子量分别为3.66万和4.97万,最大双键保留率分别为77.4%和76.3%,最大催化剂用量为1.0 g/kg,含1,4-丁烯二醇/顺酐和HTPB/顺酐的吸氧材料24 h最大吸氧量为3.17 mL/g和10.04mL/g。

工业用地“退二进三”的义乌市发展路径探索

伴随城市产业结构调整以及大量企业自发进行“退二进三”等多重因素,义乌市城市产业发展空间不断重构。研究着眼于义乌市工业用地“退二进三”发展现状,厘清存在的现实困境,进而从政策、收益分配等方面为义乌市工业用地“退二进三”工作的高质量开展提供发展思路与可行路径。