Fabrication and Properties of Microencapsulated n-octadecane and Paraffin

Microencapsulated n-alkanes as energy- storage materials have promising application prospects. The ndcrocapsules containing 100 - 50 wt% of n - octadecane, 0 -20 wt% of paraffin and 0 - 30 wt% of cyclohexane were synthesized by in-situ polymerization using melamine- formaldehyde polymer as shell. Cyclohexane was removed after heat-treated the microcapsules at 100℃. The morphologies, cell parameters, phase change properties, thermal stable temperatures of these microcapsules were examined. The diameters of these microcapsules are lower than 5 μm. The effect of paraffin in the microcapsules on the cell parameters of n-octadecane is negligible. The paraff＇m is effectively used as a nucleating agent to decrease the degree of supercooling. The melting enthalpy is decreased from 132 J/g to 111 J/g due to the increase of the cyclohexane contents. The thermal stable temperature is enhanced 6 - 16℃ after heat-treated the microcapsules at 160℃ for 30 min.     

Isothermal Crystallization Behavior of Biodegradable Poly （butylene succinate-co-terephthalate） （PBST） Copolyesters at High Undercoolings

Poly （butylene succinatc-co-terephthalate） （PBST） copolycsters were prepared by polycondensation. The crystallization behavior of the as-prepared copolyesters was investigated by depolarized light intensity （DLI） at high undercoolings. According to Avrami equation, the exponent n, independent of the crystallization temperature, is at a range of 2. 5 to 3. 4, which probably corresponds to the heterogeneous mucleation and a 3-dimensional spherulitic growth. The maximum crystallization rate, very useful to polymer processing, was found at about 90℃ based on the half-crystallization time t1/2 analysis.     

热处理对聚丙烯结晶形态的影响

用偏光显微镜研究了热处理对聚丙烯的结晶形态的影响。结果表明,缓冷等温结晶时PP球晶尺寸大,大小不均匀,但形态清晰,结晶度高,而在快冷非等温结晶条件下的PP球晶细化且较均匀,但形态模糊,结晶度降低,结晶不完善。     

黄土高原祖厉河流域咸水淡化与高效利用

为缓解我国北方苦咸水分布地区淡水资源紧缺的状况,开展咸水多级冰冻淡化试验,揭示咸水结冰过程水质变化机理。试验结果表明:冷冻结冰法能有效淡化咸水,Ⅰ级冰融水的脱盐率可达60%以上;咸水多级冷冻结冰过程,不同离子结冰迁移速率不同,致各级冰融水离子组成发生变化。多级冰冻淡化方法可以在祖厉河流域推广和应用,其充分利用自然能源,具有经济环保,简单易行,既可小规模分户实施也可大规模处理等优势,是解决当地春旱期生活用水及农业用水困难的有效途径之一。     

基于PIC16F872单片机的塑料再生机自动控制系统的设计

文中给老式的废旧塑料再生机提出了一种自动控制系统设计方案,这个方案的硬件电路采用了美国Micmship公司生产的PIC16F872单片机,使得该系统具有智能控温、控制灵活的特点,可以有效地提高塑料再生的自动化程度和降低塑料再生的废品率．     

Peridotite-melt interaction: A key point for the destruction of cratonic lithospheric mantle

This paper presents an overview of recent studies dealing with different ages of mantle peridotitic xenoliths and xenocrysts from the North China Craton, with aim to provide new ideas for further study on the destruction of the North China Craton. Re-Os isotopic studies suggest that the lithospheric mantle of the North China Craton is of Archean age prior to its thinning. The key reason why such a low density and highly refractory Archean lithospheric mantle would be thinned is changes in composition, thermal regime, and physical properties of the lithospheric mantle due to interaction of peridotites with melts of different origins. Inward subduction of circum craton plates and collision with the North China Craton provided not only the driving force for the destruction of the craton, but also continuous melts derived from partial melting of subducted continental or oceanic crustal materials that resulted in the compositional change of the lithospheric mantle. Regional thermal anomaly at ca. 120 Ma led to the melting of highly modified lithospheric mantle. At the same time or subsequently lithospheric extension and asthenospheric upwelling further reinforced the melting and thinning of the lithospheric mantle. Therefore, the destruction and thinning of the North China Craton is a combined result of per- idotite-melt interaction （addition of volatile）, enhanced regional thermal anomaly （temperature increase） and lithospheric extension （decompression）. Such a complex geological process finally produced a ＂mixed＂ lithospheric mantle of highly chemical heterogeneity during the Mesozoic and Cenozoic. It also resulted in significant difference in the composition of mantle peridotitic xenoliths between different regions and times.     

Non-catalytic nucleation coating for undercooled Cu50Ni50 melt

A non-catalytic nucleation coating (B-F3) was prepared by the high temperature curing process of the sol-gel glass film based on the viscous flow mechanism of the coating. X-ray diffraction technology was adopted to study the crystallization behavior of the coating as a function of treating temperature. It was evident that no crystallization phenomenon happened on the coating which kept stable after the heat treatment of 60 min at 1773 K. The purified melt of Cu₅₀Ni₅₀ was selected to evaluate the effectiveness of undercooling heredity of the coating in the undercooling experiments. The maximum undercooling of the melt solidified in the coated mold could reach 236 K. Based on the solidified microstructural evolution at different undercoolings, a single crystal of the alloy Cu₅₀Ni₅₀ was achieved with no aid of the selection process of the crystal in the mold with the B-F3 coating by means of undercooling technology.     

合金熔体活度数据的模型计算及非对称性组元在计算中的应用

根据最基本的物性参数及热力学基本关系式建立了计算任意三元合金系活度数据的通用模型;通过与实验推荐值进行比较,发现其吻合程度良好,且预测值随原子序数的增大而有一定的变化规律,计算精度随着实验可靠性的提高而提高;在三元系Feij中按以下顺序优先选取非对称组元:B,N,C→Si,P→i,j中与Fe元素性质相差大的金属     

可切削玻璃陶瓷的透明玻璃形成及云母析晶

基于SiO2MgOAl2O3K2OCaOB2O3F系可切削玻璃陶瓷,进行了成分对透明玻璃的形成与云母析晶影响的研究·结果表明,通过适当调整K2O,CaO含量及比例,既可防止失透,又能获得大量的云母相·在CaO稳定作用下,ZrO2的加入可抑制云母晶体的长大,并在室温仍可保留较多的四方相ZrO2,大大提高了云母玻璃陶瓷的强度·     

灰黄霉素在超临界CO2中的溶解与沉析

研究了灰黄霉素在超临界ＣＯ２中的溶解沉析过程,测定了其溶解度。结果表明在实验范围内灰黄霉素在超临界ＣＯ２中处于反常冷凝区;通过超临界流体沉析过程,可获粒度〈５μｍ的灰黄霉素颗粒,反常冷凝区与正常冷凝区内操作的沉析过程,具有相反的温度影响与相同的压力影响。