纳微结构聚醚酮结晶物生产工艺及设备的开发

为缩短聚醚酮精制时间、降低能耗,将试验中间歇操作获得纳微结构聚醚酮结晶物的制备方法,改进成一种连续的工艺并应用于生产。运行结果表明:160℃左右结晶的聚醚酮在混合物中的晶型全部类似海绵状,晶体间孔隙较大、空隙率高,其精制时间是12.3h,为原传送带水冷精制时间的65.4%。对同批次结晶的聚醚酮进行物性检测对比,未见发生变化。此工艺较大程度的降低了聚醚酮精制的能耗,提高了生产效率。     

结晶产品的精制方法

通过提高结晶混合物的温度，使其熔解，密度不同于所要组份的不纯物从混合物中排除，使再结晶，将再结晶的晶体混合物置于压榨机中压榨，除去其中的液体杂质，截留住该组份的晶体，而得到增浓的结晶混合物中的一种晶体成份。本方法尤其适合于对二氯苯精制。     

2,6-二异丙基萘的分离精制

研究了从萘与丙烯合成的异丙基萘混合物中分离、精制2,6 二异丙基萘(2,6 DIPN)的方法. 考察了精馏操作条件对精馏分离结果的影响,并研究了结晶温度及溶剂对产品纯度和收率的影响. 实验结果表明,以自行合成的烷基化产品混合物为粗产品,在1000 Pa真空度下减压精馏,收集165℃的馏出物可得到含量约50 的2,6 DIPN,将此馏分在9℃下结晶,所得晶体以乙醇为溶剂洗涤2次后,可精制出纯度为99.42 的2,6 DIPN.     

盐湖粗硫酸镁提纯工艺研究

对运城盐湖滩田结晶的粗制硫酸镁进行了提纯实验，确定了精制工艺路线。工艺条件为：溶解温度80～90℃，密度1．37—1．39g／cm^3，热滤温度≥75℃，冷却结晶时间8h，搅拌速度50～60r／min，冷抽滤温度18℃，烘干温度45～55℃。该工艺技术可行，经济合理，所得产品符合工业七水硫酸镁标准的指标要求。     

等规聚丙烯无定形相和中间相向α晶的等温转变机理研究

用宽角X射线衍射和傅立叶变换红外光谱仪研究了等规聚丙烯的低温等温结晶.结果表明,在快速淬冷过程中中间相与α晶的生成动力学之间存在竞争,而在恒温结晶的过程中晶型的转化则是由热力学稳定性来决定的.淬冷到40℃至55℃的聚丙烯可以同时形成中间相和α晶,在恒温过程中α晶有增加,但是转化来源会因温度不同而不同.     

基于硅酸盐对建筑垃圾过滤分离的脱水机理研究

硅酸盐是典型的建筑垃圾,硅酸盐的脱水性能直接影响了建筑垃圾的处理效率.为探究硅酸盐结晶状态对脱水效果的影响,在不同的合成温度、合成时间条件下得到不同结晶状态的硅酸盐,并从宏观水平、介尺度水平和分子水平对所得的硅酸盐晶体的脱水效果加以分析.研究表明,在合成温度为200℃时硅酸盐结晶过程较复杂,是非晶态到晶态的过渡区,对应的硅酸盐晶体脱水效果最好.同时,在合成温度200℃、合成时间4 h得到的硅酸盐晶体过滤速度最快,过滤后滤饼含水率最低,而合成8h得到的硅酸盐晶体过滤效果较差,其原因是受微观形貌、层间水释放、比表面积和水分赋存状态的影响.     

12-氨基十二酸精制工艺条件的研究

采用1,1'-过氧化双环已胺(PXA)法制备尼龙-12,需要对含有其单体-12-氨基十二酸(12-ADA)的11-氰基十一酸加氢产物予以精制.以12-ADA的产品纯度与收率为目标函数,用有机溶剂重结晶法进行精制,考察了结晶工艺条件对精制效果的影响.实验结果表明,优化工艺条件为:结晶介质为异丙醇-水-浓氨水(质量比3:3:1)的混合溶液、初次结晶温度为15℃、重结晶温度为40℃、重结晶母液重复利用1次,在此条件下,精制的12-ADA晶体纯度和收率分别可达99.6%和92.3%.     

12-氨基十二酸精制工艺条件的研究

采用1,1'-过氧化双环已胺(PXA)法制备尼龙-12,需要对含有其单体-12-氨基十二酸(12-ADA)的11-氰基十一酸加氢产物予以精制.以12-ADA的产品纯度与收率为目标函数,用有机溶剂重结晶法进行精制,考察了结晶工艺条件对精制效果的影响.实验结果表明,优化工艺条件为:结晶介质为异丙醇-水-浓氨水(质量比3:3:1)的混合溶液、初次结晶温度为15℃、重结晶温度为40℃、重结晶母液重复利用1次,在此条件下,精制的12-ADA晶体纯度和收率分别可达99.6%和92.3%.     

CPP薄膜专用树脂的结晶性能及加工应用

用差示扫描量热仪和偏光显微镜研究了流延薄膜专用无规共聚聚丙烯树脂在不同降温速率下的结晶性能及结晶形态,并分析了在实际加1=应用过程中不同冷辊温度对薄膜性能的影响.结果表明:试样的降温速率越快,形成的晶体尺寸越小,且结晶度越低,当降温速率由5℃/min增加到40℃/min时.结晶度由38.15%降至33.18%;在流延膜...     

水铝石热分解的晶体形貌

借助场发射扫描电子显微镜和X射线衍射分析研究了水铝石在不同温度分解后的形貌特征。研究表明：铝土矿中水铝石晶体呈短柱状、粒状,晶粒尺寸小于30gm;经500℃,3h受热后该水铝石晶体形状基本不变,而此时已转化为α-A1203,被称为水铝石假象;700℃,3h受热后晶体开裂成更小的柱状;温度升高至1000℃恒温3h后可辨识...     

Heat Treatment and Chemical Composition of Fatty Acids and Rosin Acids Mixtures: Effects on Their Thermal Properties and Morphology

Mixtures of fatty acids and rosin acids are industrially important products utilized as a raw material for several purposes. Their thermal properties, especially cold stability and crystallization behavior is also important. Several fatty acid and rosin acid mixtures both from industrial products and from commercially available fatty and rosin acids were prepared and treated for 30 min at 80 °C under an inert atmosphere. Thereafter, the mixture was cooled to the desired temperature. Determination of the cloud point, chemical analysis of liquid and solid phase, thermal analysis by differential scanning calorimetry as well as morphology analysis by scanning electron microscopy were performed. The results revealed that crystallization was more rapid when it occurred at 10 °C compared to 25 °C. The crystal sizes increased with decreasing the crystallization temperature. Furthermore, crystals were of irregular shape and agglomerated when rapid cooling of the mixture occurred. Chemical analysis revealed that liquid phase was enriched with stearic acid, whereas crystals contained large amounts of abietic, dehydroabietic and linoleic acids. The cloud point of the mixtures increased with increasing amount of stearic and rosin acids. Dehydroabietic acid addition improved the cold stability of the synthetic fatty acid–rosin acids mixture.     

非牛顿煤灰配渣的结晶特性

气流床气化炉内熔渣的结晶会对渣层的黏度产生重要影响,使熔渣由牛顿流体转变为非牛顿流体。采用单热电偶在线观察系统(SHTT)、高温淬冷炉、X射线衍射(XRD)等对一种五元组分的模拟煤灰渣从结晶的角度进行研究,在线记录了晶体的生长形貌,获得了熔渣析晶的时间-温度-转变(TTT)曲线,研究熔渣在不同温度和冷却速率下的结晶特性以及晶体的类型。实验结果表明温度的降低使结晶驱动力增加,结晶孕育时间减少,但温度过低使黏度增加,晶体生长受限,因此生成的晶体尺寸较小。熔渣的结晶在不同温度区间析出的矿物不同,主要的晶体产物在高温区为透辉石,低温区有少量钙长石生成。冷却速率的增加会使晶体的生长尺寸减小,非晶态含量增加,但对晶体的种类影响不大。     

不同温度和冷却速率下高温灰渣的结晶行为

采用单热电偶在线观察系统（SHTT）、图像分析程序等研究等温过程中温度和连续冷却过程中冷却速率对于人工配制灰渣结晶行为的影响,通过计算结晶动力学参数分析其析晶机理,并采用FactSage软件预测晶体类型。实验结果表明,等温过程中,温度降低,结晶所需时间先减小后增大,晶体尺寸减小,结晶比例先增大再稳定最后减小,不同温度区间生成晶体类型不同,导致结晶比例在某些温度出现较大的变化。连续冷却过程中,冷却速率增大,初始结晶温度降低,晶体由块状向颗粒状转变,结晶比例先稳定后减小,由于析出的晶体类型不同,结晶比例出现多个稳定区间,达到临界冷却速率后熔渣全部凝固为玻璃态,无晶体析出。由DSC得到的熔渣结晶放热曲线与SHTT得到的结果吻合较好。     

Crystal shape monitoring and supersaturation measurement in cooling crystallization with quartz crystal oscillator

A crystallization monitoring system using a quartz crystal oscillator was utilized to predict different shapes of crystal formation by measuring crystal growth rate and to measure supersaturation. Applying different rates of cooling, crystal formation of different shapes was induced, and the frequency variation of the oscillator and the crystal shape observed with an SEM were compared to determine how the frequency variation can be interpreted for the prediction of produced crystal shape. The experimental results obtained from the crystallization of potassium nitrate and cupric sulfate solutions showed that the proposed frequency measurement technique could be applied in the prediction of crystal shape of cooling crystallization processes. In addition, supersaturation was determined from the measurements of solution and coolant temperatures.     

Effect of processing conditions on crystallization kinetics of a milk fat model system

Crystallization behavior of three blends of 30, 40, and 50% of high-melting fraction (MDP=47.5°C) in low-melting fraction (MDP=16.5°C) of milk fat was studied under dynamic conditions in laboratory scale. The effect of cooling and agitation rates, crystallization temperature, and chemical composition of the blends on the morphology, crystal size distribution, crystal thermal behavior, polymorphism, and crystalline chemical composition was investigated by light microscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD) and gas chromatography (GC). Different nucleation and growth behavior were found for different cooling rates. At slow cooling rate, larger crystals were formed, whereas at fast cooling rate, smaller crystals appeared together. Slowly crystallized samples had a broader distribution of crystal size. Crystallization temperatures had a similar effect as cooling rate. At higher crystallization temperatures, larger crystals and a broader crystal size distribution were found. Agitation rate had a marked effect on crystal size. Higher agitation rates lead to smaller crystal size. Cooling rate was the most influential parameter in crystal thermal behavior and composition. Slowly crystallized samples showed a broader melting diagram and an enrichment of long-chain triacylglycerols. Crystallization behavior was more related to processing conditions than to chemical composition of blends.     

FOX-7晶体的制备和热性质

为了解FOX-7晶体形状和尺寸对其热性质的影响,通过冷却结晶和阻溶剂结晶的方法从DMF/H2O、NMP/H2O体系中获得FOX-7晶体.SEM结果表明,得到的晶体基本为延长的四面或六面棱柱和斜方菱晶两种类型,不同溶剂体系中得到晶体的尺寸不同和包含的颗粒数量也不同,超声处理得到的晶体具有单一形状,只是其表面较粗糙.DSC测试结果表明,不同结晶方式和不同溶剂体系中获得的FOX-7晶体的热性质有一定的差别.由此得出,不同的结晶方式和溶剂体系可以获得不同形状、尺寸和热性质的FOX-7晶体,而超声处理可以很好地控制晶体的形状.     

Effect of processing conditions on microstructure of milk fat fraction/sunflower oil blends

The effect of processing conditions on the crystallization of blends of a high-melting milk fat fraction and sunflower oil was investigated. Two cooling rates were selected for all studies: 0.1°C/min (slow rate) and 5.5°C/min (fast rate). Blends were crystallized in two conditions: (i) with agitation in an 80-mL crystallizer (dynamic), and (ii) on a microscope slide without agitation (static). The selected crystallization temperatures were 25, 30, and 35°C for both cooling rates. Photographs of the development of crystals with time were taken in both static and dynamic conditions, and the crystal size distribution was determined at the moment that the laser signal reached its peak. Photographs showed that when samples were cooled slowly, crystals had a more regular boundary, appeared to be more densely arranged, and were larger. In dynamic conditions, crystal sizes were smaller and the background contained numerous small crystals, which were not found in statically crystallized samples. All images showed that crystals were not single crystals, but grew by accretion.     

Turbidimetry for crystalline fractionation of lard

Development of specific properties of lard, a well-known edible animal by-product and one which plays an important role in Chinese-style foods, was studied by means of multiple-step crystalline fractionation. A method for monitoring the crystallization temperature and crystallization time of lard by spectral turbidity was also studied. The capabilities of the proposed method were experimentally demonstrated through recovery of the fat crystal mass. Six significant changes in turbidity spectra, which correspond to the formation of fat crystals, were observed at various temperatures while cooling the melted lard from 50°C to the final vessel temperature at a constant cooling (0.5°C/min) and agitator rate (50 rpm). Crystallization time for each lard fraction was determined while the peak in turbidity was observed in the process of cooling at a specific temperature. Determination of crystallization time by means of turbidimetry correlated with the increase in deposition of fat crystals. No significant increase in fat crystal mass was observed when cooling prolongation after the turbidity peak for the sample was measured. Attributes of lard fractions were characterized by iodine value, saponification value, fatty acid composition, and melting profile of crystallization temperature. Based on the results, turbidimetry might be suggested as a fast and inexpensive method for monitoring the crystallization temperature and crystallization time for the routine crystalline fractionation process.     

PTT/PE共混体系结晶动力学及结晶形态研究

采用差示扫描量热法(DSC)研究了聚对苯二甲酸丙二醇酯/聚乙烯(PTT/PE)共混体系的非等温结晶动力学,通过热台偏光显微镜(POM)对共混物在等温条件下的结晶形态进行了研究。结果发现:PTT/PE共混体系各样品的结晶峰温度随着冷却速率的提高而下降,而半结晶时间t1/2随着冷却速率的提高而提高;结晶动力学常数Zc随着冷却速率的提高而下降,表明共混体系的结晶速率随着冷却速率的提高而降低;在POM观察的时间范围内各样品的球晶尺寸随着时间的延长而增大,PTT/PE(30/70)共混体系在190℃结晶时,球晶尺寸较大,即球晶生长较快。     

Chicken fat dry fractionation: Effects of temperature and time on crystallization,filtration and fraction properties

A surface response experimental design was used to quantify the effects of the final cooling temperature and the residence time at this temperature on the filtration characteristics of the crystal suspension and the quality of the fractions during chicken fat dry fractionation. The crystal morphology was monitored to gain insight into the observed effects. Temperature affected crystallization and the characteristics of the olein and stearin fractions. The crystals became fragmented as the residence time increased, thus leading to a decrease in the filterability of the crystal suspension and an increase in the proportion of the entrained liquid phase. The residence time only affected the quality of the stearin fraction. This time effect was noted at high cooling temperatures in the investigated experimental domain. At low temperatures, increasing the residence time enhanced crystal growth and increased the extent of unsaturation of both fractions without modifying the filtration features.