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71.
W. L. Ng 《Journal of the American Oil Chemists' Society》1990,67(11):879-882
Nucleation from a supercooled melt of palm oil was studied by optical microscopy and differential scanning calorimetry (DSC).
Despite being a multicomponent system, palm oil exhibits a rather simple cooling thermogram with its high- and low-T exotherms
exclusively related to the “hard” and “soft” components of the oil. As the “hard” components are being removed, the position
of the high-T peak shifts down toward the low-T peak with diminishing peak intensity, while the position of the latter remains
virtually unchanged.
At 288°K, nucleation in a palm oil melt is instantaneous. Its induction time-temperature curve shows an abrupt discontinuity
at 297°K, which demarcates the occurrence of one polymorph from another. Nucleation data fit very well into the Fisher-Turnbull
equation. Its larger activation free energy of nucleation is accompanied by lowering of the melting point and an increase
in the crystal/melt interfacial free energy as compared to palm stearin. The slow rate of nucleation in palm oil is attributed
to intermolecular interaction between its “hard” and “soft” components.
Partly presented at the 1989 PORIM International Palm Oil Development Conference, September 5–9, Kuala Lumpur, Malaysia. 相似文献
72.
73.
The importance of some relative surface characteristics which determines the strength of adhesive joints: specific surface of substrate , relative contact area β and specific contact area β in the adhesion interaction process were emphasised. Existing and potential methods of experimental evaluation of these characteristics were shortly analysed. The durability of the adhesive joints in water media significantly increases with growth of specific surface * of chemically treated substrate evaluated from the SEM micrographs. Specific surface calculated from the experimental data of hexane adsorption measurements for iron particles (particulate model of steel substrate) is more then ten times greater than respective * values. The relative contact area β of the Al2O3 particles (in wide range of ) with PE melt was in a roundabout way evaluated by experimental determination of the affect of on kinetic of peel strength formation of adhesive joints: Al2O3 filled PE-steel. The speculation was based on the ability of Al2O3 to adsorb low-molecular products of contact oxidation of PE which takes place in the process of formation of adhesive joints and determines their strength. The ability of sorption in its turn is proportional to efficient value of β. The availability of the Al2O3 surface was evaluated. 相似文献
74.
Two types of SBS/OMMT composites are prepared by melt blending using a twin‐screw extruder. An X‐ray diffractometer indicates that polymer chains have intercalated into the gallery of the clay. It is shown in TEM photos that the thickness of the layer aggregate in the SBS1301 matrix is approximately 200 Å, but in the SBS4402 matrix the size of the filler particle is in micrometers. When SBS1301 is intermingled into SBS4402/OMMT, the particle size is reduced obviously. The tensile strength and elongation at break of the nanocomposite, SBS1301/OMMT, increase with the addition of OMMT; and when addition is 5phr, they achieve maximum. A small content of OMMT (less than 5phr) can prevent the deterioration of the mechanical properties of the SBS1301/MMT. In addition, a small content of SBS4402 (less than 20 wt %) can improve the mechanical properties of the SBS1301/OMMT composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 146–152, 2005 相似文献
75.
采用丁基橡胶研制用于中空玻璃单道密封的热熔胶.研究主体树脂品种、增黏剂、改性剂、填料的类型及用量对材料性能的影响.实验采用正交方法对胶料成分进行配比,在开放式塑炼机的混炼下得到热熔密封胶胶料,并测得胶料与玻璃的黏接性、拉伸性及流变性.实验结果表明:加入具有良好增黏作用的低分子聚异丁烯以及石蜡,都有利于提高胶条的黏接性能,丁基橡胶对胶条的拉伸性能影响最大,加入少量石蜡,可以降低黏度,增加其流动性. 相似文献
76.
语言是跨文化交流中最主要的手段,而词汇又是语言中最活跃的因素。由于受各自民族文化的影响,在跨文化交际过程中,会出现词汇空缺现象,给跨文化交际带来障碍。研究词汇空缺现象,了解并掌握造成词汇空缺现象的原因,明白其内涵,就可以避免在跨文化交际中产生误解,减少障碍,从而使跨文化交际得以顺利进行。 相似文献
77.
以强水敏砂岩油藏实际岩样为例,通过水驱油渗流实验和渗流物理分析,探讨强水敏砂岩油藏水驱油过程相对渗透率曲线异常现象及其对油藏开发的影响。 相似文献
78.
在研究北太平洋海温异常对黑龙江冰坝的影响中,从预测黑龙江上游冰坝需要出发,利用反映北太平洋海域表面温度变化的分布型指数(该指数较好地表征出海温的年际变化特征及厄尔尼诺和拉尼娜事件),以及黑龙江上游水文站的封江水位距平构建了该站的冰坝预报模型,该模型可以较好地预测出黑龙江上游冰坝,实际预测结果表明,该方法是可行的,在冰坝预报中可以发挥重要作用。 相似文献
79.
In order to in situ measure chemical parameters of deep-sea water and hydrothermal fluids at midocean ridge(MOR), it is necessary to use high temperature and high pressure chemical sensors.Developing new sensors is essential to measure in-situ pH and other chemical parameters(dissolved H2, dissolved H2S) of deep-sea water and hydrothermal fluids in a wide temperature range(2℃―400℃) at MOR vents.The YSZ(Yttria Stabilized Zirconia, 9%Y2O3) ceramic-based(HgO/Hg) chemical sensors possess excellent electrochemic... 相似文献
80.
Mahmoud A.‐Halim Abdel‐Goad 《应用聚合物科学杂志》2004,93(1):37-40
Agricultural residues (cotton straw) were added as very small particles to polystyrene (PS) at different weight ratios by using a melt‐mixing technique. The dynamic mechanical tests were performed over a wide range of temperatures and frequencies by using an ARES rheometer (Rheometrics Scientific) operated in the dynamic mode. The dynamic mechanical properties in terms of the storage modulus (G′), loss modulus (G″), compliance moduli, loss tangent, and dynamic viscosity were studied and compared for PS and PS composite. The results showed that the dynamic mechanical moduli and viscosity were found to increase with the addition of cotton straw and rise further with its loading increasing. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 37–40, 2004 相似文献