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1.
Hua Liu Roman Przybylski N. A. Michael Eskin 《Journal of the American Oil Chemists' Society》1996,73(9):1137-1141
The effect of acetone on phase transition behavior of sediment in canola oil was studied by differential scanning calorimetry
under dynamic heating/cooling regimes. The melting temperature of sediment decreased with an increase in the solvent content
of canola oil, suggesting an increase in the solubility of sediment in the oil solution. The crystallization of sediment in
oil solution was facilitated by acetone, as indicated by the increase in the sediment crystallization temperature. Acetone
dramatically reduced the viscosity of canola oil, particularly in the first 30% addition. The reduction of viscosity was far
less with further addition of acetone. These results suggested that the optimum range of acetone content needed for sediment
precipitation in canola oil would be in the range of 30–40%. A linear relationship was found between the density of canola
oil and temperature. The influence of solvent on the density of canola oil/acetone solution can be accounted for by the mixing
theory of ideal solutions, whereas the effect of temperature on the dynamic viscosity of oil solution is best described by
a modified Arrhenius equation. 相似文献
2.
Phase transitions of canola oil sediment 总被引:3,自引:0,他引:3
H. Liu C. G. Biliaderis R. Przybylski N. A. M. Eskin 《Journal of the American Oil Chemists' Society》1993,70(5):441-448
Canola sediment was obtained from an industrial filter cake by solvent extraction. When heated in the differential scanning
calorimeter (DSC) (5–100°C), the sediment exhibited a single narrow melting peak at around 74.8°C. No solid-state polymorphic
transformation of the material could be detected over this temperature range. The X-ray powder diffraction pattern of canola
sediment resembled waxes from other sources with an orthorhombic unit cell. The phase transition behavior of canola sediment
in oil was studied by both DSC and polarizing microscopy. With increasing ratio of oil/sediment, a reduction in both melting
temperature and transition enthalpy was observed. The shape of the supercooling curve resembled that of the melting curve.
The induction time was determined by spectrophotometry and was used to calculate the interfacial free energyσ between sediment and oil; σ=4.71 erg/cm2. The effect of temperature and sediment concentration on the clouding time of canola oil was studied; the clouding time was
the shortest at 5°C. 相似文献
3.
Comparison of the composition and properties of canola and sunflower oil sediments with canola seed hull lipids 总被引:1,自引:0,他引:1
H. Liu R. Przybylski K. Dawson N. A. M. Eskin C. G. Biliaderis 《Journal of the American Oil Chemists' Society》1996,73(4):493-498
The phase transition behavior and chemical composition of sediments from Canadian and Australian canola oils, as well as from
sunflower oil, were studied by differential scanning calorimetry, X-ray diffraction, polarized-light microscopy, and chromatographic
techniques. Australian canola sediment was similar to Canadian canola sediment in both melting and crystallization behaviors
and chemical composition. Compared to canola sediment, sunflower sediment underwent phase transformation (melting and crystallization)
at lower temperatures, and the enthalpies associated with the phase changes were greater. The X-ray diffraction patterns for
these materials were similar, indicating identical crystalline structures. Sunflower sediment contained mainly wax esters
(99%), while canola sediment contained about 72–74% of waxes. Moreover, sunflower sediment consisted of shorter-chainlength
fatty acids and alcohols than canola sediment. A hexane-insoluble fraction from Canadian canola hull lipids had fatty acid
and alcohol profiles and X-ray diffraction pattern similar to the corresponding oil sediment. 相似文献
4.
As complex lipid systems, the phase and crystallization behavior of mixtures of a high-melting milk fat fraction with a low-melting
milk fat fraction or canola oil was studied. A turbidity technique was developed to estimate solubility and metastability
conditions of these lipid mixtures. Both solubility and metastability of the high-melting milk fat fraction in liquid lipids
increased exponentially with temperature. At a given equilibration temperature, liquid phases and solid fractions with nearly
identical melting profiles and TAG compositions were obtained regardless of the original concentration of the lipid mixture.
The maximum melting temperature (MMT), as measured by DSC, of the liquid phase increased dramatically in the equilibrium temperature
range of 27.5–35.0°C but did not change at temperatures below and above this range (down to 25.0°C and up to 40°C in this
study). The content of long-chain TAG (C46−C52) increased and short-chain TAG (C36−C40) decreased in the liquid phases as the equilibrium temperature increased. A plot of the TAG group ratio (i.e, long-short-chain
TAG) vs. equilibrium temperature was generated to illustrate the phase behavior of the complex lipid system and to represent
a solubility curve, from which the supersaturation level for crystallization kinetics was determined. Higher supersaturation
and lower temperature resulted in higher nucleation and crystallization rates. Compared to the system with a low-melting milk
fat fraction, mixtures of the high-melting milk fat fraction with canola oil had higher nucleation and crystallization rates
due to the lower solubility found for this system. 相似文献
5.
Shu‐Ling Zhang Gui‐Bin Wang Zhen‐Hua Jiang Wei‐Chun Wu Rong‐Tang Ma Zhong‐Wen Wu 《应用聚合物科学杂志》2004,94(3):839-844
PA1010/TPU blends were prepared by melt blending. The melting, crystallization behavior, and isothermal crystallization kinetics were investigated using differential scanning calorimetry (DSC). The results showed that the DSC thermograms of blend samples exhibit double melting peaks. With increasing the TPU content, the position of the double melting peaks shifted to a lower temperature, and the total heat of fusion decreased. With increasing the heating rates, the position of the lower melting peak shifted to a higher temperature, while the position of the higher melting peak shifted to a lower temperature; however, the total heat of fusion remained almost constant. With prolonging the annealing time and increasing the crystallization temperature, the position of the lower melting peak shifted to a higher temperature, while the position of the higher melting peak almost did not change; however, the total heat of fusion increased. The addition of TPU could promote the crystallization of PA1010 but not affect the crystallization mechanism. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 839–844, 2004 相似文献
6.
H. Liu C. G. Biliaderis R. Przybylski N. A. M. Eskin 《Journal of the American Oil Chemists' Society》1994,71(4):409-415
The effects of various factors on sediment formation in canola oil were studied. The crystallization temperature of sediment
varied with cooling rate, whereas the melting temperature depended on heating rate as well as the cooling rate during sediment
formation. The final crystal size depended on cooling rate. The crystal habit of sediment was generally rod-like but could
change to a round and leaf-like shape at low cooling rates (<0.5°C/min). Crystal nucleation occurred in the initial stage
of crystallization, while crystal growth was observed during the whole crystallization process, decreasing as cooling proceeded.
Crystal growth rate of the sediment was proportional to the crystal surface area Lecithin did not affect the phase transition
temperatures of sediment, but retarded crystal growth. 相似文献
7.
Perla Relkin Amel Ait-Taleb Stéphanie Sourdet Pierre-Yves Fosseux 《Journal of the American Oil Chemists' Society》2003,80(8):741-746
The thermal behavior of hydrogenated palm kernel oil-in-water emulsions, which differed in their milk-protein composition,
was studied in parallel with other characteristic parameters such as the aggregation/coalescence of fat droplets, and the
proportion of adsorbed proteins at the oil/water interface. DSC was applied to monitor the crystallization and melting behavior
of nonemulsified and emulsified fat samples. Comparison between nonemulsified and emulsified fat samples showed that in emulsified
samples the initial temperature of fat crystallization and the temperature of the completion of melting were invariably lower
and slightly higher, respectively. Furthermore, in complex food emulsions the supercooling temperature needed to initiate
fat crystallization and the variation in its growth rate in the cooling experiment were dependent on the amount and nature
of the adsorbed proteins. Our results indicate that the total replacement of milk proteins by whey proteins affected the fat
crystallization behavior of emulsified fat droplets, in parallel with changes in their protein surface coverage and in their
physical stability against fat droplet agglomeration. 相似文献
8.
Fatemeh Maleky Nuria C. Acevedo Alejandro G. Marangoni 《European Journal of Lipid Science and Technology》2012,114(7):748-759
The effects of cooling rate and solid mass fraction on the polymorphism, nano and microstructure, thermal and rheological properties of binary mixtures of fully hydrogenated canola oil and canola oil at 20°C have been studied. The β‐polymorph was observed in fully hydrogenated canola oil (FHCO) when crystallized at slow cooling rates (0.1C°/min), however crystallization at higher cooling rates (0.7 and 10°C/min) resulted in the formation of the α form. The β‐polymorph was detected in all the binary mixtures of FHCO/canola oil and was not affected by crystallization at different cooling rates. Melting thermograms obtained from 100% FHCO displayed three melting peaks, associated with the development of the β‐polymorph via α→ β′→ β‐polymorphic transition in the DSC pan. Some solubilization of solid FHCO into canola oil was observed and the solubility was proportionally higher with increasing liquid oil fraction. The strong influence of the matrix concentration on micro/nanoscale structure was demonstrated by characterization of crystal size using cryogenic transmission electron (Cryo‐TEM) and polarized light microscopy (PLM). Crystallization under higher cooling rates lead to formation of smaller nano and meso‐structural elements. Furthermore, oscillatory rheology showed the influence of structural elements' size and polymorphism on material strength. The shear storage modulus (G′) of the mixtures was higher when crystallized at fast cooling rates (10°C/min). In contrast, for pure FHCO, G′ increased by lowering the cooling rate and the highest storage modulus was observed after crystallization at 0.1°C/min. 相似文献
9.
D. Rousseau S. M. Hodge M. T. Nickerson A. T. Paulson 《Journal of the American Oil Chemists' Society》2005,82(1):7-12
Hydrogenated cottonseed oil (HCSO) is commonly used as a β′-stable fat in margarines and shortenings. In the present study,
the crystallization behavior of HCSO is altered via dilution, agitation, tempering regime, and the addition of an emulsifier [polyglycerol polyricinoleate (PgPr)]. Key properties
assessed include crystal morphology (with polarized light microscopy), polymorphic behavior (with X-ray diffraction), and
crystallization kinetics (with DSC). It is demonstrated that on considerable dilution with canola oil (4% w/w), HCSO can be
crystallized in the β′ or β polymorph with associated changes in crystal morphology, depending on tempering regime. Crystallization
from the melt to 25°C results in the β′-form, as there is insufficient supercooling to form the β polymorph but enough to
form the metastable β′. With cooling from the melt to 5°C, there is adequate supercooling for the δ polymorph to form, with
the presence of the canola oil facilitating the transformation toward this stable phase. Static vs. crystallization under
agitation does not lead to visible changes in either polymorphic behavior or crystal morphology. However, there is extensive
secondary nucleation and growth as a result of crystals breaking off accreting agglomerates. The presence of PgPr, added as
a crystal modifier, does not affect the final crystal polymorph or morphology, except under one set of conditions—crystallization
from the melt to 5°C with agitation, whereby it considerably alters crystallization behavior. 相似文献
10.
采用直接酯化熔融缩聚法合成了一系列不同含量的2-甲基-1,3-丙二醇(MPO)改性的共聚酯,并采用差示扫描量热仪(DSC)研究了其熔融结晶行为。结果表明,MPO的加入使聚对苯二甲酸丙二醇酯(PTT)熔点和结晶温度降低,加入摩尔比为20 %的MPO可以使PTT熔点由原来的226.64 ℃降至201.78 ℃,加入摩尔比为10 %的MPO可以使PTT结晶温度由原来的159.01 ℃降至137.50 ℃,同时使半结晶时间(t1/2)增大;随降温速率的提高,各样品的结晶温度向低温方向移动,放热峰由窄变宽,t1/2变小;不同降温速率下,改性共聚酯的结晶速率常数(Zc)比纯PTT的Zc减小。 相似文献
11.
Layer melt crystallization was applied for the dry fractionation of multi-component mixtures using coconut oil as a model substance. The aim of the experiments was to optimize the crystallization parameters (e.g. crystallization temperature, melt temperature, cooling rate, agitation speed) in order to obtain the solid fraction with a higher melting temperature and solid fat properties. The isothermal crystallization behavior of coconut oil was investigated via differential scanning calorimetry (DSC). The efficiency of the crystallization process was monitored by determining the melting point and solid fat content (SFC) of the fractionated products. The morphology of crystal layer was studied by a light microscope. Cool finger temperature was found to have the greatest impact on product properties. Applying a cooling rate of 0.2 K/h resulted in sufficient growth rates providing the required products. The micrographs of the solid fraction revealed lamellar particle arrangement compared to coconut oil possessing spherulites. 相似文献
12.
The spatial confinement of poly(ε‐caprolactone) (PCL) in the matrix of PMMA was synthesized by insitu polymerization and characterized by WAXD and SEM. The nonisothermal crystallization behavior and the kinetics of PCL in PMMA/PCL (85/15) blend and pure PCL were investigated by means of DSC. Jeziorny and Ozawa's theoretical prediction methods were used to analyze the crystallization kinetics. The melting behavior after cooling was also studied. There was an additional interesting phenomenon of double‐melting peak for pure PCL. Peaks at lower temperature shifted to lower temperature, and peaks at higher temperature did not shift with the increasing cooling rate. This behavior can be due to recrystallization. For the high‐crystallization activity energy and low‐crystallization rate, PCL in bulk would recrystallize during the melting process, and displayed a double‐melting behavior. Under spatial confinement of the rigid PMMA, PCL had much lower crystallization activity energy and had only one melting peak. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
13.
通过熔融共混法制备了间规立构聚苯乙烯/聚丙烯酸丁酯无规立构聚苯乙烯核壳乳胶粒子(sPS/PBA-aPS)共混物,采用差示扫描量热仪、X射线衍射仪和偏光显微镜研究了PBA-aPS对sPS结晶性能、结晶形态的影响,以及共混物在不同降温速率下、等温结晶条件下所得试样的熔融行为。结果表明, PBA-aPS的引入对sPS的结晶起阻碍作用,sPS及其共混物存在明显熔融重结晶再熔融现象,sPS平衡熔点为293.2 ℃,共混物的平衡熔点随PBA-aPS含量增加而降低,sPS形成β型大球晶完善性变差,sPS/PBA-aPS共混物的冲击强度明显提高,sPS/PBA-aPS质量比为80:20时,冲击强度提高了117 %。 相似文献
14.
应用常压差示扫描量热(DSC)仪和高压DSC仪研究了熔融温度、熔融时间、冷却速率以及压力对不同分子量的超高分子量聚乙烯(PE–UHMW)熔融再结晶行为的影响。常压DSC的研究表明,随着熔融温度、熔融时间以及冷却速率的增加,PE–UHMW的结晶峰值温度(Tc)逐渐下降。在相同的熔融温度和熔融时间下,PE–UHMW的Tc随分子量的增加而逐渐增加,但在所研究的冷却速率范围内(2.5~40℃/min),在相同的冷却速率下,Tc随分子量的增加变化不大。高压DSC的研究结果表明,结晶过程中增加压力导致PE–UHMW的Tc有所下降,并且结晶峰半峰宽变大。 相似文献
15.
Hua Liu Roman Przybylski N. A. Michael Eskin 《Journal of the American Oil Chemists' Society》1996,73(11):1557-1560
Formation of turbidity in canola oil was facilitated with addition of acetone, and a method to measure the sediment content
based on the oil turbidity has been developed. Canola oil was mixed with acetone at the ratio of 60:40, and the turbid solution
developed in an ice bath for 20 min. The turbidity of the oil solution was determined by a turbidimeter. The relation between
turbidity of the oil solution and sediment content was nonlinear and could be correlated by a second-order polynomial. There
was no difficulty in the development of turbidity in canola oil solutions in the presence of added lecithin (2%, w/w). However,
with added lecithin, turbidity was 23% higher at the same sediment content. 相似文献
16.
Naofumi Naga Yuji Yoshida Masaya Inui Keiichi Noguchi Shigemitsu Murase 《应用聚合物科学杂志》2011,119(4):2058-2064
Crystallization of amorphous poly(lactic acid) (PLA) was investigated in various organic solvents, such as acetone, ethylacetate, diethylether, tetrahydrofurane, methanol, hexane, toluene, xylene, and o‐dichlorobenene. Most of the solvents, except hexane, induced crystallization of amorphous PLA. Acetone was the most effective solvent to accelerate the crystallization among the solvents used. The crystallization was induced by permeation of acetone into the amorphous phase of PLA, and the permeation obeyed Fick type diffusion. The crystallization rate increased with increasing of conducting temperature. Crystallized PLA formed α crystalline structure. The permeated acetone in the crystallized PLA gradually evaporated as time passes, and the elimination of acetone affected thermal and mechanical properties of the crystallized PLA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
17.
The crystallization and melting behavior of poly(β‐hydroxybutyrate‐co‐β‐hydroxyvalerate) (PHBV) and a 30/70 (w/w) PHBV/poly(propylene carbonate) (PPC) blend was investigated with differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR). The transesterification reaction between PHBV and PPC was detected in the melt‐blending process. The interaction between the two macromolecules was confirmed by means of FTIR analysis. During the crystallization process from the melt, the crystallization temperature of the PHBV/PPC blend decreased about 8°C, the melting temperature was depressed by 4°C, and the degree of crystallinity of PHBV in the blend decreased about 9.4%; this was calculated through a comparison of the DSC heating traces for the blend and pure PHBV. These results indicated that imperfect crystals of PHBV formed, crystallization was inhibited, and the crystallization ability of PHBV was weakened in the blend. The equilibrium melting temperatures of PHBV and the 30/70 PHBV/PPC blend isothermally crystallized were 187.1 and 179°C, respectively. The isothermal crystallization kinetics were also studied. The fold surface free energy of the developing crystals of PHBV isothermally crystallized from the melt decreased; however, a depression in the relative degree of crystallization, a reduction of the linear growth rate of the spherulites, and decreases in the equilibrium melting temperature and crystallization capability of PHBV were detected with the addition of PPC. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2514–2521, 2004 相似文献
18.
19.
L. deMan J. M. deMan B. Blackman 《Journal of the American Oil Chemists' Society》1989,66(12):1777-1780
Fully hydrogenated soybean oil, beef fat, rapeseed oil, a rapeseed, palm and soybean oil blend, cottonseed oil and palm oil
were characterized by fatty acid composition, glyceride carbon number and partial glyceride content, as well as melting and
crystallization properties. The latter were established by differential scanning calorimetry. Polymorphic behavior was analyzed
by X-ray diffraction of the products in the flake or granulated form and when freshly crystallized from a melt. The hard fats
were dissolved in canola oil at levels of 20, 50 and 80% and crystallized from the melt. Palm oil had the lowest crystallization
temperature and the lowest melting temperature; rapessed had the highest crystallization temperature and soybean the highest
melting temperature. All of the hard fats crystallized initially in the =00 form. When diluted with canola oil, only palm
oil was able to maintain β′ stability. 相似文献
20.
熔融条件对聚醚醚酮结晶熔融行为的影响 总被引:2,自引:0,他引:2
用DSC法研究了熔融温度和熔融时间对聚醚醚酮地晶熔融行为的影响。实验表明,聚醚醚酮的结晶峰随熔融延长向高温移动,且峰形变窄,峰的强度增大,继续延长熔融时间,结晶峰降低,峰形变宽;熔融时间延长时,聚醚醚酮的玻璃化转变温度和冷结晶峰温度均提高,熔融峰强度减弱。熔融温度升高时,聚醚醚酮的结晶峰强度减弱,峰宽增强;而冷结晶温度提高。 相似文献