The state of water and several transitions were examined in the systemsn-decanephosphonic acid (DPA)—water and the sodium salts of DPA—water. Temperature — composition phase diagrams are reported.
The results show that several liquid crystalline phases plus isotropic liquid, and two solid phases (a waxy solid phase and
a crystalline phase) are formed. Several types of water were detected: bulk-like water, interfacial water and hydration water.
Authors:J. Silverio, E. Svensson, Ann-Charlotte Eliasson, and G. Olofsson
In the present study, isothermal microcalorimetry was introduced as a tool to investigate properties of starch retrogradation during the first 24 h. The study was made on purified amylose and amylopectin from corn, as well as on native starches, such as wheat, potato, maize, waxy maize and amylomaize, differing in their amylose content. The results were obtained in the form ofP-t traces (thermal powervs. time), and integration of these traces gave a net exothermic enthalpy of reaction, caused by the crystallization of amylose and amylopectin. TheP-t traces reflected the quantities of amylose and amylopectin in the starch studied. Depending on the amylose content and the botanical source of the starch, the rate of crystallization of amylose was high and predominated over that of amylopectin during the first 5–10 h. The contribution from amylose crystallization to the measured exothermic enthalpy was very substantial during this period. After ∼10 h, amylose crystallized at a lower constant rate. During the first 24 h, amylopectin crystallized at a low steady rate. The exothermic enthalpies obtained by the isothermal microcalorimetric investigations during the first 24 h of retrogradation were generally low in relation to the endothermic melting enthalpies observed by differential scanning calorimetry (DSC) measurements after 24 h of storage. The discrepancies in enthalpy values between the two methods are discussed in relation to phase separation and the endothermic effects owing to the decrease in polymer-water interactions when polymer-rich regions in the starch gel separate. Besides the exothermic enthalpies obtained, theP-t traces also made it possible to study the initial gelation properties of amylose from different botanical sources. The present study further demonstrated that isothermal microcalorimetry can provide a possible way to investigate the antistaling effect of certain polar lipids, such as sodium dodecylsulphate (SDS) and 1-monolauroyl-rac-glycerol (GML), when added to starches of different botanical origin. The net exothermic heat of reaction for starch retrogradation during the first 24 h was decreased when GML or SDS was added to the starch gels. The recordedP-t traces also showed how the effect of the added lipid influenced different periods during the first 24 h of starch retrogradation, and that the effect depended mainly on the amylose content, the botanical source of the starch, and the type of lipid used. When GML or SDS was added to waxy maize, the isothermal microcalorimetric studies clearly indicated some interaction between amylopectin and the polar lipids. These results concerning the action of anti-staling agents are further discussed in relation to the helical inclusion complexes formed between amylose-polar lipid and amylopectin-polar lipid.
On evaporation at room temperature of an aqueous reaction mixture of Ln(III) sulfate and ethanolammonium sulfate in a molar
ratio higher than 1∶16, crystal products with a waxy feel were obtained. They were identified by means of the X-ray powder
diffraction patterns and it was concluded that they are isostructural. The results of elemental analysis and the mass losses
by TG analysis indicated the formation of double sulfates with general formula: (HOCH2CH2NH3)4Ln2(SO4)5·4.5H2O (Ln=La, Ce, Pr or Nd)
Their thermal decompositions in static atmosphere in the temperature range from ambient up to 1173 K took place in a similar
way, and mainly Ln2O2SO4 was obtained as final product. The exception was the Ce compound, which decomposed to CeO2. The double sulfates decomposed in many not well-differentiated steps. From the mass losses occurring during thermal decomposition,
the mode of thermal decomposition was presumed. The X-ray powder diffraction patterns of Ln2O2SO4 (Ln=La, Pr and Nd) show that they are also isostructural.
Authors:P. Schulz, J. Rodríguez, F. Soltero-Martínez, J. Puig, and Z. Proverbio
The phase behaviour of the twin-tailed surfactant dioctadecyldimethylammonium bromide with water was studied by DSC, FT-IR,
X-ray and polarizing microscope. The phase diagram of DODAB-water system is very similar to that of DODAC-water. The dihydrate
is in equilibrium with isotropic solution below 55°C. Above this temperature there is a lamellar liquid crystalline region,
in equilibrium with isotropic liquid and solid crystals of DODAB·2H2O, up to 69°C. From 69 to 86°C, the lamellar mesophase is in equilibrium with ‘waxy’ anhydrous DODAB. From 86 to 116°C and
very high DODAB content, there is a very narrow region of existence of inverse hexagonal mesophase, in equilibrium via a narrow
biphase region with lamellar mesophase. AtT > 116°C an isotropic liquid appears. There seems to exist two different lamellar mesophases, one of them between 10 and 40
wt.% DODAB and the other between 60 and about 97 wt.% DODAB, with a biphase zone between them.
On evaporation at room temperature of an aqueous mixture of Ln(III) sulphate and ethanolammonium sulphate in a molar ratio
higher than 1:12, in the presence of sulphuric acid, double sulphates of Sm, Eu, Ho, Tm, Yb and Y with a waxy feel were obtained.
The stoichiometry of the obtained compounds was determined by means of elemental and TG analysis. On the basis of X-ray powder
diffraction patterns it was concluded that an isostructural group with a general formula: Ln2(HOCH2CH2NH3)8(SO4)78H2O was obtained. The above compounds have a stoichiometry and a crystal structure different from those of the double sulphates
of La, Ce, Pr and Nd with the same monovalent cation, as presented earlier.
The thermal decomposition of the investigated compounds in the temperature range from ambient temperature up to 1173 K occurred
in a similar way, mainly in three not well-differentiated steps. Lanthanide oxysulphates were obtained as final products.
Authors:Robert A. Shanks and L. M. Wasantha K. Gunaratne
interpreted in terms of molecular processes that constitute gelatinization. X-ray data are used to characterize crystallinity of the starches.
Raw materials: low amylose starch (waxy), high amylose starches Gelose 50
Authors:Luis Alberto Alcazar-Vara and Eduardo Buenrostro-Gonzalez
-equilibrium and rheological properties of waxy model systems has been submitted for publication. Table 1 shows some of the molecular parameters of the asphaltenes used in this study. As can be seen, the AsphPC asphaltenes are more aromatic than AsphIri
fillers, thus allowing better response to chemical modification such as acetylation.
Moreover, the presence of waxy substances on the filler surface contributes immensely to ineffective filler to modifier bonding, and poor surface wetting. Hon et
Authors:Dora Melucci, Giuseppe Chiavari, Simona Montalbani, and Silvia Prati
, Bonaduce , I , Colombini , MP , Gautier , G , Modugno , F , Ribechini , E . Combined GC/MS analytical procedure for the characterization of glycerolipid, waxy, resinous, and proteinaceous materials in a unique paint microsample . Anal Chem 2006