Wax Distribution Research Articles

Phase change materials formed by uv curable epoxy matrix and Fischer–Tropsch paraffin wax

The use of an oxidized hard Fischer–Tropsch paraffin wax as phase change material in an epoxy resin matrix has been investigated. Samples were prepared by mechanical mixing of the wax powder with liquid resin at room temperature, followed by uv-curing of the samples. The results indicated the presence of spherical wax particles in the epoxy matrix, even after heating the sample to a temperature above the melting point of the wax, and cooling. At low wax contents the wax distribution was fairly heterogeneous, but the homogeneity improved with increasing wax content. The epoxy–wax interaction seems to be weak, and the presence of wax has an observable influence on the dynamic mechanical properties of the samples, especially above the melting point of the wax. Although the wax starts decomposing at a much lower temperature than the epoxy resin, the decomposition of the mixtures occurred in a single step.

Sunflower‐Oil Wax Reduction by Seed Solvent Washing

AbstractWax distribution in sunflower seeds was determined by capillary‐gas chromatography, as well as both the wax composition in sunflower oils obtained from washed seeds and the wax composition in the solvent extracts. The dehulling efficiency was evaluated by using a laboratory centrifugal process. The washing effect on hull morphology and on wax distribution was observed by scanning‐electron microscopy. Washing preferentially removed the crystallized fraction, hexane being the most effective solvent. Short contact times (20 s) at 25–40 °C were sufficient to extract the insoluble waxes by hexane washing. The extracted material consisted of C40–C54 waxes with higher percentages of extracted C44, C46 and C48. These are superficially in the hull of sunflower seed presenting a non‐uniform distribution as observed by microscopy. Solvent washing with pre‐heating of the seeds caused a decrease in sample moisture content, which reduced dehulling ability. Ethanol‐washed seeds were the easiest to dehull, but higher production of fines was also observed. Solvent washing improves both the dehulling‐seed ability increment and the recovery of sunflower waxes as a by‐product for commercial use.

Dimensional stability of MDF panels produced from fibres treated with maleated polypropylene wax

Medium-density fibreboard (MDF) was produced from fibres treated with maleated polypropylene wax. The objectives of this study were to improve the dimensional stability of MDF panels by this treatment; to observe the maleated polypropylene wax distribution within the MDF panels using conventional fluorescence microscopy; and to determine the effects of the treatment on the mechanical properties and vertical density profile of the panels. MDF panels were produced from two resin types (urea-formaldehyde and melamine-urea-formaldehyde) and three maleated polypropylene wax contents (0, 3 and 5%). Photomicrographs show that maleated polypropylene wax forms agglomerates within the MDF panels which is an evidence of its poor distribution in our experimental conditions. Our results show an important reduction on thickness swelling and water absorption after water soaking for panels produced from treated fibres. Linear expansion and contraction in adsorption and desorption conditions between 80 and 50% relative humidity increased following fibre treatment. However, thickness swelling and shrinkage in similar conditions showed an important reduction following fibre treatment. The fibre treatment did not have negative effects on the mechanical properties or the vertical density profile of MDF panels. The modulus of rupture and modulus of elasticity in bending were increased by the treatment independently of maleated polypropylene wax content. The internal bond strength increased following the addition of 5% maleated polypropylene wax content.

Studies on Carbon Number Distribution of High Melting Microcrystalline Waxes

Carbon number distribution of microcrystalline wax derived from tank sludges of Bombay High crude oil (India) and its various high melting fractions have been studied by High Temperature Gas Chromatography (HTGC). Binodal, Gaussian distribution and a wide range of alkanes, ranging from C21–C75, along with their many isomers with predominant alkanes being C40 and C67, have been observed in the microcrystalline wax. Higher melting wax fractions have Gaussian distribution.

Raman spectroscopic study of spatial distribution of propolis in comb of Apis mellifera carnica (Pollm.).

Micro-Raman spectroscopy and Raman mapping are applied to investigate the spatial distribution and chemical composition of wax and propolis in the comb of Apis mellifera carnica (Pollm). A thick layer of propolis at the rim of some cells is identified by Raman spectroscopy. Raman mapping is applied to resolve the distribution of propolis and wax on a micron scale. Both components are connected at the rim of the cell with a mixture of wax and propolis. A layer of almost pure propolis is found on top of the mixture. It appears that even in the mixture, where both components come into close contact, the propolis and the wax remain separated and keep their chemical identity.

The extrusion of alumina composite billets

To prepare an extruded body with uniform wax distribution, the extrusion of a laminated billet that consists of plates of discs with a low aspect ratio is attempted. Surface micro-cracks arising from the lack of formability of a low wax content billet can be overcome by placing a higher wax content disc at the bottom of the composite billet. By extrusion of these billets, the lower part of the billet coats the upper part, and as a result, a flow-free extruded body can be obtained. Further, by the vacuum-sealing of the composite billet, a specimen free from air or water inclusions derived from penetration between the constituent disc can be prepared. The specimen obtained from this procedure shows higher flexural strength than those from non-sealed billet.

Effect of wax on the adhesion strength between acrylic urethane film and chromated steel sheet, and the friction coefficient of the film

The effect of wax in an acrylic urethane (AU) film on the adhesion strength between AU film and steel sheet treated with Zn-Ni and chromium was investigated by varying the amount of wax using a pull-off test. The adhesion strength decreased as the amount of wax increased. Since the wax in the AU film can react with the reactive functional groups of imine ester (hardener), the cohesive strength of the AU film can be reduced. The distribution of wax in the AU film on a polar and a nonpolar substrate, whose contact angles with water were 30° and 75°, respectively, was examined using contact angle measurements and X-ray photoelectron spectroscopy (XPS). The distribution of wax in the AU film was greatly affected by the degree of polarity of the substrate. In the case of the nonpolar substrate, the wax in the AU film migrated towards the film/nonpolar substrate interface to form a weak boundary layer, where the failure occurred. In the case of the polar substrate, the amount of wax at the film/polar substrate interface was much smaller than that at the film/nonpolar substrate interface and increased linearly with increasing wax content in the AU film. The friction coefficient of the AU film against chromated steel sheet was also measured with varying amounts of imine-ester and additives such as wax and colloidal silica. The friction coefficient appears to be influenced only by the amount of wax.

Epicuticular Wax of the First Leaves of Two Barley Cultivars Studied by Cryo Scanning Electron Microscopy

Chemical fixation and critical point drying of plant tissue prior to scanning electron microscopy often degrades the outermost layer of the specimen, i.e. the epicuticular wax. Knowledge of the unaltered wax, including its morphology, is important because the wax constitutes the interface between the plant and its surroundings. Having worked previously with barley leaves (anatomy, infection biology of pathogens), we found it of interest to examine and describe the wax morphology on barley leaves and to determine whether or not there were differences between cultivars. Hence, the morphology of the epicuticular wax on the first leaf of two spring barley cultivars has been studied by scanning electron microscopy following cryofixation. The wax on both cultivars consists chiefly of scales with a small proportion of rods and granules. There is little variation in wax morphology over each leaf side, and only minor differences between the abaxial and adaxial sides of the same leaf. Distinct differences are, however, observed between the two cultivars, especially regarding the thickness and the shape of the wax scales. The wax bodies cover the entire surface of a leaf except for parts of trichomes and guard cells, and some scattered wax free areas. The morphology and distribution of wax are discussed in relation to studies made on barley leaves using different techniques. Also, the implications of wax morphology for disease resistance are briefly discussed.

Comparison of surface polishing techniques used for InP wafers

InP wafers prepared using different polishing and mounting methods were compared by Makyoh topography, which is capable of detecting extremely small surface height variations. In some wafers a cellular surface ridge structure due to uneven mounting wax distribution was observed. It is shown that the ridge structure can be completely eliminated by the optimisation of the wafer mounting procedure or by the use of a “free floating” double sided polishing technique.

Supercritical Propane Fractionation of Wax-Bearing Residue

Abstract Supercritical propane fractionation of Sheng-Bei wax-bearing residue was investigated using laboratory-scale apparatus. The residue was fractionated by increasing the pressure stepwise. The properties of the extracted fraction, the wax distribution in the fraction, and the properties of deoiled wax were studied. The experimental results show that this method can fractionate the residue in molecular weight order. It has very high selectivity; the saturates are easier to extract than the aromatics in the process. The application of the process in residue fractionation and upgrading was also discussed.

Polarity Homogeneity and Structure Affect Water Vapor Permeability of Model Edible Films

ABSTRACTA continuous gravimetric measurement method was perfected to determine with accuracy the water vapor permeability of edible films. Two substances, methylcellulose and paraffin wax, with different physicochemical properties, were used as films. Factors affecting permeability included the polarity of film components, the homogeneity or dispersion of material in the film and the structure which depends on the distribution of paraffin wax in the composite films. The thickness and the Water Vapor Transmission Rate (WVTR) measurement methods resulted in different values for permeability. WVTR increased with hydrophilicity and heterogeneity. Modeling trials con‐cerning water vapor transport indicated the major influence that structure had on permeability. Waxlaminated fiIms had a very high barrier efficiency, comparable with that of synthetic films.

Types of Florin rings, distributional patterns of epicuticular wax, and their relationships in the genus Pinus

The shape of Florin rings and the distributional patterns of epicuticular wax of 51 species, including three varieties, in the genus Pinus were observed and classified with a scanning electron microscope. Six types of Florin rings and three types of wax distribution were observed. Florin ring structures and wax distribution correspond to subgenera. The restriction of the epicuticular waxes to the needle surface on which stomatal complexes occur suggests that the wax originates in association with the stomatal complex. In the subgenus Pinus, the Florin ring with a small opening size had little wax in the epistomatal chamber; the Florin ring with a large opening size had large amounts of wax. This suggests that the amount of wax in the epistomatal chamber and the opening size of the Florin ring are correlated with gas diffusion. Common thin, fibrillar wax, rare thick, winding wax, and occasional amorphous wax were observed. The relationships among the types of Florin rings are further discussed from the viewpoint of a developmental process.

Surface wax, structure and function in leaves of Polytrichaceae

Abstract The form and distribution of epicuticular wax has been examined by SEM in 35 species of Polytrichaceae. Australian and New Zealand species of Dawsonia have a dense covering of prominent angular platelets (or more irregular wax) on the lamella-margins; Polytrichadelphus magellanicus is very similar. In Polytrichum the epicuticular wax forms an angular to rounded granularity which varies in quantity from species to species; abundant and prominent on the lamella-margins of, e.g., P. formosum and P. commune, hardly detectable in, e.g., P. sexangulare. Pogonatum spp. show sparse to dense angular to rounded granularity on both surfaces, generally more abundant on the upper surface but (with the exceptions of P. grandifolium and (especially) P. urnigerum) less differentiated on the lamella-margins than in Dawsonia or Polytrichum. The parallel between Polytrichum alpinum, Pogonatum grandifolium, P. urnigerum, Psilopilum australe and P. crispulum is noteworthy. Oligotrichum, Batramiopsis, Atrichum and the...

The use of carbon-14 radiotracers to determine wax distributions in resins and laminates

Paraffin waxes, and similar compounds, are sometimes added to unsaturated polyester resins in small quantities for processing purposes. The final distribution of wax in the crosslinked resin and in glass laminates can be determined by incorporating 14C-labelled analogues, and tracing the distribution by autoradiography. Hexadecane (C 16 H 34) and pentacosane (C 25 H 52) were used in this study.

Absorption and distribution of jojoba wax injected subcutaneously into mice

Abstract14C‐Labeled jojoba wax was injected subcutaneously into mice and14C was determined 1–90 days after application in several internal organs, in the skin and in the lipids extracted from the carcass. A control group of mice was similarly treated with triolein. The major part of the injected lipids was not absorbed or metabolized. Some label was found in the organs examined, but there was no accumulation of labeled lipids with time. About 20% of label derived from triolein was found in polar lipids, whereas only 2–4% of that derived from jojoba wax was found in this fraction. There was some (1–5%) incorporation of the label of jojoba wax into body triglycerides.

Scanning Electron Microscopy of Plant Surfaces - Applications

Previous studies and our own observations of surface features in more than 80 species show that the SEM can be of great value in determining the nature and distribution of stomata, trichomes, wax, cuticular ridges, silica bodies, spores and other particulate pollutants as well as meristems and their derivatives. We suggest applications of surface studies to the fields of taxonomy and plant water relations.Many epidermal surfaces can be observed with or without coating at 15 KeV with no detectable alterations in the wax pattern. Wax is deposited as granular, rod-like, thread-like or plate-like structures. Of particular interest are the wax patterns around stomatal apparatuses.

Investigation of sheep dips. 3. The influence of breed on stripping and deposition in the fleece of diazinon.

SummaryGroups of 30 sheep of four breeds (Merino, Dorset Horn, Romney Marsh and Border Leicester), that had been maintained under the same environmental and nutritional conditions were used in showering experiments with a diazinon emulsion.The fleeces of all breeds stripped (or depleted) diazinon from the dipping fluid. Diazinon was not deposited evenly down the length of the wool staple. On the Merino fleece, more diazinon was deposited on the outer section and less on the inner section near the skin. On the other breeds, more diazinon was found in the inner and less on the outer sections.Differences in the magnitude and location of the diazinon deposits are discussed, with the aid of supplementary in vitro dipping experiments, in relation to the compactness of the fleece and the amounts and distribution of wax, suint and dirt found there.

STUDIES ON THE GROWING PROCESS OF CELLULOSE FIBER

The weight percent and absolute weight of wax in lint during the growing process of cotton fiber were daily measured in order to make clear the distribution of wax in cotton fiber. From this series of experiments, it may be concluded that the wax is the surface constituents of cotton fiber and exists only in the primary wall of the cotton fiber and can not be found in any appreciable amount in the inner structure i.e. the secondary wall of cotton fiber.

The Distribution of Wax in Cocoon Silk

The ether soluble fraction of silk, which consists mainly of silk wax, is not evenly distributed in the various strata of the cocoon. In yellow Italian and white Chinese cocoons the wax content decreases steadily from the external to the inside layers. The significance of these observations has been discussed.