Hot Glycerine Research Articles

Effect of gelation time on the microstructures, mechanical properties and cyclization reactions of dry-jet gel-spun polyacrylonitrile fibers

The use of gel spinning technology in the formation of polyacrylonitrile (PAN)-based carbon fibers has led to significant tensile property improvements. PAN, dimethylsulfoxide (DMSO) and dimethylformamide (DMF) solutions were dry-jet spun, gelled in methanol at −20 and −50 °C for different times from 0 to 40 d, and vacuum-dried at 0 °C for 24 h to obtain PAN fibers that were drawn to a drawing ratio (DR) of 4 in a hot glycerin bath at 110 °C, and then to various DRs in a glycerin bath at 155 °C. The effects of gelation time on the microstructures, mechanical properties and cyclization reactions of the gel-spun PAN fibers were investigated. Results showed that the gelation time affected the gel structure and the maximum possible draw ratio. The gelation effects were significant in the first 5-10 d, and were more prominent for the DMSO system than the DMF system. The maximum possible draw ratio, strength and modulus, orientation and crystallinity of the PAN fibers increased with gelation time. The cyclization temperature decreased and the reaction enthalpy increased with gelation time in cyclization, indicating an improved chain orientation and crystallinity with gelation time. Gelation was an important step affecting the microstructures and properties of gel-spun PAN fibers for making high performance carbon fibers.

Production of polystyrene-nanoclay nanocomposite foam and effect of nanoclay particles on foam cell size

This paper seeks to study the effect of nanoclay particles on polystyrene-nanoclay nanocomposite foam cells. In this study, first using a melt method, nanocomposites were injected into a mold in proportions of 4, 5 and 6% of nanoclay with a twin-screw extruder. To determine the distribution pattern of nanoclay particles in a polystyrene basis, X-ray diffraction and scanning electron microscope tests were conducted on the samples. To produce nanocomposite foam parts using mass foam process, first the samples were placed and maintained for 40 hours in a chamber pressurized to 60 bars. Removed and weighed, the samples were placed in a hot glycerin bath heated to 85, 95, 100 and 105℃. The foam samples were tested to measure the density and grain size using a scanning electron microscope. The results showed that proportions 4% and 5% of nanoclay caused an increase in density and a decrease in grain size. However, in the nanocomposite foam sample with a proportion of 6% nanoclay, there was a decrease in density and an increase in grain size due to accumulated nanoclay layers.

The experience of using glycerin during processing of larval cyst cavity

The paper intends to define influence of the hot glycerine to the structure of the germinal elements and chitin surface. It also observes the extent to the extent to which the hot glycerine affects the fibrous capsule and adjoining tissue. We carried out the study of morphology of excretory capsules and protoscolexes by the influence of glycerine as warmed up until temperature 60 o, and as in room temperature. During the processing of larval cyst cavity by hot glycerine the chitin membrane, germinal elements were exposed to full destruction. This indicates to the irreversibility of changes caused by this intervention; significant changes of fibrosis capsule testify about the deep penetrating and antiparasitic effects of glycerine. The structure of excretory capsules of protoscolex is significantly changed even in applying glycerine of room temperature. Morphological investigations showed that the influence of glycerine led to structure disorders of germinal elements of echinococcus .

English

In this study we tested the antiviral activity of a crude hot glycerine extract of Aloe vera gel which was grown in Bushehr (Southwest of Iran) against HSV-2 replication in Vero cell line. The extract showed antiviral activity against HSV-2 not only before attachment and entry of virus to the Vero cells but also on post attachment stages of virus replication. The IC50 before attachment and entry of virus to the cells is 428 µg/ml and the CC50 value which is the cytotoxicity of the extract for Vero cells is 3238 µg/ml, while the calculated selectivity index (SI) is 7.56. Also, IC50 of extract on post attachment stages of replication is 536 µg/ml and the SI value for inhibition of the post attachment stages of HSV-2 replication is 6.04. Therefore, compounds of Aloe vera from Bushehr could be a good candidate as a natural source for antiviral drug development against HSV-2.

Numerical simulations of a viscous-fingering instability in a fluid with a temperature-dependent viscosity

We have performed numerical simulations of the flow of hot glycerine as it displaces colder, more viscous glycerine in a radial Hele–Shaw cell. We find that fingering occurs for sufficiently high inlet velocities and viscosity ratios. The wavelength of the instability is independent of inlet velocity and viscosity ratio, but depends weakly on cell width. The growth rate of the fingers is found to increase with inlet velocity and decrease with the cell width. We compare our results with those from experiments.PACS No.: 47.54.–r

Viscous fingering with a single fluid

We study fingering that occurs when hot glycerine displaces cooler, more viscous glycerine in a radial Hele-Shaw cell. We find that fingering occurs for a sufficiently large initial viscosity contrast and for sufficiently high flow rates of the displacing fluid. The wavelength of the fingering instability is proportional to the cell width for thin cells, but the ratio of wavelength to cell width decreases for our thickest cell. Similar fingering is seen in numerical simulations of this system.PACS Nos.: 47.54.+r, 68.15.+e, 47.20.–k

Facilitated transport of ethene through Nafion membranes. Part II. Glycerine treated, water swollen membranes

A poly(perfluorosulfonic) ionomer membrane (Nafion N-117) was ion-exchanged with sodium, heated in glycerine and immersed in water to increase the water content from about 15 to about 55 weight %. When a sodium-exchanged membrane was heated dry and quenched prior to the swelling in hot glycerine, the water content was increased to about 67 weight %. Ethene fluxes versus ethene feed pressures were measured for both Na-membranes, and the effective diffusion coefficient for ethene was calculated from flux data. The Na-membranes were soaked in aqueous 2 M AgBF 4. The flux of ethene through the Ag-membranes obtained were measured at several feed partial pressures, and the flux data were used to estimate the equilibrium constant for the coordination of ethene to silver ions within the membrane and the effective diffusion coefficients for ethene. Separation of ethene from ethane with the highly water-swollen Nafion Ag-membranes was measured with a 1:1 mole ratio of ethene and ethane as feed at atmospheric pressure. The ethene flux corresponded to a permeability of 9700–12,500 barrer, and the separation factors obtained by the flux ratios were in the range of 500–540. For membranes which were soaked in aqueous 6 M AgBF 4, the ethene flux corresponded to a permeability of 26,800 barrer on average for a 1:1 mole ratio of ethene and ethane as feed at atmospheric pressure. The separation factor expressed by the flux ratios was 1950 on average.

Inactivation of enveloped viruses by anthraquinones extracted from plants

To determine the extent of antiviral activity present in a number of plant extracts, hot glycerin extracts were prepared from Rheum officinale, Aloe barbadensis, Rhamnus frangula, Rhamnus purshianus, and Cassia angustifolia and their virucidal effects were tested against herpes simplex virus type 1. All the plant extracts inactivated the virus. The active components in these plants were separated by thin-layer chromatography and identified as anthraquinones. A purified sample of aloe emodin was prepared from aloin, and its effects on the infectivity of herpes simplex virus type 1 and type 2, varicella-zoster virus, pseudorabies virus, influenza virus, adenovirus, and rhinovirus were tested by mixing virus with dilutions of aloe emodin for 15 min at 37 degrees C, immediately diluting the sample, and assaying the amount of infectious virus remaining in the sample. The results showed that aloe emodin inactivated all of the viruses tested except adenovirus and rhinovirus. Electron microscopic examination of anthraquinone-treated herpes simplex virus demonstrated that the envelopes were partially disrupted. These results show that anthraquinones extracted from a variety of plants are directly virucidal to enveloped viruses.

Facilitated transport of CO2 through highly swollen ion-exchange membranes: The effect of hot glycerine pretreatment

A pretreatment for perfluorosulphonic acid ion-exchange films, using glycerine and heating, causes the membranes to swell and imbibe greater (up to three-fold) amounts of water than obtained using standard membrane hydration techniques. The permeation of CO, CO 2 and H 2 S has been tested for these membranes in the diffusive transport mode and with carrier-mediated (facilitated) transport, using ethylenediamine (EDA). When compared to ‘normally’ hydrated membranes the results indicate that: 1, these membranes are up to 50% thicker; 2, have four to six times higher flux in both diffusive and facilitated transport; 3, maintain a high degree of facilitation for CO 2 and H 2 S; and 4, maintain similar selectivity versus non-carrier reactive gases as previously observed. Experimental results show the effects of pretreatment temperature on the CO 2 flux.

A comparative study of water boiling in a vertical tube under temperature-controlled or power-controlled boundary conditions

The Simulant Boiling Flow Visualization (SBFV) loop is an experimental facility where natural-convection boiling of water was accomplished in a transparent vertical tube by using hot glycerine; thus, direct observation was possible. As a result, heating was obtained through a temperature-controlled rather than a power-controlled boundary condition. To compare the SBFV data with previous experiments using a stainless steel test section and a power-controlled boundary condition, a comparative study of the effect on water boiling with the two different boundary conditions was performed. The computer program LOOP-W was used for this purpose. This program has been used successfully in analyzing data from the SBFV, and it was modified so that analogous cases could be run with the two different boundary conditions. The period and the amplitude of the oscillations calculated by the computer code using either boundary condition were essentially the same. Calculations also predicted the effect on the boiling process of using different test section materials (glass and stainless steel). Important differences were noted in the calculated periods and amplitudes. These calculations suggest that the SBFV loop can adequately simulate a power-controlled experimental facility.

Effect of rapid curing procedures on polymer implant materials

This investigation of standard curing methods for PMMA implants has demonstrated that alternate means of using the air oven may produce good strength properties along with a considerable degree of porosity, when desired, in a relatively short period of time. Curing of polymers in a pressure pot offers few advantages owing to the length of time required to produce, at best, equivalent strength for the porous materials. The method also poses dangers inherent in the use of superheated salt solution or hot glycerin. The autoclave is widely used in dental offices for sterilizing and will fully and consistently cure polymers within 30 minutes. The best properties for the PMMA resin were achieved with this method (61 MPa or 9,130 p.s.i., tensile strength). The microwave oven has become relatively inexpensive in recent years, and it offers time savings of up to 90 per cent which would be beneficial in implant dentistry or in dental laboratory procedures in general. The exact condition for curing particular polymers must be carefully determined to adjust the time of irradiation in order not to under- or overcure the polymer object. Curing polymers which contain intrinsic foaming agents under pressure conditions slightly reduced the total pore volume. But, pore volume and pore diameter in the large-bead polymers are determined predominantly by packing conditions, not curing conditions. Biologic tolerance to materials cured by these methods in primates is presently being evaluated.

RELATIONSHIP BETWEEN THE STRUCTURE AND THE SURFACE STATE OF THE SIMULTANEOUSLY BIAXIALLY STRETCHED POLY (ETHYLENE TEREPHTHALATE) FILMS

In this report, the orientation mode in the film plane and the relationship between the molecular structure and the surface state are discussed for the uniaxially stretched and simultaneously biaxially stretched poly (ethylene terephthalate) films prepared by wet-process.Sample films used in this study were the T-die extruded film with 140μ thickness. The uniaxial and the biaxial stretching of the films were done using a film-stretcher in a recirculating hot glycerin bath.The following results were obtained:(1) The crystalline orientation of simultaneously biaxially stretched films was random in the plane, however, that of two-way successively biaxially stretched films was selective to some extent.(2) The selective planar orientation parameter of the simultaneously biaxally stretched films was larger as compared with that of the uniaxially under constant width stretched films, in the machine direction and same stretch ratio.(3) The tautness-parameter of molecular chain in the simultaneously biaxially stretched films was smaller than in the two-way successively biaxially stretched films, but this tendency was reversed by the heat treatment under the fixed length.(4) The size of crystallite in the simultaneously biaxially stretched films was nearly equal in both the machine and the transverse directions.(5) On the electromicroscopic observation, the simultaneously biaxially stretched films with lower stretch ratio showed no charactristic surface structure, however, these films with higher stretch ratio represented the fibril-like structure.The molecular chain is locally uniaxially oriented in various directions in the plane, but the orientation is totally cancelled by averaging in the thickness direction which is due to the multilayer structure. That is, the simultaneously biaxially stretched films shows the uniplanar orientation.

A new synthetic fiber made of nylon 3

Nylon 3 fibers were produced by wet spinning, and properties and structures of the fibers were investigated. Fiber- and film-forming abilities of nylon 3 dopes in various coagulants, using various solvents, were investigated and it was found that only the nylon 3 spinning dope dissolved in formic acid showed excellent fiber- and film-forming abilities in coagulation baths of ethers, esters, or alcohols. As for mass transportation in these coagulants, solvent (formic acid) was diffused into coagulants, with scarce penetration of the coagulants into protofibers. This was due to the fact that these coagulants had moderate solubility parameter values and moderate proton-accepting power, which means the existence of some interaction between solvent and coagulants and no interaction between coagulants and polymer. Protofibers thus obtained were already crystallized and stretching them at room temperature was impossible. However, in such media as silicone oil, hot air, and Wood's metal, which were thought to have no interaction with polyamides, nylon 3 fibers were stretchable above their glass transition temperature (170°–180°C), while in such media as hot water, hot glycerin, and hot steam, which were thought to have some interaction with polyamides, nylon 3 fibers could not be stretched. Mechanical properties of nylon 3 fibers were as follow: strength, 2–3 g/d; elongation, 10%–20%; Young's modulus, 11 × 105–17 × 105 psi. High Young's modulus, high transition temperature, and high moisture regain are pointed out as characteristic features of nylon 3 fibers, compared with other synthetic fibers.

A new synthetic fiber made of nylon 3

AbstractNylon 3 fibers were produced by wet spinning, and properties and structures of the fibers were investigated. Fiber‐ and film‐forming abilities of nylon 3 dopes in various coagulants, using various solvents, were investigated and it was found that only the nylon 3 spinning dope dissolved in formic acid showed excellent fiber‐ and film‐forming abilities in coagulation baths of ethers, esters, or alcohols. As for mass transportation in these coagulants, solvent (formic acid) was diffused into coagulants, with scarce penetration of the coagulants into protofibers. This was due to the fact that these coagulants had moderate solubility parameter values and moderate proton‐accepting power, which means the existence of some interaction between solvent and coagulants and no interaction between coagulants and polymer. Protofibers thus obtained were already crystallized and stretching them at room temperature was impossible. However, in such media as silicone oil, hot air, and Wood's metal, which were thought to have no interaction with polyamides, nylon 3 fibers were stretchable above their glass transition temperature (170°–180°C), while in such media as hot water, hot glycerin, and hot steam, which were thought to have some interaction with polyamides, nylon 3 fibers could not be stretched. Mechanical properties of nylon 3 fibers were as follow: strength, 2–3 g/d; elongation, 10%–20%; Young's modulus, 11 × 105–17 × 105 psi. High Young's modulus, high transition temperature, and high moisture regain are pointed out as characteristic features of nylon 3 fibers, compared with other synthetic fibers.

HEAT TREATMENT OF NYLON 3 FIBERS AND WET SPINNING OF NYLON 3 COPOLYMER

In order to improve the mechanical properties of nylon 3 fibers, especially to increase tensile elongation, the heat treatment were investigated. By treating drawn nylon 3 fibers in such media as hot silicone oil and hot air which were thought to have no interaction with polyamides, elongational properties were not improved. However, by treating the drawn nylon 3 fibers in such media as hot water, steam and hot glycerine which were thought to have some interaction with poly amides, elongational properties were improved. Further, the effects of spinning conditions, especially drawing conditions on the elongational properties of heat treated fibers were investigated. With increased drawing temperature and draw ratio, shrinkage of nylon 3 in boiling water was decreased. From these results a mechanism of hot water treatment of nylon 3 fibers was proposed. Mechanical properties of nylon 3 fibers obtained by heat treatment were as follows: strength; 2-3g/d, elongation; 20-30% Young's modulus; 800-1200kg/mm2.The copolymerization of nylon 3 and its wet spinning were also investigated to improve the mechanical properties. Relations between mechanical properties of nylon 3 fibers and its copolymer composition of nylon 3 fibers were discussed.

DRY SPINNING OF NYLON 3 FIBERS

Dry spinning of nylon 3 was investigated for two samples of molecular weight of 90, 000 and 240, 000, using formic acid as solvents. With the polymer having molecular weight of 90, 000 filaments could not be wound continuously, while for the polymer of molecular weight of 240, 000 dry spinning was possible, and filaments could wound continuously. Thus the spinnability of spinning dope is thought important for dry spinning of nylon 3. Even for the maximum draft ratio (ratio of the winding speed to extrusion velosity), about 20 no chain orientation. was observed. Formic acid content in fibers was mainly controlled by spiuning temperature and by output of the dope, and was not affected by winding speed. Cross section of the fibers was dogbone-shaped for the polymer having molecular weight of 90, 000 and was extra-ordinal-shaped for the polymer of molecular weight of 240, 000. Dry-spun fibers could be drawn in such media as silicone oil and hot air, which were thought to have no interaction with polyamides, but in such media as hot water, steam and hot glycerine, which were thouget to have some interaction with polyamides, drawing was impossible, Relations between spinning conditions and properties of fibers are discussed.

The dry casting of viscose film

AbstractRegenerated cellulose film prepared by a dry‐cast method has demonstrated outstanding superiority over similar film produced by the conventional wet‐cast process. Factors contributing to the superior quality of film prepared by the dry cast process are: (1) physical properties several times greater than for wet‐cast film of corresponding thickness; (2) high durability at conditions of low temperature and low humidity even without the addition of softening agents, and (3) outstanding dimensional stability when exposed to conditions of varying temperature and humidity. The dry‐cast cellophane differs structurally from the commercial product in having a lower degree of order, a lower degree of swelling in the gel form, and minor differences in molecular orientation. A commercial process for producing dry cast cellophane may be envisioned as a heated, polished support for drying the viscose film; a regenerating system of alcoholic hydrochloric acid, hot glycerine, or a hot, oxygenfree gas; a water both for purifying the film; and a conventional cellophane dryer. The ideal viscose composition for producing dry‐cast cellophane is high cellulose content, moderately high DP, sufficient degree of substitution on the cellulose to yield a high degree of dispersion, and low caustic content.