Nylon Substrate Research Articles

Ultrasound-assisted pressureless infiltration of molten aluminium into alumina capillaries

The wettability between molten metal and reinforcement significantly affects the characteristics and the productivity of metal-matrix composites (MMCs) fabricated by pressure casting, which is one of the promising methods to produce MMCs. In wetting composite systems, full infiltration into fibre or particulate preforms can be achieved without an external applied pressure, and non-infiltrated defects are then inhibited from appearing at contact points of reinforcement. However, most composite systems strengthened with ceramic reinforcements are unfortunately known to be non-wetted. A variety of methods to improve the wettability have been studied vigorously: addition of appropriate alloying elements to molten metal matrix [1, 2], surface treatment on reinforcements [3, 4] and the optimum selection of processing parameters such as a molten metal temperature [5]. These are chemical approaches that reduce the contact angle by changing the balance of interfacial energies between the molten metal, reinforcement and atmosphere. In contrast, a water droplet on the nylon substrate vibrated with 200-800 Hz was found to reduce its contact angle compared with that on the stationary substrate [6]. In order to realize full infiltration with an extremely low applied pressure in non-wetted composite systems, it was aimed to improve the apparent wettability between molten metal and ceramic reinforcement by ultrasonic vibration as a physical approach. The ultrasonic vibration system consisted of a Langevin-type Pb(ZrxTil_x)O3 oscillator and a titanium step-horn. The resonant frequency (f) of 20.5 kHz was measured by an impedance analyser with the step-horn end immersed in molten aluminium. Ultrasonic vibration was transmitted into molten aluminium through a direct contact of the step-horn and melt. TiB2 was coated on the tip of the step-horn by a spark coating method, so as to avoid the dissolution of titanium into molten aluminium. The longitudinal amplitude (bu), which was measured at the end-surface of step-horn by an optical displacement sensor, was affected by the ultrasonic power (Iu). The f and I~ reported below are the values measured in an immersed state, unless otherwise stated. oi-A120 3 capillaries with inside diameter 0.80 mm and length 15 mm were supplied for the infiltration

Photoelastic Stress Analysis of Bonded Lap Shear Joints Having Thermoplastic Adherends

Abstract The effects of substrate stiffness and modulus on joint strength and stress distribution were investigated for a series of nylon substrates bonded with an epoxy adhesive. Substrate stiffness and modulus were controlled by the level of glass filler in the resin. Single lap shear samples having both identical (“self-bonded”) and dissimilar (“cross-bonded”) substrates were investigated. For the self-bonded samples, lap shear strength was found to increase with increasing substrate modulus and stiffness. The strengths of the cross-bonded samples were intermediate to the strengths of the corresponding self-bonded samples. Photoelastic techniques were used to observe stress patterns in the lap joints during testing. One type of stress pattern was observed for all self-bonded samples regardless of substrate stiffness. Two patterns, one for the stiff substrate and one for the more flexible substrate, were observed for cross-bonded samples. The photoelastic analysis agreed qualitatively with predictions o...

Culture patterns and sorting of rat Sertoli cell secretory proteins.

A cocultivation chamber and two types of permeable substrates have been used to study: (1) the culture patterns of rat Sertoli and peritubular cells, and Sertoli cells cocultured with spermatogenic cells or peritubular cells; and (2) the polarized secretion of Sertoli cell-specific proteins transferrin, S70 and S45-S35 heterodimeric protein. Substrates included a nylon mesh (with openings of 100 micron) coated with extracellular matrix (ECM) material and an uncoated microporous filter (with pores of 0.45 micron). Sertoli cells cultured on ECM-coated nylon mesh organized a continuous sheet of multilayered epithelial cells essentially devoid of spermatogenic cells while peritubular cells formed a layer of squamous cells. Sertoli cells cultured on uncoated microporous substrate formed a continuous sheet of cuboidal epithelial cells with numerous basal cytoplasmic processes projecting into the substrate and abundant apically located spermatogenic cells, while peritubular cells organized one or two layers of loose squamous cells. [35S]methionine-labelled secretory proteins resolved by two-dimensional polyacrylamide gel electrophoresis and autoradiography displayed cell-specific patterns that were slightly influenced by the type of substrate. Sertoli cells cocultured with peritubular cells on uncoated microporous substrate under conditions that enabled separation of apical and basal surfaces, secreted proteins in a polarized fashion. While transferrin was released bidirectionally, S45-S35 heterodimeric protein was released apically. S70 was detected in both apical and basal compartments. We conclude from these studies that: (1) the number of spermatogenic cells decreases when Sertoli-spermatogenic cell cocultures are prepared on ECM-coated nylon substrate; and (2) Sertoli cells in coculture with spermatogenic or peritubular cells on uncoated microporous substrate, organize continuous sheets displaying polarized protein secretion.

Photolytic Behavior of Some Popular Disperse Dyes on Polyester and Nylon Substrates

The photodegradation products that form when disperse red 1, red 17, and blue 3 dyed fabrics and films are exposed to carbon arc and xenon arc light sources have been identified. The effects of black panel and dye carrier on the nature of the deg radation products and the fading process itself were also studied. The results of this research indicate that the same photodegradation products occur in comparisons in volving carbon arc versus xenon arc exposures, polyester versus nylon substrates, black panel versus no black panel exposures, and exposures of carrier dyed versus no carrier dyed PET. It is clear that photo-reduction pathways account for the products that form when the two azo disperse dyes (red 1 and red 17) photofade, but photo oxidation characterizes the fading of the anthraquinone disperse dye blue 3. The pho todegradation products were determined with the aid of GC mass spectrometry and by TLC comparisons with authentic samples.

Transport of acid dye in nylon and concentration dependence of the diffusion coefficient

The dyeing kinetics of an acid dye (C. I. Acid Blue 40) in a nylon 6 film were investigated using partition-cell and film-roll methods at 80°C and pHs 2.3 and 3.05. The concentration dependence of diffusion coefficient of the dye in the nylon substrate measured by both methods was interpreted in terms of parallel diffusion with biomodel sorption of the Nernst and Langmuir modes. As the concentration of dye increases, the transport of dye inside the nylon film becomes dominated by pore diffusion and surface diffusion of sorbed Nernst populations.

Evaluation of the gas transfer characteristics of porous copolyurethane oxygenator membranes

Porous copolyurethane membranes were prepared by solvent casting thin polymer films onto fibrous substrates. Pore size, water filtration rates, and gas transmission rates were measured to determine the influence of substrate, polymer type, and coating thickness on the membrane properties in the dry and wet state. Cellulosic substrates were not as satisfactory as were polyethylene, polyester, or nylon substrates. Porous membranes formed on these latter substrates had gas transfer rates similar to silicone rubber membranes. Although O2 transfer was similar to Gore-Tex and Celgard, CO2 transfer was less, apparently due to fewer pores in the copolyurethane membranes and possible wetting of the pores by water.

Preliminary data on size composition and settlement ofDreissena polymorpha (Pallas) (Mollusca: Bivalvia) in lakes differing in trophic state

Size composition of colonies and settlement of larvae on nylon substrates as function of depth inDreissena polymorpha demonstrated differences in three lakes of different trophic state. In one lake, the data on size distribution in the colony and of the settled larvae also differed. The explanation requires further research.

Comparative determination of bromine and iodine in three air sampling media via instrumental thermal and epithermal neutron activation analysis

A comparative determination of bromine and iodine in three distinct air sampling media by instrumental thermal and epithermal neturon activation analysis is presented. Open ocean air samples from the mid-Atlantic region were collected on ultra-pure nylon, Nuclepore, and activated charcoal substrates. The bromine and iodine content of each substrate was determined by both epithermal and thermal activation techniques. Good agreement was found within most thermal-epithermal pairs. Relative to the thermal activation procedure, the epithermal technique yields peak/background ratio improvements ranging from a factor of 1.30 to 9.5. Nylon substrates showed the smallest improvement at 1.30 and both Nuclepore and activated charcoal substrates showed improvement factors of 6.7 and 9.5 for bromine and iodine respectively.

Temperature dependence of the fading of basic dyes on acrylic and nylon substrates

The effect of temperature on the fading of two basic dyes on acrylic, poly(vinyl alcohol) and nylon substrates has been studied. Arrhenius plots of initial quantum yields of dye fading gave straight lines with nylon as substrate, curves with pronounced inflection points with acrylic, and intermediate behaviour with poly(vinyl alcohol). It was concluded that the less ordered regions of acrylic substrates have such a compact structure, under normal temperature and atmospheric conditions, that the possible conformational and diffusional processes which might normally contribute to dye fading are very restricted, thus ensuring a high resistance to fading. No such restrictions apply with nylon under the same conditions.

Azide Reactive Dyes

Reactive dyes containing a sulphonylazide group can undergo fixation on nylon substrates by two different mechanisms. Under aqueous dyeing conditions, at or below 120d̀ C, the free amino end‐groups of the polymer attack the sulphonylazide group with displacement of azide ion, and results in attachment of the dye to the substrate by a sulphonamide linkage. In contrast, if the dyed substrate is subjected to dry heat fixation at 170d̀ C, the azide group decomposes to a sulphonylnitrene species which undergoes insertion into C‐H bonds of the polymer. The dye is again attached by a sulphonamide bridge, but in this case the amount of dye that can be fixed is independent of the amino end‐group content of the polymer.