摘要:
The temperature of a heat reservoir is varied according to a linear function which is AC modulated. At this time, the temperature difference between two points located in a heat flow path going from the heat reservoir to an unknown sample is measured. Also, the temperature difference between two points located in a heat flow path going from the heat reservoir to a reference sample is measured. These two pairs of points are arranged symmetrically. Then, the resulting signals are demodulated, and each signal is divided into an AC component and a low-frequency component. Using these signals, the DSC signal is separated into a heat capacity component and a latent heat component.
摘要:
Polybenzoxazole or polybenzothiazole polymer dopes are spun through a spinneret having an orifice density of more than 0.25 per cm.sup.2 to form filaments. The filaments formed then pass through an air gap which has a gas flowing into it at a temperature of between about 5.degree. C. to about 100.degree. C. and at a flow rate between about 0.1 meters/second and about 2.0 meters/second. The filaments cool in the air gap and are then coagulated. During or after coagulation the filaments are combined into one or more fibers. By this method of controlling the temperature in the air gap it is possible to stably spin polybenzoxazole or polybenzothiazole fibers at relatively high final line speeds.
摘要:
Polybenzazole polymer dopes are spun into fibers at high speed by passing through a spinneret with proper selection of hole geometry, followed by spin-drawing to a spin-draw ratio of at least 20, washing, taking up and drying. The take up speed is at least about 150 meters per minute, and the fibers are spun in at least 10 km lengths without a break.
摘要:
A process for producing polyester fibers having excellent tensile properties, particularly suitable as reinforcement material for tires, belts, etc., involves melt-spinning an ethylene terephthalate polyester to form highly oriented low crystalline polyester filaments which, at the state of being taken-up and prior to being drawn, having birefringence (.DELTA.n) and specific gravity (SG) within the below indicated ranges (a) and (b), and then, without winding-up, subjecting the said filaments immediately to drawing and heat treatment between the first godet rolls and second godet rolls under a draw ratio (DR) defined by the following formulas:.DELTA.n.gtoreq.5SG-6.64 (a).DELTA.n.gtoreq.0.100 (b)2.0.gtoreq.DR>1.0 (c)
摘要:
A sealed sample capsule for thermal analyzers comprises a vessel and a plug. Sample material to be analyzed is packed in the vessel, the plug is next pushed in upon the material and the upper end portion of the vessel is pressed inwardly to hold the plug in place sealing the capsule. The capsule has a remarkably high capacity to bear internal pressure and can be made of steel or iron which is not affected by such active material as mercury or gallium.
摘要:
To provide fibers which retain the excellent heat resistance and flame retardancy inherent in polybenzazole fibers and pyridobisimidazole fibers, have improved post-processability and neither necessitate considerable change in production process conditions nor require a high-temperature and long-time heating treatment. With respect to the polybenzazole fiber and pyridobisimidazole fiber, in an electron diffraction diagram of a surface layer part (from the surface to 1 μm) of the fibers, the fibers containing a crystal present in a state satisfying that S2/S1 is in a prescribed range, wherein S1 is a diffraction peak area derived from a crystal (200) plane and S2 is a diffraction peak area derived from a plurality of other crystal planes along an equatorial direction profile.
摘要:
There is provided a differential scanning calorimeter for exactly measuring a calorie variation of the measured sample on the basis of the temperature difference between sample container and the reference container without the influence of the heat irregularity incoming from the surroundings and the noise components. The differential scanning calorimeter includes a heating furnace of an approximately H-shaped section having an approximately drum-shaped wall part and an approximately plate-shaped heat inflow part, a heater disposed outside the wall part so as to heat the heating furnace, a approximately bar-shaped heat-resistance member that is arranged along the center axis L of the wall part, that protrudes from both sides of the heat inflow part by an approximately equal length, that is made of a material heat conductivity lower than that of the material of the heating furnace, a sample container disposed at one end of the heat-resistance member, a reference container disposed at the other end of the heat-resistance member, and a differential heat flow detector measuring a difference between the temperature of the sample container and the temperature of the reference container as a measured value.
摘要:
A high strength polyethylene filament having tenacity of at least 15 cN/dTex, which comprises a polyethylene having a weight-average molecular weight of 300,000 or less and a ratio of a weight-average molecular weight to a number-average molecular weight (Mw/Mn) of 4.0 or less as determined in a state of the filament, and containing 0.01 to 3.0 branched chains per 1,000 backbone carbon atoms. When cut fibers are obtained by cutting the polyethylene filament, a rate of dispersion-defective fibers is 2.0% or less.
摘要:
In a process for preparing polybenzoxazole or polybenzothiazole filaments by extruding a polybenzoxazole or polybenzothiazole dope, drawing the dope filament across an air gap, and coagulating the dope filament; the number of filament breaks can be reduced by placing a stress isolation device after extruding but before coagulating the filament.
摘要:
A system for determining photo-chemical reaction heat evolved from a sample material irradiated with radiant energy comprises a calorimeter having a pair of sample holders connected to heat-leakage type thermo-electric elements which develop electric output signals proportionate to the amount of heat energy conducted therethrough. Both sample holders are initially irradiated with radiant energy before disposing the sample material thereon to heat the sample holders and thereby develop electric output reference signals. The amount of radiant energy being irradiated on at least one of the sample holders is then selectively adjusted to effectively compensate for any difference between the two reference signals. Then the sample material is mounted on at least one of the sample holders and both sample holders are irradiated with the adjusted radiant energy thereby enabling determination of the exothermic or endothermic heat value generated by the sample material due to the photo-chemical reaction heat evolved therefrom in accordance with the difference in the electric output signals developed by said thermo-electric elements.