Wataru Okumura

Direct Measurement of Fiber Temperature in the Continuous Drawing Process of PET Fiber Heated by CO2 Laser Radiation

Abstract Poly(ethylene terephthalate) (PET) fiber was heated by carbon dioxide laser radiation during the continuous drawing process. Numerical calculation shows that the PET fiber can be heated much more rapidly and uniformly by heat radiation than by convective heat transfer through the fiber surface. During CO2 laser heated drawing, temperature in the vicinity of a neck-like deformation can be measured on-line with high precision, because the neck-like deformation is located within a range of 0.5 mm. We measured the fiber temperature profiles on the drawing process by IR thermometer that has a range resolution of 0.355 mm. The temperature at which neck-like deformation of the fiber initiates is higher than Tg when draw ratio is less than 4.5, but lower than Tg when draw ratio is more than 5.5. The maximum fiber temperature in the drawing process increases with draw ratio, up to 208°C for a draw ratio of 6.0. The rate of orientation-induced crystallization in the drawing process was estimated by comparison of measured temperature profiles with calculated temperature profiles.

Diameter Profile Measurements for CO2 Laser Heated Drawing Process of PET Fiber

Abstract Poly (ethylene terephthalate) (PET) fiber was heated by carbon dioxide laser radiation in the continuous drawing process. By this procedure, the position of the deformation region could be fixed precisely in the air. The location of neck-like deformation fluctuated within a range of about 0.2 mm for draw ratios of 4.0 to 4.5 and within a range of about 0.5 mm for draw ratios of 5.5 to 6.0, but the location fluctuated over a range of 1.0 mm for a draw ratio of 5.0. Fiber diameter profiles, which were used to calculate Hencky strain rate profiles and apparent elongational viscosity profiles, were obtained from high-speed video camera images of the deformation region. Regardless of draw ratio, apparent elongational viscosity exhibited almost the same minimum value. Apparent elongational viscosity is much lower than the value obtained by measurement at a low, constant strain rate, but the elongational stress acting at the point where apparent elongational viscosity begins to increase steeply (Hencky strain of about 1.0) is of the same order of magnitude as the reported value. For draw ratios less than 5.0, the temperature where apparent viscosity is lowest is about 100 to 120°C, which corresponds to the flow temperature of amorphous PET, whereas for draw ratios exceeding 5.0 the temperature where apparent viscosity is lowest is about 80°C, which corresponds to the glass transition temperature. Thus, the former corresponds to so-called neck-like deformation typically observed in high-speed spinning, and the latter corresponds to necking typically observed in cold drawing. These two types of deformation appear in turns for a draw ratio of 5.0, and therefore the location of the deformation region fluctuates greatly. This measurement system can be used as a high-strain-rate elongational rheometer for analyzing practical polymer processing systems, which can easily measure the precise on-line deformation history with a time resolution in the μs level.

Formability of Braided CFRTP Cylindrical Pipe in Pipe Bending

Carbon fiber reinforced thermoplastic (CFRTP) is able to change a shape after molding by re-heating. By using the characteristic, we contrived a CFRTP pipe which can be re-shaped at an on-site, for example, in construction work or in earthwork. In this study, we estimated bend property of CFRTP pipe. The CFRTP pipes which had various Vf and braiding angle were prepared by using braid with commingled yarn, and by using low compression molding with heat shrink tube. The commingled yarn was composed of carbon fiber and polyamide12 fiber. The CFRTP pipes had 4 plies, 25mm of outside diameter, and 22mm of inside diameter. The CFRTP pipes were bent into U-shaped of radius 90mm, after heating 190°C. As the results, CFRTP pipe which had 40% of Vf and 50 degrees of braiding angle could be bent well without fold or void.

Fiber Structure Development and Mechanical Properties in Continuous Drawing and Annealing of Poly (phenylene sulfide) Filament

Poly(phenylene sulfide) (PPS) multi-filaments were continuously drawn and annealed. The maximum values of birefringence, crystallinity, tensile strength and Young′s modulus in the drawn and annealed PPS filament were 249×10−3 ‚ 27%, 5.3 cN/dtex and 64 cN/dtex‚ respectively. The orientation-induced crystallization was observed at 150×10-3 of birefringence. The crystal orientation factor f′ was estimated by wide angle X-ray diffraction. The λnet was estimated by the strain shifting of true stress - true strain curve to the master curve. The orientation estimated by the λnet differed from that estimated by birefringence. The fiber structure development and the mechanical properties of resultant fibers were discussed in terms of orientation parameters, which were birefringence‚ network draw ratio (λnet) and crystal orientation factor (f′). The birefringence shows a good correlation with the Young’s modulus. On the other hand, λnet shows a good correlation with the tensile strength. The f′ shows good correlations with both Young′s modulus and tensile strength‚ however‚ they tend to saturate at high f′. The melting temperature of PPS changed from 280.1oC to 288.7oC with the increase of birefringence and λnet.

High-performance Industrial Polypropylene Fiber produced with use of Laser-heated Drawing

Polypropylene fibers, prepared by melt-spinning of the resins which have various melt flow rates (MFRs), were drawn with the laser irradiation heating. As a result of WAXD measurements, it was revealed that the as-spun fibers made from the resin whose MFR less than 30 contains α crystal. Comparing with the same draw ratio, the higher tensile strength and Youngs modulus were obtained for the lower MFR. However, the maximum draw ratio was increase with the increase of MFR. Therefore, the maximum Youngs modulus of 156 cN/dtex was obtained from the highest MFR resin. In contrast, the maximum tensile strength of 9.59 cN/dtex was obtained for the fiber made of MFR11/MFR30 melt-blend. Moreover, the utility as the concrete pieces fall protection sheets was evaluated for the fabrics made by the drawn fiber. The punching load of 1.5 kN was obtained for the fabric of mock leno weave with the use of acryl resin adhesive.