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We experimentally discussed the effects of airflow geometries in an air suction gun on the suction characteristics of running yarn. Geometry parameters focused on were 1) compressed-air inflow angle of nozzle, 2) diverging angle of nozzle, 3) throat diameter of de Laval tube, 4) converging angle of de Laval tube and 5) yarn propulsion tube length. As a result, effects of the geometry parameters on the yarn suction force, the mass flow rate of compressed-air and the yarn suction efficiency, which is defined as the yarn suction force divided by the mass flow rate of compressedair, were made clear and the optimum geometry of an air suction gun was obtained on the basis of the energy efficiency. In addition, the yarn suction force showed two types of time dependency because of different yarn motion on some experimental conditions.

This study investigates the preparation, characterization, and mechanical properties of nanocomposites prepared from poly(lactic acid) (PLA), an organoclay, hereafter referred to as Clay, and poly(-caprolactone) (PCL) by melt compounding in a co-rotating type, twin screw extruder. The molecular weight of the PCL used was 10K, 40K, or 70 -100K. Tensile test data show that the Young's modulus of the PLA/Clay nanocomposite was about 19% higher than that of neat PLA. The tensile strength of the PLA/PCL(10K and 40K)/Clay nanocomposites was about 17% higher than that of neat PLA. On the other hand, the tensile strength of the PLA/PCL(70 -100K)/Clay sample was about 7% lower than that of neat PLA. The elongation of the PLA/PCL/Clay composite also improved. The effect of d-spacing, resulting from adding PCL to the PLA/Clay nanocomposite, depends on the molecular weight of the PCL. The size of the clay agglomerates in the PLA/PCL/Clay nanocomposites is larger than those found in the PLA/Clay. Furthermore, the thermal stability of the PLA/Clay nanocomposite increases with the addition of PCL. On the whole, PCL(10K) was found to be the best additive for PLA/ Clay nanocomposites. POLYM. ENG. SCI., 46:1001-1007, 2006.

Poly(lactic acid) (PLA)/organoclay nanocomposites were prepared by melt compounding in a co‐rotating twin screw extruder. Two types of commercialized organoclay (dimethyl benzyl stearyl ammonium ion and dimethyl distearyl ammonium ion intercalated between clay platelets named as Clay A and Clay B, respectively) and two grades of poly(ethylene glycol) (PEG) with different molecular weight (Mw = 2,000 and 300,000–500,000 named as PEG2k and PEG500k, respectively) were used in this study. The Young's modulus improved by the addition of organoclay to PLA matrix. The Young's modulus decreased with the addition of PEG to PLA/organoclay nanocomposites. The tensile strength and elongation of PLA/Clay B nanocomposites increased with the addition of PEG2k. The effect of the addition of PEG on d‐spacing of PLA/organoclay nanocomposites is dependent upon the kind of organoclay. The sizes of clay agglomerations in PLA/PEG/organoclay nanocomposites are larger than those of PLA/organoclay ones in the same organoclay. Addition of PEG to PLA/organoclay nanocomposites during melt compounding will not be useful for the preparation of PLA/organoclay having fully exfoliated clay platelets. The shear thinning properties of the nanocomposites are independent of the addition of PEG. On the whole, PEG2k is good plasticizer for PLA/organoclay nanocomposites. POLYM. COMPOS. 27:256–263, 2006. © 2006 Society of Plastics Engineers

This study analyzes the effect of different screw rotating speeds on the clay dispersion and mechanical properties of nanocomposites prepared by melt compounding polylactic acid (PLA) with an organoclay in a co‐rotating twin screw extruder. Polyamide 12 (PA12) was used as an additive. Two different screw rotating speeds, 65 rpm and 150 rpm, were used in this study. According to the tensile strength data, the Young's modulus of the PLA/clay nanocomposites showed improvement at a screw rotating speed of 150 rpm. The Young's modulus improved with the addition of the organoclay to PLA matrix, but decreased when PA12 was added to the PLA matrix. The tensile strengths and elongations become small by adding organoclay to PLA matrix. The tensile strengths of the PLA/organoclay nanocomposites increased for the higher screw rotating speed (150 rpm). The d‐spacing of PLA/PA12/Clay nanocomposites was independent of the addition of PA12. The size of the clay aggregates in the PLA/PA12/Clay nanocomposites is smaller than that of PLA/Clay. Furthermore, the thermal stability of the PLA/Clay nanocomposite increases with addition of PA12, while on the whole, it had little influence on the tensile properties. POLYM. COMPOS., 29:1–8, 2008. © 2007 Society of Plastics Engineers

This study deals with the effect of cross-sectional shape of yarn duct of interlacer on the performance of interlaced yarn and aims at finding the interlacers with better performance. The performance of the interlaced yarn is evaluated by the number and strength of tangles. Seven interlacers with different shapes of yarn duct were designed. Each of them has the same cross-sectional area of yarn duct. Experiments were carried out at various supplied air pressures, yarn speeds and feed ratios. We have found that the interlacer with round cross-sectional shape of yarn duct is capable of producing an interlaced yarn with a large number of tangles and the cornered cross-sectional shape is effective in improving the strength of tangles. Among these seven interlacers, the interlacer with an elliptical or an inverse-triangular shape has the best processing performance. And the interlacer with a square cross-sectional shape has the worst processing performance.

ABSTRACT:We discuss the effect of screw rotation speed on the mechanical and rheological properties and clay dispersion state of polystyrene (PS)/organoclay (clay) nanocomposites prepared by melt compounding with a counterrotating-type twin-screw extruder. Poly(styrene-co-vinyloxazolin) (OPS) was used as an additional material. The Young's modulus of the PS/OPS/clay nanocomposites showed the maximum value at a screw rotation speed of 70 rpm in this study. This implied the existence of an optimized screw rotation speed for the melt compounding of the polymer/clay nanocomposites. For PS/clay systems without the addition of OPS, the peak intensity from clay increased and the distance between clay platelets in the nanocomposites decreased with the screw rotation speed. On the other hand, inverse results were obtained for PS/OPS/clay systems.According to the transmission electron microscopy photographs, the PS/OPS/clay nanocomposite at 70 and 100 rpm had fully exfoliated clay platelets. The dynamic rheological properties of the PS/clay nanocomposites were almost the same as those of neat PS. On the other hand, the storage and loss moduli of the PS/OPS/clay nanocomposites at the same frequency were larger than those of the PS/clay system. On the whole, the bonding between clay platelets and PS was important for increasing the viscosity and elasticity in the melts of the PS/clay system.

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