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Draw Ratio (draw + ratio)
Selected AbstractsRheological, morphological, mechanical, and barrier properties of PP/EVOH blendsADVANCES IN POLYMER TECHNOLOGY, Issue 3 2001Jong Ho Yeo Using the biaxially oriented film process, polypropylene (PP)/ethylene-vinyl alcohol copolymer (EVOH) blends with an improved barrier property could be obtained by generating a laminar structure of the dispersed phase in the matrix phase. This laminar morphology, induced by biaxial orientation, was found to result in a significant increase in the oxygen barrier property of PP/EVOH (85/15) blends by about 10 times relative to the pure PP. In this study, compatibility in the PP/EVOH blend system was evaluated by investigating the influence of compatibilizer on the rheological, morphological, and mechanical properties of the blends. In addition, the effects of compatibilizer content, draw ratio, and draw temperature on the oxygen permeability and morphology of biaxially drawn blend films were also studied. It was revealed that an optimum amount of compatibilizer, maleic anhydride grafted PP, should be used to improve the barrier property of the PP/EVOH blends with a well-developed laminar structure. The draw ratio and draw temperature had a significant influence on the permeability of the blends. The blend films exhibited a more pronounced laminar structure when the blends were stretched biaxially under processing conditions of higher draw ratio and draw temperature, resulting in higher barrier properties. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 191,201, 2001 [source] Studies on , to , phase transformations in mechanically deformed PVDF filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Vijayakumar R. P. Abstract PVDF cast films were drawn at different temperatures to different draw ratios at constant draw rate to understand the mechanism of , to , phase transformation during mechanical deformation. WAXD and FTIR studies were carried out to determine the formation and content of , phase in the drawn films. Lower stretch temperatures gave higher fractions of , phase. The cast PVDF films were also drawn at suitable temperatures below the PVDF ambient melting point to the draw ratio of 6.4. The highest fraction of , phase obtained in these ultra drawn films was 0.98. SALS studies carried out for films at different stretch ratios show the change in spherulitic structure with the stretching parameters and give information for the understanding of phase transformation during stretching of PVDF films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of process parameters on properties of wet-spun poly(L,D -lactide) copolymer multifilament fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2009Marja Rissanen Abstract Poly(L,D -lactide) [P(L,D)LA], LL/D ratio 96/4, and poly(L,DL -lactide) [P(L,DL)LA], L/DL ratio 70/30, multifilament fibers were prepared by wet-spinning and the effects of the spin draw ratio and the coagulant on the morphological, thermal, and mechanical properties of the filaments were studied. The hydrolytic degradation of filaments was studied in vitro. The filament diameter and the mechanical properties of filaments were highly dependent on the spin draw ratio, whereas the coagulant had no or minor effect. The filament diameters were in the range of 11,36 ,m and the maximum tenacity of 150 MPa was obtained at the spin draw ratio of 7.0 for both copolymers. The copolymer had the main importance on the crystallinity of filaments, but it was also affected by the duration of the coagulation process. The crystallinities of P(L,D)LA 96/4 filaments were in the range of 5,16%, whereas P(L,DL)LA 70/30 filaments were totally amorphous. The degree of crystallinity had effect on the hydrolytic degradation of filaments. The tenacity loss of P(L,D)LA 96/4 filaments was about 10% and that of P(L,DL)LA 70/30 filaments was as high as 50% after 24 weeks in vitro. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Study of PET/PP/TiO2 microfibrillar-structured composites, part 1: Preparation, morphology, and dynamic mechanical analysis of fibrillized blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Wenjing Li Abstract The objective of this study was to manufacture and investigate a novel microfibrillar-reinforced material based on fibrillized blends of polyethyleneterephthalate (PET), polypropylene (PP), and TiO2 nanoparticles (300 nm and 15 nm in size). The uncompatibilized and compatibilized blends (polypropylene grafted maleic anhydride as compatibilizer) were extruded and subsequently cold-drawn into strands with a draw ratio of 10. The effects of compatibilizer and TiO2 particles on the structure and properties of drawn strands were investigated. Upon addition of compatibilizer, the preferential location of TiO2 particles shifted from the PET-dispersed phase to the PP matrix, which brought about different structures of the drawn strands. Differential scanning calorimetry study provided indications for a heterogeneous nucleation effect of the PET fibrils on the PP matrix and of the TiO2 particles on the PET fibrils. Dynamic mechanical analysis demonstrated that the mechanical properties of the drawn strands are strongly dependent on the strand structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Structure,properties relations of the drawn poly(ethylene terephthalate) filament sewing threadJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Andreja Rudolf Abstract This article presents research into draw ratio influence on the structure,properties relationship of drawn PET filament threads. Structural modification influence due to the drawing conditions, i.e., the birefringence and filament crystallinity, on the mechanical properties was investigated, as well as the shrinkage and dynamic mechanical properties of the drawn threads. Increasing draw ratio causes a linear increase in the birefringence, degree of crystallinity, filament shrinkage, and a decrease in the loss modulus. In addition, loss tangent and glass transition temperature, determined at the loss modulus peak, were increased by drawing. The observed structural changes influence the thread's mechanical properties, i.e., the breaking tenacity, elasticity modulus, and tension at the yield point increase, while breaking extension decreases by a higher draw ratio. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and characterization of poly(butylene terephthalate)/mica nanocomposite fibers via in situ interlayer polymerizationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Jin-Hae Chang Abstract Intercalated nanocomposites consisting of poly(butylene terephthalate) (PBT) incorporated between mica layers were synthesized from dimethyl terephthalate (DMT) and 1,4-butanediol (BD) by in situ interlayer polymerization. PBT nanocomposites of varying organoclay content were melt-spun to produce monofilaments. The samples were characterized using wide angle X-ray diffraction, electron microscopy, thermal analysis, and tensile testing. Some of the clay particles were found to be well dispersed in the PBT matrix, but other clay particles were agglomerated at a size level greater than approximately 20 nm. The glass transition temperatures (Tg) and the thermal degradation properties (TDi) of undrawn PBT hybrid fibers were found to improve with increases in the clay content. At draw ratio (DR) = 1, the ultimate tensile strengths of the hybrid fibers increased with the addition of clay up to a critical content and then decreased. However, the initial moduli monotonically increased with increases in the amount of organoclay in the PBT matrix. The ultimate strengths were found to decrease linearly with increases in DR from 1 to 18. In contrast to the trend for the tensile strengths, the initial moduli of the hybrid fibers increased only slightly with increases in DR up to 18. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Draw ratio enhancement in nonisothermal melt spinningAICHE JOURNAL, Issue 3 2009Balram Suman Abstract Nonisothermal melt spinning of materials having a step-like viscosity variation with temperature is studied in this work. A set of nonlinear equations is used to describe the fiber behavior and to obtain the draw ratio, the square of the ratio of the fiber diameter at the entrance to that at the exit of the fiber-spinning device. The fluid-flow equation is based on a slender-jet approximation, and external heating and cooling have been accounted for with a one-dimensional model in order to obtain the fiber temperature and viscosity along the fiber length. The model is similar to that used by Wylie et al. (J Fluid Mech. 2007;570:1,16) but accounts for inertia, shear stress at the fiber surface, surface tension, gravity, cooling, and larger heating rates. Steady-state analysis reveals that the draw ratio increases with an increase in the pulling force, passes through a maximum, and then starts increasing again, resulting in three possible pulling forces for the same draw ratio. However, linear stability analysis reveals that depending on the strength of heating and/or cooling, at most two of the steady states are stable. The stability analysis also predicts complicated oscillatory and nonoscillatory dynamical behavior as the pulling force varies. Nonlinear simulations reveal that an unstable system always tends to limit-cycle behavior. Systems predicted as stable by the linear stability analysis are also stable for large-amplitude perturbations. External heating is found to dramatically enhance the draw ratio of the melt-spinning process. The addition of a cooling section suppresses the draw ratio, but this can be compensated for with a higher heating strength. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Morphology and Properties of Polyethylene/Clay Nanocomposite Drawn FibersMACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2008Francesco Paolo La Mantia Abstract The influence of an elongational flow on the morphology of PE/clay nanocomposite drawn fibers was studied. An increase of the elastic modulus and the tensile strength as well as a decrease of the elongation at break are observed with increasing draw ratio. The applied elongational gradient orients the polymer chains and the clay particles along the spinning direction. When the applied flow results in the formation and the orientation of exfoliated nanoparticles, a pronounced increase of the mechanical properties is observed. The dispersed clay particles can be broken and oriented by the extensional flow, which might indicate a flow-induced intercalated/exfoliated morphology transition. [source] Preparation and characterization of nylon 6/organoclay nanocomposite filament fibersPOLYMER COMPOSITES, Issue 3 2009Kap Jin Kim A series of nylon 6 (NY6)/organoclay nanocomposites were prepared via in situ polymerization of ,-caprolactam in the presence of 1,2-aminododecanoic acid-intercalated montmorillonite (ADA-MMT) organoclay (1,5 wt%) using 6-aminocaproic acid as polymerization catalyst. The extent of organoclay dispersion in NY6 matrix was analyzed using WAXD and SEM measurements. DSC studies revealed marginal shift in melting and melt-crystallization peaks toward lower temperature with increasing clay content. Melt viscosity studies for NY6/ADA-MMT exhibited higher shear-thinning behavior than neat NY6 probably due to the slip between NY6 matrix and exfoliated organoclay platelets during shear flow. The prepared nanocomposites were melt-spun and studied for their property improvements against varying clay content, draw ratios, and annealing conditions. Birefringence and sonic velocity values increased initially at lower draw ratios (,2.5) due to increased orientation of molecular chains along the drawing direction but saturated at higher draw ratio (3.0) for all the samples. At the same draw ratio; compared to neat NY6, NY6/organoclay fibers showed increased chain orientation along the drawing direction which can be attributed to the "tethering effect" of organoclay on NY6 matrix. The initial modulus and stress at break were sensitive to factors such as draw ratio, clay content, and annealing conditions. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Self-reinforced polypropylene/LCP prepregs and laminatesPOLYMER COMPOSITES, Issue 5 2002Y. C. Liang Polypropylenes (PPs) of various molecular weights were mixed with a thermotropic liquid crystal polymer (LCP) to prepare unidirectional sheets (prepregs), quasi-isotropic and unidirectional laminates. The mechanical properties and the morphology of the prepregs and the laminates at 0° and 90° with respect to the machine direction were investigated as a function of draw ratio, LCP concentration and molecular weight of the PP. The results for prepregs and laminates showed that both drawing and LCP concentration generally enhanced modulus and tensile strength in machine direction. The morphology of LCP changed from spherical or ellipsoidal droplets to elongated fibrils as the draw ratio increased. The diameter of LCP fibrils decreased with increasing molecular weight of the PP matrix, indicating more effective droplet breakup and better mixing in the case of high molecular weight PP. [source] Orientated crystallization in drawn thermoplastic polyimide modified by carbon nanofibersPOLYMER ENGINEERING & SCIENCE, Issue 2 2009Valentina E. Smirnova The solid state crystallization in drawn thermoplastic polyimide films is studied as a function of draw ratio (DR) under the effect of vapor grown carbon fiber nanoinclusions. The nucleating effect of the nanoinclusions coupled with the orientation effect of drawing generates a unique orientated layered lamellar structure, characteristic of smectic-like mesophase. The degree of draw induced orientated crystallization increases with the content of nanoinclusions and with the DR, and is reflected in the mechanical behavior of the film. Generally, the Young's modulus and the yield point of the drawn crystalline films in the drawing direction are significantly higher compared with the noncrystalline counterparts. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers [source] Influence of post-extrusion parameters on the final morphology of polystyrene/high density polyethylene blendsPOLYMER ENGINEERING & SCIENCE, Issue 10 2003H. Padilla-Lopez The deformation of the dispersed phase in polystyrene/high density polyethylene (PS/HDPE) blends produced by ribbon extrusion was studied numerically and experimentally. A mathematical model for the deformation of the dispersed phase in ribbon extrusion processing of polymer blends was developed assuming uniaxial deformation of the ribbon and the equilibrium shapes of the dispersed particles with a pressure balance over a drop. Simulated morphologies as function of the post-extrusion parameters were obtained and compared with experiments. The analysis of the ribbon extrusion process showed that parameters such as draw ratio (DR) and ribbon-water contact length (X) significantly influence the ribbon dimensions, the extensional stress, and the stretching force. The results also showed that deformation and coalescence of the dispersed phase in the ribbon extrusion processing of polymer blends increase at higher DR and/or lower X values. The comparison between the model and the experimental morphologies of PS/HDPE produced a good agreement. [source] Microstructural effects on hot drawing syndiotactic styrene P-methyl styrene copolymerPOLYMER ENGINEERING & SCIENCE, Issue 10 2001R. J. Yan Crystalline syndiotactic styrene/p-methyl styrene copolymer (SPMS) has been oriented by tensile drawing at various temperatures between the glass transition and crystalline melting point. The microstructural changes resulting from drawing have been studied using differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). WIth increasing draw temperature, both melting temperature and crystalline dimensions of the oriented samples increase. The heat of fusion increases with increasing draw temperature up to ,200°C. It also increases with draw ratio and draw rate, while the crystalline width increases only with draw ratio. THe amorphous fraction shows a clear glass transition, the temperature of which (Tg) increases with draw ratio. However, Tg decreases somewhat with increasing draw temperature. This is interpreted in terms of the stretching of the randomly coiled amorphous phase molecules. [source] Structure and performance of impact modified and oriented sPS/SEBS blensPOLYMER ENGINEERING & SCIENCE, Issue 4 2001R. J. Yan Blends of syndiotactic styrene/p-methyl styrene copolymer (SPMS) and poly (styrene)-block -ploy(ethene-co-butylene)-block-polystyrene (SEBS) as well as theiruniaxial drwing behavior andd performance were investigated. Mixing was performed using a batch mixer at 280°C. Morphology was evaluted using scanning electron microscopy (SEM).Thermal properties, orientation and tensile properties were determined using differential scanning calorimetry (DSC), the spectrographic birefringence technique, and a tensile testing machine, respectively. The blends of SPMS/SEBS, 90/10 and 80/20 showed a two-phase structure with an SEBS disperse phase in SPMS matrix. The average sizes of the SEBS paticles and tensile properties of the blends were affected by blending time and compositions. No significant effects on the modulus and strength were observed for the blends containing 10%SEBS or below. The quenched SPMS and SPMS/SEBS (90/10) blends were drawn at 110°C. and their crystallinity and orientation development compared. These were similar for both samples at low draw rations (<3.2), but were much faster for SPMS at higher draw ratios. The orientation process is shown to substantially invrease the strength and modulus in the drawing direction for SPMS and the blends. The toughness (energy under the stress-strain curve) increased upon addition of SEBS and orientation, with a marked effect of the latter. SEM observation reveals that the dispersed SEBS has been extended to about the same draw ratio as the bulk blend in the drawn blends, indicating effcient stress transfer at the interface. [source] Compatibilized poly(ether imide)/LCP blends: drawing ability and mechanical properties of the ribbonsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2002F. J. Vallejo Abstract The effects of the addition of polyarylate (PAr) on the drawing ability of poly(ether imide) (PEI)/Rodrun liquid-crystalline 5000 (Ro LC5000) (Ro) blends and on the mechanical properties of their ribbons were studied. The compatibilizing effect of the PAr led to an increase in the drawing ability of the blends, as seen by the fact that the maximum Ro content compatible with the drawing process increased from 15 to 30%. This may lead to new applications in the field of gas barrier materials. The presence of PAr also led to an increase in the adhesion between the two phases of the blends and consequent improved ductility. However, the very high modulus of elasticity and tensile strength in the direction of orientation (up to three-fold those of the matrix) due to the less developed fibrillation were smaller than the corresponding values before compatibilization. These very large modulus of elasticity and tensile strength values and those perpendicular to the direction of orientation, which were similar to those of the matrix, led to a high anisotropy in the extruded ribbons that increased with the draw ratio (DR) and the Ro contents. The high mechanical properties of the ribbons may be used and the anisotropy diminished by layering the ribbons in, and perpendicular to, the direction of orientation, according to the expected external load. Copyright © 2002 John Wiley & Sons, Ltd. [source] Properties of uniaxially stretched polypropylene filmsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008Farhad Sadeghi Abstract Polypropylene (PP) films have been prepared through two different cast extrusion processes: one using a machine direction orientation (MDO) unit and the other stretching the films at the die under high cooling conditions (lab unit). Films for two PP resins different in molecular structure have been prepared using both processing techniques. The effect of the resin structure and the processing conditions on the film properties has been examined. It was found that the MDO unit generated a highly oriented fibrillar crystalline structure with a distribution of elongated thick fibrils while extrusion under high cooling conditions generated an oriented row nucleated lamellar structure. The films showed distinctive tensile responses in stretching, with a strong solid-elastic response for the oriented MDO films and a steady strain hardening after yielding for the sample obtained from lab unit cast extrusion. It was found that the strength in the transverse direction (TD) was particularly very low for the oriented MDO films made of the bimodal PP. The oxygen permeability was reduced with increasing draw ratio (DR) for the MDO films. The haze property for the MDO samples reduced to a plateau for DR up to 5 while clarity improved continuously with DR. Des films de polypropylène ont été préparés dans deux procédés d'extrusion différents: l'un utilise une unité MDO (orientation dans la direction de la machine) et l'autre l'étirement des films à la filière dans des conditions de refroidissement intense (unité de laboratoire). Des films de polypropylène (PP) venant de deux résines de structure moléculaire différente ont été préparés à l'aide de ces deux techniques de mise en forme. L'effet de la structure de la résine et des conditions de mise en ,uvre sur les propriétés des films a été examiné. On a trouvé que l'unité MDO donne une structure cristalline fibrillaire hautement orientée avec une distribution de fibrilles épaisses allongées, tandis que l'extrusion sous refroidissement intense donne une structure lamellaire nucléée orientée en rangée. Les films montrent des réponses en contraintes à l'étirement distinctes, avec une forte réponse élastique solide pour les films MDO orientés et un écrouissage stable après déformation irréversible pour l'échantillon obtenu par extrusion avec l'unité de laboratoire. On a trouvé que la tenacité dans la direction transverse était particulièrement faible pour les films MDO orientés faits de PP bimodal. La perméabilité à l'oxygène a été réduite avec l'augmentation du rapport d'étirage pour les films MDO. La propriété de perte de transparence légère pour les échantillons MDO montre un plateau pour un rapport d'étirage allant jusqu'à 5 tandis que la clarté s'améliore continuellement avec le rapport d'étirage. [source] Studies on , to , phase transformations in mechanically deformed PVDF filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Vijayakumar R. P. Abstract PVDF cast films were drawn at different temperatures to different draw ratios at constant draw rate to understand the mechanism of , to , phase transformation during mechanical deformation. WAXD and FTIR studies were carried out to determine the formation and content of , phase in the drawn films. Lower stretch temperatures gave higher fractions of , phase. The cast PVDF films were also drawn at suitable temperatures below the PVDF ambient melting point to the draw ratio of 6.4. The highest fraction of , phase obtained in these ultra drawn films was 0.98. SALS studies carried out for films at different stretch ratios show the change in spherulitic structure with the stretching parameters and give information for the understanding of phase transformation during stretching of PVDF films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Investigation of the ultradrawing properties of gel spun fibers of ultra-high molecular weight polyethylene/carbon nanotube blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Jen-Taut Yeh Abstract The carbon nanotubes (CNTs) contents, ultrahigh-molecular-weight polyethylene (UHMWPE) concentrations and temperatures of UHMWPE, and CNTs added gel solutions exhibited significant influence on their rheological and spinning properties and the drawability of the corresponding UHMWPE/CNTs as-prepared fibers. Tremendously high shear viscosities (,s) of UHMWPE gel solutions were found as the temperatures reached 140°C, at which their ,s values approached the maximum. After adding CNTs, the ,s values of UHMWPE/CNTs gel solutions increase significantly and reach a maximum value as the CNTs contents increase up to a specific value. At each spinning temperature, the achievable draw ratios obtained for UHMWPE as-prepared fibers prepared near the optimum concentration are significantly higher than those of UHMWPE as-prepared fibers prepared at other concentrations. After addition of CNTs, the achievable draw ratios of UHMWPE/CNTs as-prepared fibers prepared near the optimum concentration improve consistently and reach a maximum value as their CNTs contents increase up to an optimum value. To understand these interesting drawing properties of the UHMWPE and UHMWPE/CNTs as-prepared fibers, the birefringence, thermal, morphological, and tensile properties of the as-prepared and drawn fibers were investigated. Possible mechanisms accounting for these interesting properties are proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effect of flow history on poly(vinylidine fluoride) crystalline phase transformationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Hadi Sobhani Abstract This study was devoted to the effect of extensional flow during film extrusion on the formation of the ,-crystalline phase and on the piezoelectric properties of the extruded poly(vinylidine fluoride) (PVDF) films after cold drawing. The PVDF films were extruded at different draw ratios with two different dies, a conventional slit die and a two-channel die, of which the latter was capable of applying high extensional flow to the PVDF melt. The PVDF films prepared with the two-channel die were drawn at different temperatures, strain rates, and strains. The optimum stretching conditions for the achievement of the maximum ,-phase content were determined as follows: temperature = 90°C, strain = 500%, and strain rate = 0.083 s,1. The samples prepared from the dies were then drawn under optimum stretching conditions, and their ,-phase content and piezoelectric strain coefficient (d33) values were compared at equal draw ratios. Measured by the Fourier transform infrared technique, a maximum of 82% ,-phase content was obtained for the samples prepared with the two-channel die, which was 7% higher than that of the samples prepared by the slit die. The d33 value of the two-channel die was 35 pC/N, which was also 5 pC/N higher than that of the samples prepared with the slit die. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Enzymatic degradation of poly(L -lactic acid) fibers: Effects of small drawingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Hideto Tsuji Abstract The enzymatic degradation of poly(L -lactic acid) (PLLA) fibers with different low draw ratios (1.0, 1.2, and 1.4 times) was investigated in tris-HCl buffer solution (pH = 8.6) with proteinase K by the use of gravimetry, scanning electron microscopy (SEM), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and tensile testing. Surprisingly, even the small drawings (1.2 and 1.4 times) disturbed the proteinase K catalyzed enzymatic degradation of the PLLA fibers. This should have been because the enzyme could not attach to the extended (strained) chains in the amorphous regions of the uniaxially oriented PLLA fibers or could not catalyze the cleavage of the strained chains. The accumulation of crystalline residues formed as a result of selective cleavage, and removal of the amorphous chains was not observed, even for as-spun PLLA fibers. This indicated the facile release of formed crystalline residues from the surface of the as-spun PLLA fibers during enzymatic degradation. Such release may have been because the crystalline regions of the as-spun PLLA fibers were oriented with their c axis parallel to the machine direction, as reported for biaxially oriented PLLA films. Gravimetry, SEM, and tensile testing could trace the enzymatic degradation of the PLLA fibers, although the enzymatic degradation of the PLLA fibers was untraceable by GPC and DSC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2064,2071, 2007 [source] Preparation and characterization of nylon 6/organoclay nanocomposite filament fibersPOLYMER COMPOSITES, Issue 3 2009Kap Jin Kim A series of nylon 6 (NY6)/organoclay nanocomposites were prepared via in situ polymerization of ,-caprolactam in the presence of 1,2-aminododecanoic acid-intercalated montmorillonite (ADA-MMT) organoclay (1,5 wt%) using 6-aminocaproic acid as polymerization catalyst. The extent of organoclay dispersion in NY6 matrix was analyzed using WAXD and SEM measurements. DSC studies revealed marginal shift in melting and melt-crystallization peaks toward lower temperature with increasing clay content. Melt viscosity studies for NY6/ADA-MMT exhibited higher shear-thinning behavior than neat NY6 probably due to the slip between NY6 matrix and exfoliated organoclay platelets during shear flow. The prepared nanocomposites were melt-spun and studied for their property improvements against varying clay content, draw ratios, and annealing conditions. Birefringence and sonic velocity values increased initially at lower draw ratios (,2.5) due to increased orientation of molecular chains along the drawing direction but saturated at higher draw ratio (3.0) for all the samples. At the same draw ratio; compared to neat NY6, NY6/organoclay fibers showed increased chain orientation along the drawing direction which can be attributed to the "tethering effect" of organoclay on NY6 matrix. The initial modulus and stress at break were sensitive to factors such as draw ratio, clay content, and annealing conditions. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] | |||||||||||||