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1.
By melt spinning of incompatible polymer blends, the deformation of the dispersed phase was investigated in the fiber spinning process, for polypropylene/polystyrene (PP/PS) blend fiber and low density polyethylene/polyamide 6 (LDPE/PA6) blend fiber, respectively. Two kinds of the take-up fiber all exhibit the matrix fibrillar morphology, but with the opposite morphology. For PP/PS take-up fiber, the dispersed PS fibrils were finer in the core than near the surface. On the contrary, the dispersed PA6 fibrils were finer near the surface than in the core for LDPE/PA6 take-up fiber. However, for the special fiber in which the extensional flow was absent, there was the uniform morphology in either PP/PS or LDPE/PA6. Thus, fibrils’ non-uniform deformation, occurred in the drawing process, was considered to be due to the radial non-uniform processing conditions across the spin-line cross-section. The distribution of fibrils’ diameter was also investigated on the whole cross section. Rheological properties of each component were measured by the capillary rheometer. The non-uniform phase structure in blend fiber is a new phenomenon in the extensional flow.  相似文献   

2.
The deformation of dispersed polystyrene (PS) droplets in immiscible polypropylene (PP) matrices during melt spinning of blend fibers were simulated by adopting the droplet deformation criteria. The ratios of number-average length to diameter were measured through morphology analysis, and compared with the simulated values. It was found that the adopted deformation models described the deformation behavior of the dispersed droplets during melt spinning very well. Dispersed droplets in the center of the fiber tend to be stretched longer than those of near to the surface, due to the radial temperature gradient during fiber formation. Moreover, combining with the rheological studies of raw materials, a theoretical relation between temperature and deformation was established and used to determine the radial temperature differences along the spinning line. It was found that the radial temperature gradients vary from 0.22 to 0.35 °C/μm at 40 cm beneath to the spinneret at the discussed take-up velocities.  相似文献   

3.
The migration phenomenon was investigated in polypropylene/polystyrene (PP/PS) blend fiber and low density polyethylene/polyamide 6 (LDPE/PA6) blend fiber. The migration of fibrils in melt spinning was evaluated by the variation of fibrils’ area ratio over the cross section of blend fiber. In PP/PS blend fiber, the dispersed PS deformed into many highly oriented fibrils in the PP matrix, and PS fibrils migrated towards the surface of the take-up fiber in the fiber spinning process. On the contrary, PA6 fibrils migrated into the core of the take-up fiber, while the dispersed PA6 deformed into many highly oriented fibrils in the LDPE matrix for LDPE/PA6 blend fiber. Otherwise, no migration phenomenon was observed in the special fiber that was prepared without any drawing, neither in PP/PS nor in LDPE/PA6. Therefore, in the fiber spinning process, the migration phenomenon actually occurred mainly in the drawing process, which is the non-isothermal uniaxial extensional flow. Comparing with migration mechanisms in the shear flow, the migration phenomenon in melt spinning was probably due to the radial non-uniform extensional stress, the extensional viscosity.  相似文献   

4.
Siloxylated polypropylene fibers composed of polypropylene (PP) and aluminosiloxane (AS) were prepared by melt blending followed by spinning. The effects of blend compositions on the thermal behaviors, surface and tensile properties of PP/AS blend fibers were investigated by DSC, WAXD, SEM, static honestometer, etc. The heat of fusion of PP/AS blends decreased with increasing AS contents. In addition, the peak intensity of PP/AS blends in X-ray diffraction patterns decreased with increasing AS contents. It was observed that the silicone molecules exist and well distribute on the surface of siloxylated polypropylene fibers. From the results of the half-life period measurements, the anti-static properties of PP fibers siloxylated with AS was found to be significantly modified.  相似文献   

5.
In melt spinning of low density polyethylene/polyamide6 (LDPE/PA6), fibrils’ number in LDPE/PA6 blend fiber is calculated at different take-up velocity. Firstly, PA6 fibrils are dispersed in the LDPE matrix in LDPE/PA6 blend fiber (55:45, weight ratio). The number of PA6 fibrils increases with an increase of the take-up velocity. Because the shorter processing time suppresses the coalescence at the high take-up velocity, it causes an increase of PA6 fibrils. Besides, the irregular shape of PA6 fibrils’ cross section also confirms fibrils’ coalescence. Secondly, LDPE fibrils are dispersed in the PA6 matrix in LDPE/PA6 blend fiber (6:94, weight ratio). However, the number of LDPE fibrils doesn’t change no matter how the takeup velocity is. In case of LDPE/PA6 (6:94) blend fiber, the low weight ratio of the dispersed LDPE causes the absence of fibrils’ coalescence, so fibrils’ number does not change. In conclusion, the variation of fibrils’ number implies the existence of the coalescence phenomenon in the fiber spinning process. The variation of fibrils’ number in the sea-island fiber is of practical importance for manufacturing the micro-fine fiber, and is a method to investigate the coalescence behavior in the extensional flow.  相似文献   

6.
PLA/LPCL/HPCL blend fibers composed of poly (lactic acid) (PLA), low molecular weight poly (ɛ-caprolactone) (LPCL), and high molecular weight poly (ɛ-caprolactone) (HPCL) were prepared by melt blending and spinning for bioabsorbable filament sutures. The effects of blending time and blend composition on the X-ray diffraction patterns and tensile properties of PLA/LPCL/HPCL blend fibers were characterized by WAXD and UTM. In addition, the effect ofin vitro degradation on the weight loss and tensile properties of the blend fibers hydrolyzed during immersion in a phosphate buffer solution at pH 7.4 and 37°C for 1–8 weeks was investigated. The peak intensities of PLA/LPCL/HPCL blend fibers in X-ray diffraction patterns decreased with an increase of blending time and LPCL contents in the blend fibers. The weight loss of PLA/LPCL/HPCL blend fibers increased with an increase of blending time, LPCL contents, and hydrolysis time while the tensile strength and modulus of the blend fibers decreased. The tensile strength and modulus of the blend fibers were also found to be increased with an increase of HPCL contents in the blend fibers. The optimum conditions to prepare PLA/LPCL/HPCL blend fibers for bioabsorbable sutures are LPCL contents of 5 wt%, HPCL contents of 35 wt%, and blending time of 30 min. The strength retention of the PLA/LPCL/HPCL blend fiber prepared under optimum conditions was about 93.5% even at hydrolysis time of 2 weeks.  相似文献   

7.
Electrospun atactic polypropylene (PP) fibers are thicker than those obtained from isotactic PP, although the viscosity of molten PPs is almost same. Thus we focused on the effect of tacticity of PP on fiber diameters. The PP samples with various tacticity were prepared by changing the blend ratio of isotactic PP and atactic PP. Melt-electrospinning is performed by using blended samples, and then electrospun fibers were observed by scanning electron microscope to evaluate fiber diameter of obtained fibers. It is clear that the diameter of electrospun PP fibers decreases as high tacticity content of PP increases. This result suggests that tacticity of samples is an important factor to control the electrospun fiber diameter.  相似文献   

8.
In the present study, effect of OPP (oxidized PP) fraction on the mechanical and structural properties of produced fibers is investigated. Polypropylene powder without antioxidant materials was oxidized at the suitable thermal condition. The various fractions of OPP were blended with PP in the chips shape, and employed as starting material in a melt spinning machine for production of filament yarn. Then as-spun filaments were drawn and finally textured. Structural properties including density, birefringence and FTIR and physical properties consisting of shrinkage, tensile properties and crimp properties were measured. Results show that blending of OPP with virgin PP reduces tacticity and crystallinity, but it hasn’t any effect on orientation. Physical properties of drawn yarns and textured yarns were reduced with increasing of OPP fraction. Moreover, increasing of OPP fraction in blend, reduce crimp properties of textured yarn.  相似文献   

9.
Natural fiber reinforced polypropylene (PP) biocomposites were fabricated by blending long-and-discontinuous (LD) natural fibers (NF) with LD PP fibers. Firstly, random fiber mats were prepared by mixing NFs and PP fibers using a carding process. Then, heat and pressure were applied to the mats, such that the PP fibers dispersed in the mats melted and flowed out, resulting in the formation of consolidated sheets upon subsequent cooling. The effect of the fiber volume fraction on the mechanical properties of the bio-composites was scrutinized by carrying out tensile and flexural tests and observing the interface between the fiber and matrix. It was observed that the natural LD fiber content needs to be maintained at less than the nominal fiber fraction of 40 % by weight for the composites fabricated using the current method, which is quite low compared to that of continuous or short fiber reinforced composites. The limited fiber fraction can be explained by the void content in the biocomposites, which may be caused by the non-uniform packing or the deficiency of the matrix PP fibers.  相似文献   

10.
In the paper, one kind of super draft ring spinning frame with four drafting rollers and corresponding three drafting zones were introduced. The yarn qualities spun by the super draft ring spinning frame were analyzed by studying the shape of spinning triangles. Using the high speed camera system OLYMPUS i-speed3 and one kind of transparent front top roller, the spinning triangles were captured, and the geometry size of spinning triangle were measured. Then, according to the theoretical model of fiber tension in the spinning triangle, fiber tension distributions in the spinning triangles were presented by using Matlab software. Using the combed roving of 350 tex as raw material, three kinds of cotton yarns, 27.8 tex (21S), 18.2 tex (32S) and 14.6 tex (40S), were spun in the common ring spinning frame with three different suitable spindle speeds, travelers and twist factors. Using the combed roving of 350 tex and 500 tex as raw material, 14.6 tex cotton yarns were spun in the super draft ring spinning frame with three different drafting ratios at back zone. It is shown that with the increasing of spindle speed, a more asymmetric shape of spinning triangle would be produced, and lead to worsen yarn evenness. With the decreasing of traveler weight, the height and horizontal deviation of the spinning triangle is decreased, and may lead to better yarn evenness and less long hairiness. By taking suitable large yarn twist factors, the comprehensive qualities can be improved. Comparing with the common ring spinning, the spinning triangle is larger in the super draft ring spinning. That is, in the super draft ring spinning, the fibers in the strand in the front roller nip are more dispersed, and not benefit for yarn qualities. Therefore, the compact device was introduced into the super draft ring spinning, and the cotton pure yarns and blend yarns were spun, and the yarn qualities were measured and analyzed.  相似文献   

11.
Flexible tubular structures fabricated from solution electrospun fibers are finding increasing use in tissue engineering applications. However it is difficult to control the deposition of fibers due to the chaotic nature of the solution electrospinning jet. By using non-conductive polymer melts instead of polymer solutions the path and collection of the fiber becomes predictable. In this work we demonstrate the melt electrospinning of polycaprolactone in a direct writing mode onto a rotating cylinder. This allows the design and fabrication of tubes using 20 μm diameter fibers with controllable micropatterns and mechanical properties. A key design parameter is the fiber winding angle, where it allows control over scaffold pore morphology (e.g. size, shape, number and porosity). Furthermore, the establishment of a finite element model as a predictive design tool is validated against mechanical testing results of melt electrospun tubes to show that a lesser winding angle provides improved mechanical response to uniaxial tension and compression. In addition, we show that melt electrospun tubes support the growth of three different cell types in vitro and are therefore promising scaffolds for tissue engineering applications.  相似文献   

12.
Blends of poly(phenylene sulfide) (PPS) and polyethylene, either linear low density polyethylene (LLDPE) or metallocene-catalyzed polyethylene (MPE), that were prepared by melt blending, were investigated. From the rheological properties as determined by capillary rheometry, the melt viscosity of both PPS/LLDPE and PPS/MPE blends was low when PE was in dispersed phase, but high melt viscosity was observed for both blends with PPS in dispersed phase. Significant differences depending on the composition were found in the mechanical properties such as percent elongation at break and notched Izod impact strength. In addition, dispersed phase morphology of the blends was analyzed by a scanning electron microscope (SEM), together with brief discussion about the difference between them.  相似文献   

13.
In this research, possibility of producing and processing antibacterial organic/inorganic nanocomposite polypropylene filament yarns for permanent antimicrobial efficiency has been investigated. First PP powder and inorganic nanocomposite filler were mixed in a twin screw extruder and modified masterbatch was produced. Continuous filament yarn was made by a pilot plant melt spinning machine from the blend of PP granule and various blending contents of the prepared masterbatch. Pure PP and all other combined samples showed acceptable spinnability at the spinning temperature of 240 °C and take-up speed of 2000 m/min. After producing as-spun filament yarns, samples were drawn, textured and finally weft knitted. Physical and structural properties of as-spun and drawn yarns with constant and variable draw ratios were investigated and also tensile and crimp properties of textured yarns were evaluated. Moreover, the DSC, SEM, FTIR techniques have been used for characterization of samples. Finally antibacterial efficiency of knitted samples was evaluated. The experimental results indicated that the maximum crystallinity reduction of modified drawn yarns has reached to 5 %. The observed improvement in the tensile properties of modified as-spun yarns compared to the pure PP was significant. Drawing process improved generally the tensile properties of as-spun yarns. Tensile properties of modified textured and drawn yarns were higher than the pure PP. An optimum of antibacterial activity has been observed in the sample containing 0.75 wt% of nano-filler. It is interesting that the optimum of tensile properties has been also obtained for the sample with maximum bioactivity.  相似文献   

14.
Aluminum particles (Al) were added to polypropylene (PP) in the presence of poly ethylene glycol (PEG) and polypropylene-graft-maleic anhydride to produce composites. The composites were then melt-spun into a mono filament and tested for tensile properties, diameter evenness and morphology. Melt rheological properties of Al/PP composites were studied in linear viscoelastic response regions. It was observed that level of dispersion of aluminum particles within a polypropylene composite fiber could be improved by incorporating polyethylene glycol. The improvement of dispersion led to an improvement in the fibers mechanical properties through a reduction of the coefficient of variation of fiber diameter.  相似文献   

15.
Polyacrylonitrile (PAN) oriented nanofibers were produced by homemade needleless electrospinning device. Spiral coils were adopted to replace the traditional spinning needles in this equipment. The tracks of multi-jets were controlled by adjusting the microcurrent during the eletrospinning process. The microcurrent value and the motion track of the spinning jet during the spinning process were observed, the fiber morphology and the mechanical properties of fiber membranes were measured. The results revealed that the average diameters of the electrospun fibers were increased from 490 nm to 740 nm. with the addition of organic salt. Meanwhile, the self-clustering phenomenon was obviously observed, and the mechanical properties of obtained fibers were also altered, the tensile strength was improved from 3.63 MPa to 23.90 MPa, while the strain decreased from 74.6 % to 27.1 %.  相似文献   

16.
Firstly, the effects of the spinning temperature, spinning voltage, tip-to-collector distance and ambient temperature on the diameter of melt-electrospinning polypropylene (PP) fibers were studied. The results showed that with the increase of the spinning temperature, spinning voltage and tip-to-collector distance, the fiber diameters first decreased and then increased. However, when the ambient temperature increased, the fiber diameters increased gradually. Secondly, based on the previous results, the response surface methodology (RSM) was used to investigate the combined effects of processing parameters on fiber diameters and establish a second-order polynomial equation to predict the fiber diameter. The results showed that the effect order of four factors on fiber diameter was as follows: spinning temperature > tip-to-collector distance > ambient temperature > spinning voltage. Moreover, the fiber diameter predicted by response surface analysis fitted well with the experimental result. Finally, three layer melt-electrospinning PP webs with different fiber diameters were online compounded with conventional non  相似文献   

17.
The present paper deals with improvement in disperse dyeability as well as imparting of cationic dyeablility to difficultly dyeable polypropylene by a melt blending technique. Isotactic polypropylene (PP) was blended with fibre grade polybutylene terephthalate (PBT), cationic dyeable polyethylene terephthalate (CDPET) and polystyrene (PS), individually. The resulting binary blends were spun and drawn into fibres at draw ratio 2, 2.5, and 3. The compatibility of blends, structural changes of fibres in terms of X-ray crystallinity, relative crystallinity, sonic modulus, birefringence and thermal stability were examined. The blended fibres were found to be disperse dyeable by the conventional method of high temperature and high pressure dyeing. And this dyeability increased with increase in the level of substitution. PP/CDPET blend also exhibited dyeablility with cationic dyes in addition to that with disperse dyes. The optimum level of blending was predicted keeping in view of tenacity and thermal stability of melt blend fibres. The wash fastness properties of the dyed fibres were found to be of high rate.  相似文献   

18.
The flame-retardant poly(lactic acid) (FR-PLA) fibers with different contents of modified α-zirconium phosphate (α-ZrP) and polysulfonyldiphenylene phenyl phosphonate (OP) were prepared by melt spinning. The organic modification of α-ZrP was characterized by Fourier transform infrared spectroscopy, wide angle X-ray diffraction, and thermo gravimetric analysis. The limiting oxygen index, vertical burning test, and cone calorimeter test were used to investigate the synergistic effect of OP/α-ZrP on flame-retardant property of FR-PLA, the test results suggested that the combustion of PLA fibers was efficiently inhibited by OP/α-ZrP. The results of scanning electron microscopy, Raman spectrum, and X-ray photoelectron spectroscopy indicated that the flame-retardant mechanism of OP/α-ZrP mainly depended on condensed phase. The tensile strength and morphology of FR-PLA fibers with OP/α-ZrP were better than those of fibers treated only with OP, demonstrating that α-ZrP could significantly improve the mechanical property of FR-PLA fibers.  相似文献   

19.
The fire resistant poly(lactic acid) fibers with polysulfonyldiphenylene phenyl phosphonate flame retardant were prepared by melt spinning. The rheology property and spinnability of samples were measured by a capillary rheometer and recording the number of fiber breakage during a 30-min melt spinning. The thermal stability and combustion behaviors of fibers were investigated by Thermogravimetric Analysis, Limiting Oxygen Index and Vertical Burning tests, respectively. It was found that the flame retardation and anti-dripping performance of PLA were distinctly improved by OP. The pyrolysis behavior of fibers was tested by a Pyrolysis-Gas Chromatography-Mass Spectrometry, the structure and degree of graphitization of char residue were analyzed by Scanning Electronic Microscopy and Raman Spectroscopy. The results suggested that OP can promote the forming of char layer on the surface of PLA matrix during burning. The miscibility and spinnability of PLA was negatively affected by OP and the breaking strength of FR-PLA fibers dropped from 3.30 to 2.30 cN/dtex at the presence of 10 wt. % OP.  相似文献   

20.
Blends of poly(butylene terephthalate) (PBT)/thermoplastic polyurethane (TPU) were prepared by melt compounding. The miscibility, crystallization behaviors and toughening mechanism of the PBT/TPU blends were studied. Dynamic mechanical analysis results demonstrated that PBT was immiscible with TPU. Differential scanning calorimetry and wide angle X-ray diffraction results showed that the crystallinity of PBT decreased with increasing TPU content. Furthermore, blending with TPU did not modify the crystal structure of PBT. The small angle X-ray scattering results indicated that the crystal layer thickness decreased and the amorphous layer thickness increased with increasing TPU content, indicating that TPU mainly resided in the interlamellar region of PBT spherulites in the blends. An obvious improvement in toughness of PBT was achieved with addition of TPU. Neat PBT had elongation at break and impact strength of about 15 % and 2.9 kJ/m2, respectively. However, the elongation at break and impact strength of the 70/30 PBT/TPU blend reached 410 % and 62.9 kJ/m2, respectively. The morphology of the PBT/TPU blends after tensile and impact tests was investigated, and the corresponding toughening mechanism is discussed. It was found that the PBT showed obvious shear yielding in the blend during the tensile and impact tests, which induced dissipation of energy and, therefore, led to the improvement in toughness of the PBT/TPU blends.  相似文献   

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