Rheological behavior of polyester blend and mechanical properties of the polypropylene–polyester blend fibers

The article deals with method of preparation, rheological properties, phase structure, and morphology of binary blend of poly(ethylene terephthalate) (PET)/poly(butylene terephthalate) (PBT) and ternary blends of polypropylene (PP)/(PET/PBT). The ternary blend of PET/PBT (PES) containing 30 wt % of PP is used as a final polymer additive (FPA) for blending with PP and subsequent spinning. In addition commercial montane (polyester) wax Licowax E (LiE) was used as a compatibilizer for spinning process enhancement. The PP/PES blend fibers containing 8 wt % of polyester as dispersed phase were prepared in a two‐step procedure: preparation of FPA using laboratory twin‐screw extruder and spinning of the PP/PES blend fibers after blending PP and FPA, using a laboratory spinning equipment. DSC analysis was used for investigation of the phase structure of the PES components and selected blends. Finally, the mechanical properties of the blend fibers were analyzed. It has been found that viscosity of the PET/PBT blends is strongly influenced by the presence of the major component. In addition, the major component suppresses crystallinity of the minor component phase up to a concentration of 30 wt %. PBT as major component in dispersed PES phase increases viscosity of the PET/PBT blend melts and increases the tensile strength of the PP/PES blend fibers. The impact of the compatibilizer on the uniformity of phase dispersion of PP/PES blend fibers was demonstrated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4222–4227, 2006     

Solvent‐crazed PET fibers imparting antibacterial activity by release of Zn2+

Poly(ethylene terephthalate) fibers containing zinc chloride in the fiber bulk were prepared by solvent crazing. Fibers containing 6 g/Kg and 13 g/Kg Zn²⁺ were investigated. SEM‐EDX analyses and the formation of the pink bis(1,5‐dithiocarbazonato‐N,S) complex inside the fibers confirm the presence of zinc. UV‐Vis spectroscopy indicates a slow release of zinc ions into the aqueous media and, thus, the fibers serve as a release system to inhibit the growth of Escherichia coli during the first exposure. Thermal annealing of the freshly prepared fibers above T_g was shown to modify the release profile so that bacterial growth was also inhibited during repetitive and prolonged exposures. The washing fastness is fair and after 10 washing cycles, ～ 30% of the original zinc content still remains in the fiber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Hydrogen bonding effect on the poly(ethylene oxide), phenolic resin,and lithium perchlorate–based solid‐state electrolyte

The interaction behavior of solid‐state polymer electrolytes composed of poly(ethylene oxide) (PEO)/novolac‐type phenolic resin and lithium perchlorate (LiClO₄) was investigated in detail by DSC, FTIR, ac impedance, DEA, solid‐state NMR, and TGA. The hydrogen bonding between the hydroxyl group of phenolic and ether oxygen of the PEO results in higher basicity of the PEO. The higher basicity of the ether group can dissolve the lithium salts more easily and results in a greater fraction of “free” anions and thus higher ionic conductivity. DEA results demonstrated that addition of the phenolic increases the dielectric constant because of the partially negative charge on the ether group induced by the hydrogen bonding interaction between ether oxygen and the hydroxyl group. The study showed that the blend of PEO(100)/LiClO₄(25)/phenolic(15) possesses the highest ionic conductivity (1.5 × 10^?5 S cm^?1) with dimensional stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1207–1216, 2004     

Characterization of PET nanocomposites produced by different melt‐based production methods

Poly(ethylene terephthalate) (PET) based nanocomposites containing 3 wt % of different nanoparticles (MontMorilloniTe–MMT; titanium dioxide–TiO₂; and silica dioxide–SiO₂) were prepared via two independent procedures: mechanical mixing with subsequent direct injection molding (DIM) and mechanical mixing, followed by extrusion blending and injection molding (EIM). The contributions of nanofillers with respect to pure PET were evaluated. The incorporation of nanofillers reduces the intrinsic viscosity of the polymer matrix when processed by DIM and EIM. SAXS results showed that: MMT layers were intercalated for both processing procedures, but slightly higher for EIM; a better dispersion with smaller agglomerates size is achieved for TiO₂ and SiO₂ nanoparticles for EIM than for DIM. According to the results of DSC analysis, all fillers behave as nucleating agents for PET except SiO₂ that acts as inhibitor in case of DIM procedure. The mechanical behavior was assessed in tensile testing. The mechanical test revealed that the addition of nanoparticles have a slight influence on the elastic modulus and yield stress, but a drastic negative influence on the deformation capabilities of the moldings. The measured optical properties of the moldings gloss and haze are also strongly affected by the presence of nanoparticles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Characterization of the physical and molecular structure of thermally elongating poly(ethylene terephthalate) fibers

The mechanism of thermally induced elongation in poly(ethylene terephthalate) fiber spun at 3500 m min⁻¹ has been examined. This partially oriented fiber has a crystalline content of about 25% and a high degree of orientation. The effect of time and tension during heat treatment was examined, and it was found that yarns that were allowed to relax during an initial brief heat treatment at 130°C subsequently elongated by up to 5% during a long heat treatment at the same temperature. Yarns that were not allowed to relax during the brief heat treatment did not elongate on subsequent heating. The morphological and mechanical changes associated with these processes have been studied using differential scanning calorimetry, X-ray diffraction (XRD), birefringence measurement, microscopy, and tensile testing. A large increase in crystallinity was observed during the brief heat treatment, but a much smaller increase took place during the long heat treatment. XRD indicated that substantial crystal reorganization occurred during both heat treatments, but c-axis growth was most significant in those materials that elongated during long heat treatment. It is proposed that it is this c-axis growth, in conjunction with conversion of disordered amorphous material into oriented crystalline material, that is responsible for the observed elongation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 989–995, 1997     

PET/PTT共混体系的研究进展

综述了PET/PTT共混体系的国内外发展现状,重点对共混体系的相容性,共混体系的结构形态,熔融结晶行为和结晶动力学和结晶熔融行为进行了论述,并对其发展前景进行了展望。     

Improvement of adhesion of PET fibers to rubber by argon-oxygen plasma treatment

Polyethylene terephthalate fibers cords were modified with argon, oxygen, and successive argon/oxygen cold plasmas as a function of treatment time. Plasma treated cords were coated with resorcinol formaldehyde latex, then tested as rubber reinforcing materials. The peel strength was discussed with respect to the polar component of the surface energy and the etching of the fibers. An increased adhesion of ∼ 280% was obtained with 30 min argon plasma followed by 30 min oxygen plasma, at 75 W power and 40 Pa pressure without altering the traction strength of the fibers cords. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2321–2330, 1998     

The fine structure of bicomponent polyester fibers

The application of alkaline hydrolysis to study the change in the fine structure of bicomponent polyester fibers as their surface is removed progressively was explored. The samples were prepared with a poly(butylene terephthalate) (PBT) sheath and a poly(ethylene terephthalate) (PET) core. The reagent used to hydrolyze the PBT was 1M NaOH in 75/25 methanol to water since it appeared to react topochemically with the fiber. The solution reacted more rapidly with PET than with PBT. Thus, when necessary to retard the weight loss of the bicomponent fibers, after a 2‐h hydrolysis with this reagent to remove PBT, it was replaced with aqueous 1M NaOH solution containing 0.1% cetrimmonium bromide. Unlike homofil PET or PBT fibers, where alkaline attack appeared to be confined to the surface and left the residue relatively smooth, the bicomponent fiber was attacked unevenly, and penetration to the PET core occurred before all the PBT at the surface was removed. Nevertheless, most of the reaction was confined initially to the PBT sheath. The tenacity and extension at break of the PBT–PET fiber passed through a maximum as hydrolysis progressed. The fall in tenacity at high weight losses is ascribed to increasing surface defects in the fiber surface. After removal of the PBT by the hydrolysis, the birefringence of the residue became progressively higher. The synergistic effect of the PBT sheath on the properties of the PET core and the possible causes of the nonuniform hydrolysis at the PBT surface are discussed. An equation is proposed that includes an interaction parameter, which can be utilized to determine which property is affected most by the hydrolysis of a bicomponent fiber. In this instance, it appears from the parameters that the order is strength > extension at break ≈ birefringence. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1163–1173, 1999     

Studies on high‐speed melt spinning of noncircular cross‐ section fibers. I. Structural analysis of as‐spun fibers

Flat fibers and hollow fibers were prepared through the high‐speed melt spinning of poly(ethylene terephthalate) (PET), and the structures of these fibers were compared with those of circular fibers. The cross‐sectional shape of each fiber changed to a dull shape in comparison with that of the respective spinning nozzle. The change in the cross‐sectional shape was slightly suppressed with an increase in the take‐up velocity. There was a significant development of structural variation in the cross section of flat fibers in that the molecular orientation and crystallization were enhanced at the edge. Despite the difference in the cross‐sectional shape, the structural development of flat, hollow, and circular fibers with increasing take‐up velocity showed almost similar behavior. Considering that the tensile stress at the solidification point of the spin line is known to govern the structure development of high‐speed spun PET fibers, it was speculated that the effects of the enhancement of cooling and air friction on the tensile stress at the solidification point cancel each other. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1575–1581, 2001     

Strengthening interfaces between biaxial oriented PET and PSMA: Effects of nitrogen plasma and bonding treatments

The fracture toughness, G_c, of the interface between a nitrogen plasma-treated poly(ethylene terephthalate) (PET) film and a poly(styrene-co-maleic anhydride) (PSMA) substrate was measured by using asymmetric double cantilever beam method. The effects of plasma treatment condition on PET films and post-plasma bonding treatment of the bi-material on the adhesion and the failure mechanism were investigated. For a given plasma pressure and energy, the amount of incorporated nitrogen on the PET surface as determined from X-ray photoelectron spectrometry (XPS) increased with increasing plasma treatment time and reached a plateau value of 7.7 at.%. XPS measurement showed that the incorporated nitrogen was primarily in the form of amine and amide. For bonding temperatures between 130 °C and 160 °C, the fracture toughness increased with increasing nitrogen incorporation on PET surface and reached a saturation G_c which significantly depended on the bonding temperature. The saturation G_c increased from 10 J/m² at 130 °C to 40 J/m² at 140 °C, reached a maximum of 120 J/m² at 150 °C, and then decreased to 60 J/m² at 160 °C. The location of failure also changed drastically with the bonding temperature. SEM and XPS measurements showed that for bonding temperature < 140 °C, failure occurred at the PET/PSMA interface. For bonding temperature = 150 °C, the interfacial adhesion exceeded that of the cohesive strength of PET film and failure occurred within the PET film. At the bonding temperature of 160 °C, failure occurred within PSMA bulk material. XPS measurement was used to measure the areal joint density, Σ_cross of PSMA chains pinned on the functionalized PET film surface. A transition in areal joint density below which G_c scales linear with Σ_cross and above which G_c scales with was found. The transition was identified as the transition from the pure chain scission of in situ formed copolymers to plastic deformation of the interface.     

End‐group determination in poly(ethylene terephthalate) by infrared spectroscopy

A complete infrared (IR) spectroscopy experimental procedure was used to determine end‐group concentrations of poly(ethylene terephthalate) (PET). The correlations of the hydroxyl and carboxyl units were derived independently for accurate calibration results. The intermediate monomer of PET, bis(hydroxyethyl terephthalate), was used to prepare hydroxyl end‐group standards and titration measurements were used to determine the carboxyl content for the carboxyl end‐group standards. A double‐Gaussian form equation was defined to account for the interference between the hydroxyl and the carboxyl absorbance peaks in the PET IR spectrum. Some deviation was found from the assumption traditionally used for end‐group determination, stating that carboxyl and hydroxyl are the only end‐group units available in PET. © 2002 Society of Chemical Industry     

New functional bicomponent fibers with core/sheath‐configuration using poly(phenylene sulfide) and poly(ethylene terephthalate)

Bicomponent fibers using the high‐performance polymer poly(phenylene sulfide) (PPS) together with poly(ethylene terephthalate) (PET) were melt‐spun. Both possibilities of using PPS, either as core or as sheath material, were realized to provide special functionalities like improved thermobonding capability, flame retardancy, or chemical resistance. Parameters that guarantee stable processing of PPS and PET during coaxial extrusion with different core/sheath volume ratios were explored. Microscopic studies of the cross‐sections showed holes and cavities, which were formed at the interface between PPS and PET. Possible mechanisms for cavity formation were evaluated. Results of thermal and mechanical characterization by means of TGA, DSC, and tensile testing revealed a strong influence of the processing parameters, namely draw ratio and core/sheath volume ratio, on the crystallization and the tensile strength of the drawn fibers. By changing the core/sheath volume ratio from 2 to 0.5 in the PPS/PET fiber, the crystallinity of the PET‐component was switched from 10 to 50%, whereas the crystallinity of the PPS dropped from 68 to 7%. It was determined that bicomponent fibers can exceed the strength of monocomponent fibers up to 28%. The flammability and chemical resistance of the new developed fibers were characterized. In contrary to what was expected, the encasing of PET with PPS reduced the flame retardancy, though PPS has a higher flame resistance than PET. The chemical resistance of the PET core against hydrolysis was imparted by coextruding a PPS sheath. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Structural relaxation in poly(ethylene terephthalate) studied by positron annihilation lifetime spectroscopy

Positron lifetime technique was used to study the physical ageing process in poly(ethylene terephthalate) (PET). Positron lifetime results show that the structural relaxation processes in PET encompass two different time regimes, one short and the other long. The relaxation function constructed from the measured o‐Ps intensity I₃ exhibits non‐exponential character, which can be best fitted with two additive exponentials. The Narayanaswamy model (Kohlraush‐William Watt (KWW) function) is invoked to extract the stretching parameter β indicating the extent of deviation from exponential relaxation. Based on the relaxation times, the activation energies calculated seem to label the different kinetic units of PET structure participating in the relaxation process. © 2002 Society of Chemical Industry     

Superfine structure,physical properties,and dyeability of alkaline hydrolyzed soly(ethylene terephthalate)/silica nanocomposite fibers prepared by in situ polymerization

In this study, poly(ethylene terephthalate) (PET)/SiO₂ nanocomposites were synthesized by in situ polymerization and melt‐spun to fibers. The superfine structure, physical properties, and dyeability of alkaline hydrolyzed PET/SiO₂ nanocomposite fibers were studied. According to the TEM, SiO₂ nanoparticles were well dispersed in the PET matrix at a size level of 10–20 nm. PET/SiO₂ nanocomposite fibers were treated with aqueous solution of sodium hydroxide and cetyltrimethyl ammonium bromide at 100°C for different time. The differences in the alkaline hydrolysis mechanism between pure PET and PET/SiO₂ nanocomposite fibers were preliminarily investigated, which were evaluated in terms of the weight loss, tensile strength, specific surface area, as well as disperse dye uptake. PET/SiO₂ nanocomposite fibers showed a greater degree of weight loss as compared with that of pure PET fibers. More and tougher superfine structures, such as cracks, craters, and cavities, were introduced, which would facilitate the certain application like deep dyeing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3691–3697, 2006     

Poly(ethylene terephthalate) nanocomposite fibers with functionalized multiwalled carbon nanotubes via in-situ polymerization

Poly(ethylene terephthalate) (PET) hybrids with newly synthesized functionalized multiwalled carbon nanotubes (MWNTs) were obtained by carrying out the in situ polycondensation of ethylene glycol with dimethyl terephthalic acid. The PET hybrids were melt-spun to produce monofilaments with various functionalized MWNT contents and draw ratios (DRs). The thermomechanical properties and morphologies of the PET hybrid fibers were determined using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffraction (XRD), electron microscopy (SEM and TEM), and a universal tensile machine (UTM). The XRD analysis and TEM micrographs show that the levels of nanosize dispersion can be controlled by varying the MWNT content. It was found that the addition of only a small amount of functionalized MWNTs was sufficient to improve the properties of the PET hybrid fibers. The maximum enhancement in the ultimate tensile strength was found to arise at a functionalized MWNT content of 0.5 wt %. However, the initial modulus was found to increase linearly with increases in the functionalized MWNT loading from 0 to 1.5 wt %. The thermal properties and conductivities of the PET hybrid fibers were found to be better than those of pure PET fibers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Studies on high‐speed melt spinning of noncircular cross‐section fibers. III. Modeling of melt spinning process incorporating change in cross‐sectional shape

A numerical analysis program for high‐speed melt spinning of flat and hollow fibers was developed. Change in cross‐sectional shape along the spin line was incorporated adopting a formulation in which energy reduction caused by the reduction of surface area was assumed to be equal to the energy dissipation by viscous flow in the plane perpendicular to the fiber axis. In the case of flat fiber spinning, the development of temperature distribution in the cross section was considered. It was found that the empirical equations for air friction and cooling of the spin line of circular fibers can be applied for the flat fiber spin line if the geometrical mean of long‐axis and short‐axis lengths was adopted, instead of fiber diameter, as the characteristic length for Reynolds number and Nusselt number. Three features expected through the high‐speed spinning of noncircular cross‐section fibers could be reproduced: (1) although cooling of the flat fiber spin line was enhanced, calculated tension at the position of solidification was not affected much by the difference in cross‐sectional shape; (2) change in cross‐sectional shape proceeded steeply near the spinneret; and (3) temperature at the edge became significantly lower than that at the center in the cross section of flat fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1589–1600, 2001     

改性涤纶研究进展

综述了改性涤纶的最新研究进展。重点介绍了舒适性涤纶、阻燃涤纶、抗凝血涤纶、超临界二氧化碳处理、纳米技术。指出通过涤纶的吸湿性和输水性的改善、纤维截面形状的改变、接枝共聚改性、碱水解处理、超仿真技术等方法可制得舒适性涤纶,舒适性涤纶也是改性涤纶的主要发展方向。     

我国聚酯工业的发展现状及对策

综述了世界聚酯工业的发展的历史与现状,指出我国聚酯工业高速发展的同时存在的一些问题并对此进行了详细的论述。重点就现阶段我国聚酯工业如何更好发展,从产业链、工业结构、国产化、新技术、品牌战略、国际市场、研发等方面提出了相应对策。     

PET／PTT共混体系在无定形区的相容性

计算了不同温度下PET/PTT、共混体系的混合自由能，预测了其在热力学上的相容性。通过对不同组分共混物DSC图谱的分析和对玻璃化转变温度的Fox方程及Gordon-Taylor方程的拟合以及冷结晶峰温随组分的变化，表明其为在无定形区相容的体系。针对组成接近的共混体系的玻璃化转变温度范围变宽的现象，使用扫描电镜观察共混物，未发现相分离现象，从而提供了PET／PTT体系相容性在形态方面的证据。     

Study of compatibilization of HDPE–PET blends by adding grafted or statistical copolymers

The reactive compatibilization of blends of HDPE–PET [high‐density polyethylene–poly(ethylene terephthalate)] was investigated in this study. The compatibilizers used were two grafted copolymers prepared by reactive extrusion containing 1.20–2.30 wt % GMA such as HDPE‐g‐GMA and one statistical copolymer containing 1 wt % GMA such as Lotader AX8920. HDPE was successfully functionalized using a melt free‐radical grafting technique. Grafting was initiated in two ways: adding an initiator in the polymer–monomer mixture or activation by ozone of polymer. Ozonization of HDPE by the introduction of a peroxide lead to a better grafting yield and to better grafting efficiency of the samples. The effects of the three compatibilizers were evaluated by studying the morphology and the thermal and mechanical properties of HDPE–PET (70/30 wt %) blends. Significant improvements were observed, especially in morphology, elongation at break, and Charpy impact strength of the compatibilized blends. A more pronounced compatibilizing effect was obtained with the statistical copolymer, for which the elongation at break and the impact strength were increased by 100%, while the uncompatibilized blends showed a 60% decrease in the Young's modulus and the strength at break. We also were able to show that the grafting yield increase of 1.20–2.30 wt % of GMA did not affect the properties of the blends because the grafted copolymers possess very similar chemical structures. However, compatibilization of blends with grafted copolymers is an interesting method, particularly for recycled blends, because the synthesis of these compatibilizers is easy and cheap in comparison to statistical copolymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2377–2386, 2001