Poly(butylene terephthalate)/phenoxy blends: Synergistic behavior in mechanical properties

The mechanical properties of miscible poly(butylene terephthalate) (PBT)/poly (hydroxy ether of bisphenol A) (phenoxy) blends obtained by melt mixing have been studied by means of the tensile test. The crystallinity of the blends has been studied by means of DSC and density measurements. A synergistic behavior, principally in the break properties, at high PBT contents in the blends is observed. As can be seen from the torque and density data, this synergistic behavior is related with the high level of miscibility which seems to exist at high PBT contents compared with that of the high phenoxy content region.     

Electron induced modification in poly(ethylene terephthalate)

Abstract

The effect of 100 kGy dose of 2 MeV electron irradiation on Poly(ethylene terepthalate) (PET) has been studied by different characterisation techniques such as the Fourier transformed IR spectroscopy, electron spin resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction analysis. Oxidative degradation leading to amorphisation of the polymer has been observed from spectral analysis. The thermal stability of the polymer was found to decrease due to electron irradiation. The thermal decomposition temperature as well as the melting temperature in case of irradiated PET was found to be decreased due to electron bombardment. A decrease in crystallinity of the polymer has also been observed after irradiation.     

Electroless plating of nickel–phosphorous on surface-modified poly(ethylene terephthalate) films

Chemical surface preparation for Ni–P electroless metallization of poly(ethylene terephthalate) (PET) films without using Chromium-based chemicals, was studied. The applicability of this method was verified by a subsequent metallization process. Thermal analysis was conducted to observe the main thermal transitions and stability of the polymer and metallized films. Contact angle analysis was performed to assess the surface hydrophilicity so as to optimize the substrate preparation process. X-ray diffraction, EDAX and SEM analysis were used to understand the composition and morphology of the polymeric substrate and Ni–P coat growing process. Adherence strength, contact sheet resistivity and optical diffuse reflection were measured on the metallized films. The time of chemical etching affects the polymer surface hydrophilicity, polymer/metal adherence strength, surface resistance and optical diffuse reflection, while Ni coating morphology is controlled by the pH of the electroless bath. High wettability of the polymer surface, adherence strength of 800 N cm⁻², high optical diffuse reflection and low surface resistivity of the Ni coating, were found for films etched for 60 min. Metallizations performed at pH 7.5 produce Ni–P coatings with 12.0 wt.% phosphorous content, which were amorphous and flexible. The contact sheet resistivity of the plated films is sensitive to roughness variations of the substrate. The method proposed in this work allows the production of metallized films appropriate for the fabrication of flexible circuits.     

Structure-property and composition-property relationships for poly(ethylene terephthalate) surfaces modified by helium plasma-based ion implantation

The surfaces of untreated and helium plasma-based ion implantation (He PBII) treated poly(ethylene terephthalate) (PET) samples were characterised by reflectance colorimetry, contact angle studies and measurements of surface electrical resistance. The results were related to the structural and compositional data obtained by the authors earlier on parallel samples by XPS and Raman spectroscopy. Inverse correlations between lightness and I_D/I_G ratio and between chroma and I_D/I_G ratio were obtained, suggesting that the PBII-treated PET samples darken and their colourfulness decreases with the increase of the portion of aromatic sp² carbon rings in the chemical structure of the modified layer. Direct correlation between water contact angle and the I_D/I_G ratio and inverse correlations between surface energy and I_D/I_G ratio and between dispersive component of surface energy and I_D/I_G ratio were found, reflecting that surface wettability, surface energy and its dispersive component decrease with the formation of surface structure, characterised again by enhanced portion of aromatic sp² carbon rings. The surface electrical resistance decreased with the increase of the surface C-content determined by XPS and also with the increase of the surface concentration of conjugated double bonds, reflected by the increase of the π → π* shake-up satellite of the C 1s peak.     

Exclusive attributes of undoped poly (ethylene terephthalate) for alpha particle detection

Poly (ethylene terephthalate) (PET) is available worldwide and has a broad range of applications. However, its basic properties as a scintillation material that is undoped with fluorescent guest molecules are not completely known. Here, we optically characterise undoped PET for use in radiation detection. Light absorption is primarily below 350 nm, with an emission maximum at 385 nm. An effective refractive index, determined from the emission spectrum and the wavelength dependence of the refractive index, is 1.62, which is greater than that for the sodium D line (N_D = 1.57). The density of PET is 1.33 g/cm³, and its stopping power for 1-MeV electrons is 1.72 MeV cm²/g. Distinct peaks generated by alpha particles from ²¹⁰Pb and ²⁴¹Am radioactive sources appear in PET light-yield distributions. The PET response to 5-6-MeV alpha particles is approximately one-eighth that for electrons. These results demonstrate that undoped PET has special attributes for alpha particle detection. This knowledge will enable better performance of radiation equipment based on PET and its blends with other aromatic ring polymers.     

Electron beam induced modification of poly(ethylene terephthalate) films

Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film-liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid-base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700 keV, current 1 mA, absorbed dose 50 kGy).     

Proton induced modification in Poly(ethylene terephthalate)

A systematic investigation of 62 r MeV proton irradiated Poly(ethylene terephthalate) (PET) has been carried out using Fourier Transformed Infrared Spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction spectroscopy. The experiments revealed a restoration of the crystalline matrix and simultaneous decrease in thermal stability in the irradiated polymer as a function of dose, indicating that PET underwent both degradation and cross-linking by proton irradiation.     

Isothermal Crystallization and Subsequent Melting Behavior of Poly(ethylene terephthalate)/Silica Nanocomposites

The crystallization process of poly(ethylene terephthalate)/silica nanocomposites were investigated by differential scanning calorimetry (DSC) and then analyzed using the Avrami method. The results indicated that the crystallization of pure poly(ethylene terephthalate) (PET) was fitted for thermal nucleation and three‐dimensional spherical growth throughout the whole process, whereas the crystallization of PET/silica nanocomposites exhibits two stages. The first stage corresponds to athermal nucleation and three‐dimensional spherical growth, and the second stage corresponds to recrystallization caused by the earlier spherulites impingement. The crystallization rate increases remarkably and the activation energies decrease considerably when silica nanoparticles are added. The subsequent melting behavior of the crystallized samples shows that the melting point (T _m) of nanocomposites is higher than that of pure PET, which might be caused by two factors: (1) The higher melting point might be due to some hindrance to the PET chains caused by the nanoparticles at the beginning of the melting process; (2) it might also be the case that more perfect crystals can be formed due to the higher crystallization temperatures and lower activation energies of PET/silica nanocomposites.     

Preparation and Properties of Poly(ethylene terephthalate)/Silica Nanocomposites

A kind of poly(ethylene terephthalate) (PET)/Silica nanocomposite (PETS) was synthesized via in situ polymerization using the compatibility between silica nanoparticles and ethylene glycol (EG). Transmission electron microscopy (TEM) micrographs revealed that the silica nanoparticles were well dispersed in the PET matrix, the particle size was about 10 nm with narrow distribution, and there existed strong interaction between the particles and the polymer chains. Differential scanning calorimetry (DSC) results indicated that the thermal properties of PETS with 2 wt% silica (PETS‐2) are different from those of pure PET (PETS‐0). The properties of the as‐spun fibers show that the tenacity and LASE‐5 (load at a specified elongation of 5%) of PETS‐2 were higher than those of PETS‐0, while the heat shrinkage of PETS‐2 was lower than that of PETS‐0. We suggest that the increasing of crystallinity and the strong interface interaction of the nanocomposite caused the fibers of PETS‐2 to not only have higher tenacity and LASE‐5 but also to have lower heat shrinkage.     

Transport properties of poly(ethylene terephthalate)/Rodrun 3000 blends

The transport properties of incompatible blends of poly(ethylene terephthalate) (PET) and a thermotropic liquid crystalline polymer (TLCP) composed of 40 mol% of PET and 60 mol% of p-hydroxybenzoic acid (Rodrun 3000) have been investigated using dichloromethane as permeant. Films, obtained by a blown film extrusion process, were analyzed and compared with the same samples stored 2 and 15 days at 60°C. With respect to the as-blown films, blends submitted to physical aging show a decrease in permeability by a percentage that increases with the amount of the LC phase present and a larger contribution derived from the polymeric matrix. The decrease of permeability is essentially attributed to a lowering of sorption because diffusional behavior for the different samples is the same.     

Miscibility, Crystallization, and Rheological Behavior of Solution Casting Poly(3-hydroxybutyrate)/poly(ethylene succinate) Blends Probed by Differential Scanning Calorimetry, Rheology, and Optical Microscope Techniques

应用差示扫描量热、流变及偏光显微镜等方法研究了聚3-羟基丁酸酯/聚丁二酸乙二醇酯(PHB/PES)共混体系的相容性、结晶和流变行为．相图显示该共混体系有两个玻璃化转变,但PHB的熔点随其含量的减少而降低,这个结果证明该共混体系是部分相容的,同时应用偏光显微镜观察体系结晶形态的发展证实了这个结论．依赖于结晶温度和组成,PHB和PES能同时结晶,也能分步结晶,且PHB的球晶生长速率随PES含量的增加而增大．对于部分相容的聚合物共混体系,共混组成对球晶生长速率的影响也做了详细地讨论．     

Determination of the debris produced from poly(ethylene terephthalate) during KrF excimer laser ablation

Pulsed UV laser beams, which are widely used in the processing of polymers, have many advantages because their photon energy is higher than the binding energy of polymers. Fabricating polymers with a UV laser process is faster, cleaner, and more convenient than with other processes. Nevertheless, some problems occur in the precision microprocessing of polymers. For example, the formation and deposition of surface debris, which is produced from the breakdown of either polymer chains or radical bonds.To determine the formation and origin of surface debris, a KrF excimer laser beam (248 nm) was used in the processing of poly(ethylene terephthalate) (PET). The investigation of the debris formation was facilitated by UV-vis spectroscopy, ATR FT-IR spectroscopy, and NMR spectroscopy. The UV-vis absorption peak indicates that the primary chromophore in the PET is benzoate. Furthermore, because benzoate causes the primary absorption, the absorbed energy is transferred by heat generation to an unsaturated ester. The ATR FT-IR spectrometer measurements show that the phenyl systems in the benzoate are demolished by ablation. This phenomenon indicates that the photochemical reaction causes the benzoate bonds to break down, and this breakdown in turn causes the carbonization to leave debris on the PET.     

BLENDS OF THERMOTROPIC LIQUID CRYSTALLINE POLYESTER AND POLY(ETHYLENE TEREPHTHALATE)

Two kinds of blends of thermotropic liquid crystalline polymers (LCPs) and poly(ethylene terephthalate) (PET) were prepared by solution and melt blending, respectively. Crystallization behavior of the blends was observed by differential scanning calorimetry (DSC). The LCP in both blends considerably decreased the cold crystallization temperature of PET and increased the crystallization rate in the low-temperature region, but did not show any significant effect on crystallization in the high-temperature region. Phase behavior of samples prepared by melt blending was investigated with the scanning electronic microscope (SEM). It was found that LCP/PET blends display a biphasic structure with an aromatic unit-rich phase as a dispersed domain, and a highly oriented fibrous structure was formed on the fracture surface of the blends. During the melt blending process, PET reacted with LCP through transesterification, as indicated by both DSC and SEM measurements.     

Isothermal Crystallization Kinetics and Melting Behavior of Poly(ethylene terephthalate)/Attapulgite Nanocomposites Studied by Step-scan DSC

The crystallization kinetics of poly(ethylene terephthalate)/attapulgite (AT) nanocomposites and their melting behaviors after isothermal crystallization from the melt were investigated by DSC and analyzed using the Avrami method. The isothermal crystallization kinetics showed that the addition of AT increased both the crystallization rate and the isothermal Avrami exponent of PET. Step-scan differential scanning calorimetry was used to study the influence of AT on the crystallization and subsequent melting behavior in conjunction with conventional DSC. The results revealed that PET and PET/AT nanocomposites experience multiple melting and secondary crystallization processes during heating. The melting behaviors of PET and PET/AT nanocomposites varied in accordance with the crystallization temperature and shifted to higher temperature with the increase of AT content and isothermal crystallization temperature. The main effect of AT nanoparticles on the crystallization of PET was to improve the perfection of PET crystals and weaken its recrystallization behavior.     

Effect of PMMA on crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate) blend prepared in semi-dilute solutions

Films of poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend were derived from a special procedure of casting semi-dilute solutions. Hydrophilic character and crystallization of PVDF were optimized by variation of PMMA concentration in PVDF/PMMA blends. It was found that a PVDF/PMMA blend containing 70 wt% PMMA has a good performance for the potential application of hydrophilic membranes via thermally induced phase separation. The films presented β crystalline phase regardless of PMMA content existed in the blends. Thermal analysis of the blends showed a promotion of crystallization of PVDF with small addition of PMMA which induced larger lamellar thickness of PVDF, leading to the largest spherulitic crystal of PVDF (10 wt% PMMA) is about 8 μm. SEM micrographs illustrated no phase separation occurred in blends, due to the high compatibility between PVDF and PMMA.     

Morphology of ternary immiscible polymer blends

Ternary blends consisting of thermoplastic and thermotropic immiscible polymers were studied. Both thermodynamic and kinetic considerations were found to affect their multiphase structure. Thermodynamics is expressed by means of spreading coefficients, whereas the kinetic effect is driven by the dispersed phase viscosity ratio. Some morphologies could be predicted, when both effects acted cooperatively. However, in cases where the effects were opposing, kinetics hindered the development of the expected structure; interpenetration between the two minor phases, rather than engulfing or separately dispersed morphology, took place. In cases where two relatively polar phases were dispersed in a nonpolar matrix (e.g., nylon and polycarbonate in polypropylene), the interaction between the two dispersed minor phases always existed due to their low interfacial tension. Spreading of one minor phase over another, rather than penetration, is the dominating mechanism of encapsulation in polymer blends, contrary to low molecular weight liquids where both spreading and penetration play an important role in the structurization.     

Phase Ordering and Crystallization Kinetics in Ultrathin Poly(ethylene oxide)/Poly(methyl methacrylate) Blend Films

Crystallization in ultrathin Poly(Ethylene Oxide)/Poly(Methyl Methacrylate) (PEO/PMMA) blend films with thickness of ca. 10 nm was investigated by means of microscopic and in situ spectroscopic methods. It was revealed that the blend films undergo a phase ordering in a humid atmosphere before or during crystallization, with PEO de-mixing with PMMA and segregating to the free film interface on the PMMA layer. The de-mixed PEO chains crystallize into a fractal-like morphology by a diffusion-limited process, and the crystal growth is 1-dimensional with Avrami exponent n ≈ 1, resulting in flat-on crystal lamellae with the PEO chains oriented normal to the film plane.     

Clustering of magnetic nanoparticles using a double hydrophilic block copolymer, poly(ethylene oxide)-b-poly(acrylic acid)

The use of a double hydrophilic block copolymer (DHBC), poly(ethylene oxide)-block-poly(acrylic acid) (PEO-b-PAA) to prepare magnetic nanoparticle (MNP) clusters was investigated. In this one-pot synthesis method, the DHBC controlled the particle growth and served as both stabilizer and clustering agent. Depending on the iron-to-polymer ratio, the synthesized particles can be in the form of colonies of small iron oxide particles or clusters of these particles with size larger than 100 nm. Compared to the previous reported result using random copolymers, the clusters prepared with DHBC were more compact and homogeneous. The yield of clusters increased when the amount of polymer added was limiting. Insufficient amounts of polymer resulted in the formation of bare patches on the magnetite surface, and the strong van der Waals attraction induced cluster formation.     

Ultrasound enhances lipase-catalyzed synthesis of poly (ethylene glutarate)

The present work explores the best conditions for the enzymatic synthesis of poly (ethylene glutarate) for the first time. The start-up materials are the liquids; diethyl glutarate and ethylene glycol diacetate, without the need of addition of extra solvent. The reactions are catalyzed by lipase B from Candida antarctica immobilized on glycidyl methacrylate-ter-divinylbenzene-ter-ethylene glycol dimethacrylate at 40 °C during 18 h in water bath with mechanical stirring or 1 h in ultrasonic bath followed by 6 h in vacuum in both the cases for evaporation of ethyl acetate. The application of ultrasound significantly intensified the polyesterification reaction with reduction of the processing time from 24 h to 7 h. The same degree of polymerization was obtained for the same enzyme loading in less time of reaction when using the ultrasound treatment. The degree of polymerization for long-term polyesterification was improved approximately 8-fold due to the presence of sonication during the reaction. The highest degree of polymerization achieved was 31, with a monomer conversion of 96.77%. The ultrasound treatment demonstrated to be an effective green approach to intensify the polyesterification reaction with enhanced initial kinetics and high degree of polymerization.     

Optical,thermal and mechanical characterization of Al(III)/Sb(III)-doped tris(thiourea)zinc(II) sulphate crystals

The influence of Al(III)/Sb(III)-doping on the properties of tris(thiourea)zinc(II) sulphate (ZTS) crystals grown by slow evaporation solution growth technique is reported. The as-grown crystals belong to orthorhombic system and cell parameters are, a = 7.77 Å, b = 11.13 Å, c = 15.47 Å, V = 1338 Å³ (Al(III)-doped) and a = 11.1996 Å, b = 7.770 Å, c = 15.5598 Å, V = 1368.3 Å³ (Sb(III)-doped). The structure and the crystallinity of the materials are further confirmed by powder X-ray diffraction analysis. The modes of vibrations of different functional groups present are identified by Fourier transform infrared studies. Thermogravimetric/differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. Surface morphological changes due to doping are observed by scanning electron microscopy. Microhardness study was carried out to elucidate the mechanistic behavior microhardness studies were carried out to elucidate the mechanistic behavior. Second harmonic generation activity is much better in the case of Sb(III)-doping. The specimen is also characterized by dielectric studies.