Transmission Electron Microscopic Investigation of the Morphology of High-Speed Spun Poly(Ethylene Terephthalate) Fibers

Permanganic etching was performed on high-speed spun (HSS) and regular fibers of poly(ethylene terephthalate) (PET), and their surface morphologies were investigated via the two-stage carbon replica method using a transmission electron microscope (TEM). The HSS PET fibers, with disordered amorphous regions, showed peculiar surface morphology; many small warts corresponding to the pits of etched disordered amorphous regions were observed. Such unevenness, however, was hardly observed on the surface of the permanganic-etched regular PET fibers, with well-oriented amorphous regions, or on the surface of alkali-etched HSS PET fibers. The permanganic etchant removed the disordered amorphous regions more preferentially compared with the alkali etchant.     

Effect of melt viscosity and surface tension of polymers on the percolation threshold of conductive-particle-filled polymeric composites

The electrical conductivities of carbon-black-filled low-density polyethylene (LDPE), poly(methyl methacrylate) (PMMA), and poly(vinyl chloride)-vinyl acetate (PVC/ VAc) copolymer were measured as functions of carbon content and melt viscosity of the matrix at the temperatures at which the composites were prepared. Sharp breaks in the relationship between the carbon filler content and the conductivity of composites were observed in all specimens at some content of the carbon filler. The conductivity jumps as much as 10 orders of magnitude at the break point. This phenomenon has been known as the “percolation threshold”. The critical carbon content corresponding to the break point     

Optimisation of mould surface temperature and bottle residence time in mould for the carbonated soft drink PET containers

Polyethylene terephthalate (PET) bottles, which are usually produced by injection stretch blow moulding (ISBM) are widely used for carbonated soft drinks (CSD) storage and transportation. Stretch rod movement, blow pressure, preform temperature profile, mould surface temperature and material properties are among the most important factors affecting the final product's quality in terms of the thickness distribution, burst pressure and top-load resistance of the bottles. However, the residence time of the blown bottle inside the mould is also an important factor affecting its final properties. Especially in PET bottle production for hot fillings, the residence time is a very important factor because the longer the residence time the better the crystalline structure of the PET. In this production, the lid section is desired to have a fully crystalline form so that it can withstand hot fluids. In this study, the aim was to optimise the mould surface temperature and the blown bottle's residence time inside the mould for 1 L soft drink PET bottle production based on the final properties using the ECHIP 7 design of experiment (DOE) program. The method employed through this program was a quadratic one. Optimum process parameters were determined by the response surface method (RSM) and the process settings ensuring maximum top-load, burst pressure, Tg and degree of crystallinity were regarded to be optimum. It was found that the optimum mould surface temperature and blown bottle residence time inside the mould were 10 °C and 20 s, respectively.     

On the molecular mechanism of the crystal transformation (tetragonal-hexagonal) in polybutene-1

The phase transformation from the tetragonal to the hexagonal crystal modification in highly oriented lamellae of poly-butene-1 has been followed by transmission electron microscopy (TEM). It is found that the reaction-controlling step is the nucleation process. No lattice orientation relationship (besides the [001]-direction, which is parallel in both crystal modifications) exists between non-transformed and transformed crystals. The nucleation is strongly enhanced by thermal or external stresses. Crystal growth, nucleated by external stresses, was observed at temperatures as low as — 150°C. The molecular mechanisms of the transformation are discussed.     

Composite coating of 58S bioglass and hydroxyapatite on a poly (ethylene terepthalate) artificial ligament graft for the graft osseointegration in a bone tunnel

The purpose of this study was to determine the effect of the combination of hydroxyapatite (HA) and bioglass (BG) on polyethylene terephthalate (PET) artificial ligament graft osseointegration within the bone tunnel. The results of in vitro culturing of MC3T3-E1 mouse osteoblastic cells proved that this HA/BG composite coating can promote the cell compatibility of grafts. A rabbit extraarticular tendon-to-bone healing model was used to evaluate the effect of this composite coating on PET artificial ligaments in vivo. The final results demonstrated that HA/BG coating improved new bone formation at the graft-bone interface and increased the load-to-failure property of graft in bone tunnel compared to the control group at early time. The study has shown that HA/BG composite coating on the PET artificial ligament surface has a positive effect in the induction of artificial ligament osseointegration within the bone tunnel.     

Plasma Treatment of Polymers

Abstract

Plasma treatment of polymers encompasses a variety of plasma technologies and polymeric materials for a wide range of applications and dates back to at least the 1960s. In this article we provide a brief review of the United States patent literature on plasma surface modification technologies and a brief review of the scientific literature on investigations of the effects of plasma treatment, the nature of the plasma environment, and the mechanisms that drive the plasma–surface interaction. We then discuss low‐radio‐frequency capacitively coupled nitrogen plasmas and their characteristics, suggesting that they provide significant plasma densities and populations of reactive species for effective plasma treatments on a variety of materials, particularly when placing the sample surface in the cathode sheath region. We further discuss surface chemical characterization of treated polymers, including some results on polyesters treated in capacitively coupled nitrogen plasmas driven at 40 kHz. Finally, we connect plasma characterization with surface chemical analysis by applying a surface sites model to nitrogen uptake of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) treated in a 40 kHz nitrogen plasma. This example serves to suggest an interesting practical approach to comparisons of plasma treatments. In addition, it suggests an approach to defining the investigations required to conclusively identify the underlying treatment mechanisms.     

Morphology Development in Multi‐Component Polymer Blends: I Composition Effect on Phase Morphology in PP/PET Polymer Blends

The relationship of the phase morphology of polypropylene/polyethylene‐terephthalate (PP/PET) blends and their corresponding compatibilized blends with composition was investigated using digital image analysis. A diameter, d _g , was defined and calculated to discuss the phase morphology of this polymer blend system. A figure‐estimation method was introduced to determine the width of the distribution of d _g . Based on the method, it is proven that the distribution of d _g obeys a log‐normal distribution and consequently, the distribution width, σ was calculated. Further, a fractal dimension, D _f , was introduced to describe the distribution of main sizes of the particles of the dispersed phase. The results showed that, while d _g increased with the concentration of the dispersed phase, σ and D _f show different dependence relations on composition;σ increases monotonously but D _f shows a maximum at a PET content of 30%, indicating that, even though the whole size distribution is much broader, the distribution of the main body of size becomes more uniform when the content of PET is less than 30%.     

Poly(ethylene terephthalate) copolymers containing 5‐nitroisophthalic units. II. Crystallization studies

The microstructure and crystallization behavior of a set of poly(ethylene terephthalate‐co‐5‐nitroisophthalate) copolymers (PETNI) containing 5‐nitroisophthalic units in the 10–50 mol % range were examined and compared to those of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate‐co‐isophthalate) (PETI) copolymers. A ¹³C NMR analysis of PETNI copolymers in a trifluoroacetic acid solution indicates that they are random copolymers with average sequence lengths in accordance with ideal polycondensation statistics. Differential scanning calorimetry (DSC) studies show that PETNI containing 5‐nitroisophthalic units up to 20 mol % are able to crystallize and that crystallization takes place in these copolymers at much slower rates than in PET. Wide‐angle X‐ray diffraction from powder and fibers reveals that crystallizable PETNI adopts the same triclinic crystal structure as PET, with the nitroisophthalate units being excluded from crystallites. Fourier transform infrared in combination with cross‐polarization/magic‐angle spinning ¹³C NMR spectroscopy demonstrates the occurrence of a gauche–trans conversion encompassing the crystallization process. A correlation between DSC and spectroscopic data leads us to conclude that the content of trans conformer in the noncrystallized phase of PETNI is higher than in both PET and PETI copolymers and suggests that secondary crystallization in the homopolymer must proceed by a mechanism different than that in copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1553–1564, 2001     

The dispersion of pigment slurries via incorporation with water-soluble sulfonate poly(ethylene terephthalate)

A water-soluble sulfonate poly(ethylene terephthalate) copolymer has been synthesized and identified as a high-temperature endurable surfactant. The glass-transition temperature and the storage modulus increase in correlation to the increase in sulfonate content. Various characterization studies were performed, including light scattering, zeta-potential measurement and a sedimentation test. The results suggest that at equal numbers of sulfonate units in a solution, a low concentration of a dispersant of high sulfonate content is more effective than a high concentration of a dispersant of low sulfonate content. Received: 6 April 2000 Accepted: 23 September 2000     

动态力学温度谱分析的新方法及其应用——第3部分:动态力学温度谱分析法在PET非晶区结构研究的应用

本文在第1,2部分文章的基础上,以经拉伸、热处理的PET纤维为对象,将动态力学温度谱分析结果应用于PET的非晶区结构的研究。研究结果认为,可用PETα转变的松弛时间分布来描述PET非晶区分子链段运动能力的大小和分布;纤维非晶区取向因子f_α与松弛时间均值及方差存在很好的线性关系,反映了非晶区取向与平均松弛时间之间的密切联系。