Structural investigations of segmented block copolymers. II. The morphology of poly(ether ester)s based on poly(tetramethylene oxide) “soft” segments: Comparison between poly(ether ester)s and poly(ether esteramide)s

The morphology of poly(ether ester)s (PEES) of the general formula [(4GT)_k-PTMO]_z has been investigated by wide and small angle X-ray scattering and electron microscopy techniques. The copolymers are based on poly(tetramethylene terephthalate) (4GT) “hard” segments (containing an average number k of consecutive 4GT units) alternating poly(tetramethylene oxide) (PTMO) “soft” segments of constant length (MW ～ 900). The fraction of crystallized 4GT slightly increases by increasing the weight fraction of PTMO up to ca. 0.5; then it rapidly decreases so that an amorphous material is obtained for a PTMO weight fraction of 0.76. PEES display a lamellar-type morphology in which lamellar domains of crystalline 4GT alternate with slightly heterogeneous interlamellar amorphous regions containing both 4GT and PTMO. For high contents of PTMO these domains evolve toward amorphous domains formed by short 4GT segments (k = 2, 3). PEES and the structurally related poly(ether esteramide)s are compared in terms of their morphological structure.     

Hysteresis of the stress-induced crystalline phase transition in poly(butylene terephthalate)

The stress-induced crystalline phase transition in poly(butylene terephthalate), (4GT), has been investigated by X-ray diffraction and laser Raman spectroscopy. A well defined stress hysteresis effect has been demonstrated and a continuum theory has been developed which satisfactorily describes the temperature dependence of the phenomenon.     

Thermal and mechanical properties of block copolymers of poly(hexamethylene terephthalate) and poly(oxyethylene) units

Block copolyetheresters of poly(hexamethylene terephthalate) (6GT) with poly(oxyethylene) terephthalate (POET) units have been prepared by polycondensation and certain of their thermal, morphological and mechanical properties have been determined. The copolymers rich in 6GT or POET units show the crystalline characteristics of the single respective homopolymers, whereas in the middle of the composition range crystalline phases of both types coexist. Increase in the proportion of POET units causes a decrease in the melting and glass transition temperatures and in the crystallisation rates whilst concomitantly the mechanical properties change from fibrous to elastomer in type. The results are interpreted in terms of a polycrystallite model in which the compostion-dependent nature of the crystallites and tie bars determines the overall mechanical properties of the copolymers.     

Photochemical degradation of poly(ethylene terephthalate). I. Irradiation experiments with the xenon and carbon arc

Poly(ethylene terephthalate) films were irradiated in a carbon-arc Fade-Ometer and in a xenon-arc Weather-Ometer. The changes in tensile properties, intrinsic viscosities, infrared absorption, and fluorescence emission spectra resulting from these irradiations were measured. Quantitative comparisons between changes in surface (ATR) and transmission infrared spectra, in conjunction with the other results obtained, have established the importance of surface reactions in the photodeterioration of poly(ethylene terephthalate).     

A comparative radiation degradation of some aromatic polyesters

Summary A comparative investigation of radiation degradation of poly(1,4-butylene terephthalate), PBT; poly(ethylene terephthalate), PET; and poly(ethylene 2,6-naphthalene-dicarboxylate), PEN, was carried out. These polyesters were irradiated under vacuum at doses from 0.5 to 4 MGy. Data on solubility of the irradiated polyesters revealed absence of cross-linking. Molecular weights of PBT and PET decreased noticeably after irradiation, and radiation-chemical yields of destruction were quantified. NMR and UV spectra revealed changes in molecular structure upon irradiation of PBT. Efficiency and mechanism of radiation degradation of PBT, PET and PEN were discussed.     

Structural changes in glassy polymers

It has previously been shown that glassy poly(ethylene terephthalate) gives rise to endothermal peaks in DTA when annealed at temperatures near to the glass temperature. The present work describes results obtained from DTA and DSC on annealing a number of glassy polymers which have been rapidly cooled from above the glass temperature and on slowly cooled samples of the same polymers. The polymers which have been studied are: poly(ethylene terephthalate), poly(methyl methacrylate), atactic and isotactic polystyrene, bisphenol-A polycarbonate, poly(ethyl methacrylate) and poly(vinyl acetate). In every case, evidence of structural reorganization is observed, and the rate at which this takes place is reported. Separate studies on poly(ethylene terephthalate) reflect density changes which also take place upon annealing. These results are discussed in the context of the calorimetric observations.     

Conformational structure of poly(ethylene terephthalate). Infra-red,Raman and n.m.r. spectra

Infra-red and Raman spectra of unoriented samples of poly(ethylene terephthalate) in the crystalline and amorphous states and in solution were measured. The dissolved polymer was also studied by n.m.r. spectra. Digital separation of the vibrational spectra of amorphous and crystalline components made possible the detection of some new bands, the interpretation of which is presented. By comparison with the vibrational spectra of model compounds combined with analysis of n.m.r. spectra, the conformational forms present in the amorphous and liquid states of poly(ethylene terephthalate) were characterized and their populations were determined. Bands in vibrational spectra which are characteristic of various conformational forms were defined.     

A new fiber-sampling technique for infrared spectroscopy as applied to nylon 6 and poly(ethylene terephthalate)

A number of techniques have been used in the past for obtaining the infrared spectra of fine fibers. A new technique has been developed which overcomes many of the problems of previous methods. The present technique involves winding a single filament between two salt windows which are separated by a spacer which is the same or slightly greater in thickness than the fibers. This results in a layer of adjacent parallel fibers. Good-quality polarized infrared spectra were obtained on oriented poly(ethylene terephthalate) and oriented nylon 6 fibers with the new technique. The data demonstrate the high level of “A” conformation orientation present in highly drawn nylon 6 fibers and the existance of chain folds in drawn poly(ethylene terephthalate) fibers. The structural changes which occur during the shrinkage of nylon 6 fibers are also demonstrated.     

An investigation into the structure of poly(ethylene terephthalate) fibres by the use of optical transforms

An investigation has been made into the structural changes in poly(ethylene terephthalate) fibres brought about by drawing in a texturing machine. Evidence from both wide-angle and small-angle X-ray scattering is presented. The main feature of the small-angle X-ray scattering is a transition from two, meridional diffraction peaks to a symmetrical, four-point pattern as the draw ratio is increased. Optical transform methods have been used to investigate possible structural changes which could produce the observed transition. A tentative structure for poly(ethylene terephthalate) fibres is proposed.     

裂解气相色谱质谱技术鉴定聚酯纤维

应用傅里叶变换红外光谱、裂解气相色谱质谱(PyGC-MS)联用技术鉴定聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚对苯二甲酸丙二醇酯(PTT)、聚对苯二甲酸-1,4-环己二甲醇酯(PETG)纤维。结果表明:PET,PBT,PTT,PTEG纤维可以应用红外光谱初步鉴定为聚酯纤维,但4种纤维的红外光谱类似,难以具体鉴别,而该4种纤维的PyGC-MS具有各自的特征裂解产物,其中PET,PBT,PTT的特征裂解产物分别具有100%相对丰度的苯甲酸、对苯二甲酸单丁烯酯、对苯二甲酸单丙烯酯,PETG的特征裂解产物为1,4-二亚甲基-环己烷、2,4,6-辛三烯等,以此4种聚酯特征裂解产物为鉴定PET,PBT,PTT,PTEG纤维的依据。该方法简便、快速、准确,已应用于实际检测。     

Determination of intrinsic physical constants of poly(trimethylene terephthalate) from drawn filament

The intrinsic lateral sonic moduli of the crystalline and amorphous regions of poly(trimethylene terephthalate) (3GT) (about 4.1504 ± 0.8396 GPa and 1.6096 ± 0.0368 GPa, respectively) were obtained from sonic moduli and crystallinities of unoriented 3GT filaments annealed under different conditions. Using the obtained intrinsic lateral sonic moduli of the crystalline and amorphous regions, the degree of orientation of the amorphous region of uniaxially drawn 3GT filaments could also be obtained from the crystallinity, sonic modulus, and the degree of crystalline orientation estimated from X‐ray azimuthal scan data. Thus, the intrinsic birefringences of the perfectly oriented crystalline and amorphous regions of the 3GT fibre (about 0.2057 ± 0.0160 and 0.2175 ± 0.0923, respectively) could be obtained from the appropriate combinations of birefringence, crystallinity, and the degree of orientation of the crystalline and amorphous regions. © 2003 Society of Chemical Industry     

PBT共混改性研究最新进展

综述了最近几年国内外聚对苯二甲酸丁二醇酯(PBT)共混改性的研究进展,分类介绍PBT/聚烯烃、PBT/同系聚酯、PBT/液晶、PBT/弹性体、PBT/聚碳酸酯等不同共混体系,讨论了各体系中的相行为、相容性、热稳定性、力学性能等,并对该类共混物的发展趋势作了简要的分析。     

Mechanism of light fading of dyes on cellophane and poly(ethylene terephthalate)

Studies of relative rates of fading of dyes and Hammett σ-value of substituents in their molecules lead to further evidence that fading of azo dyes on Cellophane and poly-(ethylene terephthalate) is probably an oxidation type of reaction. Absorption spectra of the same dye on these two substrates tend to indicate a very high state of aggregation of dyes on Cellophane as compared to that on poly(ethylene terephthalate).     

Effect of alkali on filaments of poly(ethylene terephthalate) and its copolyesters

The alkali hydrolysis of poly(ethylene terephthalate), anionic copolymer of poly(ethylene terephthalate), and block copolymer of poly(ethylene terephthalate)–poly(ethylene glycol) is investigated under a variety of conditions of alkali concentration in aqueous bath, additives, time, and temperature. Measurements of loss in weight, linear density, breaking load, tenacity, elongation to break apart from intrinsic viscosity, fiber density, COOH-end group content, diameter of filaments, and scanning electron micrographs have been analyzed to identify the differences in the action of alkali on these polymer materials.     

Thermomechanical studies of semicrystalline polyether–ester copolymers. Effect of thermal,mechanical, and solvent treatment

The thermomechanical spectra of a series of elastoplastic polyether–ester copolymers were determined at 110 Hz and between ?120°C and 200°C at five compositions. Emphasis was given to samples containing an increasing amount of poly(tetramethylene terephthalate) constituting the hard segment in these copolymers. The effects of thermal history, uniaxial drawing, and solvent absorption were examined. Specimens cut from injection-molded slabs were also included in the study. Thermal and mechanical treatment had an important effect on the dynamic mechanical properties. The relaxation spectra do not indicate distinct phase separation, but rather a structure of closely interacting hard and soft segments. The molecular origin of the various relaxations was characterized, and it is shown that as the amount of the hard component increases, features in the relaxation spectrum characteristic of poly(tetramethylene terephthalate) become prominent.     

聚对苯二甲酸丙二醇酯的合成研究进展

综述了1,3-丙二醇和PTT的合成方法、技术路线,并回顾了1,3-丙二醇和PTT的产业化过程。     

Fourier‐transform infrared spectroscopic study of plasticization effects on the photodegradation of poly(fluorostyrene) isomers films

The photodegradation of poly(fluorostyrene) isomers with different amounts of phthalate and terephthalate plasticizers has been investigated with the aid of Fourier‐transform infrared spectroscopy. Photo irradiation was carried out with light from a Hydrogen‐Xenon lamp at 265 nm and 293 K. As irradiation time increased, changes occurred in the structure of the polymers due to the destruction of polymeric chains and the formation of new photo products during the degradation. The photo products caused shifts, an increase or decrease of the polymer vibrational frequencies, as well as changes in numerous infrared band intensities. The increase in the intensities of the analyzed ranges is attributed to the formation of carbonyl, hydroxyl, and aliphatic ketones and to the increase in the number of polyene structures that resulted from hydrogen abstraction during photodegradation reactions. The analysis of the Fourier‐transform infrared spectra of the irradiated and nonirradiated samples showed a noticeable formation of a new broad band centered at (1,727 cm^?1, C=O), assigned to the growth of aliphatic ketones formerly from the reaction of reactive alkoxy radicals. Its intensity was found to increase with the increase in irradiation time and also with the increase in the amount of added terephthalate and phthalates plasticizer, indicating an increase in the efficiency of the photo degradation process. Trends of photostability of these isomers were found such that poly(para‐fluorostyrene) > poly(meta‐fluorostyrene) > poly(ortho‐fluorostyrene). The photodegradation process for these plasticized isomers was found to increase by the increase in the bulkiness of the plasticizer molecule . J. VINYL ADDIT. TECHNOL., 24:75–83, 2018. © 2015 Society of Plastics Engineers     

Copolyester studies. III. Melt-spinning,drawing, and mechanical properties of tetramethylene terephthalate–tetramethylene sebacate copolymer fibers

Fibers have been prepared from tetramethylene terephthalate–tetramethylene sebacate copolymers, containing up to 20 mol % of the latter, using a conventional melt-spinning technique. The mechanical properties of these undrawn fibers and of highly oriented fibers prepared from them have been evaluated. The changes in mechanical properties brought about by the introduction of sebacate groups in poly(tetramethylene terephthalate) have been related to the glass-transition temperatures of the copolymers and to the flexible nature of the sebacate unit. The formation of voids during a continuous drawing process and during mechanical testing is discussed.     

Synthesis,characterization and polycondensation of Bis-(4-hydroxybutyl) terephthalate

Summary Monomeric Bis-(4-hydroxybutyl) terephthalate has been synthesized and characterized. Titanium iso-propoxide has been found to be a superior catalyst for transesterification compared to metal acetates. Further polycondensation of Bis (HBT) yields poly (1,4-butylene terephthalate). The effect of various titanium derived catalysts on the polycondensation of Bis (HBT) has been studied. The catalytic efficiency of these derivatives is ascribed to their relative hydrolytic stability and the degree of interaction between the carbonyl oxygen and the metal.     

Liquid-induced crystallization of poly(ethylene terephthalate)

Amorphous unoriented poly(ethylene terephthalate) was crystallized at 25°C by various organic liquids. The crystalliznity induced in the amorphous polymer was measured by differential scanning calorimetry and infrared spectroscopy. The ability of liquids to interact with and induced crystallinity in the amorphous polymer was classified on the basis of their solubility parameters. Measurements of the density of liquid-crystallized 0.8-mil films of poly(ethylene terephthalate) indicated the presence of extensive internal voids in the semicrystalline polymer matrix. Comparison of differential scanning calorimetric thermograms and infared spectra of heat-crystalized and liquid-crystallized polymer indicated significant differences in the polymer morphologies induced by the two crystallization processes.