Thermal and Thermo-Oxidative Destruction of Poly(Ethylene Terephthalate) Modified with Formulation Based on Polyfluorinated Alcohol

Stabilizing effect of 1,1,9-trihydroperfl uorononanole-1 immobilized on a montmorillonite support on the stability of poly(ethylene terephthalate) at elevated temperatures was studied. Gas chromatography, IR Fourier spectroscopy, and mass spectrometry were used to examine gaseous products of its thermal and thermooxidative destruction. It was found that the initial formation rate of aldehydes and carbon dioxide decreases in the course of thermostating of the fl uorine-containing composite polyester material. The method of thermogravimetry demonstrated that modified poly(ethylene terephthalate) has a higher thermal stability.     

Synthesis and characterization of poly(pentabromostyrene) micrometer-sized particles of narrow size distribution for flame-retardant applications

Flame-retardant microspheres are important due to their ability to increase the thermal stability of host materials. Bromine-containing compounds have been used for centuries due to their flame-retardant properties. A problem with many currently used fire retardants is their escape from their host material, decreasing their effectiveness as well as polluting the environment. In this work, a pentabromostyrene (PBS) monomer was synthesized and polymerized by dispersion polymerization for preparation of flame-retardant microspheres. The effect of various polymerization parameters on their size and size distribution was also elucidated. In order to demonstrate the potential of poly(PBS) microspheres as flame retardants, poly(PBS)/polystyrene (poly(PBS)/PS) blends were prepared, and it was shown that the higher the percentage of poly(PBS) in the blend, the higher the combustion temperature. An additional test for the performance of the poly(PBS) microparticles as flame-retardant additives was performed by coating polyethylene terephthalate (PET) films with the poly(PBS) microspheres, decreasing their flammability, as was illustrated by a vertical burn test. The high thermal stability and low flammability of both the poly(PBS) particles and the poly(PBS)/polymer blends indicate the potential of these microspheres as flame-retardant additives.     

Three‐Dimensional Printing with Biomass‐Derived PEF for Carbon‐Neutral Manufacturing

Biomass‐derived poly(ethylene‐2,5‐furandicarboxylate) (PEF) has been used for fused deposition modeling (FDM) 3D printing. A complete cycle from cellulose to the printed object has been performed. The printed PEF objects created in the present study show higher chemical resistance than objects printed with commonly available materials (acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), glycol‐modified poly(ethylene terephthalate) (PETG)). The studied PEF polymer has shown key advantages for 3D printing: optimal adhesion, thermoplasticity, lack of delamination and low heat shrinkage. The high thermal stability of PEF and relatively low temperature that is necessary for extrusion are optimal for recycling printed objects and minimizing waste. Several successive cycles of 3D printing and recycling were successfully shown. The suggested approach for extending additive manufacturing to carbon‐neutral materials opens a new direction in the field of sustainable development.     

Melting and crystallization of poly(ethylene terephthalate) under pressure

A piston-cylinder-type high-pressure dilatometer has been built and the effect of pressure on melting behavior of poly(ethylene terephthalate) (PET) has been studied. The melting temperature increases but the rate of change of the melting temperature decreases with increasing pressure. Poly(ethylene terephthalate) crystallized from the melt at elevated pressure and temperature was studied by thermal analysis, and wide-angle and small-angle x-ray diffraction and electron microscopy. Chain-extended PET crystals were observed for the first time and some of their properties are described. A similarity to extended-chain polyethylene is suggested.     

多嵌段聚醚-酯共混物的微相结构与血液相容性研究

本工作合成了两种性质不同的聚醚-酯多嵌段共聚物,一种是以聚对苯二甲酸乙二酯为硬链段,聚乙二醇(PEGT)为软链段的亲水性多嵌段共聚物,另一种是以聚对苯二甲酸乙二酯为硬链段,聚四亚甲基醚二醇(PTMGT)为软链段的疏水性多嵌段共聚物。将两种共聚物以一定的比例共混,制备多嵌段聚醚-酯共混物。 改变共混物的组成,研究其微相结构与血液相容性的关系。采用动态力学谱(VES)、示差扫描量热(DSC)、透射电镜(TEM)和扫描电镜(SEM)等测定共混物的微观结构,采用微球柱法评价共混物的血液相容性。实验结果表明:材料的微观非均相结构及亲水平衡是决定血液相容性的重要因素。     

Effects of comonomer sequential structure on thermal and crystallization behaviors of biodegradable poly(butylene succinate‐co‐butylene terephthalate)s

In this work, new investigations on the effect of comonomer sequential structure on the thermal and crystallization behaviors and biodegradability have been implemented for the biodegradable poly(butylene succinate‐co‐butylene terephthalate) (PBST) as well as aliphatic poly(butylene succinate) (PBS). At first, these copolyesters were efficiently synthesized from dimethyl succinate and/or dimethyl terephthalate and 1,4‐butanediol via condensation polymerization in bulk. Subsequently, their molecular weights and macromolecular chain structures were analyzed by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. By means of differential scanning calorimeter (DSC) and wide‐angle X‐ray diffractometer (WAXD), thermal and crystallization behaviors of these synthesized aromatic–aliphatic copolyesters were further explored. It was demonstrated that the synthesized copolyesters were revealed to have random comonomer sequential structures with thermal and crystallization properties strongly depending on their comonomer molar compositions, and that crystal lattice structures of the new crystallizable copolyesters shifted from the monoclinic crystal of semicrystalline PBS to triclinic lattice of the poly(butylene terephthalate) (PBT) with increasing the terephthalate comonomer composition, and the minor comonomer components were suggested to be trapped in the crystallizable component domains as defects. In addition, the enzymatic degradability was also characterized for the copolyesters film samples. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1635–1644, 2006     

Relations between dynamic mechanical properties and melting behavior of nylon 66 and poly(ethylene terephthalate)

Nylon 66 films exhibiting form I melting behavior show the γ mechanical relaxation at ?140°C. Samples which have form II melting behavior do not show this relaxation. The γ relaxation disappears when material having form I behavior is converted to material having form II behavior by annealing or by cold drawing. The form I and form II types of melting behavior are also found in poly(ethylene terephthalate); the interconversions and thermal behavior of the forms are analogous to the nylon 66 case. In poly(ethylene terephthalate), the β relaxation at ?40 to ?60°C is present only when form I melting behavior is found. Conversion to form II melting behavior by annealing or drawing (80°C) again causes the relaxation to disappear. No β relaxation was found in amorphous polymer. The γ dispersion in nylon 66 and the β dispersion in poly(ethylene terephthalate) can therefore be associated with the crystalline structure responsible for form I melting behavior. Form I melting behavior has been associated with foldedchain crystals based on previous work. It is therefore postulated that the γ dispersion in nylon 66 and the β dispersion in poly(ethylene terephthalate) are associated with motions in the chain folds. This assignment is not inconsistent with the change in the γ dispersion of nylon 66 with the number of backbone CH₂ units, since these will affect the fold structure.     

Some properties of polyethylene terephthalate-acrylic acid copolymers and ionomers

Acrylic acid has been grafted to polyethylene terephthalate (PET) by mutual irradiation, and the resulting copolymers converted to their sodium, calcium and lead salts. The electrical surface resistance of PET was reduced by grafting, the effect being most pronounced for the copolymer in the form of its sodium salt. The thermal stability of PET was studied by thermogravimetric analysis and differential thermal analysis, and activation energies were derived for the thermal decompositions; similar studies were made for the acidic and ionomeric copolymers. The stability of acidic copolymer was found to be lower than that of ungrafted PET; enhanced thermal stability was obtained only in the metallated copolymers.     

Preparation of copolyesters from diols and bisphenols by the solution polycondensation with TsCl/DMF/Py as a condensing agent

A novel synthetic method for the preparation of copolyesters comprised of diols and bisphenols using tosyl chloride (TsCl)/DMF/pyridine (Py) as a condensing agent has been developed. A variety of combinations of monomers could produce relatively high molecular weight copolymers, and better results were obtained by initial oligomerization of diols followed by bisphenols. In order to demonstrate usefulness of this method, copolymers comprised of IPA/TPA (50/50), bis(2‐hydroxyethyl)terephthalate (BHET),and several bisphenols were prepared and compared to the poly(ethylene terephthalate) (PET) modified by TPA and 2,2‐bis(4‐hydroxyphenyl)propane (BPA) diacetate in terms of their thermal properties. The length of mesogenic unit segments in the thermotropic IPA/TPA (50/50)‐BHET/ 4,4′‐dihydroxybenzophenone (4,4′‐DHBP) (50/50) copolymer was changed by initial reaction of BHET followed by dropwise addition of 4,4′‐DHBP in the two‐stage polycondensation and also by varying the amounts of BHET used at the initial and final stages in the three‐stage copolycondensation, and the results were studied by NMR and their thermal properties. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1270–1276, 2000     

ABA／PET液晶共聚酯酰胺的结构与性能

研究了对象基苯甲酸（ＡＢＡ）／聚对苯二甲酸乙二酯（ＰＥＴ）液晶共聚酯酰胺的晶体结构，以及热性能、流变学和力学性质。广角Ｘ射线衍射研究结果表明ＡＢＡ链节的引入使ＰＥＴ的晶态结构发生畸变，但大部分结晶衍射峰仍然存在。随着ＡＢＡ含量的增加，各晶面间距基本不变，微晶尺寸显著增大，结晶度急剧降低。差示扫描量热分析和热失重结果表明共聚酯胺具有优良的热稳定性，并且随着ＡＢＡ含量的增加，共聚物的热稳定性提高，共聚     

Sulphur-containing polymers: Synthesis and thermal properties of novel polyesters based on dithiotriethylene glycol

Poly(dithiotriethylene terephthalate) (PSSTET), poly(dithiotriethylene adipate) (PSSTEA), poly(triethylene terephthalate) (PTET) and poly(triethylene adipate) (PTEA), these two last for comparison, were synthesized and characterized in terms of chemical structure and molecular weight. The thermal behaviour was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the sulphur-containing polyesters. At room temperature they appeared as semicrystalline materials, except PTEA, which was an oil; the effect of substitution of ether oxygen atoms with sulphur ones was found to be a lowering in the T_g value, an increment of the melting temperature and an increase of the crystallization rate. The results were explained as due to the presence of flexible C-S-C bonds in the polymeric chain. Lastly, the absence of a rigid-amorphous phase was evidenced in PSSTET and PTET.     

Study on the pyrolysis of Moroccan oil shale with poly (ethylene terephthalate)

Investigations into the pyrolytic behaviours of oil shale, poly (ethylene terephthalate) (PET) and their mixture have been conducted using a thermogravimetric analyzer. Experiments were carried out dynamically by increasing the temperature from 298 to 1273 K with heating rates of 2 to 100 K/min under a nitrogen atmosphere. Discrepancies between the experimental and calculated TG/DTG profiles were considered as a measurement of the extent of interactions occurring on co-pyrolysis. The maximum degradation temperature of each component in the mixture was higher than those the individual components; thus an increase in thermal stability was expected. The kinetic processing of thermogravimetric data was carried out using Flynn-Wall-Ozawa (FWO) method.     

Thermal properties of microcrystalline cellulose-filled PET–PTT blend polymer composites

Polymer composite materials were prepared from poly(ethylene terephthalate)–poly(trimethylene terephthalate) blends as the matrix and different microcrystalline cellulose (MCC) filler levels (0–40 wt%) using melt compounding followed by compression molding. The composites were analyzed using dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The DSC results indicated that there is no consistent or significant influence of the MCC addition on the glass transition (T _g), melting (T _m), and crystallization temperature of the composites. With increasing MCC content, dynamic mechanical properties improved because of the reinforcing effect of the MCC. The tan δ peak values from the DMTA were not significantly changed as the MCC content increased. TG indicated that the onset temperature of rapid thermal degradation decreased with increasing MCC content. It was also found that the thermal stability of the composites slightly decreased as the MCC content increased.     

Nanocomposite of montmorillonite with telechelic sulfonated poly(butylene terephthalate): Effect of ionic groups on clay dispersion, mechanical and thermal properties

Telechelic ionomeric poly(butylene terephthalate) nanocomposites with organically modified clays have been prepared by the melt intercalation technique both in Brabender mixer and in twin screw-extruder. The presence of ionic groups tethered at the end of the polymer chains permits electrostatic interaction between the polymer and the surface of an organically modified clays providing a thermodynamic driving force for the dispersion of the clay platelets in the polymer matrix. The improved dispersion has been verified by TEM and XRD analyses. Nanocomposites with telechelic polymers present therefore consistently higher thermo-mechanical properties and improved thermal and hydrolytic stability respect to nanocomposites with standard PBT. Nanocomposite obtained using PBT with 3% telechelic ionic groups and with 5% of clay present a heat deflection temperature that is 48 °C higher compared to that of the commercial material. The presence of the clay also slightly increases the thermal and hydrolytic stability respect to standard PBT.     

Thermal degradation chemistry of poly(ethylene naphthalate) – A study by thermal volatilisation analysis

Although the fundamental degradation chemistry of poly(ethylene naphthalate), PEN, is thought to be similar to that of poly(ethylene terephthalate), PET, there is very little evidence in the literature to support this. This paper presents data on the thermal degradation of PEN, in comparison to PET, with particular reference to evolved gas analysis undertaken by thermal volatilisation analysis (TVA). Our thermal degradation studies highlight strong similarities in the degradation behaviour of PET and PEN, despite some evidence of increased thermal stability of PEN in comparison to PET. Identical primary and secondary thermal degradation mechanisms are proposed for PET and PEN, with radical degradation processes thought to dominate at high temperature.     

Investigation of the detection limit for the determination,by pyrolysis-capillary GC,of the thickness of ultra thin PMMA layers coated on to PET film

The determination of nanometer thick layers of poly(methyl methacrylate) coated on to the surface of poly(ethylene terephthalate) film has been investigated by high resolution pyrolysis gas chromatography without sample pretreatment or modification of the instrumentation used. A good linear relationship was observed between the quantity of the characteristic pyrolysate and the thickness of the poly(methyl methacrylate) layer; the detection limit was sufficient to enable the quantitation of poly(methyl methacrylate)-to-poly(ethylene terephthalate) film thickness ratios of 1:20000 in composite materials.     

Graft Copolymerization of Methyl Methacrylate onto Poly(Ethylene Terephthalate) Fibers Using Benzoyl Peroxide

Abstract

The graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers has been studied using benzoyl peroxide as initiator. The grafting reactions were carried out within the 70 to 90°C temperature range, and the variations of graft yield with monomer and initiator concentrations were also investigated. The overall activation energy for grafting was calculated as 34.1 kcal/mol. The results of dyeability with the disperse dye suggested that diffusion into the fiber structure was moderately difficult when the graft yield reached 14?15%. The maximum graft yield was obtained at a benzoyl peroxide concentration of 4.00 × 10^?3 M. The decomposition temperature values obtained from thermogravimetric analysis show that the thermal stability of poly(ethylene terephthalate) fibers decreased as a result of grafting. Further, such change in the properties of methyl methacrylate grafted fibers as density, diameter, and moisture regain were also determined.     

Preparation and characterization of poly(butylene terephthalate) nanocomposites from thermally stable organic-modified montmorillonite

In this paper, cetyl pyridium chloride (CPC) was employed to modify the montmorillonite. TGA analysis shows that the organic modified clay has higher thermal stability than hexadecyl trimethyl ammonium chloride modified montmorillonite and is suitable to be used for preparing poly(butylene terephthalate) (PBT)/clay nanocomposites at the high temperature. And then PBT/clay nanocomposites were prepared by direct melt intercalation. The results of XRD, TEM and HREM experiments show the formation of exfoliated-intercalated structure. The thermal stability of the nanocomposites does not evidently decrease, but the char residue at 600 °C remarkably increase compared with pure PBT. DSC results indicate that clay improves the melting temperature, the crystallization rate and crystallinity of the PBT molecules in the nanocomposites.     

Constant rate thermal analysis for thermal stability studies of polymers

This paper explores the relationship between the shapes of temperature-time curves obtained from experimental data recorded by means of constant rate thermal analysis (CRTA) and the kinetic model followed by the thermal degradation reaction. A detailed shape analysis of CRTA curves has been performed as a function of the most common kinetic models. The analysis has been validated with simulated data, and with experimental data recorded from the thermal degradation of polytetrafluoroethylene (PTFE), poly(1,4-butylene terephthalate) (PBT), polyethylene (PE) and poly(vinyl chloride) (PVC). The resulting temperature-time profiles indicate that the studied polymers decompose through phase boundary, random scission, diffusion and nucleation mechanisms respectively. The results here presented demonstrate that the strong dependence of the temperature-time profile on the reaction mechanism would allow the real kinetic model obeyed by a reaction to be discerned from a single CRTA curve.     

Synthesis and thermal behavior of new poly(ethylene terephthalate‐imide)s

Copoly(ethylene terephthalate‐imide)s (PETIs) were synthesized by the melt copolycondensation of bis(2‐hydroxyethyl)terephthalate with a new imide monomer, N,N′‐bis[p‐(2‐hydroxyethoxycarbonyl)phenyl]‐biphenyl‐3,3′,4,4′‐tetracarboxydiimide (BHEI). The copolymers were characterized by intrinsic viscosity, Fourier transform infrared, ¹H NMR, differential scanning calorimetry, and thermogravimetric analysis techniques. Although their crystallinities decreased as the content of BHEI units increased, the glass‐transition temperatures (T_g) increased significantly. When 5 or 10 mol % BHEI units were incorporated into poly(ethylene terephthalate), T_g increased by 10 or 24 °C, respectively. The thermal stabilities of PETI copolymers were about the same as the thermal stability of PET, whereas the weight loss of PETIs decreased as the content of BHEI units increased. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 408–415, 2001