Surface resistivity and rheological behaviors of carboxylated Multiwall carbon nanotube‐filled PET composite film

Multiwalled carbon nanotube (MWNT) nanocomposites with poly(ethylene terephthalate) (PET) were prepared via in situ polymerization. The refluxing time was more important factor than the sonication time for giving carboxylic groups onto the surface of MWNT. Acid‐MWNT prepared was well dispersed in ethylene glycol, whereas the neat‐MWNT agglomerated and sedimented at the bottom. The viscosity of the composites increased with the addition of MWNT, but PET/acid‐MWNT composite showed lower viscosity than PET/neat‐MWNT because of the damage of MWNT by acid treatment and copolymerization effect by the reaction between carboxylic groups of MWNT and PET. PET/acid‐MWNT composite film showed lower surface resistivity than PET/neat‐MWNT composite film. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 900–904, 2006     

Properties of poly(ethylene terephthalate) and maleic anhydride-grafted polypropylene blends by reactive processing

The properties of poly(ethylene terephthalate) (PET) and polypropylene (PP) blends and PET/maleic anhydride-grafted PP (MAgPP) reactive blends were investigated. Two blend systems were immiscible based on tan δ measured by dynamic mechanical analyzer (DMA). In case of PET/MAgPP blends, the reaction of ester groups of PET and MA sites on MAgPP occurred during melt mixing at 280°C for 30 min. The reaction was confirmed by a new peak between the glass transition temperatures of PET-rich and MAgPP-rich phase on tan δ curves, as well as from the rheological properties. From the morphology, the improvement of the dispersibility in PET/MAgPP reactive blends was observed. The modulus of PET/MAgPP blends was higher than that of PET/PP blends, and the strength of PET/MAgPP blends showed the good adhesion compared with the PET/PP blends. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 389–395, 1998     

Investigation of alkaline hydrolysis of polyethylene terephthalate by differential scanning calorimetry and thermogravimetric analysis

The hydrolytic depolymerization of polyethylene terephthalate (PET) with alkaline hydroxides was investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The reactions of the mixtures were conducted in their solid states under nitrogen atmosphere. The experimental results showed that potassium hydroxide possessed the hydrolytic activity of depolymerizing PET into small molecules such as ethylene glycol; in contrast, sodium hydroxide did not. The production rate of ethylene glycol was enhanced by increasing charge ratio of potassium hydroxide to PET. The presence of water facilitated the alkaline hydrolysis of PET; however, the presence of metal acetates decreased the hydrolysis rate. The activation energy for alkaline hydrolysis of PET determined by the thermograms was in good agreement with the value obtained from the experiments in a batch reactor. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1939–1945, 1998     

Antielectrostatic poly(ether ester) block copolymer of poly(ethylene terephthalate‐co‐isophthalate)–poly(ethylene glycol)

Poly(ethylene terephthalate) (PET) fiber has a low moisture regain, which allows it to easily gather static charges, and many investigations have been carried out on this problem. In this study, a series of poly(ethylene terephthalate‐co‐isophthalate) (PEIT)–poly(ethylene glycol) (PEG) block copolymers were prepared by the incorporation of isophthalic acid (IPA) during esterification and PEG during condensation. PEG afforded PET with an increased moisture affinity, which in turn, promoted the leakage of static charges. However, PET also then became easier to crystallize, even at room temperature, which led to decreased antistatic properties and increased manufacturing inconveniences. IPA was, therefore, used to reduce the crystallinity of the copolymers and, at the same time, make their crystal structure looser for increased water absorption. Moreover, PET fibers with incorporated IPA and PEG showed good dyeability. In this article, the structural characterization of the copolymers and antistatic and mechanical properties of the resulting fibers are discussed. At 4 wt % IPA, the fiber containing 1 mol % PEG with a molecular weight of 1000 considerably improved antistatic properties and other properties. In addition, the use of PEIT–PEG as an antistatic agent blended with PET or modified PET fibers also benefitted the antistatic properties. Moreover, PEIT–PEG could be used with another antistatic agent to produce fibers with a low volume resistance. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1696–1701, 2003     

Poly(vinyl alcohol) hydrogel fixation on poly(ethylene terephthalate) surface for biomedical application

A surface modification technique was developed for the covalent immobilization of poly(vinyl alcohol) (PVA) hydrogel onto poly(ethylene terephthalate) (PET) to improve the biocompatibility of the film. The PET film was first graft copolymerized with poly(ethylene glycol) monomethacrylate (PEGMA) in the presence of ethylene glycol dimethacrylate (EGDMA) as crosslinker, and then oxidized with a mixture of acetic anhydride (Ac₂O) and dimethyl sulfoxide (DMSO) to produce aldehyde groups on the PET surface. Finally, the prepared PVA solution was cast onto the film and covalently immobilized on the film through the reaction between the aldehyde groups on the PET film and the hydroxyl groups of PVA. The good attachment of the PVA layer to the PET film was confirmed by observing the cross-section of the PET-PVA film using scanning electron microscopy (SEM). Heparin was immobilized on the PVA layered PET using two different methods, physical entrapment and covalent bonding, to further improve the biocompatibility of the film. Attenuated total reflectance (ATR) FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize the chemical composition of the surface modified films. The biocompatibility of the various surface modified PET films was evaluated using plasma recalcification time (PRT) and platelet adhesion.     

Glycolysis of poly(ethylene terephthalate) wastes in xylene

To reclaim the monomers or prepare intermediates suitable for other polymers zinc acetate catalayzed glycolysis of waste poly(ethylene terephthalate) (PET) was carried out with ethylene or propylene glycol, with PET/glycol molar ratios of1 : 0.5–1 : 3, in xylene at 170–245°C. During the multiphase reaction, depolymerization products transferred to the xylene medium from the dispersed PET/glycol droplets, shifting the equilibrium to glycolysis. Best results were obtained from the ethylene glycol (EG) reaction at 220°C, which yielded 80 mol % bis-2-hydroxyethyl terephthalate monomer and 20 mol % dimer fractions in quite pure crystalline form. Other advantages of employment of xylene in glycolysis of PET were improvement of mixing at high PET/EG ratios and recycling possibility of excess glycol, which separates from the xylene phase at low temperatures. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2311–2319, 1998     

Analysis of physical properties of PET/CD‐PET polyblend hollow fiber and its kinetics of alkaline hydrolysis

Cationic dyeable poly(ethylene terephthalate) (CD‐PET) was formed by copolymerizing dimethylterephthalate (DMT),5‐sodium sulfonate dimethyl isophthalate (SIPM) with a molar ratio of 2% and ethylene glycol (EG). Blends of regular poly(ethylene terephthalate) (PET) and CD‐PET were spun into hollow fibers. The fibers were then treated with aqueous NaOH. This study investigated the physical properties of PET/CD‐PET polyblend hollow fibers and their kinetic behavior of alkaline hydrolysis using differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), the density gradient method, a gel permeation chromatograph (GPC), a rheometer, and regression analysis of the statistical method. For the alkaline hydrolysis kinetics equation of PET, CD‐PET, and PET/CD‐PET polyblend materials: ? dW/dt = KC^αA^β, β values of chip and POY/ FOY hollow fibers are equal to 1. Moreover, R² of the kinetics equation of chip/POY/FOY for a from 1.09–1.35/1.08–1.32/1.06–1.29 were better than those of a = 1. Experimental results indicate that the rate constant of alkaline hydrolysis was CD‐PET hollow fiber > PET/CD‐PET polyblend hollow fibers > PET hollow fiber and FOY > POY > > Chip. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3601–3610, 2002     

Chemical Kinetics,Simulation, and Thermodynamics of Glycolytic Depolymerization of Poly(ethylene terephthalate) Waste with Catalyst Optimization for Recycling of Value Added Monomeric Products

Reaction of poly(ethylene terephthalate) (PET) waste powder with ethylene glycol (EG) was carried out in a batch reactor at 1 atm pressure and at various temperatures ranging from 100–220 °C at the intervals of 10 °C. Particle size from 50–512.5 μm, reaction time from 30–150 min, amount of catalyst from 0.001–0.009 mol, and type of catalysts required for glycolysis of PET were optimized. To increase the PET weight (%) loss, various external catalysts were introduced during the reaction at different reaction parameters. Depolymerization of PET was increased with reaction time and temperature. Depolymerization of PET was decreased with increase in the particle size of PET. Reaction rate was found to depend on concentrations of liquid ethylene glycol and ethylene diester groups in the polyester. Analyses of value added monomeric products (DMT and EG) as well as PET were undertaken. Yields of monomers were agreed with PET conversion. A kinetic model was proposed and simulated, and observed consistent with experimental data. Comparisons of effect of various amounts of catalysts and type of catalysts on glycolysis rate were undertaken. Dependence of the rate constant on reaction temperature was correlated by Arrhenius plot, which shows activation energy of 46.2 kJ/mol and Arrhenius constant of 99 783 min^?1.

Arrhenius plot of the rate constant of glycolysis at 1 atm pressure for 127.5 μm PET particle size (KZA = rate constant using zinc acetate as a catalyst, KMA = rate constant using manganese acetate as a catalyst).     

Recycling of off‐grade pet via partial alcoholysis to synthesize functionalized pet oligomer nanocomposites

Off‐grade poly(ethylene terephthalate) (PET) of industrial manufacturers was partially depolymerized using excess ethylene glycol in the presence of manganese acetate as a transesterification catalyst to synthesize PET oligomers. Influences of reaction time, Ethylene Glycol (EG)/PET molar ratio, catalyst concentrations, and particle size of off‐grade PET on yield of partial glycolysis reaction were investigated based on Box–Behnken's design of experiment. Thermal analyses of glycolyzed products are examined by differential scanning calorimetry. The optimum samples were also well‐characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy (¹H‐NMR and ¹³C‐NMR). The optimal conditions to synthesize PET oligomer (melting point of about 180°C) for a 120‐min glycolysis reaction time were EG/PET molar ratio of 2 with no catalyst using granule‐shaped PET. The same results were obtained for a 60‐min glycolysis reaction time, including EG/PET molar ratio of 1 with the weight ratio (catalyst to PET) of 0.5% using average particle size of PET. Then, maleated PET as a compatibilizer for preparing PET nanocomposites was produced via reaction between maleic anhydride/phthalic anhydride composition and optimized PET oligomers based on central composite design of experiment. The combination of reaction time of 106 min and PhA/MA molar ratio of 0.85 gave the best results based on d‐spacing and peak shift of nanocomposite samples. Hence, melt mixing of maleated PET with organoclay produced a good intercalation of layered silicate and good dispersion of clay in maleated PET matrix. Analysis of variance (ANOVA) was studied for both glycolyzed products and functionalized PET oligomers. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effect of copolymers containing glycidyl methacrylate functional groups on the rheological,mechanical, and morphological properties of poly(ethylene terephthalate)

The aim of this work was to investigate the effect of ethylene‐glycidyl methacrylate (EGMA) and ethylene‐methyl acrylate‐glycidyl methacrylate (EMAGMA) copolymers on the rheological, mechanical, and morphological properties of Poly(ethylene terephthalate) (PET). The results of torque rheometry showed an increase in the torque of PET with the addition of EGMA and EMAGMA copolymers due to the reactions between the GMA groups present in the copolymers and the carboxyl and hydroxyl groups present in PET. The torque of PET/copolymer blends increased with the increase in the copolymer content and was more pronounced for the blends containing EGMA copolymer. X‐ray diffraction and differential scanning calorimetry analyzes showed that neat PET and the PET in PET/copolymer blends are amorphous. The addition of EGMA and EMAGMA copolymers delayed the crystallization of PET. Rheological measurements showed an increase in the viscosity at low frequencies with the addition of EGMA and EMAGMA copolymers to PET. This increase was more pronounced for PET/copolymer blends containing higher amount of copolymers and for the blends containing EGMA, corroborating the results obtained by torque rheometry. The impact strength of PET/EMAGMA blends was higher than that of PET/EGMA blends. Morphology analysis by SEM showed that PET/EMAGMA blends presented higher average dispersed phase domains size than PET/EGMA blends. POLYM. ENG. SCI., 59:683–693, 2019. © 2018 Society of Plastics Engineers     

Hydraulic permeabilities of PET and nylon 6 electrospun fiber webs

The morphological and hydraulic properties of electrospun fiber webs were investigated and compared with those of spunbond nonwoven fabrics. In this study, poly(ethylene terephthalate) (PET), hydrophobic polymer, and nylon 6, with some hydrophilic groups (amide groups), were used as the polymer materials to prepare spunbonds and electrospun fiber webs. The water permeabilities of PET and nylon 6 spunbonds followed the Darcy's law, but those of PET and nylon 6 electrospun fiber webs showed properties that deviated from the Darcy's law. On the other hand, the wicking phenomenon was observed in both nylon 6 spunbond and electrospun fiber webs, but no such phenomenon was observed in PET spunbond and electrospun fiber webs. The water vapor transport rates of PET and nylon 6 electrospun fiber webs were higher than those of PET and nylon 6 spunbonds. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 167–177, 2006     

Preparation and barrier property of poly(ethylene terephthalate)/clay nanocomposite using clay‐supported catalyst

Poly(ethylene terephthalate) (PET)/clay nanocomposite was prepared by the direct polymerization with clay‐supported catalyst. The reaction degree of catalyst against the cation exchange capacity of clay was 8 wt %. The intercalation of PET chains into the silicate layers was revealed by X‐ray diffraction studies. SEM morphology of the nanocomposite showed a good dispersion of clay‐supported catalyst, ranging from 30 to 100 nm. The intercalated and exfoliated clay‐supported catalyst in PET matrix was also observed by TEM. The improvement of O₂ permeability for PET/clay‐supported catalyst composite films over the pure PET is approximately factors of 11.3–15.6. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4875–4879, 2006     

Treatment of PET nonwoven with a water vapor or carbon dioxide plasma

Gas plasma treatment of poly(ethylene terephthalate) nonwoven (NW–PET) was used to increase the hydrophilicity of single‐ and multilayer NW–PET. NW–PET was treated with a pulsatile CO₂ or with a pulsatile H₂O glow discharge. X‐ray photoelectron spectroscopy (XPS) showed significantly more oxygen with CO₂ glow‐discharge‐treated NW–PET than with H₂O glow‐discharge‐treated‐NW–PET surfaces. Moreover, the introduction rate of oxygen at a single layer of NW–PET was higher for a CO₂ than for a H₂O glow‐discharge treatment. Titration data revealed significantly higher surface concentrations of carboxylic groups for CO₂ glow‐discharge NW–PET than for H₂O glow‐discharge‐treated NW–PET. Mass spectrometry analysis revealed that the entire internal surface of a single layer of NW–PET was modified. XPS and contact measurements confirmed the modification of the internal surface of multilayers of NW–PET. H₂O and CO₂ glow‐discharge‐treated substrates consisting of six layers of NW–PET had a nonuniform surface concentration of carboxylic acid groups as determined with titration experiments. The outside layers of the substrate contained a higher surface concentration of carboxylic acid groups than did the inside layers. XPS analysis and titration data showed that the rinsing of H₂O and CO₂ glow‐discharge‐treated NW–PET with water changed the surface composition considerably. Part of the carboxylic acid group‐containing species were washed off. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 480–494, 2000     

A Preliminary Investigation on the Use of Poly[(ethylene terephthalate)‐co‐(ε‐caprolactone)] Copolymer as Compatibiliser of HDPE/PET Blends

A preliminary study on the possibility to use the copolymer poly[(ethylene terephthalate)‐co‐(ε‐caprolactone)] as a compatibilising agent in blends of high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) is reported. The copolymer was synthesised by polycondensation of low‐molecular weight PCL precursors, previously end‐capped with reactive isocyanate groups, and oligomers of PET obtained from PET waste through a controlled depolymerisation procedure. HDPE/PET blends at a composition of 70/30 w/w with and without the addition of 10 wt.‐% of compatibiliser were prepared in a single‐screw mixer extruder. The effect of compatibiliser was evaluated by studying the thermal, dynamic‐mechanical and mechanical properties and the morphology of the blends. The compatibiliser was found to be a good emulsifying agent from a morphological point of view. Nevertheless, the mechanical properties of the blend were not improved by the addition of the compatibiliser.     

Synthesis and properties of poly(tetramethylene terephthalate-co-ethylene terephthalate)–poly(tetramethylene ether) segmented copolymers

A series of polyether–copolyester segmented copolymers ((PBT–PET)PTMG) based on hard segments of tetramethylene terephthalate–ethylene terephthalate copolyester (PBT–PET) and soft segments of poly(tetramethylene ether)(PTMG) was synthesized. The hard : soft segment weight ratio was 30 : 70 and the mole ratio of PBT : PET was 1 : 10; 1 : 6; 1 : 1; 3 : 1, respectively. Their mechanical properties, morphology, crystallization behavior and optical transparency were investigated and compared with poly(tetramethylene terephthalate)–poly(tetramethylene ether)(PBT–PTMG), as well as with poly(ethylene terephthalate)–poly(tetramethylene ether)(PET–PTMG), consisting of the equivalent composition ratio of hard and soft segments. It was found that the transparency could be improved by introducing a small amount of PBT into PET–PTMG through copolymerization. However, a decrease was observed in the transparency if more PBT was added. This is due to the fact that the copolymerization makes both crystallinity and crystallization rate decrease.     

Synthesis and characterization of copolymers of poly(ethylene terephthalate) and cyclohexane dimethanol in a semibatch reactor (including the process model)

Although poly(ethylene terephthalate) (PET) has excellent basic properties, this polymer tends to crystallize rapidly and has a rather high melting temperature, a low glass‐transition temperature, and low impact on notched articles for some potential applications. Copolymerization is a reasonable method for improving the properties of PET. 1,4‐cyclohexane dimethanol (CHDM) is one of the most important comonomers for PET. In this research, PET and PET copolymers containing 5–30% CHDM were prepared from comonomer mixtures by two‐step melt polycondensation. The copolymers were synthesized in a home‐made laboratory setup. The first synthesis step was conducted under pressure, and the second was performed in vacuo at a high temperature (230–290°C). The microstructure of the synthesized copolymers was studied with Fourier transform infrared and nuclear magnetic resonance. The comonomer content in the polymer chain was determined from the nuclear magnetic resonance spectrum. The presence of the comonomer in the copolymer chain was random. Differential scanning calorimetry was used to study the thermal properties of the copolymers to detect changes in the polymer properties. CHDM reduced the heat of fusion and melting and glass‐transition temperatures of the PET copolymers. Process modeling was performed with mass balances of different functional groups and species. Equations of mass balances were integrated numerically. Numerical simulation and experimental results were in very good agreement. By modeling, the effects of the reaction temperature and feed molar ratio on the conversion and formation of diethylene glycol were studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rheologically determined phase behavior and miscibility of reactively compatibilized poly(ethylene terephthalate)/polypropylene blends

Rheology, phase behavior and morphology of poly(ethylene terephthalate)/polypropylene (PET/PP) blends compatibilized with maleic-anhydrate-grafted-PP (PP-g-MA) and n-butyl-acrylate-glycidyl-methacrylate-ethylene (EBGMA) were studied. According to infrared spectroscopy results, whereas PP-g-MA was merely capable of reacting with hydroxyl groups of PET, epoxy groups of EBGMA could react with both the hydroxyl and carboxyl end groups of PET. The enhanced compatibilizing effect of EBGMA on PET/PP systems over PP-g-MA was also revealed by scanning electron microscopy and mechanical experiments. From frequency and temperature sweep rheological experiments, the dynamic characteristics of the compatibilized blends found to be improved in comparison with those of the uncompatibilized system. Such enhancement was interpreted as a result of the higher miscibility of the compatibilized blends which was further supported by Cole–Cole plot analyses.     

Poly(ethylene terephthalate)–poly(caprolactone) block copolymer. I. Synthesis,reactive extrusion,and fiber morphology

A novel poly(ethylene terephthalate)–poly(caprolactone) block copolymer (PET–PCL) is synthesized in a reactive twin‐screw extrusion process. In the presence of stannous octoate, ring‐opening polymerization of ϵ‐caprolactone is initiated by the hydroxyl end groups of molten PET to form polycaprolactone blocks. A block copolymer with minimal transesterification is obtained in a twin‐screw extruder as a consequence of the fast distributive mixing of ϵ‐caprolactone into high melt viscosity PET and the short reaction time. The PET–PCL structure is characterized by IV, GPC, ¹H‐NMR, and DSC. Fully drawn and partially relaxed fibers spun from PET–PCL are characterized by WAXD and SAXS. A substantial decrease in the oriented amorphous fraction appears to be the major structural change in the relaxed fiber that provides the fiber with the desired stress–strain characteristics. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1858–1867, 1999     

Ionization–liquid-crystalline polymer synergistically reinforced poly(ethylene terephthalate) due to interfacial compatibilization by ion–dipole interactions

To enhance the compatibility of poly(ethylene terephthalate) (PET)/liquid crystalline polymer (LCP) composite, thereby mechanically strengthening the PET matrix, an optimally compatibilized composite of chain-extended and -carboxylated PET ionomer and poly(4-hydroxybenzoic acid–ran–6-hydroxy-2-naphthoic acid) (HBA–HNA) was successfully prepared. Upon PET carboxylated chain extension with pyromellitic dianhydride and subsequent ionization with Zn(OH)₂, the compatibility of the composite was distinctly improved, as verified by the refined dispersed-phase morphology, increased number of refined HBA–HNA fibrils, reduced crystallinity, and improved complex viscosity. Compared with PET, the optimally compatibilized composite displayed a 70.1 and 148.7% increase in Young's modulus and tensile strength, respectively. Tentatively mechanistically, the interfacial interaction may change from weak hydrogen bonding to strong ion–dipole interactions due to the introduction of ionic groups, which remarkably boosts the interfacial compatibility, thereby achieving synergistic effects of the ionization and HBA–HNA inclusion to maximally strengthen PET. It seems that the synergistic ionization/LCP inclusion by a one-pot method establishes a promising preparation approach to commercial PET engineering resins.     

Polymer blends of PET–PS compatibilized by SMA and epoxy dual compatibilizers

Poly(ethylene terephthalate) (PET) and polystyrene (PS) are immiscible and incompatible and have been well recognized. In this study, styrene maleic anhydride random copolymer (SMA–8 wt % MA) and tetra-glycidyl ether of diphenyl diamino methane (TGDDM) are employed as reactive dual compatibilizers in the blends of PET–PS. The epoxy functional groups of the TGDDM can react with PET terminal groups ( OH and  COOH) and anhydride groups of SMA at the interface to produce PET-co-TGDDM-co-SMA copolymers. SMA with low MA content is miscible with PS, whereas the PET segments are structurally identical with PET phase. Therefore, these in-situ-formed copolymers tend to anchor at the interface and act as effective compatibilizers of the blends. The compatibilized blends, depending on the amounts of TGDDM and SMA addition, result in smaller phase domain, higher viscosity, and improved mechanical properties. This study demonstrates that SMA and TGDDM dual compatibilizer can be utilized effectively in compatibilizing polymer blends of PET and PS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2029–2040, 1999