Glycolysis of polyethylene terephthalate waste fibers

Glycolysis of polyethylene terephthalate waste fibers was carried out using excess ethylene glycol in the presence of different simple chemicals, namely, glacial acetic acid, lithium hydroxide, sodium sulfate, and potassium sulfate. Good yields (> 60%) of the monomer bis(2‐hydroxyethylene terephthalate) were obtained using these chemicals as depolymerization catalysts. The purified monomer was characterized by elemental analysis, melting point, IR spectroscopy, and nuclear magnetic resonance. The qualitative and quantitative yields of the monomer obtained using these catalysts are most comparable with the conventionally used heavy metal catalysts such as zinc acetate and lead acetate. The chemicals used, being cheap and comparatively less harmful to the environment, offer further advantages in chemical recycling of polyester waste fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 513–517, 2005     

Synthesis and characterization of terephthalamides from poly(ethylene terephthalate) waste

Poly(ethylene terephthalate) (PET) waste flakes (blow‐molded‐grade industrial waste) were degraded with aqueous methylamine and ammonia at room temperature in the presence and absence of quaternary ammonium salt as a catalyst for various times. The catalyst reduced the time required for the degradation of the PET waste. The degraded products were analyzed with IR, nuclear magnetic resonance, mass spectrometry, and differential thermal analysis and were characterized as N,N′‐dimethylterephthalamide and terephthalamide in the case of methylamine and ammonia, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1515–1528, 2005     

Studies on synthesis and characterization of N‐alkyl terephthalamides using different amines from polyethylene terephthalate waste

This study deals with the degradation of polyethylene terephthalate (PET) waste through aminolysis with various amines. All of these degradation experiments were carried out at ambient temperature and at normal pressure. Although PET is known to be recycled in many ways, but still there is a need of development of other environment friendly recycling techniques. The amines used to study the degradation of PET waste were namely methylamine, ethylamine, and n‐butyl amine, respectively where the degradation of PET waste completes in 45 days. The aminolyzed products so obtained were characterized by using various conventional techniques such as spectroscopic techniques namely IR, NMR, and simultaneous differential scanning calorimeter (DSC). In the present research work, a useful method of PET recycling by using various amines was successfully established. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Novel synthesis,characterization and application of dibutyrate bis(2-hydroxyethyl) terephthalamide as a plasticizer in PVC compounding

This study focuses on the synthesis and application of dibutyrate of bis(2-hydroxyethyl) terephthalamide (DB-BHETA) as a plasticizer in poly(vinyl chloride) (PVC) compounding. DB-BHETA was synthesized from poly(ethylene terephthalate) bottle waste through aminolysis followed by condensation reaction with butyric acid. Synthesized DB-BHETA was characterized by FTIR, DSC and NMR. Plasticized PVC was prepared by melt blending of PVC in different ratios with DB-BHETA and the mechanical, thermal and rheological properties were investigated. The glass transition temperature (T _g) decreased with increasing concentration of DB-BHETA, confirming its plasticizing effect. The impact properties of PVC/DB-BHETA were maximum at weight ratio of 80/20. Shore hardness continuously reduced with increase in the concentration of DB-BHETA in PVC. Also, incorporation of DB-BHETA results in a gradual decrease in the loss modulus (viscous) and an increase in the storage modulus (elastic).     

Synthesis and characterization of novel pentaerythritol ester as PVC plasticizer

A novel bio‐based PVC plasticizer, levulinic acid pentaerythritol ketal ester (LAPKE), was synthesized and evaluated as renewable resource alternatives to traditional phthalate. The structure of LAPKE was characterized by FT‐IR, ¹H NMR, and ¹³C NMR. The LAPKE and dioctyl phthalate (DOP) at different mass ratio were added to the PVC to prepare PVC samples. The mechanical properties of PVC samples at mass ratio of 1:1 showed that its tensile strength, elongation at break was up to an optimum value. The thermal stability was measured by dynamic thermal stability and thermogravimetric analysis (TGA), and the results showed that the thermal ability of PVC was improved with the addition of LAPKE. The weight loss of migration property (volatility, leaching test and exudation) has also increased by increasing mass ratio of LAPKE. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44227.     

Using ionic liquid catalyst for conversion of waste polyethylene terephthalate and soybean oil to polyester polyol

An imidazolium ionic liquid was synthesized, characterized and used as a catalyst for conversion of polyethylene terephthalate (PET) and soybean oil to polyester polyol (PE polyol). The degradation of PET waste was carried out using glycerol and low cost soybean oil that resulted in the formation of PE polyols. Formed PE polyols were characterized using Fourier transform infrared (FT‐IR) and mass spectra method, thermo gravimetric and differential thermal analysis and gel permeation chromatoghraphy. The first step in the overall process is proposed to be the transesterification of soybean oil with glycerol to form monoglyceride or/and diglyceride of soybean oil fatty acids. In the second step, the obtained glycerides can react with PET to form PE polyol. Both steps could be combined in one process and acidic catalyzed by an ionic liquid. Ionic liquid can be used as active catalyst and show a high reusability. The influence of some factors such as amount of glycerol used in transesterification of soybean oil with glycerol, PET degradation time, and temperature on PET conversion were investigated to find the suitable conditions for the process. Under suggested optimum parameters (mass ratio of soybean oil to glycerol of 2:1, a time of 8 h and a temperature of 180 °C for PET degradation), a PET conversion of 87.3% was reached. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43920.     

Hydrolysis reaction of poly(ethylene terephthalate) using ionic liquids as solvent and catalyst

The hydrolysis of poly(ethylene terephthalate) (PET) was studied using ionic liquid 1‐n‐butyl‐3‐methylimidazolium chloride ([Bmim][Cl]) as solvent and acid‐functionalized ionic liquid 1‐methyl‐3‐(3‐sulfopropyl)‐imidazolium hydrogen sulfate ([HSOpmim][HSO₄]) as catalyst. The effects of temperature, time, and dosages of solvent and catalyst on hydrolysis results were examined. Under the optimum conditions of m(PET) : m(H₂O) : m([Bmim][Cl]) : m([HSOpmim][HSO₄]) = 3 : 4 : 6 : 0.6, reaction temperature 170°C and time 4.5 h, the conversion of PET and the yield of terephthalic acid (TPA) were almost 100% and ≥88%, respectively. After easily separated from the product, the ionic liquids could be reused eight times without obvious decrease in the conversion of PET and yield of TPA. Hence, an environmental friendly strategy for chemical recycling of PET was developed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Facile fabrication of oriented polyethylene terephthalate foams as novel solar interfacial vapor generator from waste bottles

The massive arbitrarily discarded waste of polyethylene terephthalate (PET) bottles become a major environmental pollution source for soils and oceans. Using these waste products to acquire purified water has great significance. We developed a novel strategy of inducing crystallization coupled with solvent exchanging to obtain oriented PET/carbon nanotubes (CNT) foams from waste PET bottles and to fabricate solar interfacial vapor generators (SIVGs). The obtained PET/CNT foams had low densities of 0.18 g/cm³ and high specific strength with compressive stress of 1.8 MPa. The PET/CNT foams generated excellent capillary action that the water delivering rate reached 93.60 kg/m² h. In addition, the oriented PET foams demonstrated a promising thermal concentration effect that its surface temperature reached 132.8°C. It could evaporate up to 0.82 kg/m² h under the illumination of 1 sun. Meanwhile, the foams with CNT clusters dispersion also exhibited excellent electrical resistance of 3.57 × 10³ Ω m with a low percolation threshold of 0.5 wt.% CNT. This work provides a novel strategy of manufacturing PET SIVG. The key aspect of this work is the significant increase in the surface temperature and the conductivity of PET SIVG compared with other polymer-based SIVGs, highlighting its novelty and importance.     

Synthesis and characterization of waterborne polyurethane dispersion from glycolyzed products of waste polyethylene terephthalate used as soft and hard segment

Waste polyethylene terephthalate (PET) bottles were collected, cleaned and then depolymerized by glycolysis with neopentyl glycol (NPG) and dipropylene glycol (DPG), in the presence of N-butyl titanate catalyst. The product, named glycolyzed oligoesters, obtained through the depolymerization, were employed respectively in hard segment and soft segment in the synthesis of novel waterborne polyurethane dispersions (PUDs) via a simple and environmentally benign process. In addition, a polyurethane dispersion without glycolyzed oligoesters was synthesized as a comparison. The bulk structure of PET glycolyzed oligoesters and PUDs films were characterized by Fourier transform infrared spectroscopy (FT-IR), H-nuclear magnetic resonance (¹H NMR) and Gel permeation chromatography (GPC). The results illustrated that glycolyzed oligoesters were successfully introduced into the hard and soft segment of the polyurethanes. Furthermore, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to investigate the thermal properties of the PET glycolyzed oligoesters and PUDs films. The results showed that the thermal resistance of waterborne polyurethanes obtained with glycolyzed oligoesters increased due to lower degrees of phase separation. X-ray diffraction indicated that all synthesized polyurethanes exhibited reduced degrees of orientation. Due to the balance between hard-/soft-segment of the waterborne polyurethane dispersions, the formulations containing glycolyzed oligoesters within the hard segment sections of the polyurethanes provided the best performance.     

Synthesis,characterization, and application of the sodium poly(styrenesulfonate) produced from waste polystyrene cups as an admixture in concrete

Wasted polystyrene (PS) plastic cups were used in the synthesis of sodium poly(styrenesulfonate) (NaPSS). The produced polyelectrolyte was water‐soluble. The viscosimetric molecular weight was 126,146 g mol^?1. The sulfonation of the polymer was estimated through FTIR spectroscopy and chemical analysis of the number of sulfonic groups. The presence of bands at 1326 and 1188 cm^?1 in the infrared spectra was characteristic for sulfonic groups. The polymer was obtained with 60.3% of sulfonation. An aqueous solution of NaPSS was used as an admixture in concrete of portland cement. The results showed that the slump increasing of the concrete was up to 300% with 0.3% content of NaPSS per weight of cement. It was possible to reduce the water content of the concrete in 13.2% using NaPSS solution as an admixture. The compressive strength gain was 23.9% after 28 days of curing. The results indicated that NaPSS, produced from waste PS cups, can be satisfactorily used either as a plasticizer or as an admixture for water reduction in concrete. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1534–1538, 2005     

Synthesis and application of a novel cardanol‐based plasticizer as secondary or main plasticizer for poly(vinyl chloride)

A novel plasticizer based on cardanol, hydrogenated cardanol glycidyl ether acetic ester containing phosphaphenanthrene group (HCGEP), was prepared and incorporated into poly(vinyl chloride) (PVC) for the first time. The molecular structure was characterized with Fourier transform infrared and ¹H NMR spectroscopies. The thermal degradation behavior and flame retardant performance of PVC films with HCGEP as secondary or main plasticizer were investigated using thermogravimetric analysis, combustion tests, limiting oxygen index tests and morphological analysis of residues. Furthermore, the mechanical properties of PVC films were examined based on the results of tensile testing. The results were compared to those of the petroleum‐based plasticizer dioctyl phthalate. With the substitution of dioctyl phthalate with HCGEP, PVC films exhibited high thermal stability and better flame retardant performance. The tensile test results showed that the addition of HCGEP could endow PVC resin with well‐balanced properties of flexibility, strength and hardness. © 2017 Society of Chemical Industry     

环氧增塑剂的生产工艺及其在PVC塑料加工中的应用

从环氧增塑剂的物化性能及用途、增塑剂的作用机理、PVC热降解原理、环氧增塑剂的生产工艺及应用研究等方面阐述了环氧增塑剂在PVC塑料加工中的应用。     

Chemical,thermal, and mechanical properties and ultraviolet transmittance of novel nano-hydroxyapatite/polyethylene terephthalate milk bottles

Polyethylene terephthalate (PET)/nano-hydroxyapatite (nHAp) composite granules were obtained using twin-screw extruder. Preforms were prepared by injection molding and then PET/nHAp bottles were produced by blow molding. For PET bottles with nHAp, the migration amounts of carboxylic acid (COOH), acetaldehyde (AA), diethylene glycol (DEG), and isophthalic acid (IPA); glass transition temperature (T_g); melting temperature (T_m); and the maximum crystallization temperature (T_cry) were measured. The load-carrying capacity, burst strength, stress cracking, and regional material distribution tests were carried out on the bottles. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and ultraviolet transmittance analyses were conducted to explain the changes in mechanical, chemical, physical properties, and light transmission of bottles. It was found out that the COOH amount increased and the AA content decreased with increasing nHAp amount. On the other hand, no change was observed in the amounts of DEG and IPA. Although the mechanical properties such as load-carrying capacity and burst strength of the bottles have improved, it has been determined that the standard environmental stress crack resistance test procedure cannot be applied to such a composite. Experimental findings indicate that nHAp disrupts the chemical structure of PET and it isolates harmful chemicals such as AA by forming intermolecular bonds. Moreover, with the addition of up to 0.8% nHAp, PET bottles block the light transmission approximately 80% within 400–700 nm wave length zone. The study demonstrates that the PET/nHAp composite bottles can be used in the food industry, particularly in the packaging of milk and milk products which are vulnerable to light exposure.     

Glycolyzed products from PET waste and their application in synthesis of polyurethane dispersions

Soft drinks poly(ethylene terephthalate) (PET) bottles were depolymerized by glycolysis with different molar ratio of glycol, such as propylene glycol (PG), triethylene glycol (TEG) and poly(ethylene glycol) (PEG 400), in the presence of a zinc acetate catalyst. These glycolyzed products were characterized by hydroxyl value (HV) determinations. The obtained glycolyzed products were reacted with isophorone diisocyanate (IPDI), dimethylol propionic acid (DMPA), as potential ionic center for water dispersibility, and mixed with ethylene diamine (EDA) as extender chain to prepare polyurethane dispersions. The PET glycolyzed products and polyurethane formation were characterized using Fourier transform infrared spectroscopy (FTIR). The molecular masses distribution of oligoester polyol and polyurethane dispersions were determined by using gel permeation chromatography (GPC). The effect of different PET/glycol molar ratio, on the physico-mechanical properties, such as hardness, adhesion test and gloss of polyurethane films were investigated. Thermal properties were investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC).     

Studies on synthesis and characterization of a novel acrylic aromatic amide oligomer of aminolysed endproducts generated from pet waste with hydrazine monohydrate and its photocuring with acrylate monomers

A novel acrylic aromatic amide oligomer was synthesized by using depolymerized end product of PET waste with hydrazine monohydrate. The end product of aminolysed PET waste was synthesized under ambient conditions and was used in the preparation of novel acrylic oligomer with the reaction of acryloyl chloride prepared from acrylic acid. The acrylic oligomer was characterized by spectroscopic techniques, such as FTIR, ¹H‐NMR, UV, Mass spectrometry, and by other analytical techniques such as, Iodine value, TGA, and DSC. The proposed structure of the oligomer is supported by its spectral analysis and the same is inferred from other techniques. The acrylic oligomer mixed with other acrylate monomers such as methylmethacrylate, ethylhexylacrylate, acrylic acid, and photoinitiator, can be cured by UV radiation and can thus be used as an adhesion promoter on metal/glass surface. This article presents the possibility of using a difunctional aromatic amide oligomer with excellent hydrogen bonding capacity as an alternative to urethane acrylates in radiation curable formulations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Blends of poly(ethylene terephthalate) and low density polyethylene containing aluminium: A material obtained from packaging recycling

Composites of polyethylene and aluminium (PEAL) may be obtained from the recycling of postconsumed Tetra Pak aseptic packaging. The components of the composite are low density polyethylene (LDPE), aluminium and an ethylene‐methacrylic acid random copolymer (EMAA). The presence of metallic filler and a functionalized copolymer, which may act as a compatibilizer, suggests that blending PEAL with other thermoplastic would be a way to obtain reinforced and compatibilized blends from recycled materials. Blends of PEAL and recycled poly(ethylene terephthalate) (PET) were prepared in the compositions of 30, 50, and 70 wt % of PET in a twin‐screw extruder. Blends of PET/LDPE and PET/EMAA were also prepared for comparison. The morphological analysis showed that the PET/PEAL blends present an excellent interfacial adhesion, similar to the PET/EMAA blend. The improvement of adhesion in comparison with the PET/LDPE blend is a result of the interaction between polar groups of PET and EMAA. PET/PEAL blends presented lower elongation at break and impact strength than the other blends whereas Young modulus was higher. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis,characterization, and amidoximation of diaminomaleodinitrile-functionalized polyethylene terephthalate grafts for collecting heavy metals from wastewater

Synthesis, characterization, and amidoximation of diaminomaleodinitrile-functionalized polyethylene terephthalate (PET) grafts were studied. Azobisisobutyronitrile (AIBN) was used as an initiator. Optimum conditions for grafting were as follows: monomer concentration [DAMN] = 0.5M, [AIBN] = 1.50 × 10⁻³ mol/L, T = 80°C and t = 3 h. Water uptake of the grafted-PET film increased with the increase of grafting yield. The imparted cyano group of the grafted polymer chains (with degree of grafting up to 83%) was converted into amidoxime group by reaction with hydroxylamine. The unique advantage of this polymer is that it contains double amidoxime groups per repeating unit and an additional diethylene spacer unit between neighboring amidoxime groups in each monomeric unit. The grafted-PET films were characterized by FTIR spectroscopy, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The grafted-PET films are more thermally stable than the ungrafted-PET membrane, since the grafted membrane showed a single degradation pattern despite having two components. A decrease in T_g values is observed as the grafting yield of copolymers increases indicating the incorporation of polydiaminomaleodinitrile chains in amorphous copolymers with higher thermal stability. The prepared amidoximated DAMN83-g-PET was investigated for its properties in removing heavy toxic metals, such as Pb²⁺, Cd²⁺, Zn²⁺, Fe²⁺, Cu²⁺, Ni²⁺, Co²⁺, and Ag¹⁺ from waste water. The amidoximated-film is characterized by a considerably greater binding ability with respect to heavy metals. The nature of the metal ion also has great importance in the amount binding to the polymeric material. The kinetics of the sorption/desorption process for Co²⁺, Ni²⁺, and Zn²⁺ are investigated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Utilization of polyethylene terephthalate waste as a carbon filler in polypropylene matrix: Investigation of mechanical,rheological, and thermal properties

Polyethylene terephthalate (PET) waste was converted into carbon and the feasibility of utilizing it as a reinforcing filler material in a polypropylene (PP) matrix was investigated. The carbon produced by the pyrolysis of waste PET at 900°C in nitrogen atmosphere contains high carbon content (>70 wt%). PP/carbon composites were produced by melt blending process at varying loading concentrations. Scanning electron microscopy images at the fractured surface revealed that the carbon filler has better compatibility with the PP matrix. The mechanical, thermal, and rheological properties and surface morphology of the prepared composites were studied. The thermogravimetric analysis studies showed that the thermal stability of the PP/carbon composites was enhanced from 300 to 370°C with 20 wt% of carbon. At lower angular frequency (0.01 rad/s), the storage modulus (G′) of PP was 0.27 Pa and those of PP with 10 and 20 wt% carbon was 4.06 and 7.25 Pa, respectively. Among the PP/carbon composite prepared, PP with 5 wt% carbon showed the highest tensile strength of 38 MPa, greater than that of neat PP (35 MPa). The tensile modulus was enhanced from 0.9 to 1.2 GPa when the carbon content was increased from 0 to 20 wt%.     

Alkali decomposition of poly(ethylene terephthalate) with sodium hydroxide in nonaqueous ethylene glycol: A study on recycling of terephthalic acid and ethylene glycol

Pellets of poly(ethylene terephthalate) (PET; 0.48–1.92 g) were heated in anhydrous ethylene glycol (EG; 5 mL) with 2-equivs of NaOH at 150°C for 80 min or 180°C for 15 min to convert them quantitatively to disodium terephthalate (Na₂-TPA) and EG. The disodium salt was precipitated quantitatively in pure state from the EG solution and separated readily. The other product EG, being the same component to the solvent, remains in the solution and can be obtained after distillation as a part of the solvent. The rate of decomposition was significantly accelerated by the addition of ethereal solvents to EG, such as dioxane, tetrahydrofuran, and dimethoxyethane. The reaction system is simple; no water and no extra reagent other than NaOH and EG are used. A few recycling systems of PET can be designed on the basis of the present alkali decomposition reaction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 595–601, 1997     

Aminolysis of poly(ethylene terephthalate) wastes based on sunlight and utilization of the end product [bis(2‐hydroxyethylene) terephthalamide] as an ingredient in the anticorrosive paints for the protection of steel structures

The increasing demand for poly(ethylene terephthalate) (PET) polymer, the simultaneous shortage in landfill disposal spaces, and known problems associated with PET waste specifically (e.g., its nonbiodegradability and huge accumulation) are challenges with which mankind must cope nowadays. In this study, PET postconsumer bottle wastes were cut to very small slides and then subjected to an aminolysis process with ethanol amine as a degradative agent in the presence of one catalyst from three used in this study. These catalysts were dibutyl tin oxide, sodium acetate, and cetyltrimethyl ammonium bromide. The reaction was performed in sunlight: a beneficial, clean, cheap, and renewable source of energy. The end product, which was a white precipitate of bis(2‐hydroxyethylene) terephthalamide, was subjected to spectrophotometric and thermal analyses. The product was characterized to asses its suitability for use in pigments in anticorrosive paint formulations. In general, this process was a green, environmentally friendly degradation based on the utilization of solar energy for the aminolysis reaction using simple, cheap, available chemicals as catalysts. The originality of this study was derived from the use of waste materials to yield a product with beneficial applications in the field of corrosion inhibition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011