Bis(2-hydroxyethyl) Terephthalate Research Articles

Synthesis, Degradation, Biocompatibility and Drug Release Studies of Bis 2-Hydroxy Ethyl Terephthalate-based Poly(Mannitol-Citric-Sebacate) Ester

Bis 2-Hydroxy Ethyl Terephthalate-based biodegradable poly(mannitol-citric-sebacate) has been synthesized by catalyst-free melt condensation process using two different diacids and Bis 2-Hydroxy Ethyl Terephthalate with D-mannitol as monomers having a potential to be metabolized in vivo. The biocompatibility of the polymer, Bis 2-Hydroxy Ethyl Terephthalate-poly(mannitol-citric-sebacate) has been tested using human primary stromal cells. In vitro degradation of Bis 2-Hydroxy Ethyl Terephthalate-poly(mannitol-citric-sebacate) polymer in Phosphate Buffered Saline solution carried out at physiological conditions indicates that the degradation goes to completion after 23 days. The usage of Bis 2-Hydroxy Ethyl Terephthalate-poly(mannitol-citric-sebacate) polymer as a drug carrier has been analyzed by doping the polymer with Doxorubicin model drug and the release rate has been studied by mass loss over time. The cumulative drug-release profiles exhibit a biphasic release with an initial burst release and cumulative 100 percent release within 14 days.

Synthesis and structure analysis of polyesteramides modified with bio-based diaminopentane hexanedioic salt

Abstract Two series of bio-based diaminopentane hexanedioic salt (DHS) modified polyesteramides were successfully synthesized by two different synthesis processes in which DHS reacted with bis-hydroxyethyl terephthalate (BHET) and low molecular weight polyester (LPET), respectively. The intrinsic viscosities of the polyesteramides ranged from 0.62 dl/g to 0.78 dl/g, which correlated greatly with the requirements of subsequent processing such as spinning. The results of the heteronuclear multiple bond correlation (HMBC) indicated that the diaminopentane segment was directly connected with the purified terephthalic acid (PTA) segment. The presence of ester and amide group characteristic peaks in the Fourier transform-infrared (FT-IR) spectroscopy confirmed that the final resultant products were polyesteramides. The results of elemental analysis showed that the ratio of actual nitrogen content to theoretical nitrogen content of two series of polyesteramides was 76%~90%, and the actual nitrogen content in both series was proportional to the addition of DHS.

Preparation of HTLcs from Magnesium Desulfurization Residues and their Catalytic Performance in Degradation of Waste Polyester

To recycle the solid wastes, the hydrotalcite-like compounds (HTLcs) were prepared from the magnesia flue gas desulfurization residues (MFGDR). The HTLcs as prepared and the products from degradation of Poly (ethylene terephthalate) (PET) were characterized by thermogravimetric analysis (TG) , x-ray powder diffraction (XRD) , fourier transform infrared spectrometer (FTIR) and differential scanning calorimetry (DSC) methods. Effects of calcining temperature and alkaline of solution on the structure and performance of HTLcs were studied. The main product of alcoholysis of PET was bis-hydroxyethyl terephthalate (BHET). The catalyst shows a potential application in solid waste treatment and recycle.

Ionic Liquid-Coordinated Ferrous Acetate Complex Immobilized on Bentonite As a Novel Separable Catalyst for PET Glycolysis

Ionic liquid-coordinated ferrous acetate complex immobilized on bentonite ([Bmim—Fe][(OAc)3]/bentonite) was prepared by impregnation of [Bmim—Fe][(OAc)3] on bentonite. The prepared catalyst was characterized using FTIR, XRD and total carbon (TC). The catalyst showed a high catalytic activity in the glycolysis of polyethylene terephthalate (PET) under mild condition. Maximum activity was observed with a PET conversion of 100% and bis(2-hydroxyethyl)terephthalate (BHET) yield of 44% under the optimum conditions of catalyst (1.0 g), ethylene glycol (20 g) and PET (3.0 g) at 190 °C for 3 h. The activation energy of PET glycolysis using the prepared catalyst was calculated and found to be 51.6 kJ/mol.

(Mg–Zn)–Al layered double hydroxide as a regenerable catalyst for the catalytic glycolysis of polyethylene terephthalate

(Mg–Zn)–Al layered double hydroxide (LDH) was prepared by the coprecipitation method at low super saturation conditions. The prepared (Mg–Zn)–Al LDH was analyzed using XRD, FTIR, N2 adsorption–desorption, TGA and DSC, confirming the formation of pure LDH phase. The extent of polyethylene terephthalate (PET) degradation by the glycolysis process was studied using the prepared (Mg–Zn)–Al LDH. The glycolysis process was optimized in terms of catalyst concentration, temperature, time, ethylene glycol dosage. Under the optimal conditions of 1.0wt.% of catalyst with 20g of ethylene glycol (EG) in the presence of 2.0g of PET at 196°C after 3h of glycolysis, complete PET conversion was achieved and the yield of bis (2-hydroxyethyl) terephthalate (BHET) reached 75%.

DEGRADED PET FOR THE REMOVAL OF METAL IONS FROM AQUEOUS SOLUTION

Poly(ethylene terephthalate) waste was degraded by glycolysis in order to obtain low molecular weight molecules for the batch removal of Cd(II), Cr(III), Cu(II), Ni(II), and Pb(II) from aqueous solution. The degradation product was characterized by IR, H1NMR, DSC, and GPC, being identified as bis(2-hydroxy ethyl) terephthalate (BHET). The results show that metal absorption follows the order Pb(II)>Cd(II)>Ni(II)>Cu(II)>Cr(III). Degraded PET presented an affinity to remove over 75% of lead in solution at pH 4 and 5 and cadmium over 70% at pH 6. IR spectroscopy and DSC evidenced the presence of metal ions in the structure of the material.

Chemical scavenging of post-consumed clothes

Aiming toward the rectification of fiber grade PET waste accumulation as well as recycling and providing a technically viable route leading to preservation of the natural resources and environment, the post consumed polyester clothes were chemically recycled. Post consumed polyester clothes were recycled into bis(2-hydroxyethyl) terephthalate (BHET) monomer in the presence of ethylene glycol as depolymerising agent and zinc acetate as catalyst. Depolymerized product was characterized by chemical as well as analytical techniques. The fiber grade PET was eventually converted into BHET monomer with nearly 90% yield by employing 1% catalyst concentration and at optimum temperature of 180°C without mechanical input of stirring condition.

Time, Temperature and Amount of Distilled Water Effects on the Purity and Yield of Bis(2-hydroxyethyl) Terephthalate Purification System

Polyethylene terephthalate (PET) bottle is one of the common plastic wastes existed in the municipal solid waste in Malaysia. One alternative to solve the abundant of PET wastes is chemical recycling of the wastes to produce a value added product. This technology not only can decrease the PET wastes in landfill sites but also can produce many useful recycled PET products. Bis(2-hydroxyethyl) terephthalate (BHET) obtained from glycolysis reaction of PET waste was purified using crystallization process. The hot distilled water was added to glycolysis product followed by cooling and filtration to extract BHET in white solid form from the product. The effect of three operating conditions namely crystallization time, crystallization temperatures and amount of distilled water used to the yield of crystallization process were investigated. The purity of crystallization products were analyzed using HPLC and DSC. The optimum conditions of 3 hours crystallization time, 2 °C crystallization temperature and 5:1 mass ratio of distilled water used to glycolize solid gave the highest yield and purity of the crystallization process. © 2015 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Fast and effective glycolysis of poly(ethylene terephthalate) catalyzed by polyoxometalate

Transition-metal-substituted polyoxometalates (POMs) K6SiW11MO39(H2O) (M = Zn2+, Mn2+, Co2+, Cu2+, Ni2+) show excellent catalytic activities in the glycolysis of poly(ethylene terephthalate) (PET) under mild conditions. The effects of temperature, catalyst amount and reaction time on PET degradation are investigated. The PET could be fast and completely degraded at low catalyst/PET molar ratio (0.13%) and high PET/EG weight ratio (1:4). The yield of bis(hydroxyethyl) terephthalate (BHET) exceeds 84% with the SiW11Zn as the catalyst under atmospheric pressure at 185 °C for 30 min. The catalyst and ethylene glycol (EG) can be easily separated from the products by filtration and can be reused together. After recycling eight times, the conversion of PET and the yield of BHET can still reach 100% and 83%, respectively. The possible nucleophilic substitution mechanism for PET glycolysis using the K6SiW11ZnO39(H2O) as the catalyst is proposed. The POM catalysts are hopeful to provide the possibility for other polymer degradation.

Effect of Polyethylene Glycol on Bis(2‐hydroxyethyl) terephthalate‐Based Polyurethane/Alginate pH‐Sensitive Blend for Oral Protein Delivery

ABSTRACTPolyurethanes (PUs) are synthesized by reacting two polyols, namely bis(2‐hydroxyethyl) terephthalate (BHET) and polyethylene glycol (PEG), taken in four different ratios and hexamethylene diisocyanate, where the polyol content is slightly higher than the stoichiometrically required amount. BHET is obtained by the glycolysis of polyethylene terephthalate waste. The synthesized PUs are blended with sodium alginate in the ratio of 7:3 and then cross‐linked by calcium chloride to get a pH‐sensitive protein (bovine serum albumin, BSA) carrier. X‐ray diffraction patterns of different PU compositions indicate the presence of amorphous phase. The hydroxyl value of OH‐terminated PUs is found to be increasing with increasing amount of PEG in the composition. PEGylated PU shows higher water uptake and protection against hemolysis with a rising amount of PEG in the PU. Fourier transform infrared spectroscopy of the blend shows characteristic peaks for both PU and alginate distinctly, indicating good dispersion of both the polymers. pH responsive swelling behavior in different pH media corresponding to the gastrointestinal tract (pH 1.2 and 7.4) is investigated for all the prepared blends. The minimum degree of swelling is observed for PU with the maximum amount PEG at pH 1.2, whereas the degree of swelling of the same PU significantly increased at pH 7.4. BSA encapsulation efficiency of the blends increases with an increase in PEG content in the PU and varies within the range of 88–99%. The release profile of BSA at pH 7.4 is found to be similar as observed in the swelling study.

First-Row Transition Metal-Containing Ionic Liquids as Highly Active Catalysts for the Glycolysis of Poly(ethylene terephthalate) (PET)

First-row transition metal-containing ionic liquids (ILs) were synthesized and used to catalyze the degradation of poly(ethylene terephthalate) (PET) in ethylene glycol (EG). One important feature of these IL catalysts is that they have good thermal stability, and most of them, especially [bmim]2[CoCl4] (bmim = 1-butyl-3-methyl-imidazolium) and [bmim]2[ZnCl4], exhibit higher catalytic activity, compared with traditional catalysts, conventional IL catalysts, and some functional ILs. For example, utilizing [bmim]2[CoCl4] as catalyst, the conversion of PET, selectivity of bis(hydroxyethyl) terephthalate (BHET), and mass fraction of BHET in products reach up to 100%, 81.1%, and 95.7%, respectively, under atmospheric pressure at 175 °C for only 1.5 h. Another important feature is that BHET can be easily separated from these IL catalysts and has high purity. Moreover, recycling results show that [bmim]2[CoCl4] worked efficiently after being used six times. These all show that [bmim]2[CoCl4] is an excellent IL catalyst for the glycolysis of PET. Finally, based on in situ IR spectra and experimental results, the possible mechanism of degradation with synthesized IL is proposed.

Glycolysis of Poly(ethylene terephthalate) Catalyzed by the Lewis Base Ionic Liquid [Bmim][OAc

The glycolysis of poly(ethylene terephthalate) (PET) was studied using 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) as a catalyst. The effects of temperature, time, ethylene glycol dosage, PET amount, and [Bmim][OAc] dosage on the glycolysis reaction were examined. The results revealed that [Bmim][OAc] has a PET conversion of 100% and a bis(2-hydroxyethyl)terephthalate (BHET) yield of 58.2% under the optimum conditions of 1.0 g of [Bmim][OAc] with 20 g of ethylene glycol in the presence of 3.0 g of PET at 190 °C after 3 h of glycolysis. The ionic liquid could be reused up to six times with no apparent decrease in the conversion of PET or yield of BHET. The pH plays a major role in explaining the proposed mechanism of glycolysis using the Lewis base ionic liquid [Bmim][OAc]. The kinetics of the reaction was first-order with an activation energy of 58.53 kJ/mol.

Microwave assisted glycolysis of poly(ethylene terephthalate) catalyzed by 1‐butyl‐3‐methylimidazolium bromide ionic liquid

ABSTRACTThe combination of ionic liquid (IL) associated with microwave energy may have some potential application in the chemical recycling of poly (ethylene terephthalate). In this processes, glycolysis of waste poly (ethylene terephthalate) recovered from bottled water containers were thermally depolymerized with solvent ethylene glycol (EG) in the presence of 1‐butyl‐3‐methyl imidazolium bromide ([bmim]Br) as catalyst (IL) under microwave condition. It was found that the glycolysis products consist of bis (2‐hydroxyethyl) terephthalate (BHET) monomer that separated from the catalyst IL in pure crystalline form. The conversion of PET reach up to 100% and the yield of BHET reached 64% (wt %). The optimum performance was achieved by the use of 1‐butyl‐3‐methyl imidazolium bromide as a catalyst, microwave irradiations temperature (170–175°C) and reaction time 1.75–2 h. The main glycolysis products were analyzed by 1H NMR, 13C NMR, LC‐MS, FTIR, DSC, and TGA. When compared to conventional heating methods, microwave irradiation during glycolysis of PET resulted in short reaction time and more control over the temperature. This has allowed substantial saving in energy and processing cost. In addition, a more efficient, environmental‐friendly, and economically feasible chemical recycling of waste PET was achieved in a significantly reduced reaction time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41666.

Effect of hydrolysis products on the enzymatic degradation of polyethylene terephthalate nanoparticles by a polyester hydrolase from Thermobifida fusca

The biocatalytic hydrolysis of post-consumer polyethylene terephthalate (PET) is a promising approach for an environmentally friendly plastic recycling process. The influence of intermediate hydrolysis products on the degradation of PET by TfCut2, a polyester hydrolase from Thermobifida fusca, was analyzed by reversed-phase HPLC. Nanoparticles prepared from PET films as substrate were hydrolyzed by the enzyme in the presence of ethylene glycol, terephthalic acid, bis(2-hydroxyethyl) terephthalate (BHET) and mono-(2-hydroxyethyl) terephthalate (MHET). The initial reaction rates were determined and kinetically analyzed using a model for PET degradation. BHET and MHET were identified as competitive inhibitors with similar binding constants. The reaction efficiency (Ef) for the hydrolysis of MHET was considerably lower compared to BHET indicating MHET as a relevant inhibitor of the enzymatic hydrolysis of PET nanoparticles by TfCut2. The results demonstrate the importance of product inhibition of the hydrolysis of PET by TfCut2 for the further improvement of biocatalytic plastic recycling processes.

Cu- and Zn-acetate-containing ionic liquids as catalysts for the glycolysis of poly(ethylene terephthalate)

The glycolysis of polyethylene terephthalate (PET) was studied using 1-butyl-3-methylimidazolium acetate-promoted copper acetate (Cu(OAc)2-[Bmim][OAc]) and 1-Butyl-3-methylimidazolium acetate-promoted zinc acetate (Zn(OAc)2-[Bmim][OAc]) as catalysts. The effects of temperature, time, ethylene glycol (EG) amount, PET amount and catalyst dosage on the glycolysis reaction were examined. Under the optimal conditions of 1.0 g of catalyst with 20 g of EG in the presence of 3.0 g of PET at 190 °C after 3 h of glycolysis, complete PET conversion was achieved using Cu(OAc)2-[Bmim][OAc] and Zn(OAc)2-[Bmim][OAc], and the yield of bis (2-hydroxyethyl) terephthalate (BHET) reached 53.95% and 45.6%, respectively. The ionic liquid could be reused up to 6 times with no apparent decrease in the PET conversion or BHET yield. The reaction mechanism was proposed. The reaction kinetics for Cu(OAc)2-[Bmim][OAc] and Zn(OAc)2-[Bmim][OAc] was first-order with an activation energy of 56.4 kJ mol−1 and 53.8 kJ mol−1, respectively.

Synthesis and characterization of azo dyestuff based on bis(2-hydroxyethyl) terephthalate derived from depolymerized waste poly(ethylene terephthalate) fibers

Abstract This work aimed at effectively utilizing the chemically depolymerized waste poly(ethylene terephthalate) (PET) fibers into useful products for the textile industry. PET fibers were glycolytically degraded by excess ethylene glycol as depolymerizing agent and zinc acetate dihydrate as catalyst. The glycolysis product, bis(2-hydroxyethyl) terephthalate (BHET), was purified through repeated crystallization to get an average yield above 80%. Then, BHET was nitrated, reduced, and azotized to get diazonium salt. Finally, the produced diazonium salt was coupled with 1-(4-sulfophenyl)-3-methyl-5-pyrazolone to get azo dyestuff. The structures of BHET and azo dyestuff were identified by FTIR and 1 H NMR spectra and elemental analysis. Nylon filaments dyed by the synthesized azo dyestuff with the dye bath pH from 4.14 to 5.88 showed bright yellow color. The performances of the dyestuff were described with dye uptake, color fastness, K / S , L *, a *, b *, and Δ E * values.

Chemical recycling of waste poly(ethylene terephthalate) fibers into azo disperse dyestuffs

In this study, waste poly(ethylene terephthalate) (PET) fibers were chemically recycled into azo disperse dyestuffs. First, waste PET fibers were glycolytically degraded by excess ethylene glycol utilizing zinc acetate dehydrate as a catalyst. The glycolysis product, bis(2-hydroxyethyl) terephthalate (BHET), was purified through recrystallization and hydrolyzed into terephthalic acid (TPA). Thereafter, BHET and TPA were nitrated, reduced and azotized to obtain diazonium salts. Finally, the obtained diazonium salts were coupled with N,N-dimethylaniline to obtain azo disperse dyestuffs (dye A and dye B, respectively). The depolymerized products (BHET and TPA) and azo disperse dyestuffs (dyes A and B) were characterized by FTIR and 1H NMR spectroscopy. Nylon and polyester filaments were dyed with the synthesized azo dyestuffs with the dye bath pH ranging from 3.6 to 5.8. The performances of the dyestuffs were described by maximum absorption wavelength, K/S, L*, a* and b* values.

Synthesis and Evaluation of Bifunctional Monomers Derived from Post-Industrial PET as Crosslinking Agents for Acrylic Monomers

Two bifunctional monomers, bis (acryloxyethyl) terephthalate (BAOET) and bis (allyloxycarboniloxyethyl) terephthalate (BAOCOET), derived from PET waste were tested as crosslinking agents for acrylic and methacrylic acids (AA and MA, respectively). BAOET and BAOCOET were obtained from the reactions of acryloyl chloride and allyl chloroformate, respectively, with bis (hydroxyethyl) terephthalate (BHET). This was obtained from the glycolysis of postindustrial PET with ethyleneglycol (EG). Both bifunctional monomers were characterized by NMR 1H. Polymerizations of BAOET and BAOCOET with the acrylic monomers were performed using bifunctional monomer to acrylic monomer weight ratios of 1:10, 1:2 and 1:1, for each of the four combinations, using 2 wt % of benzoyl peroxide (BPO) as thermal initiator. The obtained gel proportions of the crosslinked polymers were above 90% for most of the cases, requiring times from 10 to 60 min. For all of the experiments, complete double bond conversion was observed by FT-IR. Polymers showed thermal stabilities higher than 200°C.

Recycling of waste poly(ethylene terephthalate) into flame‐retardant rigid polyurethane foams

ABSTRACTWaste poly(ethylene terephthalate) (PET) textiles were effectively chemical recycling into flame‐retardant rigid polyurethane foams (PUFs). The PET textile wastes were glycolytically depolymerized to bis(2‐hydroxyethyl) terephthalate (BHET) by excess ethylene glycol as depolymerizing agent and zinc acetate dihydrate as catalyst. The PUFs were produced from BHET and polymeric methane diphenyl diisocyanate. The structures of BHET and PUFs were identified by FTIR spectra. The limiting oxygen index (LOI) of the PUFs (≥23.27%) was higher than that of common PUFs (16–18%), because the aromatic substituent in the depolymerized products improved the flame retardance. To improve the LOI of the PUFs, dimethyl methylphosphonate doped PUFs (DMMP‐PUFs) were produced. The LOI of DMMP‐PUFs was approached to 27.69% with the increasing of the doped DMMP. The influences of the flame retardant on the foams density, porosity, and compression properties were studied. Furthermore, the influences of foaming agent, catalyst, and flame retardant on the flame retardation were also investigated. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40857.

Metal-Containing Ionic Liquids: Highly Effective Catalysts for Degradation of Poly(Ethylene Terephthalate)

Poly(ethylene terephthalate) (PET) waste from local market was depolymerized by ethylene glycol (EG) in the presence of metal-containing ionic liquids, and the qualitative analysis showed that the bis(hydroxyethyl) terephthalate (BHET) was the main product in this process. Compared with other metal-containing ionic liquids, [Bmim]ZnCl3was considered the best catalyst in the glycolysis of PET. When the reaction temperature was 180°C, the conversion of PET reached 97.9% and the BHET was yielded to 83.3% within 5 h. At the same time, [Bmim]ZnCl3could be reused for six times without obvious decrease in the yield of BHET. Additional, the effects of waste PET’s source and size were investigated.