The use of aminolysis,aminoglycolysis, and simultaneous aminolysis–hydrolysis products of waste PET for production of paint binder

This work is concerned with the use of aminolysis, aminoglycolysis, and simultaneous aminolysis–hydrolysis products of waste PET for production of paint binder based on alkyd resin. For this purpose, first, aminolysis, aminoglycolysis, and simultaneous hydrolysis–aminolysis reactions of waste PET were carried out in the presence of different chemical agents in xylene medium at high pressures. Reactions of waste PET flakes obtained from grinding postconsumer water bottles were carried out in an autoclave at higher temperatures. Then, four alkyd resins, formulated to have oil content 40–50%, were prepared using these depolymerization products. One of resins is “reference alkyd resin” which was prepared by using soybean oil fatty acid, phthalic anhydride, glycerine, and ethylene glycol for comparison. Other three alkyds are “depolymerization product‐based alkyd resins” in which depolymerization products is used instead of ethylene glycol. Then, the physical and chemical surface coating properties and thermal behaviors of alkyd resins films were investigated comparatively. As a result, we concluded that aminolysis, aminoglycolysis, and simultaneous aminolysis‐hydrolysis products of waste PET are suitable for manufacturing both air drying and oven curing paint binder based on alkyd resins. The film prepared from alkyd resin based on simultaneous aminolysis‐hydrolysis product showed extremely good surface coating properties and thermal stability. POLYM. ENG. SCI., 54:2272–2281, 2014. © 2013 Society of Plastics Engineers     

废弃PET化学回收及制备不饱和聚酯树脂的研究进展

随着聚对苯二甲酸乙二醇酯（PET）材料用量的大幅增长,大量废弃PET制品堆积造成的环境污染问题日益突出,其回收利用技术也随之广受关注。在不同的PET回收方法中,将PET降解为单体或低聚物的化学回收是效率最高、产物利用价值最大的方法,但也存在反应条件苛刻、产物收率低等问题。本文详细梳理了水解法、甲醇醇解法、二元醇醇解法、胺解法和氨解法等化学回收方法的主要特点以及微波加热、离子液体、纳米技术等新兴技术在PET化学回收过程中的应用概况。通过对各种化学回收工艺的比较,文中得出二元醇醇解法是最具商业应用价值方法的结论。在此基础上,文中重点介绍了PET的二元醇解以及进一步制备不饱和聚酯树脂的化学过程、发展现状、制约因素和改进措施。分析表明,由PET二元醇解产物制备不饱和聚酯树脂是提高废弃PET资源化效率、丰富原料供给、推动产品升级的重要途径,开发高效、廉价、环保的新型催化剂或酶催化技术是废弃PET回收领域今后主要的发展方向。     

Chemical conversion of PET waste using ethanolamine to bis(2-hydroxyethyl) terephthalamide (BHETA) through aminolysis and a novel plasticizer for PVC

Poly(ethylene terephthalate) (PET) recycling has been carried out by various methods, e.g., mechanical recycling, chemical recycling and energy recovery method. In this study, chemical recycling of PET was carried out by aminolysis using ethanolamine and converted into bis(2-hydroxyethyl) terephthalamide (BHETA). The reaction was performed by varying the PET:ethanolamine ratio, reaction time and catalyst used for waste medical grade bottles of PET. Yield of about 81 % was obtained for PET:ethanolamine ratio of 1:4 (w/w), with 3 h reaction time, at 160 °C with zinc acetate as a catalyst. BHETA was characterized with FTIR, ¹H NMR, and DSC analysis. BHETA was further reacted with heptanoic acid at a molar ratio of 1:2.5. The product obtained was used as a plasticizer for PVC at 5, 10, 15 and 20 parts per hundred (phr) concentration. Thermal and mechanical tests were carried out and the result obtained was compared with the virgin PVC without plasticizer and with conventional plasticizer of PVC, i.e., dioctyl phthalate at 15 phr concentration since new plasticizer showed excellent properties at 15 phr concentration. This newly synthesized plasticizer was completely fused with PVC and in tensile testing helped in increasing the elongation, which was an indication of the plasticization effect shown by this developed material. Glass transition temperature also decreased with an incorporation of the new plasticizer as compared to virgin PVC.     

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     

Aminolytic depolymerization of poly (ethylene terephthalate) bottle waste by conventional and microwave irradiation heating

Poly (ethylene terephthalate) (PET) is the most popular thermoplastic polymer. The ever-growing production and utilization of PET has led to postconsumer waste disposal problems because of its nonbiodegradability. The chemical depolymerization of PET waste is a possible remedy, as it results in some recyclable products. The aminolytic depolymerization of PET bottle waste with hydrazine monohydrate by conventional and nonconventional (with microwave irradiation) heating was carried out with simple chemicals as catalysts, such as sodium acetate and sodium sulfate. The yield of the product was optimized through variations in the time of aminolysis, the catalyst concentration, and the PET:hydrazine monohydrate ratio. The pure product obtained in good yield (86%) was analyzed by Fourier transform infrared spectroscopy, NMR, and differential scanning calorimetry and was identified as terephthalic dihydrazide. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of unsaturated polyesters based on the aminolysis of poly(ethylene terephthalate)

The depolymerization of poly(ethylene terephthalate) via an aminolysis process was studied. An excess of ethanol amine in the presence of sodium acetate as a catalyst was used to produce bis(2‐hydroxyl ethylene) terephthalamide (BHETA). Unsaturated polyester (UP) resins were obtained by the reaction of BHETA with different long‐chain dibasic acids such as decanedioic acid, tetradecanoic acid, and octadecanoic acid in conjunction with maleic anhydride as a source of unsaturation. The chemical structure of the UP resins was confirmed by ¹H‐NMR. The vinyl ester resins were used as crosslinking agents for UP. The curing behavior and mechanical properties of the UP resins with vinyl ester were evaluated at different temperatures ranging from 25 to 55°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of novel biodegradable poly(ε‐caprolactone)/ poly(ethylene glycol)‐based polyurethane elastomers

Elastomeric polyurethanes with tunable biodegradation properties and suitable for numerous biomedical applications were synthesized via reaction of epoxy‐terminated polyurethanes (EUPs) with 1,6‐hexamethylenediamine as curing agent. The EUPs themselves were prepared from glycidol and isocyanate‐terminated polyurethanes made from poly(ε‐caprolactone) (PCL) or poly(ethylene glycol) (PEG) and 1,6‐hexamethylene diisocyanate. All the polymers were characterized by conventional methods, and their physical, mechanical, thermal, and degradation properties were studied. The results showed that the degradation rate and mechanical properties of the final products can be controlled by the amount of PEG or PCL present in the EUP. Increasing the PEG content causes an increase of hydrolytic degradation rate, and increasing the PCL content improves the mechanical properties of the final products. Evaluation of cytotoxcicity showed nontoxic behavior of the prepared samples, but the cytocompatibility of these polymers needs to be improved. Copyright © 2006 Society of Chemical Industry     

Unsaturated polyester resin via chemical recycling of off‐grade poly(ethylene terephthalate)

BACKGROUND: The chemical recycling of poly(ethylene terephthalate) (PET), e.g. bottles and fibre wastes, has been studied for many years. Among several methods proposed for chemical recycling of waste PET, glycolysis makes it possible to employ very low amounts of reactants and lower temperatures and pressures compared with critical methanol and thermal degradation. Furthermore, unlike hydrolysis under acidic or basic conditions, glycolysis does not cause any problems related to corrosion and pollution. RESULTS: PET from off‐grades of industrial manufacture was depolymerized using excess glycol. The effects of the reaction time, volume of glycol and catalyst concentrations on the yield of the glycolysis products were investigated. A reaction time of 3 h, weight ratio (catalyst to PET) of 0.25 wt% and PET to ethylene glycol molar ratio of 1:5 were determined as suitable conditions for depolymerization. Then, the reaction of polyesterification of maleic anhydride (MA) and glycolysed products of PET was successfully performed at 160 and 190 °C for 8 h. CONCLUSION: Differential scanning calorimetry and vapour pressure osmometry results for the product of the glycolysis reactions, under suitable condition, confirmed the structure of the desired product. This sample underwent reaction with MA to produce unsaturated polyester resin (UPR). The results of Fourier transform infrared and NMR spectroscopy confirmed that the UPR had been synthesized successfully. This is the first direct report on the glycolysis reaction of off‐grade products of petrochemical companies in order to regenerate raw materials or other secondary value‐added products. Copyright © 2009 Society of Chemical Industry     

New Motivation for the Depolymerization Products Derived from Poly(Ethylene Terephthalate) (PET) Waste: a Review

Summary: Over the last several decades, the process of recycling polymer waste has been attracting the attention of many scientists working on this issue. Polymer recycling is very important for at least two main reasons: firstly, to reduce the ever increasing volumes of polymer waste coming from many sources: from daily life packaging materials and disposables and secondly, to generate value‐added materials from low cost sources by converting them into valuable materials similar, to some extent, to virgin materials. Poly(ethylene terephthalate) (PET) occupies the top of the list of polymers to be recycled due to its easy recycling by different ways, which, in accordance, give variable products that can be introduced as starting ingredients for the synthesis of many other polymers. PET can by recycled by hydrolysis, acidolysis, alkalolysis, aminolysis, alcoholysis and glycolysis. Glycolysis is the breakdown of the ester linkages by a glycol, resulting in oligomers or oligoester diols/polyols with hydroxyl terminal groups. Oligoesters coming from the glycolysis of PET waste have been well known for a number of decades to be utilized as a starting material in the manufacture of polyurethanes, unsaturated polyesters and saturated polyester plasticizers. But, as a current motivation, we are reporting on a new application for these oligoester diols/polyols by converting the hydroxyl terminals into acrylate/methacrylate groups. These new acrylated/methacrylated oligoesters have been tested as UV curable monomers and gave promising results from the point of view of their curability by UV and their mechanical properties. The new motivations open the potential for the market to apply the depolymerization products of PET waste for UV curable coatings, useful for wood surfaces, paints and other applications.

Recycling of PET polymer by different chemical routes.     

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     

Synthesis of bio‐based polyurethanes from epoxidized soybean oil and isopropanolamine

Epoxidized soybean oil (ESO) and isopropanolamine were used to synthesize a new polyol mixture for preparation of bio‐based polyurethanes. The chemical synthetic route for reaction of ESO with isopropanolamine was analyzed by ¹H‐NMR. The results suggested that both ester groups and epoxy groups in ESO had reacted with amino group of isopropanolamine through simultaneous ring‐opening and amidation reactions. Epoxy groups in various situations exhibited different reactivity, and the unreacted epoxy groups were further opened by hydrochloric acid. The synthesized polyol mixture had high hydroxyl number of 317.0 mg KOH/g. A series of polyurethanes were prepared by curing the synthesized polyol mixture with 1,6‐diisocyanatohexance along with different amount of 1,3‐propanediol (PDO) as chain extender. Tensile tests showed that yield strengths of the polyurethanes ranged from 2.74 to 27.76 MPa depending on the content of PDO. Differential scanning calorimetry analysis displayed one glass transition temperature in the range of 24.4–28.7°C for all of the polyurethane samples, and one melt peak at high content of PDO. Thermogravimetric analysis showed that thermal degradations of the polyurethanes started at 240–255°C. In consideration of simple preparation process and renewable property of ESO, the bio‐based polyurethane would have wide range of applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

On the UV Curability and Mechanical Properties of Novel Binder Systems Derived from Poly(ethylene terephthalate) (PET) Waste for Solventless Magnetic Tape Manufacturing, 2. Methacrylated Oligoesters

Recycling of poly(ethylene terephthalate) PET waste by chemical methods is a well‐known process that generates value‐added products. Depolymerization products of PET recycling were commonly applied as starting materials for the synthesis of polyurethanes, saturated and unsaturated polyester resins. In this current work we are reporting on a novel application of the depolymerized products obtained by glycolysis of PET by converting the hydroxyl functional groups to methacrylate groups. The obtained methacrylated oligoesters were tested for UV curability by UV irradiation, in the presence of 2‐benzyl‐2‐dimethylamino‐1‐(4‐morpholinophenyl)‐1‐butanone (BDMB) as a photo initiator. This gave cured films of high mechanical properties when these methacrylated oligoesters were either cured alone or as mixtures with other commercially available diacrylate/dimethacrylate monomers. The measured tensile properties were in the range of 7.21–43 MPa for maximum tensile strength and 0.90–3.0 GPa for Young's modulus.     

Polyurethanes from vegetable oils and applications: a review

Among the various polymers, polyurethanes are likely the most versatile specialty polymers. These polymers are widely used in many applications such as foams, coatings, insulations, adhesives, paints and upholstery. Similar to many polymers, polyurethanes relies on petrochemicals as raw materials for its major components. Indeed, nowadays many researches have focused to replace petroleum-based resources with renewable ones to improve polyurethanes sustainability. Polyurethanes are synthesized by polymerization reactions between isocyanates and polyols. Only a few isocyanates are commonly used in polyurethane industries, while a variety of polyols are available. Renewable materials such as vegetable oils are promising raw materials for the manufacture of polyurethane components such as polyols. Vegetable oils are triglycerides which are the esterification product of glycerol with three fatty acids. Several highly reactive sites including carbon-carbon double bond, allylic position and ester group in triglycerides and fatty acids open the opportunities for various chemical modifications for new polyol with different structures and functionalities. Different methods such as are epoxidation, ozonolysis, hydroformylation and metathesis have been widely studied to synthesise bio-polyol from vegetable oil for new polyurethanes, which depend on triglyceride and isocyanate reagents used. The incorporation of a vegetable oil moiety can enhance thermal stability and mechanical strength of polyurethanes. Similar to bio-polyol, the development of renewable resource based bio-isocyanates is also gained attention to produce entirely bio-polyurethanes. This article comprehensively reviews recent developments in the preparation of renewable resource based polyols and isocyanates for producing polyurethanes and applications.     

Synthesis and characterization of novel thermoplastic poly(oligophosphazene‐urethane)s

BACKGROUND: Polyurethanes are some of the most popular polymers used in a variety of products, such as coatings, adhesives, flexible and rigid foams, elastomers, etc. Despite the possibility of tailoring their properties, polyurethanes suffer a serious disadvantage of poor thermal stability. Many attempts have been made in order to improve the thermal stability of polyurethanes. RESULTS: A new hydroxyl‐terminated oligomer containing sulfone groups, 2,2‐bis(4‐hydroxy‐4,4‐sulfonyldiphoneloxy)tetraphenoxyoligocyclotriphosphazene (HSPPZ), was synthesized. HSPPZ was characterized using Fourier transform infrared (FTIR), NMR and gel permeation chromatography analyses. A series of novel thermoplastic poly(oligophosphazene‐urethane)s were then synthesized via the reaction of NCO‐terminated polyurethane prepolymer with HSPPZ containing chain‐extender diols. Their structure and properties were investigated using FTIR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X‐ray diffraction, water contact angle measurement and tensile measurements. CONCLUSION: Compared to conventional thermoplastic polyurethanes, poly(oligophosphazene‐urethane)s exhibit better thermal stability, low‐temperature resistance and hydrophobicity, but their mechanical properties are slightly poorer. Copyright © 2009 Society of Chemical Industry     

废聚酯醇解制备聚氨酯胶粘剂的研究

以聚醚多元醇(PPG)和4,4′-二苯基甲烷二异氰酸酯(MDI-100LL)为原料制备了含有-NCO的聚氨酯(PU)胶粘剂的A组分,将废聚酯(PET)通过醇解、酯化和缩聚等步骤制得含有-OH的PU胶粘剂的B组分,讨论了反应条件对A组分和B组分性能的影响。结果表明:制备A组分时,反应温度80℃,反应时间3 h;制备B组分时,废PET醇解温度195～210℃(反应时间3.5 h),酯化温度140～150℃(反应时间60 min),缩聚温度190～210℃(反应时间30 min)。调节双组分的配比,可以制备出满足不同施工要求的胶粘剂,当n(A组分)∶n(B组分)=1.30∶1时,胶粘剂的粘接效果最佳;固化后PU胶膜的玻璃化转变温度(Tg)达到-31℃。     

A novel route of synthesis,characterization of terephthalic dihydrazide from polyethylene terephthalate waste and it's application in PVC compounding as plasticizer

The degradation of polyethylene terephthalate (PET) waste by making use of hydrazine monohydrate was investigated at ambient temperature and pressure. The aminolysed end products obtained were characterized with chemical tests and spectroscopic techniques namely IR, UV‐visible spectroscopy and NMR, and the differential scanning calorimeter (DSC). The end product was characterized as terephthalic dihydrazide (TPD) and further used in PVC compounding as secondary plasticizer. The hardness, tensile strength, elongation at break, thermal stability, and compatibility of the PVC sheet were studied and concluded that the aminolysed product may find potential application as secondary plasticizer in PVC formulations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polyurethanes synthesized from polyester polyols derived from PET waste. II. Thermal properties

Polyurethanes were synthesized from polyester polyols, derived from PET Waste. The PET waste was first depolymerized by glycolysis. The glycolysized products were reacted with adipic acid to yield polyester polyols, and the polyester polyols were then reacted with either MDI or TDI to obtain polyurethanes. In this article, the thermal properties of the polyurethanes obtained are discussed in detail. © 1994 John Wiley & Sons, Inc.     

木质类废弃物液化及其高效利用研究进展

木质类废弃物具有数量多、分布广、可再生等特点,采用热化学液化技术将其转变为具有反应活性的新的化学原料,能替代或部分替代化石产品制备高品质化学品。本文将不同生物质转化技术以及可利用途径进行归纳总结,回顾了近年来国内外常见的木质类废弃物液化技术如高温高压液化、快速热解液化和常压催化液化等,重点介绍了广为关注的常压催化液化及其高效利用研究现状。概述了不同的液化剂和催化剂所得液化物的性质及所制备胶黏剂、聚氨酯材料等高附加值生物质基树脂材料的性能。指出木质类生物质液化过程只有朝着低成本、绿色、高效反应方向发展,才有可能向大规模工业化转化。作者结合自己的科研实践,提出该领域目前存在的一些问题以及解决途径的建议,对液化生物质基高分子材料的产业化应用提出展望。     

Fat and oil products in urethane polymers

Urethane polymers comprise one of the most rapidly expanding areas of the organic chemical industry. Polyurethane production, estimated at about 100 million lb in 1960, is expected to rise to 500 million lb in 1965 and to have an ultimate potential in excess of a billion lb. The polymers are used in foams (flexible, semi-rigid and rigid), plastics, fibers, solid elastomers, surface coatings and adhesives. Fat- and oil-derived products have potential utility in all these applications. Fat-derived reactants include natural glycerides (e.g., castor oil), and other esters derived from reaction of fatty acids with polyols such as glycerol, pentaerythritol, sorbitol, sucrose, alkanol amines, etc., polymerized fatty acids, alkylene oxide derivatives of fatty acids and tall oil. The reactions of primary importance in the production of polyurethanes from isocyanates, including the urethane reaction, urea reaction, allophanate and biuret formation are discussed. A generalized treatment of the chemical technology involved in the preparation of representative polyurethane products is presented and the major areas in which fat and oil products are finding application in polyurethanes are noted. Presented at the AOCS meeting in New Orleans, La., 1962.     

Synthesis and characterization of polysulfone based on poly(ethylene terephthalate) waste

The recycling process of Poly(ethylene terephthalate) (PET) wastes is commercially important since it converts a waste material into a value‐added product and also helps to alleviate environmental pollution. PET waste was depolymerized in the presence of ethylene glycol and manganese acetate as a catalyst. Bis(hydroxyethyl terephthalate), (BHET) and other oligomers are predominately the glycolyzed products (GP). These GP products were reacted with a prepared dichlorodiphenylsulfone (DCDPS) in presence of dried potassium carbonate. Two polysulfones (A &B) with different number average molecular weights, 1787 and 3162 g/mol. were obtained, respectively. The chemical structures of the resulting two polysulfones were elucidated using ¹HNMR and characterized by the known conventional analysis techniques (e.g. FTIR, GPC, DSC, TGA…). The prepared polysulfone (B) disclosed higher thermal stability with respect to the initial reactants. The originality of this study was derived from the use of waste materials to yield a product that has acceptable high thermal stability which provide many beneficial applications in various industrial fields. POLYM. ENG. SCI., 55:1671–1678, 2015. © 2014 Society of Plastics Engineers