Auto-Catalyzed Hydrolytic Depolymerization of Poly(Butylene Terephthalate) Waste at High Temperature

Auto-catalyzed hydrolytic depolymerization of poly(butylene terephthalate) (PBT) waste in neutral water was carried out in an autoclave at 200°, 215°, 230°, and 245°C under autogenously pressure. The effects of particle size, agitator speed, charge ratio, and reaction time on PBT hydrolyses were studied. Reaction products were terephthalic acid (TPA) and 1,4-butanediol (BD) that were recovered, analyzed, and confirmed. Yields of TPA and BD were almost equal to PBT conversion. Analyses of PBT waste samples were also undertaken. A kinetic model for PBT hydrolysis was fitted with the experimental data. Moreover, a noncatalytic PBT hydrolysis was studied to understand the effect of auto-catalyzed action during reaction. Various kinetic parameters (i.e., hydrolysis rate constant, equilibrium constant, backward rate constant, Gibbs free energy, enthalpy, and entropy) of reaction were calculated. The transfer of laboratory data is required during process commercialization through pilot plant. The dependence of the rate constant on the reaction temperature was correlated by the Arrhenius plot giving activation energy of 87 kJ/mol and the corresponding Arrhenius constant of 5.56 × 10⁹[(g ET/mol)^1.5 min^?1] for PBT hydrolysis.     

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.     

Recycling of Waste Poly(Ethylene Terephthalate) with Naphthalene and Neutral Water

The waste poly(ethylene terephthalate) (PET) powder dissolution/reprecipitation was carried out in a batch operation at atmospheric pressure at various temperatures ranging from 180–220°C at temperature intervals of 10°C. Particle sizes of the waste PET ranged from 50–512.5 µm and operation time, which ranged from 30–90 min, were optimized. Dissolution/reprecipitation of the waste PET was carried out in naphthalene (solvent) and neutral water (nonsolvent), respectively. Dissolution/reprecipitation of the waste PET was increased with operation time and temperature. Dissolution/reprecipitation of PET was decreased with increase in the particle size of the waste PET. The waste PET particle size and agitator speed required for complete recycling of the waste PET were also optimized. Analyses of the waste PET and the recycled PET collected after the reprecipitation process was undertaken by determination of various physical properties. The operation applied at lesser time and with cheaper solvent/nonsolvent, resulted in excellent quality of the recycled PET collected after the reprecipitation process. This process of recycling of the waste PET has an industrial significance due to most economical operation for commercialization.     

Chemical Degradation of Poly(Ethylene Terephthalate)

The possibility of converting polyethylene terephthalate (PET) waste into terephthalic acid as a primary material by using different techniques through trans-esterification, with an alcohol and through hydrolysis in basic medium, has been investigated. In addition, utilization of activating agents such as inorganic salts and phase transfer catalysts has been investigated.Mineral water and beverage bottles were collected, cleaned and crushed into flakes suitable for the intended experiments. Also, the main products of chemical conversion of such wastes were isolated and confirmed by authentication with standard terephthalic acid through Thin Layer Chromatography (TLC) technique. The reaction yield % was determined to optimize the corresponding experimental conditions and the obtained results have been presented and discussed.     

间苯二甲酸改性PET的结晶行为研究

应用 DSC研究了间苯二甲酸 (IPA)改性 PET的结晶行为。结果表明 :由于第三单体破坏了 PET大分子结构的规整性 ,导致改性聚酯熔点下降 ,冷结晶温度上升 ,热结晶温度下降 ;与常规 PET相比 ,较慢的冷却速度就可使熔融状态的改性 PET保持无定形状态。     

Chemical Recycling and Kinetics of Aqueous Alkaline Depolymerization of Poly(Butylene Terephthalate) Waste

Depolymerization reactions of poly(butylene terephthalate) (PBT) waste in aqueous sodium hydroxide solution were carried out in a batch reactor at 80–140 °C at atmospheric pressure by varying PBT particle size in the range of 50–512.5 μm. Reaction time was also varied from 10–110 min to understand the influence of PBT particle size and reaction time on the batch reactor performance. Agitator speed, particle size of PBT and reaction time required were optimized. Disodium terephthalate (salt) and 1,4‐butanediol (BD) remain in the liquid phase. BD was recovered by the salting‐out method. Disodium terephthalate was separated by acidification to obtain solid terephthalic acid (TPA). The produced monomeric products (TPA and BD) and PBT were analyzed. The yields of TPA and BD were in agreement with PBT conversion. The depolymerization reaction rate was first order to PBT concentration as well as first order to sodium hydroxide concentration. The acid value of TPA changes with the reaction time as well as particle size of PBT. This indicates that PBT molecules get fragmented and hydrolyze simultaneously with aqueous sodium hydroxide to produce BD and disodium terephthalate. Activation energy, Arrhenius constant, equilibrium constant, Gibbs free energy, enthalpy and entropy were determined. The dependence of the hydrolysis rate constant on reaction temperature was correlated by the Arrhenius plot, which shows an activation energy of 25 kJ/mol and an Arrhenius constant of 438 L/min/cm².     

用废PET醇解制墨粉树脂的研究

本实验主要研究了回收PET瓶片在催化剂和二元醇存在下,进行醇解和酯交换转化为各种不同组成具有端羟基低分子链段和二醇,进而醇解产物与反丁烯二酸酯化缩聚为用于墨粉树脂的聚酯。探索了从原料配比到反应工艺条件等多方面因素合成聚酯树脂的条件。利用聚酯回收料为原料醇解后直接合成墨粉用聚酯树脂的工艺简单、产品质量稳定、具有良好的经济效益和环保效应。     

Modification of Waste Poly(Ethylene Terephthalate) (PET) by Using Poly(L-Lactic Acid) (PLA) and Hydrolytic Stability

The purpose of this study is the preparation of hydrolytically degradable copolymers of waste poly(ethylene terephthalate) (PET). To achieve this, we modified PET by using biodegradable poly(lactic acid) (PLA). Modification reactions were carried out in o-nitrophenol as solvent at 140 and 170°C for 8, 16, and 24 h in the presence of dibutil tin oxide (DBTO) as catalyst. The amount of the total polymers (PLA and PET) in the reaction mixture was 30% by weight, and the weight ratios of PLA/PET were 10/90, 50/50, and 90/10. These modified products were characterized by Fourier transform infrared spectrometer (FTIR), differential scanning calorimeter (DSC) as well as by hydrolytic degradation determinations. Hydrolytic degradations of the products were determined gravimetrically. Disc-shaped samples were placed in tubes containing phosphate buffer solution of pH 7.2 and kept in a water bath at 60°C for 28 days. The weight loss of the products after hydrolytic degradation ranged from 1.25% to 48.75% after 28 days.     

On the nature of multiple melting in poly(ethylene terephthalate) (PET) and its copolymers with cyclohexylene dimethylene terephthalate (PET/CT)

The multiple melting behavior of poly(ethylene terephthalate) (PET) homopolymers of different molecular weights and its cyclohexylene dimethylene (PET/CT) copolymers was studied by time-resolved simultaneous small-angle X-ray scattering/wide-angle X-ray scattering diffraction and differential scanning calorimetry techniques using a heating rate of 2 °C/min after isothermal crystallization at 200 °C for 30 min. The copolymer containing random incorporation of 1,4-cyclohexylene dimethylene terephthalate monomer cannot be cocrystallized with the ethylene terephthalate moiety. Isothermally crystallized samples were found to possess primary and secondary crystals. The statistical distribution of the primary crystals was found to be broad compared to that of the secondary crystals. During heating, the following mechanisms were assumed to explain the multiple melting behavior. The first endotherm is related to the non-reversing melting of very thin and defective secondary crystals formed during the late stages of crystallization. The second endotherm is associated with the melting of secondary crystals and partial melting of less stable primary crystals. The third endotherm is associated with the melting of the remaining stable primary crystals and the recrystallized crystals. Due to their large statistical distribution, the primary crystals melt in a broad temperature range, which includes both second and third melting endotherms. The amounts of secondary, primary and recrystallized crystals, being molten in each endotherm, are different in various PET samples, depending on variables such as isothermal crystallization temperature, time, molecular weight and co-monomer content.     

Effects of Blending Conditions and Catalyst Concentration on the Structural,Thermal and Morphological Properties of Polycarbonate/Poly (Ethylene Terephthalate) Blends

The effects of mixing conditions and transesterification catalyst concentration on the structural, thermal and morphological properties of a 50/50 polycarbonate (PC)/poly (ethylene terephthalate) (PET) system were investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and by solubility measurements. From the increase in the solubility of the blends in dichloromethane and the decrease of their degree of crystallinity, it was concluded that on increasing the mixing time and the catalyst concentration, transesterification becomes more important. Thermal analysis revealed also a noticeable increase of the crystallization temperature and a slight decrease of the melting temperature. These results suggest that when transesterification occurs extensively, the crystallization tendency declines progressively until finally a completely soluble material is obtained as revealed by solubility measurements.     

新型热塑性聚酯—聚对苯二甲酸丙二醇酯

本文介绍了聚对苯二甲酸丙二醇酯(PTT)的制法、结构、性能及应用,并和PET、PBT等工程塑料进行了比较。     

Preparation of HALS-Functional Core-Shell Nanoparticles and their Application in Poly(Butylene Terephthalate)

HALS-functional core-shell nanoparticles, poly(BA-MMA-PMPA), were prepared by emulsion polymerization. The chemical structure and the microstructure of the particles was confirmed by Fourier transformed infrared (FTIR) and transmission electron microscopy (TEM), respectively. The nanoparticles were used to modify PBT and had good compatibility with PBT. The mechanical properties before and after UV-irradiation analysis demonstrated that the UV-resistance and impact resistance of PBT were obviously improved by poly(BA-MMA-PMPA). The degradation degree of PBT was retarded by poly(BA-MMA-PMPA) as studied by thermogravimetry analysis (TGA). The surface chemical functional groups changes revealed that the surface of PBT was greatly protected by poly(BA-MMA-PMPA).     

Atmospheric Plasma Surface Activation of Poly(Ethylene Terephthalate) Film for Roll-To-Roll Application of Transparent Conductive Coating

An effective surface activation is crucial for high-speed roll-to-roll coating of functional films for printed electronics applications. In this article, we report a study of surface treatment of three types of poly(ethylene terephthalate) (PET) films by an argon/oxygen atmospheric pressure plasma and an ambient air atmospheric pressure plasma to obtain the required wettability for subsequent slot die coating of transparent conductive polymer layer using a poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) ink. Prior to plasma treatment, the PET surfaces, which differ in manufacturing process of their preparation, were characterized by X-ray photoelectron spectroscopy. The surface changes after the plasma treatments were characterized by water contact angle measurement and atomic force microscopy. We found that the water contact angles of the three types of untreated PET surfaces were 80.9°, 75.9°, and 66.3°, respectively, and the water contact angles after argon/oxygen plasma treatment at treatment speed of 1 m · min^?1 decreased to 36.2°, 31.9°, and 40.9°, respectively. These conditions were stable from 1 up to 4 days, which are longer than reported values of 15–60 min and sufficient for roll-to-roll coating processes.     

共聚聚酯的性能及应用

讨论了共聚聚酯的性能,成型工艺及应用情况,展望了共聚聚酯的发展前景。     

How to Make Colorless Poly(ethylene terephthalate)(PET)

Abstract

The methods and flow charts used for the industrial preparation of PET are shown and briefly discussed. Then, the three classes of contaminants usually appearing in PET are described and their causes elucidated. The organic contaminants impart to the produced PET an undesired yellow-amber tinge while those containing metal ions or elemental metals impart to the polymer various undesirable colors. Other organic contaminants are crosslinked gels and flakes, and especially the latter may cause filament rupture and may lead to the disruption of melt spin-draw processes. Some remedies to eliminate or minimize the appearance of such contaminants are then suggested, followed by a brief discussion of non-antimony catalysts which eliminate the gray discoloration usually imparted to PET by antimony-containing catalysts.     

Finite strain behavior of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate)-glycol (PETG)

Uniaxial and plane strain compression experiments are conducted on amorphous poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate)-glycol (PETG) over a wide range of temperatures (25-110 °C) and strain rates (.005-1.0 s⁻¹). The stress-strain behavior of each material is presented and the results for the two materials are found to be remarkably similar over the investigated range of rates, temperatures, and strain levels. Below the glass transition temperature (θ_g=80 °C), the materials exhibit a distinct yield stress, followed by strain softening then moderate strain hardening at moderate strain levels and dramatic strain hardening at large strains. Above the glass transition temperature, the stress-strain curves exhibit the classic trends of a rubbery material during loading, albeit with a strong temperature and time dependence. Instead of a distinct yield stress, the curve transitions gradually, or rolls over, to flow. As in the sub-θ_g range, this is followed by moderate strain hardening and stiffening, and subsequent dramatic hardening. The exhibition of dramatic hardening in PETG, a copolymer of PET which does not undergo strain-induced crystallization, indicates that crystallization may not be the source of the dramatic hardening and stiffening in PET and, instead molecular orientation is the primary hardening and stiffening mechanism in both PET and PETG. Indeed, it is only in cases of deformation which result in highly uniaxial network orientation that the stress-strain behavior of PET differs significantly from that of PETG, suggesting the influence of a meso-ordered structure or crystallization in these instances. During unloading, PETG exhibits extensive elastic recovery, whereas PET exhibits relatively little recovery, suggesting that crystallization occurs (or continues to develop) after active loading ceases and unloading has commenced, locking in much of the deformation in PET.     

聚苯乙烯磺酸钠对抗静电聚对苯二甲酸乙二醇酯流变性能的影响

用Rheometric RAD-III型平板动态流变仪对所含组分不同的抗静电聚对苯二甲酸乙二醇酯(PET)样品进行了测试,结果发现小分子抗静电剂的加入使聚合物失去其粘弹性特性,而当部分小分子抗静电剂被聚苯乙烯磺酸钠替代后,聚合物又重新表现出粘弹特性。这表明聚苯乙烯磺酸钠与小分子抗静电剂及聚合物基体之间发生了相互作用。     

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).     

IsPETase Is a Novel Biocatalyst for Poly(ethylene terephthalate) (PET) Hydrolysis

Poly(ethylene terephthalate) (PET) is one of the most widely used synthetic polyesters, but also a major cause of plastic pollution. Because the chemical degradation of PET would be uneconomical and rather burdensome, considerable efforts have been devoted to exploring enzymatic processes for the disposal of PET waste. Many PET-hydrolyzing enzymes have been reported in recent decades, some of which demonstrate excellent potential for industrial applications. This review sets out to summarize the state of investigation into IsPETase, a cutinase-like enzyme from Ideonella sakaiensis possessing ability to degrade crystalline PET, and to gain further insight into the structure–function relationship of IsPETase. Benefiting from the continuing identification of novel cutinase-like proteins and growing availability of the engineered IsPETase, we may anticipate future developments in this type of enzyme would generate suitable biocatalyst for industrial use.     

Poly(ethylene isophthalate)s: effect of the tert-butyl substituent on structure and properties

A comparative study of the two isophthalic acid deriving homopolyesters poly(ethylene isophthalate) (PEI) and poly(ethylene 5-tert-butyl isophthalate) (PE^tBI), including synthesis, crystal structure, and thermal and permeability properties, was carried out. The two polyesters were prepared by condensation polymerization in the melt. In both cases, minor amounts of cyclic dimers were observed to form, which were characterized by nuclear magnetic resonance and mass spectroscopy. PEI and PE^tBI were thermally stable up to 400 °C and they appeared to be semicrystalline polyesters, having their melting temperatures between 130 and 135 °C. Their glass-transition temperatures were 62 and 94 °C, respectively. The crystal structure adopted by the two polyesters seemed to consist of a regularly folded conformation, clearly different from the almost extended conformation characteristic of poly(ethylene terephthalate). Gas permeability measurements for N₂, O₂, and CO₂ revealed that PE^tBI is more permeable to these gases than PEI, in spite of having a higher T_g. Furthermore, water vapor diffusion was found to be increased by the insertion of the tert-butyl group, whereas water absorption diminished. The differences in gas and water vapor transport properties observed for these two polyesters were discussed on the basis of their respective molecular structures.