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Methanolsis of Poly(ethylene terephthalate) in Supercritical Phase
Yang Yong,Xiang Hong-wei
过程工程学报 , 2001,
Abstract: The depolymerization of poly(ethylene terephthalate, PET) in supercritical methanol is studied using a stainless stirred autoclave at temperature of 255~260℃, pressure of 8.5~14.0 MPa, and methanol/PET weight ratio of 3~8. Under the optimal conditions, the PET is depolymerized completely to its monomers in 60 min. The main products of the reaction are dimethyl terephthalate and ethylene glycol. There are still some small amounts of byproducts, such as methyl–(2-hydroxyethyl) terephthalate, bis(hydroxyethyl) terephthalate, dimers and oligomers. Reversed-phase high performance liquid chrom- atography and gas chromatography are used to analyze solid products and liquid products respectively. The results of depolymerization show that the yield of dimethyl terephthalate and the degree of PET depolymerization are dependent on the reaction temperature, weight ratio of methanol to PET and reaction time. But the reaction pressure has little influence on the depolymerization as long as methanol is in supercritical state.
Rod like attapulgite/poly(ethylene terephthalate) nanocomposites with chemical bonding between the polymer chain and the filler
Q. Fu,L. Chen,K. Liu,F. Chen
eXPRESS Polymer Letters , 2012, DOI: 10.3144/expresspolymlett.2012.67
Abstract: Poly(ethylene terephthalate) (PET) nanocomposites containing rod-like silicate attapulgite (AT) were prepared via in situ polymerization. It is presented that PET chains identical to the matrix have been successfully grafted onto simple organically pre-modified AT nanorods (MAT) surface during the in situ polymerization process. The covalent bonding at the interface was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The content of grafted PET polymer on the surface of MAT was about 26 wt%. This high grafting density greatly improved the dispersion of fillers, interfacial adhesion as well as the significant confinement of the segmental motion of PET, as compared to the nanocomposites of PET/pristine AT (PET/AT). Owing to the unique interfacial structure in PET/MAT composites, their thermal and mechanical properties have been greatly improved. Compared with neat PET, the elastic modulus and the yield strength of PET/MAT were significantly improved by about 39.5 and 36.8%, respectively, by incorporating only 2 wt % MAT. Our work provides a novel route to fabricate advanced PET nanocomposites using rod-like attapulgite as fillers, which has great potential for industrial applications.
Plastic Degradation and Its Environmental Implications with Special Reference to Poly(ethylene terephthalate)  [PDF]
Hayden K. Webb,Jaimys Arnott,Russell J. Crawford,Elena P. Ivanova
Polymers , 2013, DOI: 10.3390/polym5010001
Abstract: With increasing global consumption and their natural resistance to degradation, plastic materials and their accumulation in the environment is of increasing concern. This review aims to present a general overview of the current state of knowledge in areas that relate to biodegradation of polymers, especially poly(ethylene terephthalate) (PET). This includes an outline of the problems associated with plastic pollution in the marine environment, a description of the properties, commercial manufacturing and degradability of PET, an overview of the potential for biodegradation of conventional polymers and biodegradable polymers already in production.
Poly (ethylene terephthalate) synthesis with catalysts derived from chrysotile asbestos  [PDF]
Shigeki Habaue, Yusuke Takahashi, Yu Hosogoe, Hiroshi Yamashita, Meisetsu Kajiwara
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.26070
Abstract: The chrysotile asbestos was converted to the forsterite-type compounds by calcination at 740 and 800oC (F7-740 and F7-800), which were used as a catalyst for the polycondensation of bis(hydroxyethyl) terephthalate affording poly (ethylene terephthalate). The obtained forsterite-type compounds did not show any catalytic activity. However, the products obtained by simply treating them with acetic acid significantly promoted the polymerization that produced a THFinsoluble polymer. It was found that the polymer prepared with the acetic acid-treated F7-740 at 160oC for 2 h showed a 93% yield and the number average molecular weight of 6.4 × 103. The observed catalytic activity was higher than that for the acetic acid-treated magnesium oxide, as well as the typical polycondensation catalysts, such as magnesium acetate and antimony oxide.
Isothermal crystallization kinetics of poly(ethylene terephthalate) and poly(methyl methacrylate) blends
eXPRESS Polymer Letters , 2007, DOI: 10.3144/expresspolymlett.2007.48
Abstract: Different kinetic models like the Avrami, Tobin and Urbanovici-Segal models have been applied for determining the isothermal crystallization kinetics of virgin poly(ethylene terephthalate) (PET) and PET/poly(methyl methacrylate) (PMMA) blends. The different compositions investigated were PET90/PMMA10, PET75/PMMA25 and PET50/PMMA50 [wt/wt%]. The experimental data was fitted using Solver, a non-linear multi-variable regression program and linearization method. The effect of composition variation of PET/PMMA on parameters like crystallization rate constant and crystallization exponent were investigated. Urbanovici-Segal and Avrami models gave the best fit to the experimental data. Tobin model does not seem to fit the experimental data for the systems under investigation. Experimental results indicated that the crystallization rate constant values increased with decreasing temperatures.
The Glycolysis of Poly(ethylene terephthalate) Waste: Lewis Acidic Ionic Liquids as High Efficient Catalysts  [PDF]
Qun Feng Yue,Lin Fei Xiao,Mi Lin Zhang,Xue Feng Bai
Polymers , 2013, DOI: 10.3390/polym5041258
Abstract: Poly(ethlyene terephthalate) waste from a local market was depolymerized by ethylene glycol (EG) in the presence of Lewis acidic ionic liquids [Bmim]ZnCl 3 and the qualitative analysis showed that bis(hydroxyethyl) terephthalate was the main product. Compared with ionic liquid [Bmim]Cl, the Lewis acidic ionic liquids showed highly catalytic activity in the glycolysis of poly(ethylene terephthalate) PET. Significantly, the conversion of PET and the yield of bis(hydroxyethyl) terephthalate were achieved at 100% and 83.8% with low catalyst ([Bmim]ZnCl 3) loading (0.16 wt %). Investigation also showed that the catalytic activity of [Bmim]ZnCl 3 was higher than that of [Bmim]MnCl 3. Catalyst [Bmim]ZnCl 3 can be reused up to five times and 1H-NMR results show that the recovered catalyst is similar to the fresh one. A mechanism of the glycolysis of PET catalyzed by [Bmim]ZnCl 3 was proposed.
Fabrication and mechanical properties of self-reinforced poly(ethylene terephthalate) composites
eXPRESS Polymer Letters , 2011, DOI: 10.3144/expresspolymlett.2011.22
Abstract: Self-reinforced poly(ethylene terephthalate) (PET) composites prepared by using a modified film-stacking technique were examined in this study. The starting materials included a high tenacity PET yarn (reinforcement) and a low melting temperature biodegradable polyester resin (matrix), both of which differ in their melting temperatures with a value of 56°C. This experiment produced composite sheets at three consolidation temperatures (Tc: 215, 225, and 235°C) at a constant holding time (th: 6.5 min), and three holding times (3, 6.5 and 10 min) at a constant consolidation temperature of 225°C. This study observed a significant improvement in the mechanical properties obtained in self-reinforced PET composites compared to the pure polyester resin. The results of tensile, flexural, and Izod impact tests proved that optimal conditions are low consolidation temperature and short holding time. The absorbed impact energy of the best self-reinforced PET composite material was 854.0 J/m, which is 63 times that of pure polyester resin.
Preparation of poly(ethylene terephthalate)/layered double hydroxide nanocomposites by in-situ polymerization and their thermal property
Q. Jiao,W. Cui,Y. Zhao,H. Li
eXPRESS Polymer Letters , 2012, DOI: 10.3144/expresspolymlett.2012.51
Abstract: Terephthalate (TA) intercalated layered double hydroxides (LDHs) were synthesized using hydroxides as raw materials, and poly(ethylene terephthalate) (PET)/LDH nanocomposites with different contents of TA intercalated LDHs were prepared by in-situ polymerization. The structure, morphology and thermal property of PET/LDH nanocomposites were investigated. The TA intercalated LDHs were partially exfoliated and well dispersed in PET matrix. The PET/LDH nanocomposites exhibit enhanced thermal stability relative to pure PET, confirmed by the thermogravimetric analysis results. The results of differential scanning calorimetry suggest that LDH nanoparticles could effectively promote the nucleation and crystallization of PET.
Characterization of Waste Poly(Ethylene-Terephthalate) after Alkali Treatment  [PDF]
Pti?ek Siro?i?, A.,Kratofil Krehula, LJ,Katan?i?, Z.,Re??ek, A.
Kemija u Industriji , 2011,
Abstract: Poly(ethylene terephthalate), PET, recycling represents one of the most successful and widespread examples of polymer recycling. This material is fully recyclable and may be used for manufacturing new products in many industrial areas. Nevertheless, the excellent properties of PET needed for its many applications are also responsible for the difficult degradation of PET and an accumulation of polymer waste, which in turn creates serious environmental problems connected to littering and illegal landfilling or incineration. The main goal of this study was to examine the effect of alkali pretreatment on the properties of PET flakes. PET flakes were washed at twotemperatures, 70 °C and 75 °C and in various time intervals of 15, 18, 21, 25, and 30 min. All samples were characterized by FTIR spectroscopy, differential scanning calorimetry and by contact angle measurements. The results showed that during the alkali treatment the partial depolymerization of PET was obtained, which resulted in the formation of various types of oligomers with hydroxyl and carboxyl end groups, which were the result of loss of high molecular structure. Decrease of intensity of characteristic vibrational bands (CO at 1717, COO at 1265 and CH2 at 722 cm-1) with extended time was observed (Figs. 1 and 2). Further on, the formation of hydroxyl groups at = 3428 cm-1 was also observed as a result of PET depolimerization during the alkali treatment, which behaviour was better visible for samples washed at 75 °C and with extended washing time (Fig 2b). During the DSC thermal analysis, multiple melting peaks were observed in some studied samples which could be linked to partial melting and re-crystallization of PET or to the occurrence of new polymer fractions of lower molecular mass (Figs. 3 and 4). It is evident that the contact angle of PET samples (Fig. 5) decreases in comparison to the PET 0, which points to the changes on the PET surface during the alkali treatment. Decrease in contact angle (which is measured with water) indicates an increase in surface hydrophilicity and increase in the number of present polar -OH and -COOH groups formed during the partial degradation. Also, the values of total surface energies and their polar and dispersive components indicate that during the alkali treatment the surface characteristics of PET flakes were slightly changed due to depolymerization (Table 3). Generally, it can be concluded that partial depolymerization of PET flakes occurs during the alkali treatment but the material retains its good properties and it is appropriate for the further
Synthesis and NMR characterization of aliphatic-aromatic copolyesters by reaction of poly(ethylene terephthalate) post-consumer and poly(ethylene adipate)
Baldissera, Alessandra F.;Valério, Carlos E. S.;Basso, Nara. R. de S.;Guaragna, Fernando;Einloft, Sandra;Tessier, Martine;Fradet, Alain;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000200004
Abstract: an aliphatic-aromatic copolyester of poly(ethylene terephthalate), pet, and poly(ethylene adipate), pea, pet-co-pea, was synthesized by the high temperature melt reaction of post-consumer pet and pea. as observed by nmr spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. the copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. the structure of the aliphatic-aromatic copolyesters obtained in different pet/pea ratio is random as observed by nmr analysis.
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