Polyethylene terephthalate

Linear viscoelastic, shear, and extensional rheological characterization of linear and branched Poly(Ethylene Terephthalate) resins (PET) was carried out by means of both a parallel-plate and capillary rheometers. Before loading into the rheometers, the polymer pellets were thoroughly dried at well-characterized conditions long enough to obtain consistent and reproducible results. Continuing polymer degradation and poly-condensation reactions in the relatively open environment of the parallel-plate rheometer were accounted for by correcting the data using material-time super-position. The rheological data obtained were used to fit by nonlinear optimization, the linear relaxation spectrum and nonlinear parameters of a multi-mode Phan-Thien and Tanner (PTT) constitutive relation. It was found that this model can represent rheological data for PET resins very well and as a result may be used in relevant processing flow simulations, i.e. film casting.

The annealing effect was studied on PMMA/PET immiscible polymer blends. Composite ratios of 0/100,25/75, 50/50, 70/30, 80/20 and 100/0 wt % of PMMA/PET were prepared by novel injection molding methods. Morphological interactions of these blends were investigated through thermal analysis using DMA and DSC. The samples were subject to testing in their as molded form and after annealing. Thermal analysis revealed crystallite growth effect on the storage modulus and increased Tg for annealed samples.

Heavy metal contaminants in environment, especially in drinking water, are always of great concern due to their health impact. Due to the use of heavy metals as catalysts during plastic syntheses, particularly antimony, human exposure to metal release from plastic bottles has been a serious concern in recent years. The aim and scope of this study were to assess metal contaminations leaching out from a series of recycling plastic bottles upon treatments. In this study, leaching concentrations of 16 metal elements were determined in 21 different types of plastic bottles from five commercial brands, which were made of recycling materials ranging from no. 1 to no. 7. Several sets of experiments were conducted to study the factors that could potentially affect the metal elements leaching from plastic bottles, which include cooling with frozen water, heating with boiling water, microwave, incubating with low-pH water, outdoor sunlight irradiation, and in-car storage. Heating and microwave can lead to a noticeable increase of antimony leaching relative to the controls in bottle samples A to G, and some even reached to a higher level than the maximum contamination level (MCL) of the US Environmental Protection Agency (USEPA) regulations. Incubation with low-pH water, outdoor sunlight irradiation, and in-car storage had no significant effect on antimony leaching relative to controls in bottle samples A to G, and the levels of antimony leaching detected were below 6 ppb which is the MCL of USEPA regulations. Cooling had almost no effect on antimony leaching based on our results. For the other interested 15 metal elements (Al, V, Cr, Mn, Co, Ni, Cu, As, Se, Mo, Ag, Cd, Ba, Tl, Pb), no significant leaching was detected or the level was far below the MCL of USEPA regulations in all bottle samples in this study. In addition, washing procedure did contribute to the antimony leaching concentration for polyethylene terephthalate (PET) bottles. The difference of antimony leaching concentration between washing procedure involved and no washing procedure involved (AC) was larger than zero for samples A to G. This interesting result showed that higher antimony concentration was detected in experiments with no washing procedures compared with those experiments with washing procedures. Our study results indicate that partial antimony leaching from PET bottles comes from contaminations on the surface of plastic during manufacturing process, while major antimony leaching comes from conditional changes. The results revealed that heating and microwaving enhance antimony leaching significantly in PET plastic bottles. Plastic bottle manufacturers should consider the contaminations during manufacturing process and washing bottles before first use was strongly recommended to remove those contaminants.

Polyethylene terephthalate post-consume (PET-pc) glycolysis was investigated by the use of ethylene glycol (EG) and zinc acetate, as catalyst. It was focused the kinetic aspects through use of mathematical model specially developed for application in this study. The grains-lot was sieved in different size ranges and a relation between surface area and granulometry, surface area and temperature on the conversion and depolymerization rate was proposed. At temperatures ranging 180–190 °C the depolymerization rate is quite elevated and almost 100% of conversion is obtained up to 3 or 4 h reaction time. For lower temperatures (170–180 °C), equilibrium is achieved and it becomes more important as the temperature is decreased. The conversion profile showed an initial activation stage where the mass transfer between the liquid and solid phases is minimal. The proposed mathematic model was based on these findings and on reaction mechanism that differentiates the reaction sites present in the PET surface. By that model the value of rate constant (k) for each temperature, and the dependence of k with 1/T was calculated. Four our best knowledge it is the first time that a mathematical model considers the activation stage in the earlier times of PET depolymerization reaction. The inputs yielding, time and temperature were included in the used mathematical model that fits very well the experimental data obtained at temperatures higher than 180 °C. This model helps to predict the necessary mass of PET for producing a desired amount of products.► Geometric surface area determination of the PET-pc grains by geometric models with two and three parameters. ► Determination of conversion (X) as a function of the granulometry of PET-pc. ► Evaluation of time and temperature influence on the heterogeneous depolymerization reaction. ► Developed a mathematical model for kinetic of heterogeneous PET glycolysis by ethylene glycol and zinc acetate. ► Determination of operating conditions to produce any quantity of products, providing a production planning tool for recycling of PET-pc.

This paper presents a green engineering plan for using PET(polyethylene terephthalate)as opposed to the traditional used PC (polycarbonate)for packaged drinking water with a prime focus on the environmental impacts and sustainability. It presents a comprehensive material selection process for choosing the PET bottles, justifying the reasoning for choosing them over the more often used PC bottles. Furthermore, the paper also presents a product life cycle for the PET bottles with a detailed life cycle assessment analysis using life cycle assessment software i.e., openLCA software. With the help of LCA software the environmental impacts of both form of the bottles is analyzed and compared concluding that PET bottles are by far more eco-friendly and are therefore the future of plastic packaging. Keywords:  environmental impact, sustainability, pet, pc, life cycle assessment

Background, aim, and scope The interest in polyethylene terephthalate (PET) recycling is quite recent, but it has been growing steadily over the past few years. In this context, the aim of this paper is to assess the eco-profile, the energy savings and the environmental benefits of the use of recycled raw materials to manufacture products for thermal insulation of buildings in Italy (i.e., PET bottles post-consumer). Materials and methods The life cycle analysis is developed according to ISO 14040/44. In this paper, based on the LCA, the main types of environmental impact of a thermal insulation product have been outlined. This study is specifically focused on polyester nonwovens, produced by a company located in Italy. The cradle-to-gate life cycle inventory is performed for the mass of product needed to give a thermal resistance R of 1 (m2 K/W). The calculation of the impacts is done with SimaPro software. With an environmental product declaration-oriented approach, a set of impact categories is used for the classification and characterisation of the life cycle impact assessment. Results The results of the impact assessment for 1m2 K/W of thermal insulation panels made with recycled PET are then compared with similar products made with virgin PET. The lower impact associated with the recycled PET for each category is underlined: the percentage reduction is around 46% in the GWP category. In the production process, the fiber-spinning phase results as the most relevant in terms of energy consumption. In addition, the energy saved when applying the thermal insulation in a building is estimated at 87 MJ/m2 per unit area per year in Rome. All the energy used during the production of a thermal insulation panel is recovered in about 2 years. Conclusions The product shows significantly low environmental impacts thanks to the use of non-virgin PET, thus maintaining high mechanical and physical properties. If the recovery of PET from separate waste collection in Italy increases, this would reduce the share of waste PET purchased from foreign countries and would therefore reduce further the impact of transports for the production of the thermal insulation panel under investigation.

Currently, polymer modified asphalt mixture is a relatively costly mixture for paving roads. One way to reduce the cost of such constructions and rendering them more convenient is by using inexpensive polymers, i.e. waste polymers. The main purpose of this research is to determine the effect of incorporating waste plastic bottles (Polyethylene Terephthalate (PET)) on the engineering properties of stone mastic asphalt (SMA) mixture. The volumetric and mechanical properties of asphalt mixes that include various percentages of PET (0%, 2%, 4%, 6%, 8% and 10%) were calculated and assessed with laboratory tests. The appropriate amount of PET was found to be 6% by weight of bitumen. The outcomes were statistically analysed and the determination of the significance at certain confidence limits was performed with the two factor variance analysis (ANOVA). Moreover, some studies conducted on polyethylene modified asphalt mixture have also been taken into consideration in this paper. The results show that the addition of PET has a significant positive effect on the properties of SMA and it can promote the re-use of waste material in industry in an environmentally friendly and economical way.► The PET increased the stiffness level of the mixture improving its resistance level against permanent deformation. ► The effects of waste PET on Marshall Stability, air void and bulk specific gravity of the mixture are significant. ► The appropriate amount of PET was found to be 6% by weight of bitumen.

The cost of construction materials and the required natural resources to produce the materials with the enabling environment is affecting the world's construction industry which is growing at an alarming rate. Also, plastic wastes have posed a major threat to the environment due to their large usage, non-biodegradability nature, and pollution through incineration and landfill. Recycling these wastes into tiles will be a great advantage. This study aims at examining mechanical properties of tile made from PET (Polyethylene Terephthalate) wastes, fly ash, and river sand aggregate. The PET wastes of varying percentages of 100%, 90%, 70%, 50%, and 30% by weight to other aggregates. The evaluation of physical and mechanical properties shows that, in terms of material density, strength, and flammability resistance, the tiles with 30% of the plastic waste yields better results than other proportions of the waste. According to the results obtained, this composite tile has a very low % porosity value (2.8-0.11%) compared to cement or ceramic tiles. Also, the composite tile (PFST1) with 30% and 35% sand and fly ash displayed lower flammability of 7.76mm/min linear burning rate and enhanced compressive strength of 11.10 MPa. The chemical tolerance of these composite tiles was also investigated by soaking in different acid, base, and alkaline for seven days, which has no significant difference in terms of weight and appearance. In conclusion, PET plastic tiles have good strength, decrease flammability, low water absorption, and eco-friendliness as tiles products. This prospect would not only minimize the cost of building products but will also act as a waste diversion to mitigate the environment caused by plastic waste disposal.

Heat resistant conveyor belts are critical assets for a pelletizing plant because of the losses that their failures cause. Accordingly, the life cycle of these conveyor belts should be evaluated during work, in order to assist their maintenance, and, in this context, this study proposes the use of material characterization and thermal degradation of the conveyor belts components. The characterizations were performed in a comparative way between three different kinds of heat resistant conveyor belts supplied to a global mining company. The belts carcasses were characterized by FT-IR aiming at the polymers qualitative analysis. Similarly, the rubbers were characterized by the analysis of their pyrolyzed products by FT-IR and their crosslinks densities were evaluated by the use of the Flory-Rehner equation after the swelling of the rubbers, which helped to justify the belts behavior under thermal degradation, studied in a previous work. Using these results and data of mechanical properties variation according to time and process temperature, it was possible to establish the rate of damage done to each conveyor belt and, applying real process data, the belts performance during work could be evaluated.

Keywords: Conveyor belts. Synthetic fibers. EPDM. FT-IR. Flory-Rehner equation.