The kinetics of the precopolytransesterification step for the production process of the copoly(ethylene‐polyoxyethylene terephthalate), COPEPOET, has been analyzed. The prepolytransesterification step involves two competitive parallel reactions generating the same by‐product, ethylene glycol: 1. Prehomopolytransesterification reaction of bis (2‐hydroxyethylene terephthalate), BHET, with itself and 2. Precopolytransesterification reaction of BHET with poly(oxyethylene), POE. The kinetic constants of both reactions, BHET with BHET and BHET with POE, were calculated. The analysis was made as follows: 1. A kinetic model was developed in order to calculate the kinetic constants kH and kC of the prehomopolytransesterification and precopolytransesterification reactions; 2. The simulation of the precopolytransesterification step was carried out by integrating the differential equations, which describe the prepolytransesterification step. A fourth‐order Runge‐Kutta method was used for this integration. Several values that fall within the interval of 0.05 to 1.5 were assigned to the rate constant ratio kH/kC value, a set of kH/kC value, a set of kH and kC values were obtained. The parameters of the Arrhenius equation A and E were evaluated by means of a multiple regression analytical method; and 3. By comparison between theoretical and experimental data the best kH/kC value was obtained. The kH value was found to be several times smaller than that of kC.

A mathematical algorithm that optimizes the reactor to produce the elastomeric copolyester copoly(ethylene‐polyoxyethylene terephthalate), CEPT, is shown in this work. The optimization was carried out this way: First, an initial isothermal guess of temperature profile is made and the differential equtions system, which describes the CEPT production process, is solved, Second, the reaction time is fixed and the objective function is calculated. Third, the adjoint variable equations system is solved and the Hamiltonian's function is calculated. Fourth, a new temperature profile is found by using the control vector iteraction procedure. Finally, steps one to three are repeated until the objective function reaches a minimum value. The results of the optimization establish that the copolytransesterification reactor should be operated initially to high temperature (about 285°C), which should be reduced quickly to near 250°C to purposely diminish the production of by‐products.

The transport of oxygen and carbon dioxide through a set of random copolymer films based on poly(ethylene terephthalate) (PET) and poly(ethylene 2,6-naphthalate) (PEN) were explored. Diffusivity and permeability of both gases decreased with increasing PEN content. The oxygen and carbon dioxide diffusion coefficients decreased 74 and 82% from pure PET to pure PEN, respectively. The presence of stiffer PEN moieties had an effect on the glass transition temperature (T g ) of PET/PEN blends and gas barrier. In the complete range of tested blends, the differential scanner calorimeter analysis displayed a single value of thermal glass transition temperature. As the PEN content was increased, the fractional free volume (FFV) and the diffusion coefficients of the blends were decreased. The Doolittle equation provided the best fit for diffusivity and FFV and showed that the gas transport behavior was better understood when it was taken into consideration the cohesive energy of blends. As the PEN content in films was increased, their rigidity and the glass/rubber transition temperature were increased, and their capacity to be penetrated by small molecules like O 2 and CO 2 was decreased. POLYM. ENG.

In this paper, the criteria for the development, implementation, and control of operating and safety limits of parameters like pressure, temperature, level, composition, etc., are described. Operating and safety limits are required by Elements 2 “process safety information” and 4 “operating procedures” of the information package for OSHA Process Safety Management (PSM). A brief description is also given of how these limits should be established and the information, with respect to consequences, safeguards, and corrective actions, that should be obtained during a detailed analysis of deviation from an operation or process parameter. This paper looks for an easier method of developing operating and safety limits within chemical and petrochemical plants to prevent and control undesirable events (human losses, material losses, economic losses, or environmental pollution) through adequate emergency plans and response programs.