In this work the energy needed for reciprocating screw motion and heating of the barrel were examined by changing various parameters of the injection molding process, measuring the process characteristics and calculating the corresponding values of SEC (specific energy consumption). Five thermoplastic polymers were examined. It was found that the optimal condition from the energy consumption point of view to perform the plasticization of thermoplastic polymers on the research position is low value of rotational velocity of the screw. Furthermore, an increase of the SEC value with increasing barrel temperature was shown. It was also found that changes of back pressure do not affect the energy consumption of the plasticizing system of the injection molding machine.

The mathematical model of polymer plastication in a reciprocating screw injection molding machine is presented. It takes into account all characteristic features of working of a real injector, such as periodical action of the three zones screw, to-and-from screw motion with controlled stroke, static and dynamic melting, etc. Methods for description of time changes of the solid bed profile in the screw channel during injection cycle as a function of operating parameters were developed. Ways of determination of pressure and temperature profiles in the screw channel were also discussed. Methods of caculation of the most important flow characteristics such as plasticizing capacity, power requirements, screw torque, energy consumption were analyzed. Results were presented in a form, which is most convenient for numerical applications in computer simulation programs.

The mathematical model of the polymer plasticization in the reciprocating screw injection moulding machine is presented in this paper. Methods of calculation of the most important flow characteristics, such as the solid bed profile, the pressure and temperature profiles, the mass flow rate, the power demand, the screw torque and the energy consumption were analysed. According to the mathematical model, a computer program was developed. Based on the computer program, simulation studies of the injection moulding process were conducted. Thereafter, the experimental studies, evaluating the theoretical model from the accuracy and usefulness point of view, were carried out. Important output quantities, such as the temperature and pressure profiles, the power demand by the screw, the torque on the screw and the screw rotation time were measured. The studies were performed on a specially made research office. The simulation results were compared with the experimental data measured for the most popular polymers and different operating parameters of the injection machine. The experimental studies have indicated the need to introduce some corrections to the mathematical model. Several modifications have been made to the model, mainly related to the methods of stress determining in the polymer layer. Finally, the output characteristics of the plasticization process in the injection moulding are now correctly determined by the model with an average error less than 10%.

A computer program for the simulation of polymer plastication in screw injection molding machine created on basis of the theoretical model presented in part 1 of this paper is discussed. As simulation examples various process characteristics, e. g. solid bed, pressure and temperature profiles, are computed using the material parameters for high density polyethylene and three-zones-screw of diameter 20 mm. Effects of different geometric and operating parameters on plastication course are also demonstrated. Simulation results with respect to the screw rotation time are compared with experimental data measured for low density polyethylene, polypropylene, polystyrene, polyoxymethylene and polyamide 6. It was found that the computer program reflects correctly all features of a true plasticating system in injection molding machine. It provides also good agreement of model predictions with experimental data.

This study investigated the effect of eight different transition metal oxides (MOx) on the flame retardant, mechanical, and thermal properties of intumescent polypropylene (PP-IFR) composites filled with ammonium polyphosphate (APP) and pentaerythritol (PER). A novel approach is presented through a comprehensive evaluation of the performance characteristics of polypropylene (PP) composites containing various metal oxides. The flame retardant properties of these composites were assessed using both the Limiting Oxygen Index (LOI) and UL-94 V tests. For mechanical characterization, tensile strength, flexural strength, and Charpy impact strength tests were conducted. In addition, the heat deflection temperature (HDT) was also examined as an important performance parameter. Ni₂O₃, V₂O₃, MnO₂, and ZrO₂ exhibited a beneficial effect on both mechanical and flame retardant properties (LOI increase of 9–11%). ZnO significantly improved flame retardancy (8% LOI increase) while slightly reducing some mechanical properties. Composites with 2% content of Zn₂O₃, Ni₂O₃, V₂O₃, MnO₂, and ZrO₂ achieved a V-0 rating in the UL-94 V test. V₂O₃ clearly improved HDT (by 12 °C). Fe₂O₃ and Cu₂O oxides increased the flammability of PP-IFR composites (N-R vs. V-0). Analyzing the changes in mechanical properties, we observed the expected stiffening effect of the materials, which resulted in increased strength (30% for flexural strength) and moduli (over 50% increase for Young’s modulus and 30% for flexural modulus). The thermal properties and degradation behavior of PP-IFR composites as a function of temperature were investigated using TGA/DSC analysis, along with FTIR to examine interactions. Correlations were observed between the presence of interactions (hydrogen bonds) in the composites and the flammability of the materials, which also depended on the reactivity of the MOx. MOx were found to reduce thermal stability compared to PP-IFR. Their initial decomposition occurred at temperatures of 240–300 °C, while the maximum decomposition rate was observed around 400–450 °C. This initial thermal decomposition of PP-APP-PER-MOx compounds, synergistically interacting with additives in various ways, can create a barrier, acting as a protective layer against fire. Scanning electron microscopy revealed that the intumescent char surface after combustion of the samples was significantly modified in the presence of metal oxides such as ZnO, Ni₂O₃, and MnO₂.