The present research deals with the investigation of the influence of aqueous solutions of chemical substances in combination with temperature on the change of material properties of polymer composites based on epoxy resins reinforced with carbon fibers. The aim of the research was to investigate and evaluate the impact of degradation processes due to the influence of chemical environments of different temperatures and time of their action on changes in the material properties and macrostructure of carbon composite with epoxy resin. The chemical and thermal influence of the environment on the experimental material was evaluated by monitoring changes in mechanical properties, glass transition temperature, and material surface macrostructure. The achieved results show different behavior of the experimental composite material in different environments, while it was demonstrated that the degradation effect of chemical and thermal influences on changes in material properties increase with increasing temperature. Among the investigated environments (NaCl, NaOH, and H2SO4), exposure to 10% NaOH, and 15% H2SO4 had the greatest degradation influence on the polymer composite, and exposure to 20% NaCl had the smallest influence, which is also confirmed by invisible changes in material surface macrostructure and decrease of tensile strength by about 20%. Exposure to 10% NaOH resulted in significant surface roughening of the epoxy resin, white deposit creation on the surface, and a decrease of tensile strength by 35%. Opposite that, exposure to 15% H2SO4 resulted in the highlighting of the fiber yarns of the carbon fiber fabric, yellowing of the surface, surface pore occurrence, and a decrease of tensile strength by 35%.

This work deals with the study of polymers, and, in particular, polyethylene; its production, types, properties, and usage. The experimental part evaluates the changes of properties of the polyethylene film to be reused under various exposure conditions and selection of the most suitable medium for its application. The film made of low-density polyethylene (LD-PE) was influenced by aggressive media with different pH, specifically Savo for the disinfection, Savo as a Saponate for dish washing and Coca-Cola. On LD-PE films the water absorption and melting temperature evaluation tests were performed. Carried out tests show that the most aggressive medium for LD-PE film from used media is Coca-Cola. The most effective application of LD-PE film like wrapping on container transported is the Savo used as a Saponate for dish washing.

In this paper, there are published experimental results of research in the field of polymers. The thermal analysis conveys information about changes in material effected by the melting of the material. The investigated material is low-density polyethylene (LD – PE). The LD – PE films were exposed to aggressive media with different values of potencia hydrogeni (pH). The experiment aims to apply thermal gravimetric analysis (TGA), one of the methods of thermal analysis. TGA monitors the weight of polyethylene films as a function of temperature. Original LD – PE film and the effect of media is evaluated based on TGA and evaluation of the surface morphology (macrostructure) after exposure. The largest weight loss is noticed in the original film without the influence of media. At 200 °C, the wax products are released from the material. During thermal analysis is observed a weight loss of up to 1 mg in the investigated film samples. LD – PE film after the effect of Coca-Cola has the highest decrease in mass and the most changed its macrostructure. LD – PE film after effect of Saponate has the lowest decrease in mass and its macrostructure is almost the same as the original LD – PE film after production technology.

Polyethylene (PE) is the most commonly used polymer. Most of the polymers are processed by the packaging sector. PE products are the most recycled plastic due to the short life of packaging materials. The experiment is based on real issues in the recycling of plastic waste in a world that is increasingly up to date. One way of recycling it is to produce returnable plastic bottles that can be used up to 50 times. The low-density polyethylene (LDPE) film is applied to the plastic bottles before filling with a specific medium. After the contents of the bottle have been consumed, the LDPE film is stripped. Subsequently, a new recyclable film is applied to the bottles used and the process is repeated. Changes in the properties of LDPE films applied to these returnable bottles have been evaluated by several tests (tensile test and water absorption test). The tests were performed on unused LDPE films and on used LDPE films, which were filled with the medium for 3 months. The fill media was chosen from commonly available goods.

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