Politechnika Rzeszowska im. I. Lukasiewicza

Rzeszów, Poland

Politechnika Rzeszowska im. I. Lukasiewicza

Rzeszów, Poland
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This paper constitutes a presentation of the factors influencing the enzymatic hydrolysis of polymers, the corresponding degradation mechanism and also a review of the literature regarding enzymatic degradation of polyurethanes (PUR) in general. Studies on the separation and identification of PUR degradation products released as a result of enzyme activity have been presented. Moreover, the literature regarding the mathematical aspects of degradation process was reviewed. The development of such a model for the in vitro enzymatic degradation of PUR is essential in understanding the kinetics of the process and enable the prediction of polymer behavior in vivo.

A review of the state-of-the-art and developments in the field of enzymatic degradation of polyurethanes (PUR) has been presented in this part. In the review special consideration was given to the primary factors influencing the polyurethane degradation such as the type of enzyme used, its activity, duration of the process and also the structure of the polyurethanes (polymers of segmented structure). Monitoring techniques via weight loss, measurements and observations of changes of molecular weight, crystallinity, mechanical properties as well morphology were discussed.

Bolanowski M.,Politechnika Rzeszowska im. I. Lukasiewicza | Paszkiewicz A.,Politechnika Rzeszowska im. I. Lukasiewicza
Przeglad Elektrotechniczny | Year: 2013

The article presents a new model for intrusion detection in computer networks using the method based on statistical signatures. The proposed method allows for dynamic switching policy change in the demilitarized zone that will be triggered by changing network traffic statistics parameters represented by a time series. We will present selected statistical descriptors used to detect specific threats.

Kowalczyk A.,Politechnika Rzeszowska im. I. Lukasiewicza | Cieslak R.,Politechnika Rzeszowska im. I. Lukasiewicza | Chorzepa R.,Politechnika Rzeszowska im. I. Lukasiewicza
Przeglad Elektrotechniczny | Year: 2014

The paper presents the rules and the problems associated with the measurement of chlorine dioxide (ClO2), which is a fundamental parameter of optimal water disinfection when such an oxidant is used. When ClO2 sensor was installed on the described object a problem with disturbances of unknown origin, which caused false alarms about the exceeding of the permissible value of chlorine, appeared. The paper presents the way of the investigation to determine the cause of disturbances, shows how to eliminate them, and compares the real recorded data.

Pilch-Pitera B.,Politechnika Rzeszowska im. I. Lukasiewicza | Wojturska J.,Politechnika Rzeszowska im. I. Lukasiewicza
Polimery/Polymers | Year: 2012

Polyurethanes synthesized in a two-step polyaddition process of trimethylhexamethylene diisocyanate (TMDI), poly(ε-caprolactone) diols with different molecular weights (PCL 750, PCL 1250) and glycerol (GLI) were biodegraded under simulated composting conditions with the use of vermiculite as an inert solid medium. Biodegradation process was carried out over a period of 42-106 days. The degree of biodegradation was determined on the basis of weight loss of the samples as well as the changes in the roughness parameters and surface free energy components (SEP). The mechanical properties of the samples before and after degradation were also determined. Additionally changes in the surface appearance of the samples after composting at simulated conditions were documented using both optical and confocal microscopy. It was found that even after six weeks of biodegradation a significant deterioration of the samples took place.

Kozik B.,Politechnika Rzeszowska im. I. Lukasiewicza | Sobolak M.,Politechnika Rzeszowska im. I. Lukasiewicza
Diagnostyka | Year: 2015

One of the phases of existence of machinery according to [5], is among others, constructing. The aim of constructional diagnostics used in this case is to identify sources of potential risks. In a dual-path gear transmission power is transferred by two parallel paths. Due to backlash and precision of making the whole gearing, the power is not transferred evenly along both paths. It creates potential risk which makes it necessary to create such gearing with higher module. This in turn causes an increase in dimensions and weight of the gearing. The paper presents a technical solution that allows to delete backlash on teeth on all stages of the gear transmission and thus increase the uniformity of power distribution into two paths. The solution consists in applying an intermediary split shaft whose parts can be exactly positioned angularly in relation to each other in the process of assembling the gear transmission.

A review, with 35 refs., of environmental aspects of prodn. and uses of polyurethanes. In particular, the recycling of polyurethane wastes by their hydrolysis and glycolysis was presented.

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