The electron b-irradiation of isotactic polypropylene (iPP) influenced the sample chemical structure because it mostly caused the crosslinking of the polymer chains beside the macromolecule degradation. The irradiation effect led to the corresponding changes in physical properties (crystallinity, crystal size, melting and crystallisation temperatures). The amount of the b-phase in the samples decreased with the increasing b-irradiation dose, changing into the a-and amorphous phase. After the irradiation, the iPP melting and crystallisation temperatures decreased, and the spherulitic structure was partially decomposed. The imbibition of boiling xylene proved that the highest degree of crosslinking took place in the samples irradiated with a dose of 33 kGy, showing the highest crystallinity and melting temperature. Keywords: isotactic polypropylene crystal modifications, b-irradiation, structure and properties Elektronsko radioaktivno b-obsevanje vzorcev izotakti~nega polipropilena (iPP) vpliva na njihovo kemijsko zgradbo, ker to povzro~a pre~no vezavo polimernih verig, povezano z degradacijo (kraj{anjem) makromolekul. Vpliv obsevanja vpliva skladno s tem tudi na fizikalne lastnosti polimera (kristalini~nost, velikost kristalov, tali{~e in temperatura kristalizacije). S pove~e-vanjem doze obsevanja b se koli~ina b-faze zmanj{uje zaradi njenega spreminjanja v a in amorfno fazo. Po obsevanju se tali{~e in temperatura kristalizacije iPP zni`ata, sferuliti~na (krogli~na) struktura pa delno razpade. Imbibicija (razmikanje molekul) med vretjem ksilena je pokazala, da nastopa ve~ja stopnja pre~ne vezave molekul pri vzorcih, ki so jih avtorji prispevka obsevali s 33kGy dozo, kar ka`e na ve~jo kristalini~nost in vi{je tali{~e. Klju~ne besede: kristalne modifikacije izotakti~nega propilena, radioaktivno sevanje b, struktura in lastnosti
This work deals with investigative methods used for evaluation of the surface quality of selected metallic materials’ cutting plane that was created by CO2 and fiber laser machining. The surface quality expressed by Rz and Ra roughness parameters is examined depending on the sample material and the machining technology. The next part deals with the use of neural networks in the evaluation of measured data. In the last part, the measured data were statistically evaluated. Based on the conclusions of this analysis, the possibilities of using neural networks to determine the material of a given sample while knowing the roughness parameters were evaluated. The main goal of the presented paper is to demonstrate a solution capable of finding characteristic roughness values for heterogeneous surfaces. These surfaces are common in scientific as well as technical practice, and measuring their quality is challenging. This difficulty lies mainly in the fact that it is not possible to express their quality by a single statistical parameter. Thus, this paper's main aim is to demonstrate solutions using the cluster analysis methods and the hidden layer, solving the problem of discriminant and dividing the heterogeneous surface into individual zones that have characteristic parameters.
Abstract. The article deals with the area of non-conventional technologies, specifically with the effect of concentrated radiant energy on the polymer material. There was studied the laser beam and its application to two different types of polymeric materials in details. PMMA, as a representative of the amorphous polymers and POM, which is a crystalline polymer, were used for experimental cutting as they frequently applied in industrial practice. The input technological parameters were changed during machining followed by evaluation of their interaction with the concentrated radiant energy of the laser beam. The results were subjected to statistical processing.
During of aluminum alloy materials, it is possible to find three surface types which can be distinguish as primary, secondary and tertiary sections. In practice this is a big problem in case of finding the basic parameters of roughness and waviness as described by ISO 4288. According to our research, it is possible to use optical microscopy in the first step and subsequently to scan the surface in 3D in order to distinguish the type of. Another problem is how to determine the boundaries between the individual structures. The article describes methods to distinguish the boundaries in a more precise way by the cumulative functions, leading to more accurate determination of the surface quality parameters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.