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I nanocompositi di gomma mostrano generalmente una scarsa conduttività termica, che può essere parzialmente migliorata dall'aggiunta di riempitivi termicamente conduttivi, ad esempio grafite, nerofumo, fibre di carbonio, particelle di ceramica o di metallo. Per raggiungere questo obiettivo sono in genere necessari concentrazioni di riempimento elevate; tuttavia, ciò altera notevolmente il comportamento meccanico e la densità di reticolazione dei materiali finali. Inoltre, i sistemi di riempimento attualmente impiegati non sono in grado di soddisfare contemporaneamente i requisiti chiave di elevata conducibilità termica e prestazioni meccaniche. In questo contesto, l'attività di ricerca del dottorato mira a progettare nuovi riempitivi adatti allo sviluppo di nanocompositi di gomma con elevata conducibilità termica e prestazioni meccaniche soddisfacenti. Sarà condotta un'indagine su diversi nano-riempitivi termicamente conduttivi, studiando in profondità le correlazioni tra struttura, morfologia, dispersione e distribuzione delle nanoparticelle nella matrice polimerica e proprietà finali dei compositi. Le migliori formulazioni verranno selezionate ed eventualmente scalate al fine di fornire reali applicazioni tecnologiche. Rubber nanocomposites generally exhibit poor thermal conductivity, which has been partially enhanced by the addition of thermally conductive fillers, i.e. graphite, carbon black, carbon fibres, ceramic or metal particles. High filler loadings are typically necessary to achieve this target; however, this dramatically alters the mechanical behaviour and the cross-linking density of the final materials. Further, the filler systems currently employed are not able to fulfil the key requirements of high thermal conductivity and remarkable performances, simultaneously. In this context, the PhD research activity aims at design novel fillers suitable for developing rubber nanocomposites with high thermal conductivity and satisfactory mechanical performances. A survey of different conductive nanofillers will be carried out, by investigating in depth the correlations between nanoparticles structure, morphology, dispersion and distribution in the polymer matrix, and final composites properties. The best formulations will be selected and possibly up-scaled in order to provide real technological applications.

Introduction: Hydrophilicity of dental impression materials is crucial for obtaining an accurate impression and necessary for the production of a well-fitting cast restoration. The most common technique for evaluation of hydrophilicity is a contact angle measurement. The aim of the present in vitro study was to compare the water contact angles of four groups of elastomeric impression materials, before and during setting. Material and methods: Flattened specimens (n=10) of tested impression materials were prepared by the use of a Teflon mold with specific dimensions. A 5μl droplet of deionized water fell on the specimen, and photos were taken using a Nikon D3200 DSLR camera and a 105 mm macro lens (Nikorr, Nikon) in specific time points. Results: The CAD/CAM material showed the highest contact angle measurements. The light body polyvinylsiloxane (PVS) material 1, polyether and vinylsiloxanether material showed comparable contact angle measurements especially at the initial time point. A statistically significant reduction of contact angles was reported during setup time for all PVS, PE and vinylsiloxanether materials, while the most expressed reduction of contact angle measurements, and thus the most significant increase of hydrophilicity were reported for light wash PVS material 2. Conclusions: The CAD/CAM impression material showed the most hydrophobic behavior. PVS materials showed excellent hydrophilicity. Polyether and polyvinyloxanether impression materials presented lower contact angle measurements, and thus superior hydrophilicity, compared with other tested materials initially and during setting. All tested impression materials presented a stepwise development of hydrophilicity during the setting stage., Uvod: Hidrofilnost otisnih materijala ključna je za preciznost otiska i prijeko potrebna za izradu nadomjestka s dobrim dosjedom. Najčešća tehnika za njezinu procjenu jest mjerenje kontaktnog kuta. Cilj ovoga istraživanja in vitro bio je usporediti kontaktne kutove vode u četirima skupinama elastomernih otisnih materijala, prije vezivanja i tijekom vezivanja. Materijali i metode: Spljošteni uzorci (n = 10) ispitanih otisnih materijala pripremljeni su u teflonskom kalupu specifičnih dimenzija. Kapljica deionizirane vode od 5 μL kapnuta je na uzorak, a fotografije su snimljene fotoaparatom Nikon D3200 DSLR i 105 mm makroobjektivom (Nikorr, Nikon) u određenim vremenskim točkama. Rezultati: CAD/CAM materijal imao je najveći kontaktni kut. Rijetki materijali polivinilsiloksan (PVS) 1, polieter i vinilsiloksaneter imali su usporedive mjere kontaktnoga kuta, posebno u početnoj vremenskoj točki. Statistički značajno smanjenje kontaktnih kutova zabilježeno je tijekom postavljanja za sve PVS-ove, PE-ove i vinilsiloksan, a najizraženije smanjenje, pa time i najznačajnije povećanje hidrofilnosti, zabilježeno za rijedak PVS 2. Zaključci: CAD/CAM otisni materijal imao je najhidrofobnija svojstva. PVS materijali imali su izvrsnu hidrofilnost. Polieterski i poliviniloksaneterski otisni materijali imali su manji kontaktni kut, pa tako i veću hidrofilnost u usporedbi s drugim ispitivanim materijalima na početku vezivanja i tijekom toga postupka. Svi ispitani otisni materijali postupno su razvijali hidrofilnost tijekom faze vezivanja.

Hladni blok na orodjih služi za zmanjševanje porabe gume pri brizganju izdelkov. V nalogi je predstavljen razvoj pogona zaporne igle v hladnem bloku. Pogon je izveden tako, da lahko določimo poljubno pozicijo zapiralne igle in s tem povzročimo režo. Ko material potuje skozi režo se zaradi trenja segreje. Pregret material v formi pa pomeni krajši čas vulkanizacije in posledično krajši časi ciklov brizganja izdelkov. Pri snovanju je bila zelo pomembna omejitev prostor, ter povišana temperatura okolja. A cooling block is a part of the working tools. Its purpose is to minimise the consumption of rubber when injecting products. This work aims to present the development of the locking needle's drive in the cooling block. The drive enables a user to specify a location which causes a cut. When material travels through the cut, it warms up due to friction. However, the increased temperature causes a decrease in time of vulcanisation and product injection cycles. The results showed the importance of location restrictions and higher temperature of the working environment.

Darbā sintezēti vairāki jonu šķidrumi ([C2C1im][MeCO2], [C2C¬1im][C5H11CO2], [C8C1im][BF4], [C2C1im][NTf2], [C4C1im][NTf2]) un to struktūras pierādītas ar 1H KMR, 13C-KMR metodēm. Pārbaudīta to ietekme uz akrilnitrila – butadiēna elastomēra īpašībām. Noteikta stiepes izturība un maksimālais pagarinājums akrilnitrila – butadiēna blīvēm pēc izturēšanas jonu šķidrumos paaugstinātā temperatūrā 21 h – 8 dienas. Jonu šķidrumi ekstrahēti ar heptānu un analizēti ar GS-MS., Effects of imidazolium ionic liquids on nitrile elastomer properties. Vancoviča E., supervisor doc. Baķis E. Bachelor’s thesis in chemistry, 44 pages, 13 figures, 7 table, 33 literature references, 3 appendices. In Latvian. Several ionic liquids ([C2C1im][MeCO2], [C2C¬1im][C5H11CO2], [C8C1im][BF4], [C2C1im][NTf2], [C4C1im][NTf2]) have been synthesised and their structures proven using 1H NMR, 13C-NMR. Effects of [C2C1im][MeCO2], [C2C¬1im][C5H11CO2], [C8C1im][BF4], [C2C1im][NTf2] on nitrile elastomers have been studied. Tensile strenght and elongation have been determined after exposing elastomers to ionic liquids for 21 h to 8 days at elevated temperature. After that ionic liquids have been extracted and analysed using GS-MS.

V magistrskem delu smo obravnavali gredno tesnilo na teflonski osnovi, ki je namenjeno delovanju v suhih pogojih. Ker ta tehnologija v izbranem podjetju še ni bila preizkušena, smo se odločili za raziskavo in razvoj ustrezne naprave za njeno testiranje. Raziskava je v veliki meri praktične narave, oz. je osredotočena na validacijo grednega tesnila, za kar smo na začetku morali razviti testni model in načrt testiranja, s katerim določimo parametre, ki nam nato prinesejo zadovoljive rezultate, na podlagi katerih bomo lahko naredili končne ugotovitve. Iz meritev smo ugotovili, da je gredno tesnilo delovalo po specifikacijah proizvajalca, kar pomeni, da je sposobno obratovati in zagotavljati tesnost tudi po različnih obremenitvenih testih. The thesis discusses a teflon based radial shaft seal, the intended use of which is to operate in dry conditions. Because this technology has not yet been reasearched in the company, the decision was made to reasearch and develop a suitable test model. The research is of a practical nature, respectively focused on the validation of the radial shaft seal, for which the test model and test plan diagram were developed. The test plan diagram was used to define procedures and parameters of measurments, in order to ensure suitable in reliable results. Analysis results showed that the radial shaft seal worked as defined by the manufacturer and is thus capable of operating and remaining functional even after enduring different load tests.

Elastomers are amorphous polymers widely used in many applications. Degradability and durability of elastomers are very important properties, which can be strongly influenced by several types of physical and chemical processes such as impact of weather conditions, aging etc. These processes can cause structural changes, which may lead to the destruction of the quality of elastomer materials, like a deterioration of their mechanical and electrical properties, and ultimately a total loss of material functionality. A large number of investigations with various experimental procedures were carried out in order to provide a better understanding of the relationship between the structure of material and its mechanical properties. This paper presents a Fuzzy model, which was constructed for anticipation of elastomers behavior based on experimental research data. In addition, a linear model was made, based on the measured and literature data, for assessing the effect of radiation and deformation on properties of elastomer specimens. The Normalized Roth Mean Square Error (NRMSE) and the Roth Mean Square Error (RMSE) were used to evaluate the results of the Fuzzy model.

V diplomskem delu smo preizkusili vpliv reže na segrevanje brizgane zmesi v šobi hladnega kanala z zapornimi iglami. Zmes smo želeli segreti zaradi krajših časov vulkanizacije in lažjega zalivanja izdelka. S programom Sigmasoft smo izdelali parametrično simulacijo v kateri smo preverili vpliv različne geometrije, parametrov brizganja ter dve različni zmesi. Sledil je še realen preizkus podobne tehnologije brizganja z dvojno injekcijo. V simulaciji in v realnem preizkusu so bile uporabljene iste zmesi, katerih točne lastnosti imamo pomerjene. Ugotovili smo, da se z našo tehnologijo približamo temperaturnim spremembam, ki jih dosegamo tudi z dvojno injekcijo ampak za to porabimo več tlaka. In final thesis we tested the effect of the gap on heating the injected compound in the cold runner nozzle. The compound is to be heated to shorten the cycle times and facilitate filling of the product. With the program Sigmasoft we created a parametric simulation in which we examined the influence of different geometry, injection parameters and two different compounds. After the simulation followed a realistic test of the similar technology. We tested injection unit with double injections. In the simulation and the real test the same compounds were used, of which accurate properties have been measured. We found out that out concept approaches temperature increases which are achieved with double injection, but with larger pressure input.

Background/Aim. Dental impressions present a negative imprint of intraoral tissues of a patient which is, by pouring in gypsum, transferred extraorally on the working cast. Casting an accurate and precise working cast presents the first and very important step, since each of the following stages contributes to the overall error of the production process, which can lead to inadequately fitting dental restorations. The aim of this study was to promote and test a new model and technique for in vitro evaluation of the dental impression accuracy, as well as to asses the dimensional stability of impression material depending on the material bulk, and its effect on the accuracy of working casts. Methods. Impressions were made by the monophasic technique using the experimental master model. Custom trays with spacing of 1, 2 and 3 mm were constructed by rapid prototyping. The overall of 10 impressions were made with each custom tray. Working casts were made with gypsum type IV. Measurement of working casts was done 24 h later using a coordinate measuring machine. Results. The obtained results show that the working casts of all the three custom trays were in most cases significantly different in the transversal and sagittal planes in relation to the master model. The height of abutments was mainly unaffected. The degree of convergence showed certain significance in all the three custom trays, most pronounced in the tray with 3 mm spacing. Conclusion. The impression material bulk of 1-3 mm could provide accurate working casts when using the monophasic impression technique. The increase of the distance between abutment teeth influences the accuracy of working casts depending on the material bulk., Uvod/Cilj. Otisak predstavlja negativ intraoralnih tkiva, čijim se izlivanjem u gipsu njihova morfologija prenosi ekstraoralno na budući radni model. Sa laboratorijskog aspekta izrade zubnih nadoknada, izlivanje tačnog i preciznog radnog modela predstavlja prvi i veoma bitan korak, pošto svaka sledeća faza doprinosi daljem povećanju greške tokom izrade, što za krajnji ishod može imati neodgovarajuću zubnu nadoknadu. Cilj istraživanja bio je da se ispitaju novi model i tehnika za in vitro procenu preciznosti zubnih otisaka, kao i da se odredi uticaj količine otisnog materijala na dimenzionu stabilnost otisaka i preciznost izrade radnih modela. Metode. Za uzimanje otisaka korišćena je monofazna tehnika otiskivanja. Individualne kašike sa međuprostorom od 1, 2 i 3 mm napravljene su aditivnom tehnologijom za brzu izradu prototipova. Sa svakom kašikom napravljeno je po 10 otisaka. Radni modeli izlivani su u gipsu tipa IV. Merenje radnih modela vršeno je nakon 24 sata na koordinatnoj mernoj mašini. Rezultati. Rezultati pokazuju da radni modeli napravljeni pomoću sve tri individulane kašike u transverzalnoj i sagitalnoj ravni značajno odstupaju od glavnog dela modela. Visina patrljaka je u većini slučajeva bila kao na glavnom modelu. Stepen konvergencije pokazao je određena odstupanja samo kod kašike sa međuprostorom od 3 mm. Zaključak. Monofazna tehnika otiskivanja i otisni materijal debljine od 1 do 3 mm obezbeđuju izradu preciznih radnih modela. Rastojanje između zubnih patrljaka utiče na preciznost izrade radnih modela u zavisnosti od količine otisnog materijala.

Diplomsko delo vsebuje predstavitev prototipnega orodja za brizganje gumijastih izdelkov, ki se je preizkusilo v podjetju Tesnila GK, d. o. o., na Prevaljah. Uvodoma so prikazane teoretične osnove brizganja polimernih izdelkov in lastnosti konstruiranja brizgalnih orodij. V drugem delu je predstavljena sestava prototipnega orodja, opis posameznih segmentov orodja ter delovanje orodja. V zaključku dela so prikazane omejitve preizkušenega prototipnega orodja. Thesis includes presentation of a prototype mold tool for injecting rubber parts, which was tested in company Tesnila GK, d. o. o., in Prevalje. Thesis begins with theoretical bases for injection molding of polymer materials and properties of designing injection molds. The second part of thesis presents the assembly of prototype mold tool with a description of individual segments of the tool and its functioning. In the conclusion is a representation of limitations of the tested prototype tool.

Uvod: V ortotiki in protetiki so za izdelavo tehničnih pripomočkov ključnega pomena materiali, ki jih inženirji uporabljajo pri svojem delu. Izberemo jih glede na njihove lastnosti in predvideno uporabo, pri čemer pa so odločilne individualne potrebe bolnika. Ortotiki in protetiki so odgovorni in usposobljeni za ustrezno izbiro materialov in sestavnih delov za izdelavo. Najbolj so v uporabi polimerni materiali, ki se delijo v tri večje skupine: termoplasti, duroplasti in elastomeri. Njihova pomembna lastnost je, da se lahko oblikuje preko mavčnega modela. V svetu obstaja veliko proizvajalcev polimernih materialov. Zaradi lažje in hitrejše prepoznave so jih poimenovali s komercialnimi imeni in jim pripravili navodila o uporabi. Namen: Namen diplomske naloge je predstaviti termoplastične materiale ter njihove kemijske in fizikalne lastnosti. V obliki tabel bomo prikazali primerjavo lastniških imen in lastnosti nekaterih polimernih materialov petih podjetij, ki so specializirana na področju ortotike in protetike in imajo možnost njihove dobave. Metode dela: Diplomsko delo temelji na deskriptivni metodi ter analizi ponudb materialov petih večjih dobaviteljev, ki so trenutno na tržišču na področju ortotike in protetike. Rezultati: v prvi tabeli so prikazane lastnosti opisanih materialov (gostota, temperatura obdelave in tališča ter kemijska formula), v vseh ostalih pa so analizirana imena in lastnosti (uporaba, temperatura obdelave) petih podjetij, ki jih dobavljajo. Razprava in sklep: Nekateri materiali se pojavljajo pod istimi lastniškimi imeni pri več dobaviteljih, v veliki večini pa se razlikujejo. Tudi vseh ne dobavljajo vsa podjetja, določeni materiali se lahko pridobijo le pri nekaterih podjetjih. S pregledom materialov različnih dobaviteljev in predstavitvijo le-teh v tabelah smo želeli na enem mestu zbrati pomembnejše informacije o termoplastih, ki se jih uporablja za izdelavo tehničnih pripomočkov. Iz tabel bomo lahko povezali lastniška imena s polimernim materialom in njegovimi lastnostmi. Introduction: Crucial role in making technical accessories in orthotics and prosthetics is played by materials, which engineers use at their work. The materials are selected with regard to their properties and intended use, wherein a decisive factor is individual needs of a patient. Orthotists and prosthetists are responsible and educated for a suitable selection of materials and components. The most used are polymeric materials which are divided into three major groups: thermoplastics, thermosets and elastomers. Their important characteristic is the ability to be moulded in a plaster model. There are many manufacturers of polymeric materials worldwide. For making easier and faster distinction polymeric materials were named with commercial names and accompanied by instructions for use. Purpose: The aim of this diploma thesis is presentation of thermoplastic materials together with their chemical and phyisical properties. Additionally, we will use tables to show comparisons of proprietary names and characteristics of several polymeric materials produced by five companies, which are specialised in fields of orthotics and prosthetics, and are also able to supply them. Methods of work: The diploma thesis is based on a method of description as well as analysis of offers for materials formulated by five major suppliers, which currently dominate markets of orthotics and prosthetics. Results: In the first table properties of described materials (density, processing temperature, melting point and chemical formula) are shown, while in the remaining tables the names and properties (usage, temperature of processing) of polymeric materials of five suppliers are analysed. Discussion and conclusion: Some materials of different suppliers hold the same proprietary names, but a great majority of proprietary terms differs. Also, all included polymeric materials cannot be supplied by all companies, certain materials can be gained only by some of them. The overview of materials of various suppliers and their presentation in tables enabled us to collect important information on thermoplastics, which are used for making technical accessories. The tables allow us to connect proprietary names with polymeric materials and their characteristics.

Uzorci polimernih mješavina prirodne (NR)/stiren butadien (SBR) gume te gumenog granulata pripremljeni su prešanjem u laboratorijskoj preši. Određivanje reoloških svojstava uzoraka provedeno je na reometru i munimetru. Također, uzorcima su ispitana i mehanička svojstva odnosno prekidna čvrstoća, prekidno istezanje, daljnje zarezivanje, tvrdoća te odbojna elastičnost. Rezultati su pokazali da dodatak punila (gumeni granulat) ima utjecaj na mehanička i reološka svojstva svih uzoraka. Uzorci pripremljeni s većim udjelom gumenog granulata pokazuju smanjenje vrijednosti reoloških i mehaničkih svojstava u odnosu na uzorak bez gumenog granulata., Samples of polymer blends (NR/SBR/rubber granulate) are prepared by compressing in a laboratory press. Determining the rheological properties of the samples was performed on a rheometer and munimetru. NR/SBR/rubber granulate blends are characterized by determination of mechanical properties (tensile strength, elongation, further scoring, hardness and repulsive elasticity). Results showed that addition of the filler (the rubber granules) has an effect on the mechanical and rheological properties of all the samples. The samples prepared with a higher amount of added rubber granules show a reduction of rheological and mechanical properties in comparison to the sample prepared without rubber granulates.

V diplomski nalogi so prikazani poskusi sinteze poroznega elastomera z uporabo fotopolimerizacije. Želeli smo sintetizirati elastomer z dobrimi mehanskimi lastnostmi, saj so porozni materiali po navadi krhki. Kot monomer smo uporabili alifatski uretanski diakrilat (AUD, Sartomer CN 965), ki smo ga dodali v emulzijo z visokim deležem notranje faze. Emulzijo smo mešali eno uro v bučki potopljeni v termostatirano vodo z mešalom pri 250 obratih na minuto. Nastale emulzije smo vlili v kalupe in spolimerizirali v UV komori, nato smo produkte očistili v izopropanolu in posušili. Posušene produkte smo analizirali s pomočjo vrstičnega elektronskega mikroskopa in FTIR spektroskopijo. Pri poskusih smo spreminjali pogoje, kot so temperatura, delež notranje faze, topila in surfaktana. Rezultati so pokazali tvorbo emulzij v širokem temperaturnem območju in pri različnih deležih interne faze, vendar so se nam produkti po sušenju precej skrčili, postali trdni in neelastični in nadaljnje analize v večini primerov niso pokazale lepo porozne strukture. Z namenom izboljšanja elastičnosti in poroznosti materiala smo k AUDju dodali različna zamreževala (MBAA in EGDMA) ter eksperimente izvedli v dušikovi atmosferi, saj prisotnost kisika v reakcijski zmesi lahko moti potek polimerizacije. Testirana zamreževala so izboljšala poroznost materiala, a so bili materiali precej bolj krhki, dušikova atmosfera pa je povzročila zgolj nastanek nehomogenih emulzij, ki niso dobro spolimerizirale. The graduation thesis shows attempts to synthesize a porous elastomer by means of photopolymerization. We wanted to synthesize an elastomer with good mechanical properties, because porous materials are usually brittle. As the monomer, we used an aliphatic urethane diacrylate (AUD, Sartomer CN 965), which was added into an emulsion with a high percentage of the internal phase. The emulsion was stirred for one hour in a flask immersed in thermostated water with a stirrer at 250 revolutions per minute. The resulting emulsion was poured into molds and polymerized in an UV oven, then the resulting product was purified in isopropanol and dried. Dried products were analyzed by means of a Scanning Electron Microscope and FTIR. In our experiments we varied the conditions, such as temperature and the proportion of internal phase, solvent, and surfactant. The results showed emulsion formation over a wide temperature range and at various portions of the internal phase, but the products shrunk significantly afer drying, became rigid and inelastic. Further analysis did not show a porous structure of the material in most casses. In order to improve the elasticity and porosity of the material we added different crosslinkers (MBAA and EGDMA) to our monomer and carried out some of our experiments in a nitrogen athmosphere, because the presence of oxygen in the reaction mixture can interfere with the course of polymerization. The tested crosslinkers improved porosity of the material, but the materials were more brittle. The usage of a nitrogen atmosphere resulted only in the formation of non-homogeneous emulsions that did not polymerize well.

Recent investigations have shown that modification of polymer matrix with filler and elastomers significantly affects composite's mechanical properties. Isotactic PP modified with either untreated or treated talc and either SEBS or SEBS-gMA were used in these investigations. Samples were prepared by melt-mixing in a Brabender kneading chamber and were compression molded into plates on a laboratory press. The composites were characterised by measuring mechanical properties (Young's modulus, yield stress, notched impact strength) and by defining morphology. Binary sistems PP/talc and PP/elastomer containing up to 16 vol.% of talc and up to 10 vol.% of elastomer, as well as ternary PP/talc/elastomer composites with 12 vol.% talc were investigated. Ternary composite's yield stress was also calculated by semiempirical equations. We have found out, that the use of treated modifiers (talc or elastomer) improves adhesion with matrix, which reflects on mechanical properties as better stress transfer. Novejše raziskave so pokazale, da lahko z modifikacijo polimerne matrike s polnilom in elastomerno fazo znatno vplivamo na mehanske lastnosti nastalega kompozita. V raziskavah smo uporabili izotaktični PP ter ga modificirali z neobdelanim oz. obdelanim talkom in SEBS oz. SEBS-gMA. Vzorce smo pripravili preko taline v Brabenderjevem gnetilniku in s stiskanjem v plošče na laboratorijski stiskalnici. Karakterizirali smo jih z merjenjem mehanskih lastnosti (Youngov modul, meja plastičnosti, zarezna udarna žilavost) in z opredelitvijo morfologije. Preučevali smo binarne sisteme PP/talk in PP/elastomer z vsebnostjo talka do 16 vol.% in do 10 vol.% elastomera, kakor tudi ternarne kompozite PP/talk/elastomer z 12 vol.% talka. Mejo plastičnosti ternarnih kompozitov smo določili še s polempiričnimi enačbami. Ugotovili smo, da uporaba obdelanih modifikatorjev (talka oz. elastomera) izboljša adhezijo z matriko, kar odseva na mehanskih lastnostih kot boljši prenos napetosti.

Promocijas darbā pētītas poliolefīnu – multifāzu kompozīcijas ar elastomēriem un šķērssaistīšanās promotoriem. Izvērtēta radiācijķīmiskās modificēšanas un lielas indukcijas magnētiskā lauka (B = 1,0-1,7 T) ietekme uz pētīto kompozītsistēmu stiprības-deformācijas, struktūras īpašībām, kā arī novērtēta magnētiskā lauka un jonizējošā starojuma mijiedarbības ietekme uz poliolefīnu makromolekulu šķērssaistīšanās efektivitāti. Iegūtas jaunas teorētiskas un praktiskas atziņas par radiācijķīmiski modificētu poliolefīnu multifāzu kompozīciju ekspluatācijas īpašībām, kas ļāva radīt jaunus uz polipropilēna bāzētus termonosēdmateriālus., Multiphase polyolefin compositions with elastomers and cross-linking promoters have been researched in the work. The influence of radiation-chemical modification and the high intensity magnetic field (B = 1.0-1.7 T) has been researched on the tensile and structure properties of the investigated composite systems, as well as the interaction effect of ionizing radiation and magnetic field on the polyolefin cross-linking efficiency has been investigated. New theoretical and practical scientific recognitions have been determined concerning the properties of radiation-chemically modified polyolefin multiphase compositions. That capacitated the development of new thermoshrinkable materials based on polypropylene.

Polazeći od filozofskih misli O. Spenglera i Aristotela, utvrđeno je da su polimeri prastari, jer sežu tamo do postanka osnovnih prirodnih organskih i anorganskih polimera. Istodobno je uočeno da se riječ polimeri učestalo upotrebljava kao zajedničko ime za plastiku i elastomere. Od osnovnih prirodnih organskih polimera: bjelančevina, nukleinskih kiselina i polisaharida dug je povijesni put. Taj se put pokušalo opisati dijagramom toka, tokovnikom. Za navedeni opis potrebne su brojne definicije, ali i motivacijska osnova. To je učinjeno u dodatcima A i B. Zaključak je istraživanja: praoblikovanje i prastrukturiranje prirodnih polimera staro je oko 3, 5 milijardi godina, a humana obradba razdvajanjem oko 3, 4 milijuna godina. Svatko tko se bavi polimerima trebao bi biti obrazovan na odgovarajućoj razini potrebnog znanja s razvijenim tokovnikom.

Polazeći od fi lozofskih misli O. Spenglera i Aristotela, utvrđeno je da su polimeri prastari, jer sežu tamo do postanka osnovnih prirodnih organskih i anorganskih polimera. Istodobno je uočeno da se riječ polimeri učestalo upotrebljava kao zajedničko ime za plastiku i elastomere. Od osnovnih prirodnih organskih polimera: bjelančevina, nukleinskih kiselina i polisaharida dug je povijesni put. Taj se put pokušalo opisati dijagramom toka, tokovnikom. Za navedeni opis potrebne su brojne defi nicije, ali i motivacijska osnova. To je učinjeno u dodatcima A i B. Zaključak je istraživanja: praoblikovanje i prastrukturiranje prirodnih polimera staro je oko 3,5 milijardi godina, a humana obradba razdvajanjem oko 3,4 milijuna godina. Svatko tko se bavi polimerima trebao bi biti obrazovan na odgovarajućoj razini potrebnog znanja s razvijenim tokovnikom., Based on the philosophic ideas of O. Spengler and Aristotle it has been determined that polymers are ancient since they reach back all the way to the origin of the basic natural organic and inorganic polymers. At the same time it has been noted that the word polymers is frequently used as a common name for plastics and elastomers. Since the basic natural organic polymers: proteins, nucleic acids, and polysaccharides there is a long historical path. An attempt was made to present this path by means of a fl ow chart. For the mentioned description numerous defi nitions are required, as well as a motivating basis. This was done in Annexes A and B. The conclusion of the research is that primary shaping and primary structuring of natural polymers is around 3.5 billion years old and human separation with natural tools about 3.4 million years. Anyone involved in polymers should be educated at an adequate level of the necessary knowledge with the developed fl owchart.

Dezinfekcija elastomernih materijala za otiske može prouzročiti njihove dimenzijske promjene. Na našoj se klinici kao dezinficijens najčešće upotrebljava 0,5% klorheksidin glukonat. Svrha rada bila je izmjeriti i usporediti linearne dimenzijske promjene koje nastaju u trima elastomerima nakon uranjanja u spomenuti dezinficijens. Radni kalup napravljen je prema ADA specifikaciji br.19. Testirani su Panasil (adicijski silikon), Blend-a-scon (kondenzacijski silikon) i Impregum (polieter). Uzorci su izloženi dezinficijensu, vodi i zraku u četiri razdoblja (10 min., 30 min., 60 min. i tijekom 24 sata). Linearne dimenzijske promjene izmjerene su bezkontaktnim digitalnim alatnim mikroskopom. Rezultati su pokazali najmanje dimenzijske promjene adicijskog silikona s tendencijom širenja. Kondenzacijski silikon skvrčio se unutar tolerantnoga raspona od 0,2 - 0,4%, prema DIN 13913, a polieter je znatno nabubrio. Može se zaključiti da testirani polieter nije prikladno dezinficirati uranjanjem u klorheksidin glukonat, a druga dva materijala pokazuju klinički prihvatljive linearne dimenzijske promjene unutar 24-satne imerzije., Disinfection of elastomeric impression materials used in prosthetic dentistry can cause dimensional changes in the impression materials. 0.5% chlorhexidine gluconate is usually used for disinfection of impressions at the School of Dental Medicine in Zagreb. The purpose of this study was to measure and compare linear dimensional changes of three elastomeric impression materials after their immersion in a certain disinfectant. The master dies were made according to the ADA specification no 19. The tested materials were Panasil (addition silicone), Blend-a-scon (condensation silicone) and Impregum F (polyether). Twelve samples were immersed in disinfectant, twelve in water and twelve left in the air for four different periods of time (10 min., 30 min., 60 min and 24 hours). Linear dimensional changes were measured by a non-contact digital tool microscope. The smallest changes were noticed in addition silicone with the least tendency to expansion. The condensation silicone contracted within a tolerant range of 0.2 - 0.4%, according to DIN 13913. Polyether expanded in the disinfectant significantly. Our results show that the tested polyether is not appropriate for disinfection by immersion in chlorhexidine gluconate, while the other two materials underwent 24-hour immersion with linear dimensional changes within a clinically acceptable range.