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Aluminijum oksidna (Al2O3) nanovlakna pripremljena su iz vodenog rastvora aluminijum hlorohidrata/poli(vinil alkohola) (PVA) korišćenjem tehnike elektropredenja. Maseni odnos aluminijum hlorohidrata/PVA bio je 5:1. Nakon kalcinacije vlakana na 1100 °C, dobijena su kratka aluminijum oksidna vlakna prečnika od 200 do 800 nm. Morfologija vlakana je karakterisana pomoću skenirajućeg elektronskog mikroskopa sa emisijom polja (FE-SEM). Softver za analizu slike Image ProPlus korišćen je za merenje prečnika dobijenih Al2O3 vlakana. Cilj ovog rada bio je ispitivanje mehaničkih svojstava hibridnog kompozita, koji se sastoji od polimerne matrice (kopolimer etilena i vinil-acetata (EVA)), polietilenskih vlakana ultra-visoke molarne mase (UHMWPE) i Al2O3 vlakana dobijenih elektropredenjem. Al2O3 vlakna su dodavana u količini od 1 mas. % što je pokazalo poboljšanje mehaničkih svojstava matrice i hibridnog kompozita., Alumina (Al2O3) nano fibers are prepared from an aqueous solution of aluminum hydroxy chloride/poly (vinyl alcohol) (PVA)/water using the electrospinning technique. The weight ratio of aluminum hydroxy chloride/PVA was 5: 1. After calcification of fibers at 1100 ° C, continuous aluminum oxide fibers were obtained from 200 to 800 nm. The fiber morphology is characterized by a scanning electron microscope (SEM). Image analysis software (Image Pro Plus) was used to measure the diameter of the obtained aluminum oxide (Al2O3) fibers. The aim of this paper is to examine the mechanical properties of the hybrid composite, consisting of a polymer matrix (ethylene and vinyl acetate copolymer (EVA)), ultrahigh molecular weight polyethylene fibers (UHMWPE) and Al2O3 fibers obtained by electrospinning. Al2O3 fibers were added in an amount of 1 wt. % as shown by the improvement of the mechanical properties of the matrix and the hybrid composite.

Dental materials have specific requirements regarding behavior in exploitation conditions. Poly (methyl methacrylate) (PMMA) is one of the most commonly used prosthetic materials. It is of interest to improve the mechanical properties of the polymer matrix by adding reinforcements in the form of ceramic particles. It has been shown that adding very small amounts of particles to the material, substantially improved mechanical properties of PMMA modified by dimethyl itaconate (PMMA/DMI). In this paper, different sorts of alumina fillers will be examined. Commercial alumina particles and micro particles of alumina obtained from the sol-gel technique influence the mechanical properties of the composite material obtained. Sol-gel techniques was the mean to synthesize pure alumina particles and ferrous oxide doped alumina particles. Composites are prepared with 1 wt. %, 3 wt. % and 5 wt. % of alumina based particles. It has been shown that all the tested fillers improve the flexular properties of the material relative to the pure matrix PMMA/DMI and the most suitable concentration of fillers was 1 wt. %. Among the types of fillers tested alumina particles obtained by sol-gel technique, perfomed in the best way in improving the flexural strength and modulus., Dentalni materijali imaju posebne zahteve u vezi sa ponašanjem u uslovima eksploatacije. Poli(metil metakrilat) (PMMA) predstavlja jedan od često korišćenih materijala u protetici. Od značajnog je interesa da se poboljšaju mehanička svojstva polimerne matrice dodatkom ojačanja u obliku keramičkih čestica. Pokazalo se da se dodavanjem veoma malih količina čestica u materijal dobijaju bitno poboljšana mehanička svojstva PMMA modifikovanog dodatkom dimetil itakonata (PMMMA/DMI). U okviru ovog rada ispitaće se kako utiče dodatak komercijalnih nanočestica aluminijum oksida i mikro čestica aluminijum oksida dobijenih sol-gel tehnikom na mehanička svojstva dobijenog kompozitnog materijala. Sol-gel tehnikom sintetisane su čiste aluminijum oksidne čestice i čestice dopirane gvožđe oksidom. Pripremeljeni su kompozitni materijali sa 1 mas. %, 3 mas. % i 5 mas. % čestica na bazi aluminijum oksida. Pokazano je da svi testirani punioci poboljšavaju savojna svojstva materijala u odnosu na čistu matricu PMMA/DMI i da je najpogodnija količina čestica 1 mas. %. Između svih vrsta dodatih čestica, mikro čestice aluminijum oksida dobijenih sol-gel tehnikom su pokazale najbolje vrednosti poboljšanja savojne čvrstoće i modula.

The subject of this study is the quantitative adhesion of a UV-curing composite film based on Bis-GMA (Bisphenol A glycidylmethacrylate) / TEGDMA (triethylene glycol dimethacrylate) as a matrix and particles doped with ferrous oxide on a metal substrate. Two different metal substrates: silver and gold-spattered brass with nickel intermediate coating were used in adhesion evaluating. Adhesion was measured using micro-identation and it was compared with the measured wetting angle of composites to the substrate. It has been shown that the substrates, although with similar mechanical properties that are reflected in very close hardness values, differ by achieved adhesive bonding with the polymer UV-cured polymer film. The addition of ceramic particles in the polymer matrix increased the adhesion of the composite film to both substrates, but the adhesion trend was dependent on the substrate type., Predmet ovog istraživanja je kvantitativna procena adhezije između fotopolimerizujućeg kompozitnog filma na bazi Bis-GMA (Bisfenol A glicidilmetakrilata)/TEGDMA (trietilen glikol dimetakrilata) kao matrice i čestica na bazi aluminijum oksida dopiranih gvožđem na metalnoj podlozi. Korišćene su dve različite metalne podloge, jedna od srebra (u daljem tekstu 'srebro') i jedna pozlaćena mesingana pločica sa međuprevlakom od nikla (u daljem tekstu 'zlato'). Adhezija je merena korišćenjem mikroindentacije i upoređena je sa izmerenim uglom kvašenja kompozita na datim podlogama. Pokazalo se da se podloge, iako sličnih mehaničkih svojstava koje se ogledaju u veoma bliskim vrednostima tvrdoće, razlikuju po ostvarenoj adhezivnoj vezi sa polimernim fotopolimerizujućim filmom. Dodatak keramičkih čestica u polimernu matricu dodatno je povećao adheziju kompozitnog filma na obe podloge, dok je trend adhezije u zavisnosti od tipa podloge održan.

Polymer matrix composite materials have found application in dentistry because of good mechanical properties, aesthetic, easy processing, and possibilities of the repair. Acrylates are materials used to make and repair dentures. Reinforcements in the form of short glass or polymer fibers are added to improve the mechanical properties of dental polymers. In this study, the processing of composite material with a polymer matrix from commercial auto-polymerized acrylate Simgal, with reinforcement in the form of short poly(ethylene terephthalate) (PET) fibers was examined. Samples were processed in three series: pure Simgal, Simgal/PET 1 wt% and Simgal/PET 3 wt%. The influence of the reinforcement in the form of short PET fibers on the mechanical properties of composite materials was investigated. Strength and hardness were tested by impact testing and Vickers microhardness, and it was shown that there is an increase in absorbed energy and hardness. The modulus was reduced by the addition of PET fibers and by increasing the amount of fibers in the composite. The increase in the amount of PET fibers also resulted in a smaller loss of surface mass of the samples compared to the pure matrix by 63% and 93%, respectively. Cavitation test revealed better cavitation resistance of composites than the pure acrylate.

As a renewable resource, starch is considered to be fully biodegradable and nonpolluting to the environment but the hygroscopicity of starch is the main disadvantage for wider applicability in the production of a polymer-based material. Hydrophobically modified starch prepared using natural-based plasticizers/modifiers in a first step ([-]-diisopropyl D-tartrate [DiPT], ricinoleic acid [RA] and epoxidized soybean oil [ESO]), and maleated polypropylene (MAPP) in a second step contributed to better compatibility, and thus reinforcing of composites. Tailored processing conditions, structural/morphological properties, hydrophobicity, and water-resistance of the modified starch were established. In addition, the Charpy impact and tensile strength of composites, based on poly(ethylene-co-acrylic acid) (EAA) and modified starches, were determined. Increased tensile strength and Young modulus of the composite using starch-modified with DiPT-MAPP, that is, 3 and 83%, respectively, indicated the possible applicability of obtained materials.

As a renewable resource, starch is considered to be fully biodegradable and nonpolluting to the environment but the hygroscopicity of starch is the main disadvantage for wider applicability in the production of a polymer-based material. Hydrophobically modified starch prepared using natural-based plasticizers/modifiers in a first step ([-]-diisopropyl D-tartrate [DiPT], ricinoleic acid [RA] and epoxidized soybean oil [ESO]), and maleated polypropylene (MAPP) in a second step contributed to better compatibility, and thus reinforcing of composites. Tailored processing conditions, structural/morphological properties, hydrophobicity, and water-resistance of the modified starch were established. In addition, the Charpy impact and tensile strength of composites, based on poly(ethylene-co-acrylic acid) (EAA) and modified starches, were determined. Increased tensile strength and Young modulus of the composite using starch-modified with DiPT-MAPP, that is, 3 and 83%, respectively, indicated the possible applicability of obtained materials.