Curing Characteristics of Urethane-Dimethacrylate Homopolymers and Their Composites for Potential Application in Bone Cement

The polymerization of methacrylate compositions used in bone cement is often accompanied by a strong exothermic effect. The polymerizing mass heats up to very high temperatures at the cement application site, irritating the adjacent tissues and even cell death. On the other hand, a bone cement composition should have the optimal curing time, which should be long enough to allow for proper preparation of the cement and short enough to prevent leaking of the cement out of the restoration place. Therefore, new compositions are being sought to reduce the curing temperature of bone cement and maintain a sufficiently long curing time. Our proposal is based on using five homopolymers obtained by polymerizing urethane-dimethacrylates. These were composed of diisocyanate cores: toluene 2,4 diisocyanate (TDI), isophorone diisocyanate (IPDI), 4,4′-methylenebis(cyclohexyl isocyanate) (CHMDI), and di-, tri-, and tetraethylene glycol monomethacrylate wings (DEGMMA, TEGMMA, TTEGMMA, respectively). The following monomers were obtained: DEGMMA/CHMDI, TEGMMA/IPDI, TEGMMA/TDI, TEGMMA/CHMDI, and TTEGMMA/CHMDI. Neat homopolymers as well as their composites with barium sulfate and hydroxyapatite were tested for curing temperature and time. Almost all of the proposed systems were characterized by appropriate values of both parameters. The presence of fillers positively affected the studied parameters by lowering the polymerization temperature and time

Curing Characteristics of Urethane-Dimethacrylate Homopolymers and Their Composites for Potential Application in Bone Cement

The polymerization of methacrylate compositions used in bone cement is often accompanied by a strong exothermic effect. The polymerizing mass heats up to very high temperatures at the cement application site, irritating the adjacent tissues and even cell death. On the other hand, a bone cement composition should have the optimal curing time, which should be long enough to allow for proper preparation of the cement and short enough to prevent leaking of the cement out of the restoration place. Therefore, new compositions are being sought to reduce the curing temperature of bone cement and maintain a sufficiently long curing time. Our proposal is based on using five homopolymers obtained by polymerizing urethane-dimethacrylates. These were composed of diisocyanate cores: toluene 2,4 diisocyanate (TDI), isophorone diisocyanate (IPDI), 4,4′-methylenebis(cyclohexyl isocyanate) (CHMDI), and di-, tri-, and tetraethylene glycol monomethacrylate wings (DEGMMA, TEGMMA, TTEGMMA, respectively). The following monomers were obtained: DEGMMA/CHMDI, TEGMMA/IPDI, TEGMMA/TDI, TEGMMA/CHMDI, and TTEGMMA/CHMDI. Neat homopolymers as well as their composites with barium sulfate and hydroxyapatite were tested for curing temperature and time. Almost all of the proposed systems were characterized by appropriate values of both parameters. The presence of fillers positively affected the studied parameters by lowering the polymerization temperature and time

Physicochemical Properties of Novel Copolymers of Quaternary Ammonium UDMA Analogues, Bis-GMA, and TEGDMA

This study aimed to elucidate the physicochemical properties of copolymers comprising 40 wt.% bisphenol A glycerolate dimethacrylate (Bis-GMA), 40 wt.% quaternary ammonium urethane-dimethacrylate analogues (QAUDMA-m, where m corresponds to the number of carbon atoms in the N-alkyl substituent), and 20 wt.% triethylene glycol dimethacrylate (TEGDMA) copolymers (BG:QAm:TEGs). The BG:QAm:TEG liquid monomer compositions and reference compositions (40 wt.% Bis-GMA, 40 wt.% urethane-dimethacrylate (UDMA), 20 wt.% TEGDMA (BG:UD:TEG) and 60 wt.% Bis-GMA, 40 wt.% TEGDMA (BG:TEG)) were characterized in terms of their refractive index (RI) and monomer glass transition temperature (Tgm) and then photocured. The resulting copolymers were characterized in terms of the polymer glass transition temperature (Tgp), experimental polymerization shrinkage (Se), water contact angle (WCA), water sorption (WS), and water solubility (SL). The prepared BG:QAm:TEG liquid monomer compositions had RI in the range 1.4997–1.5129, and Tgm in the range −52.22 to −42.12 °C. The BG:QAm:TEG copolymers had Tgp ranging from 42.21 to 50.81 °C, Se ranging from 5.08 to 6.40%, WCA ranging from 81.41 to 99.53°, WS ranging from 25.94 to 68.27 µg/mm3, and SL ranging from 5.15 to 5.58 µg/mm3. Almost all of the developed BG:QAm:TEGs fulfilled the requirements for dental materials (except BG:QA8:TEG and BG:QA10:TEG, whose WS values exceeded the 40 µg/mm3 limit)

Characterization of the Mechanical Properties, Water Sorption, and Solubility of Antibacterial Copolymers of Quaternary Ammonium Urethane-Dimethacrylates and Triethylene Glycol Dimethacrylate

The use of dental composites based on dimethacrylates that have quaternary ammonium groups is a promising solution in the field of antibacterial restorative materials. This study aimed to investigate the mechanical properties and behaviors in aqueous environments of a series of six copolymers (QA:TEG) comprising 60 wt.% quaternary ammonium urethane-dimethacrylate (QAUDMA) and 40 wt.% triethylene glycol dimethacrylate (TEGDMA); these copolymers are analogous to a common dental copolymer (BG:TEG), which comprises 60 wt.% bisphenol A glycerolate dimethacrylate (Bis-GMA) and 40 wt.% TEGDMA. Hardness (HB), flexural strength (FS), flexural modulus (E), water sorption (WS), and water solubility (SL) were assessed for this purpose. The pilot study of these copolymers showed that they have high antibacterial activity and good physicochemical properties. This paper revealed that QA:TEGs cannot replace BG:TEG due to their insufficient mechanical properties and poor behavior in water. However, the results can help to explain how QAUDMA-based materials work, and how their composition should be manipulated to produce the best performance. It was found that the longer the N-alkyl chain, the lower the HB, WS, and SL. The FS and E increased with the lengthening of the N-alkyl chain from eight to ten carbon atoms. Its further extension, to eighteen carbon atoms, caused a decrease in those parameters

Chosen aspects of safety of maritime transport in the Baltic Sea Basin

Gospodarka morska jest w szczególny sposób narażona na niebezpieczeństwo ze względu na środowisko swojej działalności. Zagrożenia te wynikają zarówno z działań umyślnych, jak i przypadkowych (warunki hydrometeorologiczne, mechaniczne itp.). Są to zagrożenia zależne i niezależne od człowieka np. środowiskowe, bezpieczeństwo zdrowia i życia ludzi, czy mienia. Pomimo podejmowania prób ograniczania ryzyka niebezpieczeństwa, niemożliwe jest jego całkowite wyeliminowanie. Pomocne mogą być wszelkiego rodzaju systemy bezpieczeństwa, alarmowe, ratunkowe, oraz działania legislacyjne i edukacyjne armatorów i załóg statków do działań obronnych. W artykule przedstawiono wybrane aspekty bezpieczeństwa transportu w basenie morza Bałtyckiego oraz podjęto próbę analizy stanu bezpieczeństwa na tym akwenie.The maritime economy is particularly exposed to danger due to the environment of its operations. These risks result from deliberate actions, as well as incidental (hydrometeorological conditions, mechanical, etc.). These are the threat dependent and independent of human eg. environmental, safety health and life of humans or belongings. In spite of attempts to limit the risk of danger, it is impossible to completely eliminate it. May be helpful here all kinds of security systems, alarm, emergency, legislative and educational of ship owners and crews to the defense activities. The article presents some aspects of the state of transportation safety in the Baltic Sea Basin as well as undertaken the attempt to analyze the security state of this sea area

The State of Road Transport Safety in Poland and Slovakia in 2004-2014

W artykule dokonano analizy porównawczej stanu bezpieczeństwa w ruchu drogowym w Polsce i na Słowacji na przestrzeni ostatnich dziesięciu lat. Analizę uzupełniono o prezentację danych odnośnie do programów i działań na rzecz poprawy bezpieczeństwa realizowanych w obu państwach. W pracy ukazano różnice w skuteczności prowadzonych działań i dokonano próby wyjaśnienia przyczyn ich występowania.In the article is performed the comparative analysis of the state of road safety in Poland and Slovakia over the past ten years. The analysis was complemented by a presentation of data concerning the programs and activities aimed at improving safety implemented in both countries. In the paper are the differences in the effectiveness of their actions were made the attempts to explain the reasons for their occurrence