Papers by Keyword: Monomers

Abstract: This study investigated the impact of various reactive diluents on viscosity of uncured mixture at 50 °C over a 12-week period. This criterion is important to predict the shelf life of uncured composition. Studied mono-functional acrylate monomers were: hydroxypropyl methacrylate (HPMA), hydroxyethyl methacrylate (HEMA), tetrahydrofurfuryl acrylate (THFA), isobornyl methacrylate (IBOMA), isobornyl acrylate (IBOA), 2-(2-Ethoxyethoxy)ethyl acrylate (EOEOEA), acryloyl morpholine (ACMO), glacial methacrylic acid (GMAA) and phosphate acrylate monomer (PAM); and various solvents: isopropanol(IP) ethyl acetate (EA), butyl acetate (BA). There was found the difference of effect on the systems viscosity in time between the mono-functional monomers and solvents. HPMA and IPA showed the most stable viscosity values in time.

Abstract: Thin film coatings on fingernails and toenails are used for aesthetic reasons or to strengthen fragile nails. Coating disintegration is one of the most important characteristics of short-term coatings. The aim of this research was to investigate adhesion test methods for UV-cured urethane acrylate coatings. Coatings was compared evaluating gel fraction and degree of conversion of C=C bonds. Adhesion was measured using pull-off adhesion test and coating removability was evaluated after coating soak-off in solvent media with cross-cut tester. Systems with four different monomers in two concentrations was evaluated. All systems show a strong correlation of adhesion with the time of disintegration.

Abstract: In order to provide good adhesion for natural nail coatings and to avoid loss of adhesion between the substrate and the coating, the mechanical properties of the coating should be close to those of the substrate. Three different mono-functional monomers (HPMA, THFA, THFMA) and one bi-functional monomer (EGDMA) have been added to decrease the viscosity of un-polymerized composition. Optimal monomer concentration was found evaluating monomer concentration effect on viscosity. Polymerized coatings were tested with monomer concentrations of 30% and 40%. The tensile strength properties of the polymerized coatings were determined 24 hours after polymerization. Polymerization T and conversion rate of unsaturated links were also studied to find the best monomer for natural nail coatings.

Abstract: Background: The most frequently used monomer in commercial composite resins is bisphenol A glycidyl dimethacrylate. Bisphenol A glycidyl dimethacrylate free monomer and the long chain dimer acid based monomer were considered as an alternative method to improve mechanical and physical properties of composite resins. Objective: To study the surface roughness of different nanohybrid composites with different monomer compositions after finishing and polishing with different polishing systems. Materials and Methods: 72 composite disk specimens were prepared and divided into 3 groups (n=24) according to the resin composite that were used (harmonize kerr, venus diamond heraeus kulzer and n'durance septodont). Each group was subdivided into 4 subgroups (n=6) according to the polishing technique that was used (Jiffy natural universal wheels ultradent, sof-lex spiral wheels 3m espe, hiluster kerr or enhance system dentsply). Atomic force microscope was used to measure surface roughness. Results: There was statistical significant difference in surface roughness measuring among different n'durance, venus diamond and harmonize groups (Kruskal Wallis Test p<0.05). Post hock pairwise comparison revealed that venus diamond showed statistically significant higher surface roughness when compared with either n'durance and harmonize. Among the polishing systems, jiffy natural universal wheels produce the least surface roughness. Conclusion: Different monomer compositions may have direct effect on the final surface polish of the restorative materials. Clinical significance: The use of jiffy natural universal wheels may be found to result in the smoothest surface finish with the least clinical steps.

Abstract: The monomer of 2,3-di (thiophen-2-yl) quinoxaline (M1) and 2,3-di (thiophen-2-yl) 1,4-pyradiazine (M2) have been synthesized in moderate yields over two steps from readily available starting materials. The π-conjugated Polymer based on 2,3-di (thiophen-2-yl) quinoxaline was synthesized by Electrochemical workstation which was carried out in DCM/ Bu₄NBF₄ (0.1M) as the solvent/electrolyte couple. The new π-conjugated Polymer can slightly soluble in organic solvents such as methylene chloride and acetonitrile.

Abstract: Gas permselective packaging film is an emerging material which enables it with gas selective permeation functions so as to keep the preservation atmosphere of inner packages and thus extends the shelf-life of fresh fruits. In this work, Hexamethyldisilazane and Hexamethyldisiloxane were applied as the precursors to comparatively investigate the behavior on the preparation of gas permselectivy film, respectively. Also, Different reaction parameters such as plasma input power, deposition time and monomer proportions were investigated respectively. The film properties were analyzed by Water Contact Anglemeter, Surface Profiler thickness test, Fourier Transform Infrared Spectroscopy (FTIR), water vapor transmission rate test (WVTR) and oxygen transmission rate test (OTR). The results showed that HMDS is better than HMDSO to be the precursor for the formation of gas permselectivity films.The film formed from the monomer of HMDS changed the gas permeability of the film reversely which is more suitable for the preparation of such materials.

Abstract: In order to improve the value-added applications of low-quality wood, a novel Wood-Polymer Composite was fabricated by in-situ synthesis of copolymer from monomers within wood porous structure. The structure was characterized with SEM and FTIR, and its dimensional stability was also tested. The SEM observations showed that copolymer filled up wood pores and contact tightly with wood matrix, indicating strong interactions between them. FTIR analysis indicated that when the monomers copolymerized in situ wood porous structure, they also reacted with wood matrix by reaction of hydroxyl groups and ester groups, indicating chemical bond between the two phases, which is agreement with SEM observations. The volume swelling efficiency and contact angle of such composite were higher than those of wood, respectively, indicating good dimensional stability involving volume swelling efficiency and contact angle. Such composite could be potentially applied in fields of construction, traffic and indoor decoration.