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Статті в журналах з теми "Photoinitiator system"
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Kowalska, Andrea, Jerzy Sokolowski, and Kinga Bociong. "The Photoinitiators Used in Resin Based Dental Composite—A Review and Future Perspectives." Polymers 13, no. 3 (February 2, 2021): 470. http://dx.doi.org/10.3390/polym13030470.
Повний текст джерелаАнотація:
The presented paper concerns current knowledge of commercial and alternative photoinitiator systems used in dentistry. It discusses alternative and commercial photoinitiators and focuses on mechanisms of polymerization process, in vitro measurement methods and factors influencing the degree of conversion and hardness of dental resins. PubMed, Academia.edu, Google Scholar, Elsevier, ResearchGate and Mendeley, analysis from 1985 to 2020 were searched electronically with appropriate keywords. Over 60 articles were chosen based on relevance to this review. Dental light-cured composites are the most common filling used in dentistry, but every photoinitiator system requires proper light-curing system with suitable spectrum of light. Alternation of photoinitiator might cause changing the values of biomechanical properties such as: degree of conversion, hardness, biocompatibility. This review contains comparison of biomechanical properties of dental composites including different photosensitizers among other: camphorquinone, phenanthrenequinone, benzophenone and 1-phenyl-1,2 propanedione, trimethylbenzoyl-diphenylphosphine oxide, benzoyl peroxide. The major aim of this article was to point out alternative photoinitiators which would compensate the disadvantages of camphorquinone such as: yellow staining or poor biocompatibility and also would have mechanical properties as satisfactory as camphorquinone. Research showed there is not an adequate photoinitiator which can be as sufficient as camphorquinone (CQ), but alternative photosensitizers like: benzoyl germanium or novel acylphosphine oxide photoinitiators used synergistically with CQ are able to improve aesthetic properties and degree of conversion of dental resin.
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Hilborn, J., and B. Rånaby. "Photocrosslinking of EPDM Elastomers. Photocrosslinkable Compositions." Rubber Chemistry and Technology 62, no. 4 (September 1, 1989): 592–608. http://dx.doi.org/10.5254/1.3536262.
Повний текст джерелаАнотація:
Abstract EFDM rubbers can be efficiently crosslinked using multifunctional monomers. Several factors must be taken into consideration: 1. Good solubility of the crosslinking agent in the rubber is essential. 2. It is favorable to have a mechanism of crosslinking which gives an alternating addition of rubber and crosslinking agent, as in the case of the stepwise radical thiol-ene system or alternating copolymerization of bis-maleimide with the olefinic rubber. These systems utilize each radical of the photoinitiator to form crosslinks, enhance the rate of crosslinking and prevent homopolymerization of the crosslinking agent. 3. A good match of the UV absorption of the photoinitiator, the UV transmission of the rest of the system, and the UV emission from the lamp is essential. 4. Since disproportionation of photoinitiator radicals in cage is an unwanted side reaction in the rigid rubber system, it is better to choose photoinitiators that mainly recombine to reform a photoactive molecule as before scission.
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Ayub, Nur Farizah, Shahrir Hashim, Jamarosliza Jamaluddin, Roshafima Rasit Ali, and Nadia Adrus. "UV LED Curing Formulation for Polyacrylamide Hydrogels." Advanced Materials Research 1125 (October 2015): 84–88. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.84.
Повний текст джерелаАнотація:
Current studies showed that UV LED system is a green technology and highly efficient as compared to UV Mercury (UV Hg) system. In this study, the UV LED curing formulations of polyacrylamide (PAAm) hydrogels were developed. The formulations consisted of acrylamide (AAm) as a main monomer,N,N’-methylenebisacrylamide as a crosslinker and photoinitiator. UV LED emits monochromatic light sources only (365 nm or 385 nm). Thus, in order to developed formulation of UV LED curable hydrogels, a suitable water soluble photoinitiator (i.e. λ ~ 365 nm) has to be employed. A commercially available photoinitiator Oligo [2-hydroxy-2-methyl-1-[4-(1-methylvinyl) phenyl] propanone] under the trade name Chivacure 300 (λ ~ 330 nm) was chosen in the first formulations. However, due to limited solubility in water, addition of tetrahydrofuran (THF) at 9.5:0.5 ratio of water/THF was required for Chivacure 300. We also synthesized a photoinitiator based on 2,2-dimethoxy-2-phenyl acetophenone (DMPA) and methylated-β-cyclodextrin (MβCD) to be used in the second formulation. The complexation of DMPA and MβCD resulted in transparent and water-soluble supramolecular-structured photoinitiator (SSPI) (λ ~ 330 nm). Both formulations were irradiated using UV LED system (Hoenle AG, Germany, 365 nm) for 15 min. Synthesis of PAAm hydrogels with both photoinitiators has yielded almost complete conversion of hydrogels (> 80 %). Clearly, this study has revealed that enhanced formulation of UV LED curable hydrogels are due to appropriate choice of excellent water-solubility photoinitiators (Chivacure 300 and modified DMPA). We concluded that UV LED is an important tool for curing hydrogel formulations of various acrylate water-based monomers.
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Chen, Lijuan, Fan Chen, Weixin Zhu, Luoyi Chen, Yingyu Liang, and Xiaohui Guo. "Construction of Photoinitiator Functionalized Spherical Nanoparticles Enabling Favorable Photoinitiating Activity and Migration Resistance for 3D Printing." Polymers 14, no. 21 (October 27, 2022): 4551. http://dx.doi.org/10.3390/polym14214551.
Повний текст джерелаАнотація:
A straight-forward method was exploited to construct a multifunctional hybrid photoinitiator by supporting 2-hydroxy-2-methylpropiophenone (HMPP) onto a nano-silica surface through a chemical reaction between silica and HMPP by using (3-isocyanatopropyl)-triethoxysilane (IPTS) as a bridge, and this was noted as silica-s-HMPP. The novel hybrid-photoinitiator can not only initiate the photopolymerization but also prominently improve the dispersion of nanoparticles in the polyurethane acrylate matrix and enhance the filler-elastomer interfacial interaction, which results in excellent mechanical properties of UV-cured nanocomposites. Furthermore, the amount of extractable residual photoinitiators in the UV-cured system of silica-s-HPMM shows a significant decrease compared with the original HPMM system. Since endowing the silica nanoparticle with photo-initiated performance and fairly lower mobility, it may lead to a reduction in environmental contamination compared to traditional photoinitators. In addition, the hybrid-photoinitiator gives rise to an accurate resolution object with a complex construction and favorable surface morphology, indicating that multifunctional nanosilica particles can be applied in stereolithographic 3D printing.
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Xu, Rui Xin, and Guang Xue Chen. "Study on Photopolymerization Performance of Waterborne UV Cured Ink." Advanced Materials Research 174 (December 2010): 401–4. http://dx.doi.org/10.4028/www.scientific.net/amr.174.401.
Повний текст джерелаАнотація:
The anion UV-curing water soluble prepolymer was synthesized with toluene diisocyanate, dihydroxy compound, dihydroxyalkyl carboxylic acid and polyurethane acrylate. The structure of the prepolymer was characterized by infrared spectroscopy. The effect of different photoinitiators, pigment content, drying technology on the curing speed of ink was also researched. The results shown that the photoinitiator system 819DW and MBF was best matched with the yellow pigment, cyan pigment and black pigment, the optimum content of the pigment was about 10 percent, 10 percent and 11 percent. The photoinitiator system 819DW and 500 was best matched with the magenta pigment, the optimum content of the pigment was about 10 percent．Under the conditions of this experiment, the best pigment content of the yellow, magenta, cyan, black was about 6 percent, 7 percent, 6 percent and 7 percent. The curing rate without pre-drying increased.
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Santini, Ario, Iranzihuatl Torres Gallegos, and Christopher M. Felix. "Photoinitiators in Dentistry: A Review." Primary Dental Journal 2, no. 4 (December 2013): 30–33. http://dx.doi.org/10.1308/205016814809859563.
Повний текст джерелаАнотація:
Polymerization of Resin Based Composites (RBCs) initiated by a light curing unit activating photoinitiators. Different RBCs require different light energy levels for proper curing. Manufacturers are now producing RBCs with more than one initiator and not all of these will be properly polymerised with blue LED lights. An added problem is that manufacturers do not always indicate the type of photoinitiators in their materials. This review discusses the importance of matching the spectral output of LCUs to the absorption spectra of RBCs and the consequences of spectral mismatch. Resin based composites (RBCs) were first introduced in the 1960s1 and with development of effective and reliable dentine bonding systems2, have been used routinely as a filling material for both anterior and posterior teeth. The early RBCs were either chemically cured two component materials or photo-initiated materials that used UV initiators in the beginning and then transitioned to visible light initiators such as camphorquinine which was introduced in 1978.3 The first report of a light curing material was of an ultraviolet (UV) cured fissure sealant.4 However, due to the limited penetration depth of the UV light and the potential health hazards, this system was quickly abandoned. The advancement of science yielded light curing materials which contributed to a significant clinical progress over the UV and chemically cured RBCs.4 Additional advancements to direct RBC restoration materials included luting agents for ceramic restorations, pit and fissure sealants and resin modified glass ionomers. Polymerization in an RBC is initiated by a light curing unit (LCU); this technology is based on the use of photoreactive systems that absorb light irradiation from the LCUs at appropriate wavelength. Then the photoinitiators contained in the RBCs, absorb the incoming photons from the LCU and the monomers in the molecular structure become excited and in that active state, there is a change from monomers into a polymer network6. The success of this technology hinges on matching the spectral emission of the LCU with the requirements of the photoinitiator system to convert the monomers into a polymer network. The amount of activated photo initiator depends on the concentration of photoinitiator in the material, the number of photons to which the material is exposed and the energy of the photons (wavelength), the latter depending on the curing light.6 The most common photoinitiator in dental materials today is camphorquinone, which has a peak activity around 470 nanometres.6 The factors affecting polymerization include filler type, size and loading, the thickness and shade of the restorative material, the effectiveness of light transmission (eg. light guide tips being free from debris and scratches), exposure time, distance of the light source from the restorative material and light intensity.7 It is important to note that the photoinitiator activation occurs at specific wavelengths, in other words, the optimum efficiency is obtained when the peak absorptivity of the photoinitiator corresponds with the spectral emission from the LCU. Commercially available curing units have different light intensities and light sources, with energy levels in QTH, LED and other LCUs ranging from 300 to more than 2000 mW/cm.
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Gómez, María L., Carlos M. Previtali, and Hernán A. Montejano. "Two- and Three-Component Visible Light Photoinitiating Systems for Radical Polymerization Based on Onium Salts: An Overview of Mechanistic and Laser Flash Photolysis Studies." International Journal of Photoenergy 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/260728.
Повний текст джерелаАнотація:
A review of our work on two- and-three component photoinitiator systems is presented. The emphasis is in on visible light polymerization in aqueous media. The systems discussed comprise a synthetic dye as sensitizer and an onium salt as coinitiator, or a dye-amine-onium salt with the amine as coinitiator and the onium salt as an enhancer of the polymerization efficiency. The effect of the composition of the system on the photopolymerization kinetics was analyzed. To this end, the photophysics and photochemistry of the dye under polymerization conditions was explored by means of stationary and time-resolved spectroscopic methods. Different dyes and onium salts were investigated. The action mechanism of the different photoinitiators systems is discussed.
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Righi, Helouise, Ana Rosa Costa, Dayane Carvalho Ramos Salles de Oliveira, Gabriel Flores Abuna, Mario Alexandre Coelho Sinhoreti, and Fabiana Scarparo Naufel. "Influence of Photoinitiator on Accelerated Artificial Aging and Bond Strength of Experimental Resin Cements." Brazilian Dental Journal 29, no. 1 (February 2018): 82–87. http://dx.doi.org/10.1590/0103-6440201801591.
Повний текст джерелаАнотація:
Abstract The goal of this study was to evaluate in vitro the effect of the photoinitiator phenylpropanedione (PPD), alone or combined with camphorquinone (CQ), on color stability of photoactivated resin cements and their bond strength to ceramics using a micro-shear test. Four resin cements were used: a commercial brand cement (RelyX Veneer®) and 3 experimental cements with different types and concentration of photoinitiators. For color analysis, ceramic discs were cemented on bovine dentin specimens to simulate indirect restorations (n=8) and were exposed to UV for 120 h and tested for color alteration using a reflectance spectrophotometer and the CIEL*a*b* system. Data were analyzed by Anova and Tukey’s test at 5% significance level. The color test results did not present statistically significant difference for the ∆E for all the studied cements, neither for ∆L, ∆a and ∆b. For the bond strength, all the studied cements showed statistically significant differences to each other, with the highest result for the RelyX Veneer® (29.07 MPa) cement, followed by the cement with CQ (21.74 MPa) and CQ+PPD (19.09 MPa) cement; the lowest result was obtained by the cement using only PPD as a photoinitiator (13.99 MPa). So, based on the studied parameters, PPD was not advantageous as photoinitiator of resin cements, because it showed a low value of bond strength to the ceramics and no superior color stability.
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Venter, Sandro Aurélio de Souza, Gedalias Custódio Martim, Andressa Dos Santos, Tiago Roerto Detomini, Eduardo Radovanovic, and Emerson Marcelo Girotto. "Effect of the photoinitiator system on the properties of a dental material based on a hybrid polymer." Brazilian Dental Science 19, no. 1 (March 14, 2016): 96. http://dx.doi.org/10.14295/bds.2016.v19i1.1233.
Повний текст джерелаАнотація:
<p><strong>Objective:</strong> In this study, the effects of two different cure protocols upon the properties of composites using a hybrid-polymer as dental resin were evaluated. <strong>Material and Methods:</strong> Two distinct dental composites were prepared, one containing a mixture of TEGDMA/bis-GMA (50:50) and, another containing a mixture of TEGDMA/p-MEMO (50:50), [p-MEMO: oligomeric inorganic precursor]. Both composites were polymerized with lucirin and canphorquinone as photoinitiators. The composites were made with a 70 % wt of inorganic filler. Flexural strength was evaluated with a universal test machine and the degree of conversion was measured by infrared spectroscopy. A helium pycnometer was used to obtain polymer shrinkage data. Sorption tests were performed and SEM microscopy was used to show deleterious effects upon the resins’ surfaces. <strong>Results:</strong> The sample base on TEGDMA/p-MEMO polymerized with lucirin (L-T/p) showed the best values of the monitored properties. <strong>Conclusion</strong>: Lucirin is the most suitable photoinitiator for dental composites containing hybrid polymers.</p><p><strong>Keywords</strong></p><p><strong></strong>Dental resins; Flexural strength; Hybrid polymer; Photoinitiator system; Polymerization shrinkage.</p>
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Bertolo, Marcus Vinicius Loureiro, Rita de Cássia Martins Moraes, Carmem Pfeifer, Vinícius Esteves Salgado, Ana Rosa Costa Correr, and Luis Felipe J. Schneider. "Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites." Brazilian Dental Journal 28, no. 1 (February 2017): 35–39. http://dx.doi.org/10.1590/0103-6440201700841.
Повний текст джерелаАнотація:
Abstract The aim of this study was to determine the influence of photoinitiator systems on physical-chemical properties of flowable composites. Conventional (CFC), composed by bisphenol-glycidyl dimethacrylate (BisGMA)+triethyleneglycol dimethacrylate (TEGDMA), and self-adhesive (SAFC), composed by BisGMA+TEDGMA+bis{2-(methacryloyloxy) ethyl} phosphate (2MP), flowable composites were developed. Five photoinitiator systems were tested: camphorquinone (CQ), ethyl-4-dimethylaminobenzoate (EDMAB), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis (2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), CQ+EDMAB+TPO and CQ+EDMAB+BAPO. A two-peak LED was used; degree of conversion (DC) and the maximum polymerization rate (RPmax) were determined by near infrared spectroscopy. For the yellowing degree a spectrophotometer was used. Water sorption (Wsp) was obtained after 30 days of water storage (n=5). Data were submitted to two-way analysis of variance and Tukey’s test (a=0.05). BAPO presented the highest DC and RPmax values for both series. SAFCs presented lower DC and RPmax for CQ+EDMAB-based materials. Greater yellowing was observed for SAFCs compared with CFCs, except for BAPO. Greater Wsp was observed for SAFCs compared with CFCs. The photoinitiator did not influence Wsp for CFCs, but TPO and BAPO presented the highest Wsp in SAFCs. The photoinitiator system affected differently the physical-chemical properties of CFCs and SAFCs.
Дисертації з теми "Photoinitiator system"
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Schaub, Kellie M. "The effect of a novel photoinitiator system (RAP) on dental resin composite's flexural strength, polymerization stress, and degree of conversion." Connect to resource online, 2009. http://hdl.handle.net/1805/2080.
Повний текст джерелаАнотація:
Thesis (M.S.D.)--Indiana University School of Dentistry, 2009.Title from PDF t. p. (viewed Feb. 9, 2010) Advisor(s): Jeffrey A. Platt, Chair of the Research Committee, Carl J. Andres, Suteena Hovijitra, David Brown, John A. Levon. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 56-59).
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Grohmann, Caio Vinícius Signorelli 1987. "Influence of different concentration of photoinitiator system on the properties of experimental resin composites = Influência de diferentes concentrações do sistema fotoiniciador nas propriedades de compósitos experimentais." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288132.
Повний текст джерелаАнотація:
Orientador: Mário Alexandre Coelho SinhoretiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo neste estudo foi determinar a influência da concentração e proporção de canforoquinona (CQ) e etil-dimetilaminobenzoato (amina terciária - DABE) em propriedades de compósitos microhíbridos experimentais. Foram testados o Grau de Conversão (GC), Amarelamento (AM), Módulo de Elasticidade (ME), Resistência à Flexão (RF), Sorção de Água (SO) e Solubilidade (SL). Para tanto, 10 compósitos experimentais com a mesma composição monomérica (Bis-GMA, UDMA, BisEMA e TEGDMA) foram manipulados, variando-se apenas as concentrações e proporções de CQ/DABE (% em peso): 0,4/0,4 (C1); 0,4/0,8 (C2); 0,6/0,6 (C3); 0,6/1,2 (C4); 0,8/0,8 (C5); 0,8/1,6 (C6); 1/1 (C7); 1/2 (C8); 1,5/1,5 (C9) e 1,5/3 (C10). Para o ensaio de GC, 8 espécimes de cada material foram confeccionados, a partir de uma matriz de silicone em forma de barra (comprimento = 7 mm; largura = 2mm e espessura = 1mm), os quais foram fotoativados com um aparelho LED (Radii Cal, SDI, 800 mW/cm2), durante 20 segundos. Após 24 horas, o GC foi analisado por Espectroscopia de Infravermelho Transformada de Fourier (FTIR). Posteriormente, as mesmas amostras foram submetidas ao ensaio de flexão de 3 pontos em máquina de ensaio universal (Instron), e a RF e ME calculados. Para os testes de AM, SO e SL, foi utilizada uma matriz de silicone cilíndrica (diâmetro = 6 mm e espessura = 0,5 mm), e confeccionadas 5 amostras de cada material para cada teste. Todas as amostras foram armazenadas em estufa a 37º C, até que fossem submetidas aos seus respectivos testes. O AM foi mensurado após 24 horas de armazenamento em água, utilizando o espectrofotômetro Chroma Meter CR-400 (Konica Minolta). A análise se baseou no eixo b* (+b = amarelo; -b = azul). Para os testes de SO e SL, as amostras foram dissecadas por 1 semana e pesadas diariamente até que a variação máxima de massa fosse de 0,0001 g de um dia para o outro, obtendo m1. Para obter m2, as amostras foram armazenadas em água por 1 semana e pesadas novamente, uma única vez. Por último, m3 foram obtidas do mesmo modo em que m1, após recondicionamento das amostras. Para o cálculo foram utilizadas as fórmulas: SO = (m2-m3) / V e SL = (m1-m3) / V. Após os testes, os dados foram submetidos ao ANOVA one-way e teste Tukey (5%). As diferentes concentrações e proporções de CQ e DABE não alteraram significativamente as propriedades de RF e SO. Por outro lado, o GC foi influenciado positivamente, seguindo a ordem crescente da concentração CQ/DABE (C1 a C10). A SL foi inversamente proporcional à concentração do sistema CQ/DABE. Já relacionado ao ME, observou-se valores diretamente proporcionais à porcentagem em volume de CQ/DABE. Os compósitos 9 e 10, com maiores concentrações de CQ, apresentaram maior AM, comparados aos demais. Pode-se concluir que as altas concentrações de CQ/DABE levaram às melhores propriedades, porém ao maior AM. O aumento na proporção do co-iniciador (DABE) não influenciou nas propriedades de todas as formulações experimentais
Abstract: The aim of this study was to determine the influence of the concentration and ratio of camphorquinone (CQ) and ethyl-dimethylaminobenzoic (tertiary amine - DABE) on properties of microhybrids experimental composites. It was tested Degree of Conversion (DC), Yellowing (YL), Elastic Modulus (EM), Flexural Strength (FS), Water Sorption (WSP) and Solubility (SL). For this, 10 experimental composites with the same monomer composition (Bis-GMA, UDMA, BisEMA and TEGDMA) were manipulated by varying the concentration and ratio of CQ / DABE (wt%): 0.4 / 0.4 (C1); 0.4 / 0.8 (C2); 0.6 / 0.6 (C3); 0.6 / 1.2 (C4); 0.8 / 0.8 (C5); 0. 8 / 1. 6 (C6); 1 / 1 (C7); 1 / 2 (C8); 1.5 / 1.5 (C9); 1.5 / 3 (C10). For DC testing, 8 specimens of each material were prepared from a matrix of silicone-shaped bar (length = 7 mm, width = 2 mm and thickness = 1mm), which were photoactivated with one LED unit (Radii Cal, SDI, 800 mW/cm²) for 20 seconds . After 24 hours, the DC was analyzed by Infrared Fourier Transformed (FTIR). Subsequently, the same samples were subjected to bending test of three points on a universal testing machine (Instron), and the FS and EM calculated. For testing of YL, WSP and SL was used an array of cylindrical silicon (diameter = 6 mm and thickness = 0.5 mm), and made 5 samples of each material for each test. All samples were stored at 37 º C until they were subjected to their respective tests. The YL was measured after 24 hours of storage in water using the spectrophotometer Chroma Meter CR-400 (Konica Minolta). The analysis was based on the axis b * (+ b = yellow,-b = blue). For testing WSP and SL, the samples were dissected for 1 week and weighed daily until the maximum variation in weight was 0.0001 g of an overnight, obtaining m1. For m2, the samples were stored in water for 1 week and weighed once again. Finally, m3 were obtained in the same manner in which m1, after reconditioning of samples. For the calculation, were used: WSP = (m2-m3) / V and SL = (m1-m3) / V. After the tests, the data were subjected to one-way ANOVA and Tukey test (5%). The different concentration and ratio of CQ and DABE not significantly altered the properties of FS and WSP. Moreover, the DC was influenced positively in the order of increasing concentration of CQ / DABE (C1 to C10). The SL was inversely proportional to the concentration of the system CQ / DABE. Related to EM, was observed values directly proportional to the percentage by volume of CQ / DABE. The composites 9 and 10, with higher concentration of CQ showed higher YL, compared to the others. It can be concluded that high concentrations of CQ / DABE took the best properties, but the larger YL. The increase in the proportion of co-initiator (DABE) did not affect the properties of all experimental formulations
Mestrado
Materiais Dentarios
Mestre em Materiais Dentários
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Lima, Giana da Silveira. "Uso de benzodioxolas em sistemas de fotoiniciação de adesivos odontológicos." Universidade Federal de Pelotas, 2009. http://repositorio.ufpel.edu.br/handle/ri/2259.
Повний текст джерелаАнотація:
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Previous issue date: 2009-07-10The objective of this study was to evaluate the effectiveness of benzodioxole derivatives as co-initiators of radical polymerization of experimental self-etching adhesive systems. To compose the experimental self-etching adhesive systems a primer, containing methacrylate monomers and solvents, was developed. A monomer mixture, based on 50 wt % of Bisphenol A glicidyl dimethacrylate (Bis-GMA), 25 wt% of triethyleneglycol dimethacrylate (TEGDMA) and 25 wt% of 2-hydroxyethyl methacrylate(HEMA), was used as a model dental adhesive resin. Camphorquinone (CQ) 1 mol % was used as a photoinitiator to initiate polymerization. Different co-initiators (1,3- benzodioxole and piperonyl alcohol) and concentrations (0.25, 0.50, 1, 2, 4, 8, 16 mol %) were used in a model dental adhesive resin, to compose the experimental groups. Additionally, tertiary amine (EDAB) was used as co-initiator in the control group. The physical, chemical and mechanical properties and characteristics of the polymer obtained for the experimental adhesives (ABDO, APA, AEDAB) were evaluated using polymerization kinetics, sorption and solubility, flexural strength and elastic modulus. The microtensile bond strength (µTBS) to enamel and dentin, and fracture mode were investigated. Adicionalmente morphological analysis of the dentin bonding Interface were evaluated. The results indicated that the BDO and PA were effective co-initiators for the photoinitiator system based on CQ. Comparisons between the benzodioxole derivative co-initiators and traditionally used amine EDAB, showed similar performance in the kinetics of polymerization, flexural strength, water sorption and solubility of the model dental adhesive resin evaluated. In the microtensile bond strength dentin means were higher than enamel and mixed failures were predominant. APA showed higher bond strengths than AEDAB, while ABDO showed intermediate data. The hybrid layer for all groups was shown to be shallow (1-2 µm thick). No appreciable differences in homogeneity were detected along the bonded interface. BDO and PA were feasible alternatives to conventional amine as co-initiator of radical polymerization, moreover, as these benzodioxoles are found in the human diet, this characteristic made them more promising and advantageous to use in dental adhesive resin formulations than amine.
O objetivo deste estudo foi avaliar a efetividade de componentes derivados de benzodioxolas, como co-iniciadores da polimerização radicalar de um adesivo autocondicionante experimental. Para compor sistemas adesivos autocondicionantes experimentais foi desenvolvido um primer, composto por monômeros metacrilatos e solventes. O adesivo foi formulado utilizando uma resina adesiva modelo, composta por 50% de bisfenol A glicidil dimetacrilato (Bis-GMA), 25% de 2-hidroxietil metacrilato (HEMA) e 25% de trietilenoglicol dimetacrilato (TEGDMA), em massa. Canforoquinona (CQ) na concentração 1% molar foi utilizada como fotoiniciador da polimerização da resina modelo. Os grupos experimentais foram formulados com diferentes coiniciadores na resina adesiva: 1,3-benzodioxola (BDO) e álcool piperonílico (AP), em diferentes concentrações molares (0.25, 0.50, 1, 2, 4, 8, 16 %). Adicionalmente um grupo com amina terciária, etil,4-dimetilamino benzoato (EDAB) como co-iniciador, foi formulado como controle. Características e propriedades físicas, químicas e mecânicas do polímero obtido pelos adesivos experimentais foram avaliadas utilizando as metodologias de cinética de polimerização, sorção e solubilidade, resistência à flexão e módulo de elasticidade. A resistência de união à microtração (MPa) ao esmalte e à dentina, com a caracterização do tipo de fratura foi investigada. Adicionalmente, análise morfológica da interface adesiva em dentina foi avaliada. Os resultados indicaram que o BDO e PA foram co-iniciadores efetivos para sistemas fotoiniciadores à base de canforoquinona (CQ). Comparações entre os adesivos experimentais com co-iniciadores derivados de benzodioxolas (ABDO e AAP) e amina (AEDAB), mostraram performance similar na avaliação da cinética de polimerização, resistência à flexão, sorção e solubilidade da resina adesiva modelo avaliada. Na avaliação da resistência de união ao esmalte e à dentina, foi detectada diferença estatística e houve predominância de falhas mistas. APA apresentou maior resistência de união que AEDAB, enquanto ABDO mostrou resultados intermediários. A camada híbrida para todos os grupos apresentou uma espessura entre 1 e 2 Vm. Não foi observada diferença na homogeneidade da interface adesiva em dentina. BDO e PA se revelaram alternativas viáveis à amina como co-iniciadores para a polimerização radicalar. Ademais, estas benzodioxolas são mais promissoras e vantajosas que as aminas, por sua biocompatibilidade e presença na dieta humana
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Palmer, Stuart. "Photopolymerisable poly(vinyl alcohol) systems." Thesis, University of Kent, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342158.
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Fučík, Jan. "Analýza látek uvolněných z kompozitního zubního materiálu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444545.
Повний текст джерелаАнотація:
This master's thesis deals with a present problem of alternative dental fillings, which should replace amalgam fillings. Although there are health concerns about these alternative materials, especially resin composite fillings raise concerns, because they release potentionally harmful substances into the oral cavity. Accordingly even this medical device subjects various tests before releasing to the commercial market and one of these tests was carried out according to ČSN EN ISO 10993 and available scientific literature in the experimental part of this thesis. The amalgam controversy, substances used for manufacturing of resin dental fillings and analytical methods are described in the theoretical part of the thesis. In the experimental part of the thesis, 30 days long cumulative extraction experiments were carried out into various extraction mediums in order to assess suitability of new dental resin filling from ADM, a.s. by comparison with commercially available dental material from company GC EUROPE N.V. These samples were analysed by LC-MS and the amount of eluted substances from dental composites to extraction medium was quantified.
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Kenning, Nicole Lynn. "Spatial and temporal evolution of the photoinitiation rate in thick polymer systems." Diss., University of Iowa, 2006. http://ir.uiowa.edu/etd/76.
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Metral, Boris. "Systèmes photoamorceurs et modèle pour la fabrication additive par photopolymérisation." Thesis, Mulhouse, 2020. https://www.learning-center.uha.fr/.
Повний текст джерелаАнотація:
Les technologies de photopolymérisation en cuve émergent rapidement dans le domaine de la fabrication additive. Pour suivre cette expansion rapide du marché, des résines photosensibles très efficaces et abordables sont nécessaires. Dans ce travail, nous introduisons un nouveau système photoamorceur à trois composants (3K PIS) basé sur le colorant Safranine O (SFH+) qui a été identifié comme un composé très efficace dans plusieurs 3K PIS pour les processus de photopolymérisation.Le colorant est combiné avec un sel de tétraphénylborate (TPB) comme donneur d'électrons et un dérivé de la triazine (TA) comme accepteur d'électrons pour former un système photocyclique. Le mécanisme réactionnel est exploré par photolyse laser éclair (LFP) et la photopolymérisation est étudiée par spectroscopie infrarouge à transformée de Fourier en temps réel (RT-FTIR). Des expériences infrarouges avec plusieurs irradiances permettent de créer un modèle empirique prédisant la conversion en fonction du temps et de l'intensité lumineuse.Ensuite, des expériences de profondeur de polymérisation sont menées suivant l'équation de Jacobs, permettant d’obtenir les paramètres d'impression3D de la résine ; à savoir l'énergie critique (Ec) et la profondeur de pénétration (Dp). Ces paramètres sont reliés aux analyses RT-FTIR, ce qui permet de déterminer le temps critique (tc) et la conversion au point de gel.Enfin, des pièces complexes de haute résolution sont imprimées avec la résine dont la composition a été sélectionnée en fonction de nos résultats, démontrant la viabilité de cette formulation pour l'impression 3D DLPVat photopolymerization technologies are emerging quickly in the field of additive manufacturing. To follow this fast expansion of the market, highly efficient and affordable photosensitive resins are necessary. In this work, we introduce a new three-component phototiniating system (3K PIS) based on the Safranine O (SFH+) dye which has been identified as a very efficient initiator in several 3K PIS for photopolymerization processes.The dye is combined with a Tetraphenylborate salt (TPB) as electron donor and a Triazine derivative (TA) as electron acceptor to form a photochemical regenerating cycle. The photocycling mechanism is explored via laser flash photolysis (LFP) and the photopolymerization is investigated through Real-Time-Fourier Transform Infrared spectroscopy (RT-FTIR). Infrared experiments with several irradiances allow disclosure of an empirical model predicting conversion as a function of time and light intensity.Following this, cure depth experiments are conducted in agreement with Jacobs’ equation and the resin 3D printing parameters, i.e. critical energy (Ec) and penetration depth (Dp), are established. These parameters are linked to RT-FTIR data, resulting in the determination of the critical time (tc) and the conversion at gel point.Finally, high resolution complex pieces are printed with the resin which composition was tailored in accordance with our studies, demonstrating the viability of this formulation in DLP 3D printing
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Talungchit, Supitcha. "Enhancing resin-dentin bond effectiveness and durability: the role of ethanol-wet bonding technique, MMP-inhibition (chlorhexidine), and photoinitiator systems." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/2996.
Повний текст джерелаАнотація:
Current hydrophilic resin adhesives undergo hydrolytic degradation and show a decrease in bond strength over time. Nanoleakage and ultrastructure studies suggest that inadequately infiltrated collagen leads to enzymatic degradation and resin-dentin bond failure. Adequate degree of conversion (DC) of resin adhesives is also critical to resin-dentin bond strength and durability. The long-term goal of this dissertation is the realization of durable resin-dentin bond. It is hypothesized that ethanol-wet bonding technique (EW) may effectively facilitate the infiltration of hydrophobic monomers into hydrophilic acid-etched dentin by maintaining interfibrillar spacing, stiffening collagen matrix, and improving adhesive resin-demineralized dentin matrix miscibility. Chlorhexidine (CHX), Matrix Metalloproteinase-inhibitor (MMP-inhibitor), should further preserve collagen integrity and resin-dentin bond strength. Moreover, efficient photoinitiator systems that broaden light absorptivity and provide more reactive radicals may enhance polymerization.
In this dissertation, a clinically-relevant EW protocol, 3×15s absolute ethanol rinsing, provided significantly higher microtensile bond strength (πTBS) of a hydrophobic resin (70%BisGMA/30%TEGDMA) to dentin as compared to water-wet bonding (WW). All groups showed no significant drop of πTBS after 1-year storage except EW without CHX application, showing marginally significant reduction in πTBS (p=0.0558) suggesting MMP-inhibition by CHX in EW. These results were consistent with subsequent experiments. EW maintained interfibrillar width and hybrid layer thickness for resin infiltration and retention. Monomer molar concentration across the hybrid layer was significantly higher in EW than WW. An application of 2% CHX diacetate further preserved collagen banding in EW. WW showed more generalized spotted nanoleakage, while EW presented localized reticular nanoleakage. The use of Irgacure 819 (BAPO) alone and in combination with benzoyl peroxide (BPO) or camphorquinone (CQ) increased DC of hydrophobic and hydrophilic resins over resins containing the CQ/amine (4E) control. Only BAPO and BAPO/BPO demonstrated significantly higher immediate shear bond strength than CQ/4E. Within the limitations of these studies, EW improved resin-dentin bond durability by maintaining collagen interfibrillar spaces for efficient infiltration of a hydrophobic BisGMA/TEGDMA resin resulting in significantly higher πTBS and monomer molar concentrations with less nanoleakage distribution within the hybrid layer than WW. CHX further maintained collagen integrity and πTBS in EW. BAPO is a potential alternative photoinitiator of dental resins.
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Spata, Vincent Anthony. "PHOTOINITIATED-PROCESSES IN ADENINE OLIGONUCLEOTIDES: EXAMINING THE NATURE OF π-STACKING INTERACTIONS IN MULTI-CHROMOPHORE SYSTEMS". Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/388262.
Повний текст джерелаАнотація:
ChemistryPh.D.
DNA provides the genetic code which is almost universal in all living organisms. When DNA is exposed to ultra-violet light it can cause cell degradation and mutation which are two of the major causes which lead to cancer. The nature of decay in DNA oligomers is a widely studied topic. Fluorescence and Transient Absorption (TA) experiments on polynucleotides which compare the behavior of the decay to the monomer bases have revealed the presence of longer-lived components in the multimeric systems. There has been heated debate over the character of the excited states responsible for the long-lived signals. Theoretical methods are well suited to compliment experiment by providing a description of processes and physical properties on the molecular level. We have studied π-stacked adenines in the gas-phase with Quantum Mechanical (QM) methods, but also in the helical environment using high-level ab initio methods, classical simulations and the combination of the two (QM/MM). Inclusion of the environmental interactions dramatically alters the shape of the potential energy surfaces due to steric interactions from the backbone and interactions with the surrounding bases and environment. This work examines the complete picture of photophysical processes occurring in adenine oligonucleotides within the helical environment after the absorption of a photon: the nature of initial absorption and the subsequent radiative and non-radiative decay pathways. It contributes key discoveries inherent to the mechanisms which govern photo-initiated processes in DNA, and also contributes to our fundamental knowledge of the photophysical behavior of π-stacked chromophores. The work reveals the effects of π-stacking interactions and the environment on photo-initiated processes in oligonucleotides. It reveals that excitonic coupling is responsible for the key differences in features in the absorption spectrum of adenine oligomers compared to the isolated bases, illustrates the role of charge transfer (CT) mixing in both absorption and decay processes, and the importance of bonded excimers in deactivation. The work also illustrates that CT excimers are responsible for the long-lived signals evidenced in Transient Absorption and Fluorescence experiments and that neutral excimers can exist within the DNA helical environment. It also adds to the discussion in the field on the nature of photodecay mechanisms occurring within the DNA helix.
Temple University--Theses
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Torfgård, Olof. "Short wavelength UV–LED photoinitiated radical polymerization of acrylate–based coating systems—A comparison with conventional UV curing." Thesis, Uppsala universitet, Strukturkemi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-442431.
Повний текст джерелаАнотація:
The present work was performed at Sherwin–Williams Sweden group AB with the objective of comparing short-wavelength light emitting diodes (UVB/UVC) with the conventional mercury arc lamp as a curing method of acrylate-based, UV-paint undergoing free-radical polymerization when exposed to UV-radiation. Due to environmental and health risks, mercury-doped radiation sources will be phased out in the near future, according to the United Nations Minamata convention, hence new alternatives are needed. Light-emitting diodes differ from the mercury arc lamp as they provide semi-discrete output intensity lines within the UV spectrum instead of a broad output distribution with several main intensity lines. The power output is also considerably lower compared to the conventional method which limits the irradiance and dose that are key parameters in activating and propagating free-radical polymerization of UV-paint. Seven different light-emitting diodes between 260–320 nm was examinedand compared to the conventional mercury arc lamp. Cured coatings were evaluated by measuring the relative extent of acrylate conversion with ATR-FTIR and micro-hardness indentation test. Both methods correlate to the relative cross-linking density and qualitatively describe the curing process for each radiant source at a specific irradiance and dose. Three different paint formulations with widely different properties were used in the experiments. All three paints were able to cure with one or several light emitting diodes at comparable doses and 10 to 20 times lower irradiance to the conventional mercury arc lamp, resulting in similar acrylate conversion and hardness.
Частини книг з теми "Photoinitiator system"
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Dietliker, K. "Photoinitiators for Pigmented Systems." In Radiation Curing in Polymer Science and Technology—Volume II, 155–237. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1876-7_3.
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Hendrickson, W. A., and M. C. Palazzotto. "Photoinitiator Activity, Electrochemistry, and Spectroscopy of Cationic Organometallic Compounds." In Photosensitive Metal—Organic Systems, 411–30. Washington, DC: American Chemical Society, 1993. http://dx.doi.org/10.1021/ba-1993-0238.ch021.
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Hoyle, Charles E., M. Cole, M. Bachemin, W. Kuang, Viswanathan Kalyanaraman, and Sonny Jönsson. "Photoinitiated Polymerization of Selected Thiol-ene Systems." In ACS Symposium Series, 52–64. Washington, DC: American Chemical Society, 2003. http://dx.doi.org/10.1021/bk-2003-0847.ch005.
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Lee, Tai Yeon, T. M. Roper, C. Allan Guymon, E. Sonny Jonsson, and Charles E. Hoyle. "Copolymerization Mechanism of Photoinitiator Free Thiol—Vinyl Acrylate Systems." In ACS Symposium Series, 17–28. Washington, DC: American Chemical Society, 2006. http://dx.doi.org/10.1021/bk-2006-0941.ch002.
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Yamaoka, Tsuguo, and Kazuhiko Naitoh. "Visible Light Photoinitiation Systems Based on Electron and Energy Transfer Processes." In Processes in Photoreactive Polymers, 111–69. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1767-2_5.
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"Photosensitive Systems." In Photoinitiators for Polymer Synthesis, 73–88. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527648245.ch5.
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"Reactivity of the Photoinitiating System." In Photoinitiators for Polymer Synthesis, 357–58. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527648245.part4.
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"Multicomponent Photoinitiating Systems." In Photoinitiators for Polymer Synthesis, 269–82. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527648245.ch10.
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"Other Photoinitiating Systems." In Photoinitiators for Polymer Synthesis, 283–86. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527648245.ch11.
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"Cationic Photoinitiating Systems." In Photoinitiators for Polymer Synthesis, 289–341. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527648245.ch12.
Повний текст джерелаТези доповідей конференцій з теми "Photoinitiator system"
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Morlet-Savary, Fabrice, Jean-Pierre Fouassier, K. Yamashita, and S. Imahashi. "Three-component visible photoinitiator: system based on dye/iron arene complex/amine for imaging applications." In SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, edited by Roger A. Lessard. SPIE, 1996. http://dx.doi.org/10.1117/12.251829.
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Blaya, S., P. Acebal, L. Carretero, R. F. Madrigal, A. Murciano, and A. Fimia. "Analysis of the effect modification of the photoinitiator system in pyrromethene-HEMA based photopolymerizable holographic recording materials." In SPIE Optics + Optoelectronics, edited by Miroslav Hrabovský, Miroslav Miler, and John T. Sheridan. SPIE, 2011. http://dx.doi.org/10.1117/12.886947.
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Ley, Christian, Christian Carré, Ahmad Ibrahim, and Xavier Allonas. "Role of photoinitiators on self developing photopolymerizable system for holographic grating recording (Conference Presentation)." In Holography: Advances and Modern Trends, edited by Antonio Fimia, Miroslav Hrabovský, and John T. Sheridan. SPIE, 2019. http://dx.doi.org/10.1117/12.2523125.
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Arcaute, K., L. Ochoa, B. K. Mann, and R. B. Wicker. "Stereolithography of PEG Hydrogel Multi-Lumen Nerve Regeneration Conduits." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81436.
Повний текст джерелаАнотація:
Peripheral nerve regeneration conduits available today are single lumen conduits. Multi-lumen conduits offer advantages over currently available conduits in that multiple lumen better mimic the natural structure of the nerve, provide a greater surface area for neurite extension, and allow for more precisely located growth factors or support cells within the scaffold. This work describes and demonstrates the use of the stereolithography (SL) rapid prototyping technique for fabricating multi-lumen nerve guidance conduits (NGCs) out of photopolymerizable poly(ethylene glycol) (PEG). NGCs were fabricated from PEG-dimethacrylate (PEG-dma) molecular weight 1000 with 30% (w/v) aqueous solution and 0.5% (w/v) of the photoinitiator Irgacure 2959. The selection of the PEG-dma and photoinitiator concentration was based on previous work [13]. A 3D Systems 250/50 SL machine with a 250 μm laser beam diameter was used for the experiments in a slightly modified process where the NGCs were fabricated on a glass slide within a small flat-bottom cylindrical container placed on top of the SL machine’s original build platform. SL successfully manufactured three-dimensional, multi-layered and multi-material NGCs with varying overall NGC lengths and lumen sizes. Minimum lumen size, spacing, and geometric accuracy were constrained by the laser beam diameter and path, curing characteristics of the polymer solution, and UV transmission properties of the polymer solution and cured PEG-dma. Overall lengths of the NGCs were constrained by the ability of the conduit to self-support its own construction. Multiple material conduits were demonstrated by varying the build solution during the layering process. In summary, SL shows promise for fabrication of bioactive NGCs using PEG hydrogels, and the use of SL in this application offers the additional advantage of easily scaling up for mass production.
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Leatherdale, Catherine A., and Robert J. DeVoe. "Two-photon microfabrication using two-component photoinitiation systems: effect of photosensitizer and acceptor concentrations." In Optical Science and Technology, SPIE's 48th Annual Meeting, edited by A. Todd Yeates, Kevin D. Belfield, Francois Kajzar, and Christopher M. Lawson. SPIE, 2003. http://dx.doi.org/10.1117/12.508087.
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Mitkus, Rytis, Andreas Pierou, Julia Feder, and Michael Sinapius. "Investigation and Attempt to 3D Print Piezoelectric 0-3 Composites Made of Photopolymer Resins and PZT." In ASME 2020 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/smasis2020-2287.
Повний текст джерелаАнотація:
Abstract The present study demonstrates the manufacturing and characterization of 0-3 piezoelectric composites made of up to 10 vol% of Lead Zirconate Titanate (PZT) particles and photopolymer resins. The tape-casting method was used to investigate the curing behavior, PZT loading limitations and the overall feasibility of the suspensions for 3D printing. Piezoelectric composites were 3D printed with a commercial DLP type 3D printer. As a starting point, the maximum possible vol% loading of PZT ceramic for each photopolymer resin was investigated. Five different commercially available photopolymer resins from Formlabs (Somerville, MA, US) were used. It was found that the addition of PZT particles to the photopolymer increases the time required for the photopolymer to solidify because PZT particles scatter the UV light. The approximate solidification time of each composition was measured, followed by viscosity measurements. SEM imaging of the composites showed good particle dispersion with minimum agglomeration, low particle sedimentation, but the weak bond between PZT particles and the photopolymers. Best performed material composition with 10 vol% of PZT was used for 3D printing. An attempt to shorten exposure time during printing was done by adding photoinitiator TPO. Suspensions with and without TPO were 3D printed and compared.
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Sarles, Stephen A., and Donald J. Leo. "Encapsulated Interface Bilayers for Durable Biomolecular Materials." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3752.
Повний текст джерелаАнотація:
This paper introduces the concept of hydrogel encapsulated interface bilayers as a novel approach for creating durable encapsulated biomolecular materials. The regulated attachment method (RAM) is used to form encapsulated interface bilayers from lipid-encased aqueous volumes contained in a deformable supporting substrate. Physically-encapsulated interface bilayers exhibit increased durability and portability over droplet interface bilayedrs and RAM enables the in situ bilayer formation without the need to dispense and arrange individual droplets. The results presented in this paper demonstrate that poly(ethylene glycol) dimethacrylate monomers (PEG-DMA, Mw = 1000), a photopolymerizable hydrogel monomer, and Irgacure 2959 photoinitiator can be incorporated into the aqueous phase in order to form hydrogel encapsulated interface bilayers. Following bilayer formation, exposure to an ultraviolet (UV) light initiates photopolymerization of the polymer on both sides of the bilayer, creating interface bilayers between solid aqueous phases. Electrical recordings of bilayer formation in the liquid state confirm that interface bilayers formed from photopolymerizable aqueous solutions have both high electrical resistances > 1GΩ necessary for observing transmembrane protein gating and survive the UV curing procedure required to polymerize the hydrogel. Photopolymerization for 60 seconds using a 1W hand held UV spot cure light produced water-swollen solids on both sides of the membrane. Hydrogel encapsulated interface bilayers last for hours to days and retain the fluidity necessary for delivering alamethicin proteins to the interface.