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1.
This study was designed to determine whether a new dedicated adhesive system using a silorane composite exhibits better bonding performance to human dentin than conventional dimethacrylate‐based composites. The materials were used included: Adper? Easy Bond‐Z250 (AE‐Z250), iBond‐Venus (IB‐VE), XenoIII‐TPH (XE‐TPH), Clearfil S3‐Clearfil Majesty (S3‐CM), and the Filtek silorane system (SA‐FS). Polymerization volumetric shrinkage and stress development were measured using a micro‐CT instrument and universal testing machine. The push out strength of the bonds produced using the corresponding self‐etching adhesive systems were also measured. The volumetric shrinkage of the resin composite/adhesive combinations ranged from 1.05% (SA‐FS) to 3.38% (XE‐TPH) 30 min after light curing. SA‐FS had the lowest volumetric shrinkage (P < 0.05), followed by S3‐CM, EA‐Z250, IB‐VE, and XE‐TPH. The polymerization stress of the materials ranged from 1.54 (SA‐FS) to 3.49 MPa (S3‐CM). The lowest stress was also observed in SA‐FS at 30 min during the stress test (P < 0.05). Push‐out bond strength testing revealed that IB‐VE had significantly lower bond strength than other combinations (P < 0.05). The silorane composite and dedicated adhesive system exhibited excellent characteristics of low volumetric shrinkage and stress development compared to conventional dimethacrylate‐based composites. However, the silorane composite resin system possessed similar push‐out bond strength as the other materials, with the exception of the Venus/iBond combination. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

2.
New multifunctional silorane‐based systems were investigated, with respect to their photoreactivity, as potential matrix resins for low‐shrinkage/stress dental composites. The objective of this investigation was to synthesize and evaluate the reactivity of a silicon‐analogue oxaspirocyclic monomer with silorane‐based matrix resin systems during visible‐light polymerization. The experimental formulations contained (1) a silicon‐containing 1,5,7,11‐tetraoxaspiro[5.5]undecane (TOSU– IV ), (2) a phenylmethylsilane containing two cyclohexyloxiranyl groups, (3) a cyclotetrasiloxane containing four cyclohexyloxiranyl groups, and (4) a photocationic initiator system. Three main aspects were studied: (1) the photoreactivity of the tetraoxaspiroundecane (TOSU)/silorane reactant mixtures with differential scanning photocalorimetry, (2) oxirane ring‐opening reactions of siloranes during binary photopolymerization with Fourier transform infrared (FTIR), and (3) oxaspirocyclic ring‐opening reactions of the TOSU reactant during homophotopolymerization and binary photopolymerization with FTIR and NMR. A diallyl ether precursor of TOSU– IV was also included in selected studies. The main findings were as follows: (1) a feasible route for the successful synthesis of a silicon analogue (TOSU– IV ) was developed; (2) TOSU– IV was compatible and photoreactive, making possible the reduction of polymerization stress in silorane‐based matrix resins; and (3) spectroscopic evidence for both oxirane and oxaspirocyclic ring opening during the visible‐light photopolymerization of the test formulations was found. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 336–344, 2007  相似文献   

3.
Polymerization shrinkage of methacrylate‐based dental composites remains a major concern in restorative dentistry. Cyclic monomers that undergo ring‐opening polymerization are known to exhibit reduced polymerization shrinkage compared to methacrylates. In this article, the synthesis of four crosslinking 1,1‐disubstituted 2‐vinylcyclopropanes bearing rigid spacers is described. These monomers were synthesized by esterification of 1‐ethoxycarbonyl‐2‐vinylcyclopropane‐1‐carboxylic acid with the corresponding diols. The photopolymerization kinetics of these monomers was investigated by photo‐differential scanning calorimeter using bis(4‐methoxybenzoyl)diethylgermane as the photoinitiator. The synthesized vinylcyclopropanes (VCPs) were shown to be more reactive than the frequently used reactive diluent triethylene glycol dimethacrylate. Composites based on these VCPs showed good mechanical properties and exhibited a significantly reduced volumetric shrinkage and shrinkage stress compared to a corresponding dimethacrylate‐based restorative material. This work highlights the excellent potential of VCPs as alternatives to methacrylates in the development of low‐shrinkage dental composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45577.  相似文献   

4.
Polymerization shrinkage of dental composites remains a major concern. Free‐radically polymerizable cyclic monomers can be a conceivable alternative to methacrylates for the development of low‐shrinkage composites. In this study, the one‐step synthesis of the novel low viscosity difunctional vinylcyclopropanes 1 – 4 is described. Photopolymerization kinetics of these monomers are investigated by photo‐differential scanning calorimeter, using bis(4‐methoxybenzoyl)diethylgermane as photoinitiator. Real‐time near‐infrared photorheology measurements are performed to evaluate rheological behavior (i.e., time of gelation, polymerization‐induced shrinkage force) and chemical conversion (i.e., double bond conversion at the gel point, final double bond conversion) of the vinylcyclopropanes in situ. The potential of these monomers as reactive diluents in dental restorative materials is evaluated. Composites based on vinycyclopropanes 1 – 4 show good mechanical properties and exhibit significantly lower volumetric shrinkage and shrinkage stress than corresponding dimethacrylate‐based materials. The results indicate that such monomers are promising candidates for the replacement of commonly used low viscosity dimethacrylates such as triethylene glycol dimethacrylate in dental composites.

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5.
The aim of this study was to evaluate the effect of the association between bisphenol‐A diglycidyl dimethacrylate (BisGMA) or its ethoxylated version (BisEMA) with diluents derived from the ethylene glycol dimethacrylate (EGDMA), with increasing number of ethylene glycol units (1: EGDMA, 2: DEGDMA, 3: TEGDMA, or 4: TETGDMA), or trimethylol propane trimethacrylate (TMPTMA) or 1,10‐decanediol dimethacrylate (D3MA) on polymerization stress, volumetric shrinkage, degree of conversion, maximum rate of polymerization (Rpmax), and elastic modulus of experimental composites. BisGMA containing formulations presented lower shrinkage and stress but higher modulus and Rpmax than those containing BisEMA. TMPTMA presented the lowest stress among all diluents, as a result of lower conversion. EGDMA, DEGDMA, TEGDMA, and TETGDMA presented similar polymerization stress which was higher than the stress presented by D3MA and TMPTMA. D3MA presented similar conversion when copolymerized with both base monomers. The other diluents presented higher conversion when associated with BisEMA. EGDMA showed similar shrinkage compared with DEGDMA and higher than the other diluents. The lower conversion achieved by TMPTMA did not jeopardize its elastic modulus, similar to the other diluents. Despite the similar conversion presented by D3MA in comparison with EGDMA and DEGDMA, its lower elastic modulus may limit its use. Rather than proposing new materials, this study provides a systematic evaluation of off the shelf monomers and their effects on stress development, as highlighted by the analysis of conversion, shrinkage and modulus, to aid the optimization of commercially available materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

6.
The aim of study was to investigate the effects of various curing protocols with quartz–tungsten halogen (QTH) or light‐emitting diode (LED) light‐curing units on the degree of conversion (% DC) of two dual‐cured core buildup resin composites. Two dual‐cured core buildup resin composites, Clearfil Dc Core Automix (CLF) and Grandio Core Dc (GR), were selected. Specimens were exposed to the polymerization protocols as follows: there was immediate photoactivation or photoactivation delayed by 2 or 5 min by a QTH or LED source, and one group was allowed to chemically polymerize and served as a control (n = 6). The % DC of the specimens was determined with attenuated total reflectance–Fourier transform infrared spectroscopy. The GR samples polymerized with QTH for the 5‐min‐delayed photoactivation had higher % DC values than those self‐cured, and the Clearfil Dc Core Automix (CLF) samples with immediate or delayed curing protocols with halogen yielded higher % DC values than the samples that were chemically polymerized. The comparison of the two resin composites polymerized with halogen showed a higher % DC for CLF than for GR in the 2‐min‐delayed photoactivation. On the other hand, when they were cured with LED, the % DC values of GR significantly increased after the 2‐min‐delayed photoactivation. In light of the results, it might be stated that CLF polymerized with QTH, could be the better option. GR provided adequate chemical polymerization; therefore, it might be useful in areas in which light curing is not possible. Clinicians should consider the polymerization characteristics of dual‐cured resin composites. The use of different composites may require the modification of the application procedures recommended by the manufacturer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40560.  相似文献   

7.
Polymerization shrinkage, depth of cure, and in vitro cytotoxic behavior of dental restorative composite based on inorganic–organic hybrid (organically modified ceramic) resins, containing alkoxides of silicone, calcium, and titanium with various polymeric methacrylate groups were evaluated in this study. Comparison was made between dimethacrylate and tetra methacrylate resins. Statistical evaluation using analysis of variance (single factor) showed that tetramethacrylate organically modified ceramic resin‐based composites showed better shrinkage properties. P < 0.05 was considered as statistically significant. Compared to dimethacrylates, tetramethacrylates based composites showed lower depth of cure value. Cytotoxicity characteristics of these composites were mainly depending on the nature of inorganic material incorporated rather than difference in dimethacrylate or tetramethacrylate structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

8.
This study concerns to the investigation of the polymerization shrinkage in dental experimental composites filled with silanized silica Aerosil® OX‐50 and clay nanoparticulated Montmorilonita (MMT) Cloisite® 30B, in glycidyl methacrylate resin. The characterization of the experimental composites was established with the following analyses: Thermo‐Mechanical Analysis (TMA) at isotherm temperature, Differential Scanning Calorimetry Analysis (DSC) under nitrogen atmosphere, X‐Ray diffraction (DRX), and Micro Hardness analysis. Through the TMA analysis was observed that the polymerization shrinkage varies according to the filler type and concentration in the experimental composite. The polymerization shrinkage ranged from 0.98% to 0.22% in the experimental composites added with Cloisite® 30B and ranged from 2.73% to 1.01% in the experimental composites containing silanized silica. Due to the intercalation of the clay nanoparticle in relation to the polymer matrix, the experimental nanocomposites with Cloisite® 30B showed better performance compared to the composites with silanized silica. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40010.  相似文献   

9.
Novel synthetic biodegradable methacrylated anhydride oligomers (MAOs) based on methacrylated alaninyl maleamic acid (MAMA) and methacrylated aminocaproyl maleamic acid (MACMA) were synthesized and characterized. Injectable and in situ crosslinkable polymer networks were formulated by the copolymerization of MAOs with triethylene glycol dimethacrylate (TEGDMA). Furthermore, composites composed of MAOs, TEGDMA, and β‐tricalcium phosphate were prepared. The networks and composites were initiated by photopolymerization and redox polymerization, respectively. The initial compressive strength (CS) and diametral tensile strength (DTS) of these materials were determined and used to evaluate the effects of the MAO/TEGDMA ratios on the degradation behavior of the materials. The MAMA‐based composites had initial DTS values of 5.7–17.1 MPa and CS values of 30.7–114.2 MPa. The MACMA‐based composites had initial DTS values of 2.8–20.8 MPa and CS values of 19.1–119.5 MPa. During the course of degradation, the neat polymer resins lost 97 and 87% of their initial CS values after 6 months with 50/50 MAMA/TEGDMA and MACMA/TEGDMA ratios, respectively. The composite with a 25/75 MACMA/TEGDMA ratio showed a significant increase in CS after an initial decrease for 7 days and then lost 57% of its initial CS value after 3 months. The composite composed of 100% methacrylated anhydride oligomer (MAOs) showed complete degradation after 21 days. The degrees of conversion of the neat resins were 60–77%. Both the neat resins and the composites had low polymerization shrinkage ranging from 3.8 to 5.6%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1979–1984, 2005  相似文献   

10.
In this work, a method for preparation of polyamide‐6 (PA6) based laminates reinforced by glass fiber‐ (GFL) or polyamide‐66 (PA66) textile structures (PL) via reactive injection molding is disclosed. It is based on in‐mold anionic polymerization of ε‐caprolactam carried out at 165°C in the presence of the respective reinforcements performed in newly developed prototype equipment whose design concept and operation are described. Both composite types were produced for reaction times of 20 min, with conversion degrees of 97–99%. Initial mechanical tests in tension of GFL samples displayed almost twofold increase of the Young's modulus and stress at break values when compared with the neat anionic PA6. The improvement was proportional to the volume fraction Vf of glass fiber fabric that was varied in the 0.16–0.25 range. A 300% growth of the impact strength was registered in PL composites with Vf of PA66 textile of 0.1. Removing the surface finish of the latter was found to be a factor for improving the adhesion at the matrix–fiber interface. The mechanical behavior of GFL and PL composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy and the matrix crystalline structure as revealed by synchrotron X‐ray diffraction. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40083.  相似文献   

11.
A series of partially photodegradable o‐nitrobenzyl nanogels (NBNG) with different caged functional groups (COOH, OH, SH) are prepared and compared with a nondegradable nanogel as additives in photocurable materials. Photoinduced nanogel network disruption and photoinitiated polymerization of infiltrating and dispersing monomer could be controlled independently. In triethylene glycol dimethacrylate (TEGDMA), o‐NBNGs that release a COOH or OH functional group upon photodegradation of the o‐nitrobenzyl crosslinker, the reduced chemical crosslinking density of the nanogel network allows greater penetration of monomer into the partially degraded nanogel network, which results in an increase in volumetric shrinkage and polymerization stress. In contrast, the formulation of o‐NBNGs with caged SH groups also can be photodegraded but is able to rebuild the chemical crosslinking through thiol‐based chain transfer reactions when photocured as a dispersion in TEGDMA. As such, it behaves like a photo‐inert nanogel. Dynamic thermomechanical analysis and testing by three‐point bending further confirms the photoinduced crosslink density variation influences mechanical properties of the final polymer networks. This work demonstrates the inherent properties of the nanogel network and the type of crosslinking can alter the performance of the photocured resin while a separate photochemical process can be used to regulate photoinduced polymerization.  相似文献   

12.
Optical pick‐up lenses are used in optical storage devices such as CD, DVD, and Blu‐Ray Disc. The production of such lenses is based on UV‐induced polymerization of a mixture of a dimethacrylate monomer and an initiator on a spherical glass substrate. The shape of the polymer layer is defined with an aspherical transparent mold. This means that the coating is completely surrounded by glassy materials during processing. Raman spectroscopy is applied in situ to monitor the polymerization reaction under conditions that closely resemble the actual production process. As a result improvements can be made to the reaction conditions if necessary. Data are compared to results obtained with IR spectroscopy in an off‐line approach. The value of the in situ characterization using Raman spectroscopy is illustrated by the observation that contrary to expectation, the local rate of polymerization is not influenced by shrinkage effects caused by local variations in volume relaxation in the wedge‐shaped sample volume. Instead, even quartz glass mold plates with a thickness of 30 times that of liquid monomer were deformed to accommodate for thermodynamically required volume shrinkage. The assumption of isochoric polymerization in a confined volume turned out to be incorrect. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1287–1295, 2006  相似文献   

13.
A mechanism for polymerization shrinkage and stress reduction was developed for heterogeneous networks formed through ambient, photo‐initiated polymerization‐induced phase separation (PIPS). The material system used consists of a bulk homopolymer matrix of triethylene glycol dimethacrylate (TEGDMA) modified with one of three nonreactive, linear prepolymers (poly‐methyl, poly‐ethyl, and poly‐butyl methacrylate). At higher prepolymer loading levels (10–20 wt %), an enhanced reduction in both shrinkage and polymerization stress is observed. The onset of gelation in these materials is delayed to a higher degree of methacrylate conversion (~15–25%), providing more time for phase structure evolution by thermodynamically driven monomer diffusion between immiscible phases prior to network macro‐gelation. The resulting phase structure was probed by introducing a fluorescently tagged prepolymer into the matrix. The phase structure evolves from a dispersion of prepolymer at low loading levels to a fully co‐continuous heterogeneous network at higher loadings. The bulk modulus in phase‐separated networks is equivalent or greater than that of poly(TEGDMA), despite a reduced polymerization rate and cross‐link density in the prepolymer‐rich domains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40879.  相似文献   

14.
During cure of epoxy resins, polymerization induces an increase in mechanical properties, which is accompanied by a volumetric shrinkage. When the resin is cured in a constrained mold to which it adheres, tensile stresses will hence develop, which may exceed the stremgth of the resin at a given curing stage. Voids will then form. The origin and governing parameters of void formation are studied using an epoxy resin cured in a three‐dimensionally constrained glass mold following isothermal cure cycles. Two types of voids are shown to appear during cure, one early in the process and a second around the gelation point. A viscoelastic analysis of the material stress state over the whole range of cure is performed. Both the viscoelastic modulus obtained from a time‐cure‐temperature superposition and the volumetric shrinkage, which was continuously measured by density change, are taken into account. A value for the critical internal stress at void initiation is thus proposed. This criterion can be used to provide guidelines for tailoring the material properties toward an increase of the critical stress for void initiation. Also, since during theprocessing of composite materials, cases may arise where the resin cures within the interstices left between consolidated fibres that do not move, this critical stress failure criterion can be of use in the eastablishment of a process window providing guidelines for the production of void free composites.  相似文献   

15.
Poly(N‐vinylcarbazole) (PVK) composites containing different concentrations of multiwalled carbon nanotube (MWCNT) were synthesized through the oxidative polymerization of N‐vinylcarbazole with ferric chloride. The synthesized composites were characterized using Fourier transform infrared spectroscopy, ultraviolet‐visible spectra, and thermogravimetric analysis. A honeycomb‐patterned film was fabricated by casting the PVK–MWCNT composite solution under humid conditions. The morphology of the honeycomb‐patterned films in the PVK–MWCNT polymer composites and the dependence of its pore diameter and pore height on MWCNT concentration were analyzed using scanning electron microscopy. The honeycomb‐patterned films were treated at 150, 250, 400, and 490°C to study the arrangement of MWCNTs in the patterned films and to measure the DC conductivity depending on the calcination temperature. DC conductivity of the patterned films was increased by increasing the concentration of MWCNT in the composites and in the increased pretreatment temperature. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers  相似文献   

16.
17.
In this study, a new biobased isosorbide urethane methacrylic monomer [isosorbide‐derived urethane dimethacrylate (Is‐UDMA)] was evaluated as a replacement for currently used bisphenol A glycerolate dimethacrylate (Bis‐GMA) based dental restorative materials. Dental composites were prepared at different Is‐UDMA and Bis‐GMA concentrations. For these composites, the photocuring kinetics, volumetric shrinkage, viscoelastic properties, water sorption, and solubility were evaluated. The photocuring kinetics, followed by real‐time IR spectroscopy, showed higher double‐bond conversion (DC) values for the formulations containing the Is‐UDMA monomer; the highest DC (82%) was achieved by the formulation prepared with only the Is‐UDMA monomer. The volumetric shrinkage was reduced to 23.7% as compared with the dental resin formulated with Bis‐GMA. The viscoelastic properties of the formulations containing both Is‐UDMA and Bis‐GMA monomers in a 50:50 composition were superior to the rest of the tested formulations, including those prepared with pure polymers. This behavior was explained in terms of a compromise between crosslinking and rigidity (or flexibility) of the resulting polymer network. A preliminary test on microleakage in a dental enamel demonstrated that the new Is‐UDMA monomer is a potential replacement for the Bis‐GMA monomer in dental restorative materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44591.  相似文献   

18.
A composite of poly(N‐vinylcarbazole) (PVK) containing gold nanoparticles (GNPs) was synthesized via simple solid‐state in situ bulk polymerization of N‐vinylcarbazole in the presence of GNPs at a high temperature. Both PVK and PVK–GNP composites were characterized by Fourier transform infrared (FTIR) and UV–vis spectroscopy. The surface morphology of the composites was studied by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy, and transmission electron microscopy (TEM). Thermal stability was identified via thermogravimetric analysis. The composites were fabricated into films using the Langmuir–Schaefer process. The enhancement in the characteristics of room temperature I–V, pressure–area isotherms, and photoelectrochemical behaviors was observed in the composite films. Results suggest that a charge transfer process occurs across the hybrid at the interface of the PVK–GNP composites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers  相似文献   

19.
2‐Hydroxyethyl methacrylate (HEMA) solution (1–10 wt %) was prepared in methanol and phosphate glass fibers were immersed in that solution for 5 min before being cured (irradiation time: 30 min) under UV radiation. Maximum polymer loading (HEMA content) was found for the 5 wt % HEMA solution. Degradation tests of the fibers in aqueous medium at 37°C suggested that the degradation of the HEMA‐treated fibers was lower than that of the untreated fibers. X‐ray photoelectron spectroscopy revealed that HEMA was present on the surface of the fibers. Using 5 wt % HEMA‐treated fibers, poly(caprolactone) matrix unidirectional composites were fabricated by in situ polymerization and compression molding. For in situ polymerization, it was found that 5 wt % HEMA‐treated fiber‐based composites had higher bending strength (13.8% greater) and modulus (14.0% greater) than those of the control composites. For compression molded composites, the bending strength and modulus values for the HEMA‐treated samples were found to be 27.0 and 31.5% higher, respectively, than the control samples. The tensile strength, tensile modulus, and impact strength of the HEMA composites found significant improvement than that of the untreated composites. The composites were investigated by scanning electron microscopy after 6 weeks of degradation in water at 37°C. It was found that HEMA‐treated fibers inside the composite retained much of their original integrity while the control samples degraded significantly. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

20.
Bio‐based compounds (FmHPM and FdHPM) with a furan backbone and photo‐polymerizable 2‐hydroxypropyl methacrylate (HPM) group(s) were synthesized from carbohydrate‐derived furanyl alcohols (furan‐2‐methanol and furan‐2,5‐dimethanol) and their photo‐polymerizing behaviors and mechanical properties after photo‐polymerization were investigated. Half time values (t1/2) of bio‐based FmHPM and FdHPM were 10.4 s and 3.0 s and their shrinkage ratios were 3.0 and 6.1% during photo‐polymerization, respectively. Tensile‐shear strength of glass and polycarbonate joints bonded by bio‐based furanic compounds appeared in range of 0.2–0.6 MPa and pencil hardness of film coated by bio‐based furanic compounds after photo‐polymerization showed 2H–3H. Newly synthesized bio‐based furanic compounds allowed the feasibility to alternate petroleum‐based Bis‐GMA/TEGDMA, photo‐polymerizable composition widely utilized in a variety of applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

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