نتایج جستجو برای: elastomers
تعداد نتایج: 3649 فیلتر نتایج به سال:
OBJECTIVE The purpose of this study was to investigate the antimicrobial effect of silverized elastomers on mutans streptococci in dental plaque. METHODS Forty patients undergoing orthodontic treatment were randomly placed into 1 of 2 groups. We examined the maxillary right and left central incisors and premolars, and the mandibular right and left canines of all participants. We ligated the r...
OBJECTIVE: The aim of the present study was to evaluate color changes and force degradation of orthodontic elastomeric ligatures in different stretching patterns during a 8-weeks period. METHODS: Two elastomers with the minimum and two with the maximum color changing, and gray elastomers of two brands (American Orthodontics and Ortho Technology) were selected according to an opinion poll wit...
Cylindrical elastomers were prepared through the UV-initiated crosslinking of terminally acrylated, 8,000 Da star-poly(trimethylene carbonate-co-ε-caprolactone) and star-poly(trimethylene carbonate-co-D,L-lactide). These elastomers were implanted intramuscularly into the hind legs of male Wistar rats to determine the influence of the comonomer on the weight loss, tissue response, and change in ...
The present study describes the effect of NCO/OH and triol/diol ratios on the mechanical properties of Nitro functionalized Hydroxyl-terminated polybutadiene (Nitro-HTPB) elastomers. The progress of the cure reaction of Nitro-HTPB and toluene diisocyanate (TDI) is evaluated by following up the variations in the IR absorption bands of the NCO stretching and the CO ...
OBJECTIVES To compare (i) the in vivo release of fluoride from fluoridated elastomers to the in vitro release, and (ii) the residual fluoride content of the elastomers after 1 week in the mouth with and without fluoride toothpaste and mouthrinse. DESIGN A prospective, longitudinal, cross-over study. SUBJECTS AND METHOD Six subjects were recruited by poster to take part in the study. Each su...
Swellable elastomers are used to seal flow channels in oilfield operations. After sealing, the elastomers are constrained triaxially, and a contact load builds up between the elastomers and surrounding rigid materials. For these applications, the ability to predict the evolution of the contact load is important. This work introduces an experimental setup to measure the contact load as a functio...
Soft, solvent-free poly(dimethylsiloxane) elastomers are fabricated by a one-step process via crosslinking bottlebrush polymers. The bottlebrush architecture prevents the formation of entanglements, resulting in elastomers with precisely controllable low moduli from 1 to 100 kPa, below the lower limit of traditional elastomers; moreover, the solvent-free nature enables their negligible adhesive...
We study the low-frequency, long-wavelength dynamics of soft and semi-soft nematic elastomers using two different but related dynamic theories. Our first formulation describes the pure hydrodynamic behavior of nematic elastomers in which the nematic director has relaxed to its equilibrium value in the presence of strain. We find that the sound-modes structure for soft elastomers is identical to...
Polymer latexes are being increasingly used in the construction industry as modifiers, especially in hydraulic cement concrete and mortar. Figure 1 presents polymeric latexes used as cement modifiers. Among the different presentations of polymeric latexes, elastomers are the most widely used (Ohama, 1995). In practice, there are two basic elastomers applicable to cement mixes and these are natu...
OBJECTIVE To investigate the effect of fluoridated elastomers on the quantity of disclosed dental plaque surrounding an orthodontic bracket in vivo. DESIGN A randomized, prospective, longitudinal clinical trial, employing a split mouth, crossover design. SETTING The Orthodontic Departments of Liverpool and Sheffield Dental Hospitals. SUBJECTS AND METHODS The subjects were 30 individuals a...
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