Search results for "resin"
showing 10 items of 385 documents
FIA-AAS determination of salicylic acid by a solid-phase reactor of copper carbonate incorporated in polyester resin beads.
1994
Abstract The determination of salicylic acid was carried out by reaction of the drug with copper carbonate entrapped in a polymeric material in a solid-phase reactor; the released cupric ions were monitored by flame atomic absorption at 324.8 nm. The calibration graph is linear over the range 4.0–75 μg ml −1 of salicylic acid, with a relative standard deviation of less than 1.5% and a sample throughout of 257 h −1 . The influence of foreign compounds was studied and the method was applied to the determination of salicylic acid content in two different pharmaceutical formulations.
Design and use of a Fatigue Test Machine in Plane Bending for Composite Specimens and Bonded Joints
2011
Polymeric and composites materials are increasingly used in industry as structural parts, so that specific information on their mechanical properties "at long term" (creep, relaxation, fatigue) are requested. The design and implementation of these components also requires that they are permanently connected together to perform certain functions. The use of adhesives in structural joints has increased over recent years thanks to the continuous development by companies which provide the market with adhesive having better and better mechanical properties. The main areas relate to the aerospace, aeronautical and automotive industries, where requirements are required for lightness and reliabilit…
Acoustic Emission Monitoring of Chemically Bonded Anchors
2010
This paper presents a study on the use of acoustic emission (AE) to assess the structural soundness of concrete reinforced with chemically bonded anchors. The results of an experimental work based on six pullout tests monitored using an AE instrumentation suite are reported below. In every test one rebar was embedded in the hardened concrete by means of polyester resin. The AE was adopted to moni- tor the onset and progression of any structural damage. The parametric analysis, the intensity analysis and the moment tensor analysis of AE data were used to discriminate among different sources of damage. The technique shows promise for field application and may contribute to fully understand th…
Effects of Moisture and Stresses on the Structure and Properties of Polyester Resin
2004
The results of a complex study of structural changes in a cured Norpol 440 polyester resin under the action of damp environment and mechanical loading are presented. A considerable effect of absorbed moisture on the structure and some characteristics of the material is revealed by using thermophysical methods and X-ray diffractometry. The joint effect of moisture and mechanical stress is estimated by investigating the creep in stationary and nonstationary moisture conditions. The anisotropy of the material structure formed during creep is evaluated from the results of dilatometric measurements. It is found that the degree of anisotropy of the material after creep accompanied by moisture sor…
An investigation of the influence of the macroscopic heterogeneity on the thermoelstic response of fibre reinforced plastics
2005
In this work the influence of the inherent heterogeneity in fibre reinforced plastic composites on the qualitative and quantitative evaluation of the thermoelastic signal is discussed. The role of two different levels of heterogeneity is identified, distinguishing between a micro-geometric scale characterized by the presence of different constituent materials, and a macro-geometric scale characterized by a non-uniform distribution of these constituents. Attention has been focused on the macro-scale level, presenting results of experiments performed on glass fibre - polyester resin samples, intended to highlight the influence on the thermoelastic signal of the fabric texture pattern and the …
L -lysine and EDTA polymer mimics as resins for the quantitative and reversible removal of heavy metal ion water pollutants
2012
Traditional precipitation methods for inorganic micropollutant removal from waters are increasingly being replaced by sorption methods based on both natural and synthetic materials. In this context, two novel effective heavy metal ions absorbers are presented. These resins, LYMA and LMT85, were crosslinked poly(amidoamine)s carrying amine and carboxyl groups in their repeating units. In particular, the LYMA-repeating unit contains one carboxyl and two amine groups and is a mimic of L-lysine, whereas LMT85 contains two amine and five carboxyl groups and is a mimic of EDTA. Both resins were prepared at moderate cost by simple eco-friendly procedures. The heavy metal ion set adopted as benchma…
α-Chymotrypsin-Catalyzed Reaction Confined in Block-Copolymer Vesicles
2010
Herein the reactivity of the enzyme α-chymotrypsin in the confinement of polystyrene-block-poly(acrylic acid) (PS-b-PAA) vesicles was investigated. Enzyme and substrate molecules were encapsulated in PS-b-PAA vesicles with internal diameters ranging from 26 nm to 165 nm during the formation of the vesicles. While the loading efficiencies of enzyme and substrate molecules were practically identical for vesicles of identical size, they were found to increase with decreasing vesicle size. The kinetics of the α-chymotrypsin catalyzed hydrolysis of N-succinyl-Ala-Ala-Phe-7-amido-4-methylcoumarin (AMC) was evaluated following the increase of the absorption of the product 7-amino-4-methylcoumarin …
Stiffness and strength of flax fiber/polymer matrix composites
2006
Flax fiber composites with thermoset and thermoplastic polymer matrices have been manufactured and tested for stiffness and strength under uniaxial tension. Flax/polypropylene and flax/maleic anhydride grafted polypropylene composites are produced from compound obtained by coextrusion of granulated polypropylene and flax fibers, while flax fiber mat/vinylester and modified acrylic resin composites are manufactured by resin transfer molding. The applicability of rule-of-mixtures and orientational averaging based models, developed for short fiber composites, to flax reinforced polymers is considered. POLYM. COMPOS. 27:221–229, 2006. © 2006 Society of Plastics Engineers
The effect of dentine pre-treatment using bioglass and/or polyacrylic acid on the interfacial characteristics of resin-modified glass ionomer cements.
2018
Objective To evaluate the effect of load-cycle aging and/or 6 months artificial saliva (AS) storage on bond durability and interfacial ultramorphology of resin-modified glass ionomer cement (RMGIC) applied to dentine air-abraded using Bioglass 45S5 (BAG) with/without polyacrylic acid (PAA) conditioning.Methods RMGIC (Ionolux, VOCO) was applied onto human dentine specimens prepared with silicon-carbide abrasive paper or air-abraded with BAG with or without the use of PAA conditioning. Half of bonded-teeth were submitted to load cycling (150,000 cycles) and half immersed in deionised water for 24 h. They were cut into matchsticks and submitted immediately to microtensile bond strength (μTBS) …
Physicochemical properties of novel non-meat sausages containing natural colorants and preservatives
2018
In this study, novel non-meat sausage formulations (egg white, carrageenan, and modified cornstarch) was developed and evaluated for their sensory quality. Based on a full factorial design, optimal levels of ingredients and the effect of the addition of natural coloring agents such as lycopene, paprika oleoresin, and red yeast rice powder were investigated. The formulations were assessed based on models consisting of sensory attributes including cutting ability, flavor, texture, odor, and overall acceptability. According to results of overall acceptability, the optimal levels of carrageenan, modified corn starch, and egg white for the formulation found to be 0.5, 3, and 3% (w/w), respective…