Search results for "Curing"

Chromium liquid waste inertization in an inorganic alkali activated matrix: Leaching and NMR multinuclear approach

2015

A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈ 2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid ha…

Polymer matrices for composites obtained through radiation curing of epoxy resins

2004

Ethnobotanical research in Cava de' Tirreni area, Southern Italy

2019

Abstract Background To best of our knowledge, this is the first quantitative ethnobotanical study with the aim of documenting the local knowledge and practices of using plants for curing diseases in the Cava de’ Tirreni area, Salerno Province, Campania Region, Italy. The present ethnobotanical field study, carried out during 2016–2017, documents the local uses of 119 plant species for medicinal, food and domestic purposes. Methods Ethnobotanical data were documented from 70 informants: field data were collected and information on the uses of plants was gathered through semi-structured and structured interviews with persons who still retain traditional ethnobotanical knowledge. Documented da…

Sapropel as a Binder: Properties and Application Possibilities for Composite Materials

2015

Recent development trends largely look for possibilities of a wider use of natural materials and local resources. In this perspective, the use of organic rich lake sediment - sapropel - as a binding material in line with other environmentally friendly filling materials can be considered as a challenge. Sapropel itself is a valuable resource with multiple areas of application, for example, medicine, veterinary, agriculture, livestock farming, balneology, cosmetic applications, construction, and its application options have been widely studied in the 20th century in the Baltic countries, Ukraine and Russia. Birch wood fibre and sanding dust, hemp shives, 'Aerosil' are used as a filler and thr…

The effect of light curing units and modes on cytotoxicity of resin-core systems

2010

Objective: The aim of this study was to compare the cytotoxic effects of various resin-based core materials that were cured with three light curing units (LCUs) in different modes on L?929 mouse fibroblast cells over 24 h and 72 h periods. Study design: Eighty-four cylindrical discs (2 mm in thickness and 6 mm in diameter) of each material (Rebilda, Voco; Build-It FR, Pentron; Clearfil DC Core, Kuraray and Bis-core, Bisco) were cured by QTH LCU (soft-up and high-power modes), LED LCU (exponential and standard modes) and PAC LCU (normal and ramp-curing modes). Then the samples were aged for 24 and 72 hours in Dulbecco?s Modified Eagle Medium/Ham?s F12 (DMEM/F12). After each ageing interval, …

Effect of saliva contamination on bracket failure with a self-etching primer: A prospective controlled clinical trial

2010

Introduction The aim of this study was to evaluate in vivo the effect of saliva contamination at different stages of the bonding procedure on the bond failure rate and the adhesive remaining on teeth after debonding brackets bonded with a hydrophilic self-etching primer (Transbond Plus self-etching primer [TSEP], 3M Unitek, Monrovia, Calif). Methods This was a prospective controlled clinical trial. The sample consisted of 46 patients with similar treatment plans and mechanotherapies. Stainless steel brackets (n = 531) were bonded with TSEP. The patients were divided into 2 groups: contamination with saliva before TSEP application and contamination with saliva after TSEP application. In both…

The cytotoxicity of resin composites cured with three light curing units at different curing distances.

2011

Objective: The purpose of this study was to compare the effect of light curing distance on the cytotoxicity of five resin composites cured with three high-power light curing units. Study design: Seven cylindrical discs of each material (Grandio ®, Voco; Filtek ? Z250, 3M ESPE; Clearfil ? AP-X, Kuraray Co. Ltd.; Aelite ? LS, Bisco Inc. and Simile ®, Pentron) were cured. For curing, soft-up mode of quartz-tungsten-halogen, exponential mode of light emitting diode for 20 s, and ramp-curing mode of plasma arc light curing units for 6 s were used. The curing tip distances were determined as 2 and 9 mm and controlled via the use of metal rings. After ageing the samples for 24 and 72 hours in Dulb…

Biobased Epoxy Resin by Electrochemical Modification of Tall Oil Fatty Acids

2019

A biobased epoxy resin was prepared from tall oil fatty acids (TOFAs), a byproduct of the pulping industry. As free carboxylic acids compromise resin stability, TOFA was subjected to non-Kolbe decarboxylation to give alkenes upon loss of CO2. Thereby, the degree of unsaturation is significantly increased. This electrosynthetic protocol using an undivided cell setup and inexpensive graphite electrodes in a galvanostatic operation mode was scaled to a 1.5 L reactor, making use of electric current as a green and waste-free reagent. Simple, cost-efficient epoxidation using oxone subsequently gives an epoxy resin of low viscosity. Curing with anhydrides yields thermoset materials. Dynamic mechan…

2020

Epoxy resin plays a key role in composite matrices and DGEBA is the major precursor used. With the aim of favouring the use of bio resources, epoxy resins can be prepared from lignin. In particular, diglycidyl ether of isoeugenol derivatives are good candidates for the replacement of DGEBA. This article presents an effective and eco-friendly way to prepare epoxy resin derived from isoeugenol (BioIgenox), making its upscale possible. BioIgenox has been totally characterized by NMR, FTIR, MS and elemental analyses. Curing of BioIgenox and camphoric anhydride with varying epoxide function/anhydride molar ratios has allowed determining an optimum ratio near 1/0.9 based on DMA and DSC analyses a…

Processes during preparation of lead/acid battery positive plates from tetrabasic lead sulfate (4BS) pastes

1993

Abstract Tthe processes studied during this investigation were paste mixing and curing. Tetrabasic lead sulfate 4BS pastes were prepared by solution and paste methods both from α-PbO and mill oxides, and the development of 4BS was carried out already during the paste mixing stage. the 4BS pastes were characterized by SEM, TEM, XRD and wet-chemical methods, and the results were compared with those obtained from the characterization of corresponding tribasic lead sulfate (3BS) pastes. The preparation method was found to be one dominating factor affecting both the morphology and structure of 4BS active masses. The selection of raw material gave an additional effect on the morphology. Additiona…