جستجوی مقالات مرتبط با کلیدواژه « خواص گرمایی » در نشریات گروه « شیمی »

Epoxy thermoset resins have been used in the composite, construction, electronics, adhesive and coatings industries due to their good thermal, electrical and chemical properties. Distribution and dispersion of nanoparticles in polymer matrix is an important and influential issue in the mechanical properties of epoxy nanocomposites. Curing kinetics equations are used to evaluate and optimize the production process, and degradation kinetics modeling has become widely used as an essential tool for engineers to reduce costs and product quality. Addition of modified carboxyl and amine groups to pure epoxy resin does not change the curing reaction mechanism and also modifying the surface of nanodiamond increases the curing rate of epoxy nanocomposite. Investigation of hybrid thermal stability of epoxy nanocomposites in the presence of nanodiamonds and graphene oxide showed that the simultaneous presence of two different types of nano material can increase the thermal stability. In this research, the effect of adding nano diamonds and modified nano diamonds on morphology, mechanical and rheological properties, and modeling of curing kinetics and degradation kinetics and tribological properties have been investigated.

Carboxymethyl cellulose is a polysaccharide which forms strong and clear films. Montmorillonite and cellulose nanowhiskers are two types of nanoparticles with sheet and rod geometric shapes, respectively. Montmorillonite is nonrenewable and non biodegradable and cellulose nanowhiskers are renewable and biodegradable filler. Cellulose nanowhiskers are not produced commercially and in this research we prepared them from cotton linter. Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) indicated that the prepared nonowhiskers suspernsion having an average length of 240 nm and diameter of 13 nm respectively. In this study, carboxymethyl cellulose (CMC)-Polyvinyl alcohol (PVA) nanocomposite films, containing 3-10% nanoparticles (W/W CMC), were prepared by casting method and their physical properties were compared. In comparison to control film, 28.21% reduction in Water Vapor Permeability (WVP) was observed in the films containing 10% Wt cellulose nonowhiskers and samples with 7% cellulose nanowhiskers, whowed the lowest surface hydrophilicity (contact angle = 59.28°). On the other hand, nanocomposite containing 10% montmorillonite exhibited 29.06% reduction in WVP compared to the control film samples with 10% montmorillonite, shwed the lowest surface hydrophilicity (contact angle = 65.09°). Significant difference in WVP value and contact angle of two types of nanocomposit only observed at 3 and 10% content of nanoparticles, respectively, by Duncan test (Pg) of the resulted nanocomposite films. The glass transition ddisappeared gradually and no glass transition was observed in the thermograms of the films containing higher amount of nanoparticles. Adding of nanoparticles caused to decrease in melting point of the both type of films.