A study of the effect of nano materials on the physical properties of epoxy composites

Abstract


Introduction
Now a days the large use of polymer materials is attributed to their integration of characteristics, low weight and ease of manufacturing. However for refinement of some characteristics such as mechanical and thermal conductivity, some additives were added to polymeric matrix and formed polymer matrix composite. A composite is defined as an integration of two or more materials with characteristics different from of their components properties and distinguishable interface.
To improve the properties of composite materials investigate composites with lower fillers size. Nano composite refer to composites in which one phase has nanoscale morphology such as nanoparticles, nanotube or nano structure [1]. Rahman M et al studied the effect of nanosilica on the mechanical and thermal properties of composite material composed of epoxy with polysulfied rubber reinforced by different percentage of nanosilica (1, 3, 5) % wt. The result showed that the young's modulus and tensile strength decreased at 3% wt. The tensile strength and elongation increased at 5% wt compared with epoxy and polysulfide. The thermal conductivity was increased with the addition of nanosilica in the polymer matrix [2]. Motallebi M et al. prepared nanocomposite material consist of PP/nano CaCo 3 with particle size 70 nm at content (5, 10 and 15) % wt. The result of tensile test refer to the inclusion of CaCo 3 increased the modulus and the elongation at break and decreased the tensile strength. The addition of nano CaCo 3 increased the impact strength and have high value of impact strength at 15% wt [3]. Impact resistance: It is the energy absorbed by the body a certain block on the cross-sectional area [4]. Impact strength is calculated from the relation: [5] where I.S. = impact strength U = Energy of fracture in (joule) A = Cross section area in (m 2 ) Hardness can be defined a measure of materials resistance to plastic deformation [6]. Thermal conductivity: is the ability of a material to conduct heat. and heat transported from high to low temperature regions of a substance [6].

Materials and methods 1-Matrix materials 1.1 Epoxy resin (EP)
Epoxy resin used in this work was Sikadur -105 which is a two component, low viscosity epoxy resin system in the form of transparent liquid (which transforms into solid state after adding the hardener to it in a percentage of (2:1).

Styrene butadiene rubber (SBR)
SBR is derived from two monomers, styrene and butadiene. It is a liquid with white color.

2-Reinforcing materials 2.1 Magnesium oxide (MgO)
Magnesium oxide (MgO) which is manufactured by Z.D.N (china). It is a white powder with pure 99.9 % and grain size 30 nm. It is soluble in water and in acid and ammonia and insoluble in alcohol.

Copper oxide (CuO)
Copper oxide (CuO) which is manufactured by Z.D.N (china). It is a black powder with pure 99% and grain size 40nm, the chemical composition of copper oxide nanopowder is 79.87% content copper and 20.10 % content oxygen, and it is insoluble in water and soluble in dilute acids (NH 4 Cl), (NH 4 ) 2CO 3 .

Sample preparation
Hand Lay-Up method was used to prepare the samples. Polymer blends were prepared from epoxy and SBR with different ratios (95-5, 90-10, 85-15, 80-20, 75-25) %, and selected the optimum ratio (75-25) % and reinforced with MgO and CuO with weight ratio (3) %.     Table 3 show the effect of nano fillers on the hardness values, Fig. 2 and Table 4 show the values of hardness befor and after immersion, the results showed increased after the addition of nano materials, The increase in the hardness values return to increasing the overlap and stack which leads to reduction in the movement of polymer molecules and leads to increase in the resistance of materials to scratch and become more resistance to plastic deformation [8]. After immersion in water, a decrease in the values of hardness were for all samples because of the effect of water on the samples, which leads to the degradation of material and this leads to reduce the resistance of surface to indentation and scratch, and this showed the negative effects of period [9]. The reduction in the hardness values because of reduce interfacial adhesion between the fillers and matrix materials. Blend hardness decreased after immersion because of the degradation at the ends of polymer chains [6].    Table 5 show the effect of nano filler on the thermal conductivity and Fig. 3 and Table 6 show the values of thermal conductivity before and after immersion. From the results it found the reinforced with nano ceramic oxides leads to increase the thermal conductivity, the addition of ceramic oxides to polymer blend works to reduce the degree of crosslinking between the molecular chains that give them larger freedom of movement and increase the ability to Vibratory movement, which leads to increase the thermal conductivity [10]. After immersion in water, the increase in thermal conductivity was evident, where that water plays a role in the degradation of composite material, especially in the interface area between the matrix material and the reinforcing materials [11].