Evaluation of Thermal Properties of E-Glass/ Epoxy Composites Filled By Different Filler Materials
This paper compares the values of the thermal and fire resistance properties of composites made using the hand layup technique. E-Glass fiber reinforced epoxy composites was fabricated by filling varying concentration of aluminum oxide (Al2O3), magnesium hydroxide(Mg(OH)2), silicon carbide (SiC), and hematite powder. The main aim of this work was to determine the thermal conductivity, thermal expansion coefficient, time to ignition and flame propagation rate of composites. Experimental results show that Al2O3 and Mg (OH)2 filled composites exhibited low thermal conductivities. Composites filled by SiC particles exhibited low thermal expansion coefficient when compared with other filled composites. Fire test results indicated that increase the loading of Al2O3, Mg (OH)2, and hematite powder increase the time to ignition and reduces the flame propagation rate of composites.
The thermal-expansion behaviour of hot-compacted polypropylene and polyethylene composites
In this paper we describe a study of the thermal-expansion behaviour of hot-compacted woven polypropylene and polyethylene composites. The thermal expansion of the compacted sheets is shown to relate to both the molecular structure which is produced after the hot-compaction procedure has been completed and the architecture of the woven material, which includes the effects of thermal and elastic anisotropy. The annealing effect of the hot-compaction process on the structure of hot-compacted polypropylene tapes, was investigated by measurements of shrinkage force, elastic modulus and thermal expansion measurements. The hot-compaction process is seen to have a profound effect on the structure of the original polypropylene tapes, owing to the combined effects of shrinkage of the oriented amorphous phase and melting and recrystallisation of the crystalline fraction. The influence of the woven architecture of the composites has been investigated through the development of a simple model, which shows that the measured composite values can be understood in terms of the anisotropic thermal expansion of the individual fibres or tapes of which the compacted composites are composed, together with their anisotropic thermal and elastic properties: account is also taken of the woven architecture which comprises the compacted woven materials. The effect of the mechanical and thermal anisotropy was, as expected, found to be most pronounced in the hot-compacted polyethylene composites.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.