in this article, the crystallization of polyethylene is investigated by the modified weighted density approximation. also, a direct correlation function of polyethylene based on the rism theory is used. the free energy of a polyethylene is calculated using the density functional theory. the crystallization and also the solid and liquid densities of polyethylene are calculated and compared with ...

The well-known key problem with concrete is that its compressive strength and the compression modulus are insufficient for a variety of applications. Our polymer concrete (PC) consists of an unsaturated polyester resin as the polymeric matrix, silica sand as the inorganic aggregate, plus atactic polypropylene (PP) fibers. A further property improvement can be achieved by gamma irradiation and w...

in petrochemical industry, the production of polyvinyl chloride (pvc) is accompanied by formation of heavy end wastes which consist of a mixture of di and multichloro compounds as kind of materials which are generated in ethylene dichloride (edc) purifcation. a high quantity of chloro compounds found in the heavy end waste allows it to be polymerized with alkaline polysulfdes to form polysulfde...

Polymer concretes (PCs) were created by using varying concentrations of silica sand as aggregate and also hematite, colemanite and a commercial epoxy resin. Hematite is known to exhibit radiation shielding properties. Mechanical performance was evaluated including unit weight, pulse velocity, compressive strength, flexural strength, splitting tensile strength, modulus of elasticity and dynamic ...

A large database consisting of 832 axial compression tests results of fiber reinforced polymer (FRP)confined concrete specimens was assembled. Using the test database, existing conventional and evolutionary algorithm models developed for FRP-confined concrete were then assessed. New genetic programming (GP) models for predicting the ultimate condition of FRP-confined concrete were developed. Th...

The effectiveness of a pervious concrete pavement to transport water through it depends on the intrinsic permeability of the system. However, this characteristic is usually defined in terms of the porosity of the material. It has been observed that porosity alone is an inadequate indicator of the permeability of pervious concretes, since the permeability depends on pore sizes, geometry and conn...

The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by indus...

blown bitumen (110/10) was mixed with heavy vacuum slops (h.v.s), 60/70 penetration grade bitumen and recycled isotactic polypropylene (ipp) at different levels. the resulting resins were used to impregnate non-woven poly(ethylene terephthalate) fibers to form composites. the modulus and penetration grade of the resulting bituminous resins were determined. it was found that these bituminous res...