Destruction of the resins structure due to heating
This article considers a polymer composition based on acetone-formaldehyde (AFR) resin, which is used to reduce water influx into the well bore during the repair insulation work. Pumping into the well bore a composition, based on AFR resin, results in self-heating that causes destruction of its own structure and, therefore, the damage of the polymer blend structure. The purpose of the present article is to find the causes of AFR resin self-heating when injected into the well bore as part of the composite mixture that leads to the destruction of its structure. Author considers exothermic reaction between AFR resin and aqueous solution of sodium hydroxide during the curing of the polymer composition. The features of the given polymer structure are studied as well. The need for further studies of the resin structure is substantiated. Based on the study conducted, five possible reasons of the AFR resin self-heating, leading to destruction of resin structure, are revealed. Recommended practices that may decrease self-heating of the AFR resin are offered.
ACETONE-FORMALDEHYDE-RESORCINOL–BASED IPNs AND THEIR GLASS-FIBER–REINFORCED COMPOSITES
Acetone-formaldehyde (AF) resin having methylol (-CH2OH) groups has been prepared and polycondensed with resorcinol (R) at equimol. ratio of AF:R to produce acetone-formaldehyde-resorcinol (AFR) resin. The three components interpenetrating polymer networks (IPNs) have been prepared from this acetone-formaldehyde-resorcinol (AFR) resin, diglycidyl ether of bisphenol-A (DGEBA) (a commercial epoxy resin) and methyl methacrylate (MMA) (a vinyl monomer) using simultaneous mode of IPN synthesis. The curing catalyst hexamethylenetetramine (HMTA) for AFR, radical initiator 2,2′-azobisisobutyronitrile (AIBN) for MMA and curing catalyst 4,4′-diaminodiphenyl methane (DDM) for the epoxy resin was employed. The various properties of three components were evaluated. All the IPNs were characterized in terms of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The glass-fiber reinforced composites (i.e. laminates) of produced IPN systems have also been fabricated and their chemical resistivity and mechanical properties evaluated.
Selective etching of InP in NaF solution
Abstract The crossing porous structure of InP has been obtained by electrochemical etching in NaF solutions. The behavior of the periodic oscillation occurs at different potential ranges for the different concentrations of solutions, and it will disappear with the concentration of the solution decreased. The scanning electron microscope (SEM) image shows that the pores have two directions on the surface and are perpendicular to each other. The two directions are assigned to [0 1 1] and [ 0 1 ¯ 1 ], respectively. The SEM image of the cross-section also shows that the two directions are assigned to [1 1 1]B and [ 1 1 ¯ 1 ¯ ]B. Both are due to the selective etching of F− ions. The crossing porous structure of InP is a very promising feature for the three-dimensional structure of III–V compound semiconductors for photonic band gap materials.