Rigid polyurethane foam is found virtually everywhere in our modern world and is used in sound and thermal insulation applications such as refrigerators, insulated buildings, thermosets. Organometallic compounds are used as polyurethane catalysts since they are very highly selective towards the isocyanate-polyol reaction. Also, amine catalysts are used to balance both the gelling reaction and the gas-forming or foaming reaction responsible for foam formation. In this work, the effect of a tin octoate catalyst on the mechanical properties and morphology of polyurethane foam were investigated. Also, the thermal conductivity and sound absorption coefficient for polyurethane foam mortar formulations were measured. The morphological properties of polyurethane foam were investigated using scanning electron microscope to determine the influence of varying the concentration of tin octoate. It was clear from the results that polyurethane foam has good thermal and sound insulation capabilities.

If current guidelines are applied, all cases of malignancy may be picked up, but identification of patients with curable disease is poor. Use of the guidelines did not select patients with other upper gastrointestinal disease, although many patients were receiving acid-suppression therapy at the time of their endoscopy. Implementation of test-and-treat strategies would result in a significant reduction in the workload of open-access endoscopy.

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This paper describes investigations on the effect of using water-soluble polymers (polyethylene glycol (PEG) and polyacrylamide (PAM)) as self-curing agents on the water retention, degree of hydration, water absorption, permeable pores and microstructural characteristics of Portland cement mixes with and without silica fume as cement replacement. Mixes including self-curing agents showed better water retention, higher content of non-evaporable water, lower water absorption and permeable pores compared with non-cured mixes without self-curing agents. For mixes without silica fume, the use of PEG+PAM was more effective than the use of PEG alone, especially at late ages. The rate of hydration after 28 days of hardening for mixes containing 8% silica fume was higher when PEG+PAM was used than the rate of similar mixes with PEG solely. Investigation of the microstructural characteristics showed a denser microstructure and a lower tendency for microcrack formation for self-cured mixes with and without silica fume compared with similar non-cured mixes.