Back SearchTitle: MORPHOLOGY AND PHYSICO-MECHANICAL PROPERTIES OF CLOSED CELL MICROCELLULAR EPDM RUBBER VULCANIZATES: EFFECT OF CONDUCTIVE CARBON BLACK AND BLOWING AGENT
Page Range: p.127-144
Author(s): Mahapatra S P; Tripathy D K
File size: 187K
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Issue Year: cp
Volume: 23
Issue No: No. 3
Abstract
The morphology of the composite based on a controlled long chain branching grade of oil-extended EPDM (Keltan 7341A) and a highly conductive carbon black(Vulcan XC72)-filled compound was studied by SEM photomicrography with variation of blowing agent and conductive carbon black filler contents. The average cell size, maximum cell size and cell density varied with variation of blowing agent and filler contents. Physical properties such as relative density, hardness, TS, modulus and tear strength decreased with blowing agent concentration. Enclosed gas pressure in a closed cell increased the relative modulus at higher strain. EB decreased with blowing agent content at higher filler contents. At lower filler content, it increased with both filler and blowing agent contents. The elastic nature of closed cells reduced the hysteresis loss compared with solid compounds. The stress relaxation behaviour was independent of blowing agent content. 36 refs.
Title: NEW APPLICATION OF POLYURETHANE AS POROUS HYDROGEL CARRIER FOR MICROORGANISMS OF WASTE WATER TREATMENT
Page Range: p.145-159
Author(s): Sato T; Uehara T; Yoshida H
File size: 213K
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Issue Year: cp
Volume: 23
Issue No: No. 3
Abstract
A porous polyurethane-urea hydrogel was prepared by reaction of copoly(ethylene oxide-propylene oxide)triol terminated with toluene diisocyanate and water. The hydrogel was highly compatible with microorganisms and had good mechanical properties. This hydrogel was found to be very suitable for the newly-developed biological nitrogen removal process for waste water. In the biological reactor of the process, the porous hydrogel cubes on which the nitrification bacteria were fixed promoted very rapid nitrification of the nitrogen sources in the waste water. The characteristics of the porous polyurethane-urea hydrogel are reported, together with the performance of the biological nitrification process using this hydrogel as a floating carrier of microorganisms. 6 refs.
Title: CHANGE OVER TIME IN THE THERMAL CONDUCTIVITY OF TEN-YEAR-OLD PUR RIGID FOAM BOARDS WITH DIFFUSION-OPEN FACINGS
Page Range: p.161-171
Author(s): Albrecht W
File size: 104K
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Issue Year: cp
Volume: 23
Issue No: No. 3
Abstract
Various accelerated ageing processes were used to estimate the long-term change in thermal conductivity of PU rigid foam. The results provided safety increments to cover a lifetime in practice of between 25 and 50 years. A research project was conducted to compare estimated increments with the change over time in thermal conductivity of real boards. The thermal conductivity of the PU boards was examined in full thickness and the cell gas composition was determined over a period of 10 years. The shape of the curves and the measured values were compared with the typical diffusion coefficients and thermal conductivity of cell gases. The development of the curves showed that the fixed increments in the European standard EN 13165, 2001-10 for pentane-blown PU foams were correctly calculated. These fixed increments provided assurance for the users of PU rigid foam boards over very long periods, e.g. 25 years, and gave confidence to builders and building supervisory authorities. 6 refs.