Effect of High-Pressure Carbon Dioxide on the Foaming Process in Polystyrene | Chapter 7 | Chemical and Materials Sciences: Developments and Innovations Vol. 5

   This paper examines the effect of high-pressure carbon dioxide on the foaming process in polystyrene near the glass transition temperature. The foaming was studied using a cylindrical high-pressure view cell with two optical widows. The chemical structure of polymers greatly impacts CO2 solubility and diffusivity. The CO2-philic groups such as carbonyl or ether groups in the backbone or on side chains of a polymer interact with CO2 and help with the dissolution of CO2 within the polymer. This technique has potential applications in the shape foaming of polymers at lower temperatures, dye impregnation and polystyrene foaming. Three sets of experiments were carried out at operating temperatures of 50, 70 and 100oC each over a range of pressures from 24 to 120 bar. Foaming was not observed when the polymer was initially at conditions below Tg but was observed above Tg. The nucleation appeared to occur randomly leading to subsequent bubble growth from these sites, with a maximum radius of 0.02 - 0.83 mm. Three models were applied to the foaming experimental data. Bubbles appeared in all the experiments without exception. The nucleation appeared to occur randomly leading to subsequent bubble growth from these sites. With time, more bubbles nucleate and grow, and the bubbles initially appear to be circular. Model C was applied to assess whether a varying viscosity and diffusivity model with the WLF equation. The model shows very good agreement by using realistic parameter values. The expansion occurs by diffusion of a dissolved gas from the supersaturated polymer envelope into the bubble. Many theories have been proposed for the nucleation radial growth of a single bubble in an infinite expanse of melt.

 

Author(s) Details

Salah Al-Enezi
Petroleum Research & Studies Centre (PRSC), Kuwait Institute for Scientific Research (KISR), Kuwait.

 

Please see the book here:- https://doi.org/10.9734/bpi/cmsdi/v5/1555

Study of the Thermal Properties of Raffia Bamboo Vinifera L. Arecaceae: Current Developments | Chapter 7 | Emerging Trends in Engineering Research and Technology Vol. 1

 Raffia is a somewhat fast-growing touch tree, from the family of Arecaceae, attacked in marshy regions and along waterways. In this study, the “Raffia Bamboo” is the stalk of a palm, made of a dainty marrow inside a thin structure, smooth and hard to protect the latest. In our region, this material is widely used to build all the cheap traditional families and furniture, to create granaries storage of dry products, to build hen coops, to make ribbon. Tus, various tasks are organized around this material, accompanying the fight against poverty. To our information, information on allure thermal properties is nearly nonexistent. The exploratory determination of the transverse warm properties of the dry shell, the dry essence, and the whole dry bamboo assisted to find, for each, a heat required to raise temperature, a thermal diffusivity, a thermal generated power, and finally a warm effusivity. From the analysis of results, we understand that the thermal properties of raffia bamboo Vinifera L. Arecacea manage a very good warm insulator.

Author(s) Details:

E. Foadieng,
Higher Technical Teachers' Training College (HTTTC), Kumba, University of Buea, Cameroon.

P. K. Talla,
Laboratoire de Mécanique et de Modélisation des Systèmes Physiques (L2MSP), University of Dschang, Cameroon.

G. N. Kamgang,
Laboratoire de Mécanique et de Modélisation des Systèmes Physiques (L2MSP), University of Dschang, Cameroon

M. Fogue,
Laboratoire d’Ingénierie des Systèmes Industriels et de l’Environnement (LISIE), IUT-Fotso Victor, University of Dschang, Cameroon.

Please see the link here: http://bp.bookpi.org/index.php/bpi/catalog/book/147