عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In many processes polymeric foams can be produced by using chemical or physical blowing agents. In this work for polyethylene foam production, the chemical blowing agents and compression moulding process were employed. At first, by using DSC diagram of two polyethylene grades, a suitable polyethylene grade was selected for foam production and then we discuss about blowing agent critical percent in foam production.
Usually it was assumed that foam density decreases by increasing the chemical blowing agent concentration, but it is discovered in this work that there is a critical percent for each chemical blowing agent, for beyond critical percentage foam density increases by increasing blowing agent percent. The level of critical quantity is related to the amount of released gas of each chemical blowing agent. In this study, we have used three types of chemical blowing agents. Because of relationship between foam properties and foam density, a formulation is presented which is applicable for a special end use.