Atlanta, Georgia -- US manufacturers of residential refrigerators currently use non-chlorine containing hydrochlorofluorocarbons (HFCs) as blowing agents for rigid polyurethane insulating foam.
Bayer MaterialScience notes that HFCs have come under regulatory scrutiny due to their high global warming potential (GWP). Since cyclopentane is already widely used by the appliance industry in many regions around the world due to its lower GWP, some makers of residential refrigerators in the US are now showing interest in this blowing agent, due to the uncertainty surrounding future use of HFCs.
Bayer MaterialScience's Dr Steve Aprahamian has studied the relationship between various processing variables and key physical properties of experimental polyurethane foam systems blown with cyclopentane.
His findings were detailed in a technical paper: "Effects of Processing Variables on a Polyurethane Foam System Blown with Cyclopentane," presented Monday 24 Sept, as part of the Appliances/Energy Critical Foams session during the Center for the Polyurethanes Industry's 2012 Polyurethane Technical Conference in Atlanta.
Aprahamian studied two analogous polyurethane systems, including a typical cyclopentane-based system that would be used to manufacture rigid insulation for appliances, and an optimised system based on an increased catalyst level. He compared the two systems for string-gel time; minimum fill density; demould performance; core density; dimensional stability; thermal conductivity and compressive strength.
"Developing a polyurethane system involves many compromises," explains Aprahamian, in a BMS press release.
"There is a balance of robustness of the system to allow large processing windows versus optimisation of key performance indicators," he continued, emphasising that in addition to that balance, it is important to be aware of not only key independent variables that can be directly controlled, but key dependent variables that can affect other dependent variables.