五種不同溶劑用於製備五種具有不同體積之聚甲基丙烯酸甲酯薄膜,薄膜之自由體積與製備薄膜之溶劑沸點呈正比關係,薄膜自由體積增加則薄膜氣體透過係數增大,但是薄膜自由體積增加似乎不會增加薄膜氣體溶解係數,由此可知薄膜之自由體積主要影響氣體在薄膜中之擴散係數而非溶解係數。
Poly(methl methacrylate)(PMMA) was cast from five different solvents to form five membranes of different free volumes. It was found that the free volumes of the membranes followed the order of the boiling points of the solvents from which they were cast. An increase in FFV increased the gas permeability but apparently did not increase the gas solubility. The results indicated that the gas diffusivity in the membrane was strongly affected by the fractional free volume of the membrane, but that the gas solubility was not.