6ASHFORD P. Blowing agent blends: A solution to the insulation foam producers dilemma[J]. Urethanes Technology ,2006,23 ( 1 ) :56 - 58.
7LOTFABAD T B, SHOURIAN M, ROOSTAAZAD R,et al. An efficient biosurfactant-producing bacterium Pseudomonas aeruginosa MRO1, isolated from oil excavation areas in south of Iran [J]. Colloids and Surfaces B : Biointerfaces ,2009,69 ( 2 ) : 183 - 193.
8SAVOLY A, ELKO D P. Foaming agent composition and process : US ,5714001A [ P]. 1998-02-03.
9SAVOLY A, ELKO D P. Foaming agent composition and process : CA ,2081299A1 [P]. 1993-04-26.
10YANG Q, ZHU P, WU X,et al. Properties of concrete with a new type of saponin air-entraining agent[ J]. Cement and Concrete Research, 2000, 30 ( 8 ) : 1 313 - 1 317.