7HAN C D. Multiphase flow in polymer process[M]. New York:John Wiley &Sons Inc, 1982.
8Du Pont Co Ltd. Teflon/Tefzel[R]. USA: Du Pont Co Ltd,2007.
9LAU H C, BHATTACHARYA S N, FIELD G J. Melt strength of polypropylerie, its relevance to thermoforming [J]. Polymer Engineering and Science, 1998,38(11) : 192.