外文翻譯--利用一種新方法估算苯乙烯-二乙烯基苯共聚物的孔體積

1、中文 中文2345 2345字出處： 出處：Polymer testing, 2004, 23(7): 835-838 A new methodto estimate pore volume of porousstyrene–divinylbenzene copolymersMuhammadArif Malik , Munir Ahmed, Muhammad IkramAbstract：A new method to estimate

2、the pore volume of porous styrene－divinylbenzene copolymer beads is proposed.The estimatedpore volume（PVe）is basedon the solubility parameters （δi） andthe corresponding weight fractions （fi） of styrene, divinylbenzenes a

3、nd diluents in the polymerization mixture. The equation used is: PVe=1.136（∑δi fi）2－31.193∑δi fi＋98.825. Regression analysis results show that an ideally close match of the predicted pore volume andthe pore volume dete

4、rmined by mercury porosimeter is achievedwith R2=0.99, when non-polar and moderately polar liquids are employed as diluents. In the case of strongly polar (H-bonding) liquids as diluents, the method should be used only t

5、o predict a trend towards an increase or decrease in pore volume, which occurs as a result of variation in the composition of polymerization mixture. Keywords: Styrene-divinylbenzene; Pore volume estimation; Solubility

6、parameters; Macroporous resins; Polymeric adsorbents1. IntroductionPorous styrene–divinylbenzene (S-DVB) copolymer beads are produced on an industrial scale as well as in laboratories throughout the worldby o/w suspensi

7、on polymerization andthen convertedto ionexchangers,chelating resins, supports for catalysts and enzymes, etc. . The monomers are diluted with some inert organic liquidthat introduces porosity in the copolymer . The por

8、osity is determined by amount andsolvating property of the diluents andthe degree of cross-linkage in the copolymer . This has been a subject of research interest in the past 50 years, as is evident from review articles

9、 published from time to time , and some recent research articles .Porous copolymers from a number of relatedmonomers have also been synthesizedby the same technique, e.g., methacrylamide t styrene divinylbenzene , acryl

10、onitrile–divinylbenzene , glycidyl methacrylate–ethyleneglycol dimethacrylate , methacrylic acid–triethyleneglycol dimethacrylate , acrylic acid–triethyleneglycol dimethacrylate, acrylamide–ethyleneglycol dimethacrylate

11、 , 4- vinylpyridine–divinylbenzene, etc. Some important properties of the derived products depend on the porous structure of the S-DVB base copolymer . Pore volume is an important parameter that is relatedto the porous

12、 structure of the copolymer. The pore volume in the dry state of the copolymer is usually determined by nitrogen desorption(BET) or mercury penetration methods. These methods require expensive instruments. We have propo

13、seda simple, inexpensive, yet reasonably accurate methodof pore volume determination, which is based on the density of the dried copolymer beads . Here, we propose a simple empirical relation which can be usedto pre-de

14、termine pore volume of the S-DVB the data points obtained experimentally in the present work further refinedthe polynomial. The final relationship was foundto be the following: PVe=1.136（∑δi fi）2－31.193∑δi fi＋98.825. The

15、 R2 value was foundto be 0.96 for the data points taken from literature andit improved to 0.99 for the data points of the present study. The difference is explained by the fact that different research groups reported t

16、he data points in different time periods, which increases the element of random error in the data. The R2 values andthe visual observation from Fig. 1 show that pore volume can be estimatedwith reasonably goodaccuracy wh

17、en ∑δi fi ≤9.7H. It covers almost all the non-polar and moderately polar liquids employed as diluents. In the case of H- bonding diluents,the proposedmethodmay not predict the pore volume accurately, but it can predict

18、a trend towards an increase or decrease in pore volume as a result of variation in the composition of the polymerizationmixture.The methodis basedon the polymerization mechanism proposedby many researchers . According t

19、o the mechanism, the copolymer molecules stay swollen if theirδvalue is close to theδvalue of the ambient liquid. When the diluents are removed at the end, the copolymer matrix shrinks showing no pores in the dry state.

20、 The copolymers may still have large spaces between copolymer chains andcross- links, i.e., microreticular porosity, which may reappear upon swelling with some goodsolvent. On the other hand, if theδvalue of the copolym

21、er differs from theδ value of the ambient liquid, the copolymer precipitates and acquires spherical shapes callednuclei. The nuclei grow into microspheres as the polymerization progresses. The microspheres agglomerate w

22、ith each other resulting in a honeycomb like structure. When the diluents are removed, the permanent pores or macroreticular porosity is left behind, which, in fact, is the void space between microsphere agglomerates.

23、Pore volume in the dry state of the copolymer is a measure of its macroreticular porosity. The larger the difference between the d values of the copolymer andthe ambient liquid, the stronger will be the phase separation