کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5183324 | 1381014 | 2012 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Preparation and characterization of polyisoprenes and polybutadienes having 1,2-Â and 3,4-linkages preferentially Preparation and characterization of polyisoprenes and polybutadienes having 1,2-Â and 3,4-linkages preferentially](/preview/png/5183324.png)
Polyisoprenes (PI) and polybutadienes (PB) both having vinyl-type side chains preferentially were prepared and characterized. Both polymers were anionically polymerized with cumyl potassium or pottassium naphthalenide as initiators in a polar solvent, tetrahydrofuran, at low temperature. From the 1H NMR measurement, the PI contains 3,4- and 1,2-microstructures and PB does 1,2-microstructure preferentially. All the samples covering the molecular weight range of 37 k â¤Â Mw â¤Â 724 k for PI and 35 k â¤Â Mw â¤Â 197 k for PB were confirmed to have narrow molecular weight distribution. Measured glass transition temperatures, i.e., 11.0 °C for PI and â0.7 °C for PB are both considerably high compared with those of 1,4-microstructure-rich analogues. Intrinsic viscosity measurements in 1,3-dioxane for PI and 2-octanol for PB were carried out, and the segment lengths of the 3,4-/1,2-rich PI and 1,2-rich PB were estimated to be 0.60 nm and 0.59 nm, which are both considerably shorter than the values for two polydienes having 1,4-microstructures preferentially, i.e., 0.66 nm for both 1,4-rich PI and PB. Furthermore plateau moduli of both polymers are determined by dynamic viscoelastic measurements.
Journal: Polymer - Volume 53, Issue 15, 6 July 2012, Pages 3354-3359