Influence of shearing history on the rheological properties and processability of branched polymers. V. Effect of molecular structural parameters on die swell of low‐density polyethylenes

The effect of molar mass distribution on extrudate swell of linear polymers

“…The effect of average molar mass, typically expressed via the weight-average molar mass M w , and of polydispersity has been studied among others by Graessley et al [18], Rogers [19], Mendelson and Finger [20], Racin and Bogue [21], Rokudai [22], Dealy and co-workers [23,24], Koopmans [17,25], and Wang and co-workers [26,27]. This approach has generated various valuable data sets, each focusing on different aspects affecting extrudate swell.…”

Long-Chain Branched Polypropylene: Effects of Chain Architecture, Melt Structure, Shear Modification, and Solution Treatment on Melt Relaxation Dynamics

“…An early study of shear modification of long-chain branched polymers dates back to 1969, when Hanson described modification of LDPE in direct comparison to linear HDPE, finding much stronger effects in the former case . In the late 1970s, Rokudai et al published a systematic series of papers on shear modification of LDPE − using die swell in capillary rheometry as elasticity parameter and studying processing effects in addition. In none of these early works, however, was any structural investigation of the studied polymers attempted.…”

Die Swell of Complex Polymeric Systems

“…In these early studies [16][17][18], a wide range of experiments on polymer melt swelling were performed. Some workers have reported that die swell varies with temperature [19], pressure during processing [20], molecular weight and its distribution [21][22][23], as well as molecular structure [24][25][26][27] and compounding ingredients [28]. Studies of die swell as a function of length to diameter ratio of die (L/D), entry speed and shape of the die have been reported by Han [29], Cotten [30], Lenk [31] and Vinogradov and Malkin [32].…”