Effect of molecular weight on secondary Newtonian plateau at high shear rates for linear isotactic melt blown polypropylenes

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F70883521%3A28110%2F18%3A63517056" target="_blank" >RIV/70883521:28110/18:63517056 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.jnnfm.2017.11.009" target="_blank" >http://dx.doi.org/10.1016/j.jnnfm.2017.11.009</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jnnfm.2017.11.009" target="_blank" >10.1016/j.jnnfm.2017.11.009</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Effect of molecular weight on secondary Newtonian plateau at high shear rates for linear isotactic melt blown polypropylenes

Popis výsledku v původním jazyce

In this work, three melt blown grades of isotactic linear polypropylenes, with weight average molecular weights between 56 250–75 850 g/mol, have been characterized at 230 °C over a very wide shear rate range (10–107 1/s) by using conventional rotational and twin bore capillary rheometry equipped with novel orifice die, and by an instrumented capillary nozzle on an injection molding machine. A low shear rate primary Newtonian plateau, a pseudoplastic region and a well developed secondary Newtonian plateau (occurring between 2·106−7·106 1/s) were identified for all the polypropylene melts. Flow activation energy at low (E0) and high (E∞) shear rates was found to be 56.590 kJ/mol and 25.204 kJ/mol, respectively. Considering the typical value of pressure sensitivity coefficient for polypropylene melt, β = 20.00 GPa−1, and measured flow activation energy at the secondary Newtonian plateau, E∞ = 25.204 kJ/mol, it was found that the effect of viscous dissipation and pressure is mutually cancelled, i.e. that the measured viscosity data can be considered as the true material property within the whole applied shear rate range. For the first time, it has been revealed that the secondary Newtonian viscosity, η∞, depends linearly on the weight average molecular weight, Mw, in log-log scale as η∞=1.19·10−6Mw 1.084. The observed slope close to 1 between η∞ and Mw suggests that polymer chains in the melt are disentangled at the secondary Newtonian plateau region. This conclusion is supported by the experimental observation that the high shear rate flow activation energy E∞ for given PP melts is comparable with the flow activation energy of PP like oligomer (squalane, C30H62; 2,6,10,15,19,23-hexamethyltetracosane). The measured flow data were fitted by six different viscosity models, from which two, namely Modified Carreau and Quemada models, were suggested here for the first time. It has been found that the accuracy of utilized models to describe the measured data is the highest for the newly suggested models and decreases in the following order: Modified Quemada model, Modified Carreau model, Carreau-Yasuda model, Cross model, Generalized Quemada model and Carreau model.

Název v anglickém jazyce

Effect of molecular weight on secondary Newtonian plateau at high shear rates for linear isotactic melt blown polypropylenes

Popis výsledku anglicky

In this work, three melt blown grades of isotactic linear polypropylenes, with weight average molecular weights between 56 250–75 850 g/mol, have been characterized at 230 °C over a very wide shear rate range (10–107 1/s) by using conventional rotational and twin bore capillary rheometry equipped with novel orifice die, and by an instrumented capillary nozzle on an injection molding machine. A low shear rate primary Newtonian plateau, a pseudoplastic region and a well developed secondary Newtonian plateau (occurring between 2·106−7·106 1/s) were identified for all the polypropylene melts. Flow activation energy at low (E0) and high (E∞) shear rates was found to be 56.590 kJ/mol and 25.204 kJ/mol, respectively. Considering the typical value of pressure sensitivity coefficient for polypropylene melt, β = 20.00 GPa−1, and measured flow activation energy at the secondary Newtonian plateau, E∞ = 25.204 kJ/mol, it was found that the effect of viscous dissipation and pressure is mutually cancelled, i.e. that the measured viscosity data can be considered as the true material property within the whole applied shear rate range. For the first time, it has been revealed that the secondary Newtonian viscosity, η∞, depends linearly on the weight average molecular weight, Mw, in log-log scale as η∞=1.19·10−6Mw 1.084. The observed slope close to 1 between η∞ and Mw suggests that polymer chains in the melt are disentangled at the secondary Newtonian plateau region. This conclusion is supported by the experimental observation that the high shear rate flow activation energy E∞ for given PP melts is comparable with the flow activation energy of PP like oligomer (squalane, C30H62; 2,6,10,15,19,23-hexamethyltetracosane). The measured flow data were fitted by six different viscosity models, from which two, namely Modified Carreau and Quemada models, were suggested here for the first time. It has been found that the accuracy of utilized models to describe the measured data is the highest for the newly suggested models and decreases in the following order: Modified Quemada model, Modified Carreau model, Carreau-Yasuda model, Cross model, Generalized Quemada model and Carreau model.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10404 - Polymer science

Projekt

<a href="/cs/project/GA16-05886S" target="_blank" >GA16-05886S: Výzkum vlivu smykové a tahové reologie polymerních tavenin na stabilitu produkce meltblown nanovláken a fólií</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Non-Newtonian Fluid Mechanics

ISSN

0377-0257

e-ISSN

—

Svazek periodika

251

Číslo periodika v rámci svazku

Neuveden

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

12

Strana od-do

107-118

Kód UT WoS článku

000423003600010

EID výsledku v databázi Scopus

2-s2.0-85037540603