Effect of ion modification on viscoelasticity of broad molecular weight distribution polypropylene

doi:10.19491/j.issn.1001-9278.2024.01.002

Abstract

Abstract:

PP4 was obtained through treating polypropylene with a wide molecular weight distribution （BMWDPP） PP1 using an ion modifier. The molecular structures and rheological properties of PP1 and PP4 were investigated by gel permeability chromatography （GPC）， plate rotational rheology， stretch rheology， and melt strength tests. The PP degradation induced by free radicals reduced the molecular weight and polydispersity of BMWDPP. There was no real long branch chain structure generated due to the “long⁃like branched chain” effect of the ionic interaction between the metal salts on the PP chain segment. PP4 exhibits a stretch hardening phenomenon. The large molecular weight components could weaken the molecular entanglement， whereas the small molecular weight components could enhance the plasticizing effect due to the degradation of PP4. This makes its viscoelasticity lower than that of PP1.The influence of stretch strain hardening on the enhancement of melt strength is stronger than the effect of molecular weight reduction on the weakening of melt strength. Therefore， the melt strength of PP4 is higher than that of PP1 at different temperatures. This indicated that the PP was featured with linear large molecular chains at low temperature and long branched chains at high temperature.

Key words: broad molecular weight distribution polypropylene, ion modification, viscoelasticity, stretch hardening, melt strength

CLC Number:

TQ325.1⁺4

XU Yaohui, TANG Yiwen, GUO Peng, LYU Mingfu. Effect of ion modification on viscoelasticity of broad molecular weight distribution polypropylene[J]. China Plastics, 2024, 38(1): 7-13.

Figures/Tables 12

Fig.1. Long chains⁃like structure

Fig.2. Elongational viscosity curves of PP1， PP2， PP3 and PP4

样品	M_n	M_w	M_z	M_w/M_n
PP1	41 034	476 696	2 049 110	11.6
PP2	40 700	433 557	1 591 789	10.7
PP3	40 844	445 711	1 712 113	11.0
PP4	41 007	456 754	1 809 072	11.1

Tab.1. The molecular weight of PP1， PP2， PP3 and PP4

Fig.3. GPC curves of PP1， PP2， PP3 and PP4

Fig.4. Shear modulus of PP1 and PP4 against frequency

Fig.5. Shear viscosity of PP1 and PP4 against frequency at 180 ℃， 200 ℃ and 220 ℃，respectively

Fig.6. Master curves of the dynamic modulus of linear PP1 and PP4

a_T

ΔE_a/

kJ·mol^-1

a_T

ΔE_a/

kJ·mol^-1

a_T

ΔE_a/

kJ·mol^-1

Tab.2. ΔEa of PP1 and PP4

Fig.7. Cole⁃Cole plots of PP1， PP2， PP3 and PP4

Fig.8. Melt strength of PP1 and PP2 at 180 ℃， 200 ℃ and 220 ℃，respectively

Fig.9. Melt strength curves of PP1 at 180 ℃， 200 ℃ and 220 ℃，respectively

Fig.10. Melt strength curves of PP4 at 180 ℃，200 ℃ and 220 ℃，respectively

References 23

1	周持兴. 聚合物流变实验及应用［M］.上海：上海交通大学出版社，2003：57⁃62，128⁃131.
2	郭鹏，吕明福，张师军. 高熔体强度聚丙烯的研究现状与评述［J］. 化工进展， 2012， 31（2）： 158⁃162.
	GUO P， LYU M F， ZHANG S J. Research progress in high melt strength polypropylene［J］. Chemical Industry and Engineering Progress， 2012， 31（2）： 158⁃162.
3	王兴仁，李栋，杨爱武，等.宽相对分子质量分布聚丙烯技术进展［J］. 现代塑料加工应用， 2005， 17（3）： 4.
	WANG X R， LI D， YANG A W， et al.The technical progress of the breadth relativemolecular weight distributi on polypropylene［J］. Modern Plastics Processing and Applications， 2005， 17（3）： 4.
4	中国石油化工股份有限公司，中国石油化工股份有限公司北京化工研究院. 一种高熔体强度丙烯/乙烯共聚物及其制备方法：102816269［P］. 2011⁃06⁃09.
5	娄立娟，刘建叶，俞炜，等. 聚合物长支链的流变学表征方法［J］. 高分子通报，2009（10）：15⁃22.
	LOU L J， LIU J Y， YU W， et al. Rheological characterization of long chain branching［J］. Polymer Bulletin， 2009（10）：15⁃22.
6	Wu M H， Wang C C， Chen C Y. Preparation of high melt strength polypropylene by addition of an ionically modified polypropylene［J］.Polymer，2020 （202）：122743.
7	Carlos R， Lambic N， Joseph T， et al. One⁃pot synthesis of high⁃melt⁃strength isotactic polypropylene ionomers［J］.Macromolecules，2022（55）：284⁃296.
8	唐伊文，吕明福，郭鹏，等. 聚丙烯挤出物理发泡的研究进展［J］. 石油化工， 2022， 51（5）： 593⁃600.
	TANG Y W， LYU M F， GUO Peng， et al. Research progress of polypropylene extrusion physical foaming［J］. Petrochemical Technology， 2022， 51（5）： 593⁃600.
9	Guo Peng， Xu Yaohui， Lu Mingfu， et al. High melt strength polypropylene with wide molecular weight distribution used as basic resin for expanded polypropylene beads［J］. Ind Eng Chem Res， 2015， 54（1）： 217⁃225.
10	Weingart N， Raps D， Lu Mingfu， et al. Comparison of the foamability of linear and long⁃chain branched polypropylene the legend of strain⁃hardening as a requirement for good foamability［J］. Polymer， 2020， 12（20）：725⁃746.
11	Sadeghipour S M， Biglari F R， Garmabi H， et al. Rheological optimization of reactively modified polypropylene to enhance the foam extrusion performance［J］. Mater Res Express， 2019， 6（10）：105 352⁃105 363.
12	Carlos R， Joseph T， Lin T P. Extensional rheology and flow⁃induced crystal alignment in polypropylene ionomers［J］. Journal of Rheology，2022（66）：657.
13	Li Y， Yao Z， Chen Z H， et al. High melt strength polypropylene by ionic modification： preparation， rheological properties and foaming behaviors［J］. Polymer 2015（70）：207⁃214.
14	Hassager O， Mortensen K， Bach A， et al. Stress and neutron scattering measurements on linear polymer melts undergoing steady elongational flow［J］. Rheol Acta，2012（51）：385⁃394.
15	Liu J Y， Yu W， Zhou C X. Polymer chain topological map as determined by linear viscoelasticity［J］. J Rheol， 2011， 55（3）：545⁃570.
16	Carrot C， Revenu P， Guillet J. Rheological behavior of degraded polypropylene melts： from MWD to dynamic moduli［J］. Journal of Applied Polymer Science， 1996， 61（11）：1 887⁃1 897.
17	Bafna S S. Is the cross⁃over modulus a reliable measure of polymeric polydispersity？［J］. Journal of Applied Polymer Science， 1997（63）：111⁃113.
18	田敬华. 长支链聚丙烯及聚丙烯反应共混材料的制备、结构与性能的研究［D］. 上海：上海交通大学， 2007.
19	You W， Yu W. Characteristic rheological behaviors in startup shear of entangled polymer melts［J］. Nihon Reoroji Gakk， 2021， 49（1）：1⁃5.
20	Tian J H， Yu W， Zhou C X. The preparation and rheology characterization of long chain branching polypropylene［J］.Polymer，2006（47）：7 962⁃7 969.
21	Sugimoto M， Tanaka T， Masubuchi Y， et al. Effect of chain structure on the melt rheology of modified polypropylene［J］.Journal of Applied Polymer Science，1999，73（8）：1 493⁃1 500.
22	Sugimoto M， Masubuchi Y， Takimoto J， et al. Melt rheology of polypropylene containing small amounts of high molecular weight chain. I. Shear flow［J］. Journal of Polymer Science Part B： Polymer Physics， 2001， 39（21）：2 692⁃2 704.
23	Wasserman S H， Graessley W W. Prediction of linear viscoelastic response for entangled polyolefin melts from molecular weight distribution［J］. Polymer Engineering & Science， 1996， 36（6）：852⁃861.

[1]	LUO Fei, LI Cuijuan, LIU Zhuojia, LIU Yuxin, SHI Suyu, DANG Xudan, LIU Chuntai, ZHAO Yongtao. Study on Relationship between Molecular Orientation and Dynamic Viscoelasticity of Polycarbonate [J]. China Plastics, 2021, 35(9): 81-86.
[2]	LI Maodong, LI Yan, YANG Bo, WANG Zhigang, LUO Wenbo. Characterization and Constitutive Modelling of Nonlinear Creep of PE100 Grade Gas Pipe Material [J]. China Plastics, 2021, 35(11): 91-96.
[3]	. Effect of Viscoelastic Characteristics on Thermal-fluid-structure Coupling Deformation in In-mold Micro Assembly Molding Process [J]. China Plastics, 2018, 32(01): 84-89.
[4]	. Rheological Behavior of Polypropylene Modified by γ Radiation [J]. China Plastics, 2016, 30(09): 21-25 .
[5]	. Viscoelasticity Mechanics Model of Medium Density Polyethylene Pipes [J]. China Plastics, 2016, 30(04): 93-98 .
[6]	. Influence of Chain Extenders on Foam Injection Molding of Poly(lactic acid) [J]. China Plastics, 2016, 30(04): 114-118 .
[7]	XU Zhijuan, LIN Xuechun, LUO Chaoyun, XIAO Wangdong. Preparation of Blocked Polyfunctional Isocvanate and Its Application Used as Crosslinking and Foaming Agents in PA6 Extrusion Foaming#br# [J]. China Plastics, 2015, 29(08): 98-102.
[8]	. Numerical Simulation of the Influence of Melt Extrusion Velocity on the Parison Die Swell of Coextrusion-blow-molded Parisons [J]. China Plastics, 2014, 28(07): 65-71 .
[9]	. Preparation of High Melt Strength Polypropylene by Reactive Extrusion [J]. China Plastics, 2014, 28(02): 35-40 .
[10]	. Extrusion Foaming of DCP Slightly Cross-linked High-density Polyethylene by Supercritical CO₂ [J]. China Plastics, 2012, 26(06): 81-86 .
[11]	李明昆 LI Ming-Kun . Effects of SEBS-g-MAH on TPEE Foaming Performance [J]. China Plastics, 2012, 26(04): 72-76 .
[12]	. Preparation of Vinyl Nano-silica and Its Effect on Melt Strength of Polypropylene [J]. China Plastics, 2011, 25(12): 51-54 .
[13]	Qiang HUANG . Crystallization Behavior of High Melt Strength Polypropylene/Block Polypropylene Blends [J]. China Plastics, 2011, 25(11): 27-33 .
[14]	MA Pengcheng WANG Xiangdong LIU Bengang LI YIng CHEN Shihong ZHANG Yuxia XU Guozhi. Study on Preparation and Foaming Extrusion Behavior of PLA/OMMT Nanocomposites [J]. China Plastics, 2011, 25(04): 59-64 .
[15]	. Indentation Size Effect of Viscoelastic Polymers by Dynamic Nanoindentation [J]. China Plastics, 2011, 25(03): 52-56 .