Viscoelastic Rheological Behaviors of Polypropylene and LMPP Blends.

Feichao Zhu,Munir Hussain,Sohail Yasin

doi:10.3390/polym13203485

Feichao Zhu, Munir Hussain + Show 1 more

Open Access

https://doi.org/10.3390/polym13203485

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Journal: Polymers	Publication Date: Oct 11, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Zhejiang University, Zhejiang Sci-Tech University

Abstract

Dynamic oscillatory shear testing is used to investigate polymeric viscoelastic behaviors. Small and large amplitude oscillatory shear tests are the canonical method for characterizing the linear and nonlinear viscoelastic behaviors of any polymeric material. With prominent and abundant work on linear viscoelastic studies, the nonlinear behavior is evasive in terms of generating infinite higher harmonics in the nonlinear regime. For this reason, intrinsic nonlinearities from large amplitude oscillatory shear (LAOS) studies have recently been used for insights on microstructural behaviors. This study is carried out for linear and nonlinear viscoelastic behavior with a main focus on LAOS of isostatic polypropylene (iPP) and relatively new low molecular weight and low modulus polypropylene-based polyolefin (LMPP) blends. The morphological results showed reduced spherulitic crystal nucleus size and increased distribution in blends with increasing LMPP. The blends showed subtle linear viscoelastic responses with strong nonlinear mechanical responses to variant strain and stress compared to pure iPP. The intracycle strain thickening and intracycle strain stiffening of high-content LMPP blends were comparatively dominant at medium strain amplitudes.

Highlights

Isostatic polypropylene, classified as an important polymer, is often restricted due to relatively low toughness and high thermal expansion coefficients [1]
low modulus polypropylene-based polyolefin (LMPP) is a relatively new polypropylene-based polyolefin developed by Idemitsu Petrochemical, Ltd., posing variant properties associated with conventional polypropylene
POM was used to investigate the growth of the spherulite in Isostatic polypropylene (iPP)/LMPP blends

Summary

Introduction

Isostatic polypropylene (iPP), classified as an important polymer, is often restricted due to relatively low toughness and high thermal expansion coefficients [1]. Blending and polymeric modifications are required to improve the properties. Blending of iPP with a low molecular weight and low modulus (LMPP) in small amounts [2,3,4], has been reported to produce finer and softer fiber products, such as nonwovens. LMPP is a relatively new polypropylene-based polyolefin developed by Idemitsu Petrochemical, Ltd., posing variant properties associated with conventional polypropylene. High crystallinity and melting point, which is attained using metallocene catalyst, reinforces the stereoregularity of the polymer [5]. Polyolefin elastomers provide elasticity, cohesive strength and adequate melt flow rate, yet show immiscibility, even when having similar monomer chemistry [6]

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