Molecular order and density of skin and core in drawn polypropylene investigated by spectroscopic carbon-13 NMR imaging

Abstract

Introduction. Molecular order and the ratio between crystalline and amorphous portions are important factors determining the macroscopic properties of polymeric materials.1 Spatial variations of the molecular parameters, depending on the processing conditions, lead to nonuniform and spatial-dependent macroscopic behavior. For a systematic improvement of the manufacturing process, methods which record the spatial dependence of order and crystallinity are in need. On a phantom of deuterated polyethylene we have recently shown that solid-state 2H NMR spectroscopy, in combination with magneticfield gradients for spatial encoding, can indeed provide the desired information for bulk samples.2 It is the purpose of this paper to demonstrate that spectroscopic images with 13C in natural abundance can be recorded for a "real" polymer material, where spatial heterogeneities are known to exist.

Study of Uniaxially Stretched Isotactic Poly(propylene) by 1H Solid‐State NMR and IR Spectroscopy

“…One of the methods, solid-state NMR, is capable of characterizing the crystallinity, the molecular mobility, domain thicknesses and phase-selective characterization of the orientation distribution function of semi-crystalline polymers. [30][31][32][33][34][35][36][37][38] Another method is IR spectroscopy, which can be used to determine the degree of crystallinity of iPP. [39][40][41] Knowledge of strain-induced order in the crystalline and soft phases of stretched iPP under various conditions is valuable information for understanding the structure reorganization mechanisms, and their relation to the mechanical properties of iPP.…”

NMR Studies of Solid Polymers and Resins: An Introduction

“…By drawing an injection molded sPP sample, molecular orientation is introduced into each of these layers. Spiess and coworkers 37 combined spectroscopic phase discrimination to separately study the amorphous and crystalline domains, CSA to study the type and extent of orientation present and imaging to localize spatial differences existing in the skin and core layers.…”

1H NMR Imaging of Residual Dipolar Couplings in Cross-Linked Elastomers: Dipolar-Encoded Longitudinal Magnetization, Double-Quantum, and Triple-Quantum Filters

“…Diverse applications of NMR imaging in elastomers have appeared in the literature. Topics addressed are phase separation (9), selective determination of component distribution in multicomponent systems (10), aging (9,11,12), biodegradation (13), water uptake (14,15), morphology and defects (16,17), filler distribution (18), homogeneity of crosslink density (19 -21), and stress-induced effects (22)(23)(24)(25).…”