Polymer Crystallization Studied by Hyphenated Rheology Techniques: Rheo‐NMR, Rheo‐SAXS, and Rheo‐Microscopy

Räntzsch, Volker; Özen, Mürüvvet Begüm; Ratzsch, Karl‐Friedrich; Stellamanns, Eric; Sprung, Michael; Guthausen, Gisela; Wilhelm, Manfred

doi:10.1002/mame.201800586

Cited by 24 publications

(14 citation statements)

References 146 publications

(216 reference statements)

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“…Furthermore, here we have focused on the hyphenated techniques for CNC structure characterization, but a similar toolbox can and has been used, e.g., for the analysis of crystallization in polymers in general. 130 The techniques that have been reviewed are accessible as we have concentrated on commercial devices. However, there is a difference in costs of the infrastructure.…”

Section: Analysis Of Cncsmentioning

confidence: 99%

Cellulose Nanocrystal Liquid Crystal Phases: Progress and Challenges in Characterization Using Rheology Coupled to Optics, Scattering, and Spectroscopy

2021

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Cellulose nanocrystals (CNCs) self-assemble and can be flow-assembled to liquid crystalline orders in a water suspension. The orders range from nano- to macroscale with the contributions of individual crystals, their micron clusters, and macroscopic assemblies. The resulting hierarchies are optically active materials that exhibit iridescence, reflectance, and light transmission. Although these assemblies have the potential for future renewable materials, details about structures on different hierarchical levels that span from the nano- to the macroscale are still not unraveled. Rheological characterization is essential for investigating flow properties; however, bulk material properties make it difficult to capture the various length-scales during assembly of the suspensions, for example, in simple shear flow. Rheometry is combined with other characterization methods to allow direct analysis of the structure development in the individual hierarchical levels. While optical techniques, scattering, and spectroscopy are often used to complement rheological observations, coupling them in situ to allow simultaneous observation is paramount to fully understand the details of CNC assembly from liquid to solid. This Review provides an overview of achievements in the coupled analytics, as well as our current opinion about opportunities to unravel the structural distinctiveness of cellulose nanomaterials.

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Section: Analysis Of Cncsmentioning

confidence: 99%

Cellulose Nanocrystal Liquid Crystal Phases: Progress and Challenges in Characterization Using Rheology Coupled to Optics, Scattering, and Spectroscopy

2021

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“…A schematic of the setup as well as an image of the assembled magnet is illustrated in Figure . The first version of the lab-made magnet was described in our previous studies. − This newest version is smaller in size with a total weight of only 2.5 kg. It is constructed with 16 decagon magnet bars in a Halbach array , to form a homogeneous static magnetic field (Δ B 0 / B 0 ≈ 1 × 10 –3 ) in the cylindrical core with a strength of B 0 ≈ 0.59 T, i.e., corresponding to a 1 H Larmor frequency of ω L /2π ≈ 25 MHz.…”

Section: Experimental Sectionmentioning

confidence: 99%

Correlation between Macroscopic Elasticity and Chain Dynamics of Natural Rubber during Vulcanization as Determined by a Unique Rheo-NMR Combination

et al. 2021

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The cross-linking process of natural rubber (NR) is studied for the first time by a unique combination of rheology and time-domain (TD) NMR, two methods that are commonly conducted separately. The combined setup consists of a high-end rheometer and a compact 25 MHz 1 H NMR relaxometer (rheo-NMR), which allows rheological characterization and NMR relaxometry to be operated simultaneously on the same sample. During vulcanization, the elastic modulus G′(t), representing the macroscopic elasticity, was directly correlated to the molecular dynamic parameters derived from NMR, including the populationaveraged transverse relaxation rate, 1/T 2ave , and the logarithmic mean of the residual dipolar coupling constant, D̅ res . It is found that, at the same level of macroscopic elasticity, the conformational flexibility of network chains in NR cross-linked with the so-called efficient vulcanization (EV) is more restricted than that with conventional vulcanization (CV). This can be attributed to the shorter and consequently less flexible (monosulfidic) cross-links formed by EV, whereas polysulfidic links dominate in the CV vulcanizate as confirmed by high-field 13 C NMR spectroscopy.

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“…SAOS measurements with simultaneous RS, 10,11,14,25 OI, 15,16,26,27 and NMR 23,24 over the crystallization process indicate a sigmoidal dependence of the log of the modulus with the degree of space filling ξ . The degree of space filling is the volume fraction crystallinity in the sample that is normalized such that the melt state corresponds to ξ = 0 and the semicrystalline state at the end of the primary crystallization process is ξ = 1.…”

Section: Experiments: Simultaneous Rheology and Crystallinitymentioning

confidence: 99%

Percolation implications in the rheology of polymer crystallization

Kotula

Migler

2020

Polymer Crystallization

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The rheology of polymer crystallization is an old problem that often defies explanation due to the complex interrelationships between crystallization and flow properties. Although separate measurements of rheology and crystallinity can give some information on their relationship, it is only through simultaneous measurements that ideas on the rheology of polymer crystallization can be tested and developed. This Perspective details recent experimental developments in simultaneous crystallinity and rheology measurements as well as continuum modeling efforts for the case of quiescent and isothermal crystallization. Experimental results reveal that the rheology is dominated initially by growth of individual spherulites that evolve into spherulitic superstructures that eventually span the measurement geometry. A generalized effective medium model based on this concept of percolation can explain both the growth of the viscoelastic modulus during crystallization and the changes in the relaxation spectrum of the crystallizing polymer, including a critical gel response at percolation. The success of the combined measurement techniques and percolation concepts motivate research to extend the semicrystalline polymer materials space where these methods are applied as well as further develop novel techniques to gain additional insight into the evolution of structure and relaxation dynamics during crystallization.

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Polymer Crystallization Studied by Hyphenated Rheology Techniques: Rheo‐NMR, Rheo‐SAXS, and Rheo‐Microscopy

Cited by 24 publications

References 146 publications

Cellulose Nanocrystal Liquid Crystal Phases: Progress and Challenges in Characterization Using Rheology Coupled to Optics, Scattering, and Spectroscopy

Cellulose Nanocrystal Liquid Crystal Phases: Progress and Challenges in Characterization Using Rheology Coupled to Optics, Scattering, and Spectroscopy

Correlation between Macroscopic Elasticity and Chain Dynamics of Natural Rubber during Vulcanization as Determined by a Unique Rheo-NMR Combination

Percolation implications in the rheology of polymer crystallization

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