Semi crystalline polymers play an enormously important role in materials science, engineering, and nature. Two thirds of all synthetic polymers have the ability to crystallize which allows for the extensive use of these materials in a variety of applications as molded parts, films, or fibers. Here, we present a study on the applicability of benchtop 1 H NMR relaxometry to obtain information on the bulk crystal linity and crystallization kinetics of the most relevant synthetic semi crystalline polymers. In the first part, we investigated the temperature dependent relaxation behavior and identified T ¼ T g þ 100 K as the minimum relative temperature difference with respect to T g for which the mobility contrast between crystalline and amorphous protons is sufficient for an unambiguous determination of polymer crystal linity. The obtained bulk crystallinities from 1 H NMR were compared to results from DSC and XRD, and all three methods showed relatively good agreement for all polymers. In the second part, we focused on the determination of the crystallization kinetics, i.e., monitoring of isothermal crystallization, which required a robust design of the pulse sequence, precise temperature calibration, and careful data analysis. We found the combination of a magic sandwich echo (MSE) with a short acquisition time followed by a Carr Purcell Meiboom Gill (CPMG) echo train with short pulse timings to be the most suitable for monitoring crystallization. This study demonstrates the application of benchtop 1 H NMR relaxometry to investigate the bulk crystallinity and crystallization kinetics of polymers, which can lead to its optimal use as an in situ technique in research, quality control, and processing labs.

Rheological set‐ups with in situ analytical sensors, combine information on the flow and deformation behavior of soft matter, with simultaneous insights into structural and dynamic features. Furthermore, they permit the study of soft matter under well‐defined flow conditions. Herein are presented hyphenations of rheology and nuclear magnetic resonance (NMR), small angle X‐ray scattering (SAXS), and optical microscopy. They are employed to unravel relationships between the molecular dynamics, morphology, and rheology of crystallizing polymers. The results confirm a physical gelation process during polymer crystallization, mediated by the interaction of growing superstructures at volume fractions of 10–15%. The buildup of row‐nucleated structures during flow‐induced crystallization is found to reduce the time of gelation as detected by the rheological response. These investigations help to clarify the crystallization mechanism, structure–property relationships, and the hardening behavior of crystallizing polymers.

Cellulose composites with polyethylene (PE) permit to reinforce this commodity polymer, while at the same time introducing renewable content and thus minimizing the use of petroleum‐based feedstocks. Herein, we report on two fully renewably sourced and sustainably synthesized compatibilisers based on amylose and starch, which allow for such cellulose dispersion in low‐density PE (LDPE). These compatibilisers advantageously combine the hydrophilicity of carbohydrates with the hydrophobicity of fatty acids. Upon extrusion of cellulose, LDPE, and the compatibilisers, a significantly improved dispersion of cellulose within LDPE was observed using rheology at loadings of 10 wt % cellulose and 5–15 wt % compatibiliser. Moreover, an improved interfacial adhesion was observed using scanning electron microscopy and was also confirmed by the mechanical properties, notably the Young's modulus, as a result of the good stress transfer between filler and matrix material. This study highlights the potential of fully renewable compatibilisers for the preparation of composites of cellulose and the commodity plastic LDPE. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48744.

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Front Cover: In article number https://doi.org/10.1002/mame.201800586, Manfred Wilhelm and co‐workers present studies on the molecular dynamics, morphology, and flow behavior of crystallizing polymers. Material properties are correlated on broad length and time scales by using hyphenations of rheology and in‐situ nuclear magnetic resonance, small angle X‐ray scattering, and optical microscopy.