High‐resolution ¹³C–nuclear magnetic resonance study of heterogeneous amorphous polymers

Abstract

The combination of solid-state nuclear magnetic resonance (NMR) techniques is very helpful for examining the behavior of heterogeneous amorphous polymers. With the magic-angle spinning (MAS) technique, employing special conditions, only the mobile fraction of the molecule can be assigned. Cross-polarization magic-angle spinning (CPMAS) permits the evaluation of changes in the NMR line shapes and chemical shifts. The employment of proton spinlattice relaxation times (T 1 and T 1 ) gives useful information on the molecular dynamic in heterogeneous polymers. From these parameters the response of the molecular mobility behavior of the polymer chains can be obtained. The results of the present work are discussed in this article in terms of molecular mobility and domain formations of heterogeneous amorphous polymers in order to understand the relations in the structure-mobility property.

Solid State NMR

“…In the solid state, the signals are broader than in solution and especially for polymers due to their high molecular weight and mere ordination, among other factors, the signals become even wider. The second point concerns the type of response to be obtained in the solid state the number of information to be obtained is greater than in solution [11][12][13][14]. However, when the material is insoluble or has soluble difficulties, the study of the structure-property relation is of great interest because the search for responses with respect to homogeneity, phase dispersion, and interaction between the components is of great importance.…”

“…Improving the resolution of the signals in the NMR spectra obtained in the solid state requires techniques to eliminate factors that cause this signal enlargement [10][11][12][13][14]. Thus, techniques were developed using methods that mathematically eliminate these effects.…”

“…The T 1 H relaxation time é measured in the frequency of magnetic field generated by the external magnetic field. This relaxation must do with the return of the excited nuclei to its ground state after removal of the excitation frequency, and therefore, it allows to evaluate the molecular mobility of a material, global compatibility and homogeneity, as well as processes and plasticization [1][2][3][10][11][12][13][14][15]. In this process, the excess energy is emitted to the lattice in the form of dipole interaction since there is a lowering of the enthalpy of the nuclear spin system.…”

Evaluation of Composites Miscibility by Low Field NMR

“…PVC composites can be formulated using various types of filler, which are normally chosen according to the product that will be prepared from these composites [2][3][4][5][6]. Inorganic fillers have been very much used to obtain composite with special properties and applications.…”

“…This great variety has resulted in an enormous amount of research all over the world, and consequently a necessity to better characterize the new structures formed and the compatibility of both composite components. This made scientists use different techniques, among which spectroscopic methods have been very much used, because they inform on the interaction process and structure modifications [1][2][3][4][5][6][7][8][9][10].…”