Original scientific paper An SEM and EDS study of the microstructure of nitrate ester plasticized polyether propellants

Abstract: To probe the microstructures of nitrate ester plasticized polyether (NEPE) composite propellants and observe the morphology of each constitute in the propellant, the microstructure and elemental constitutes of NEPE propellants were investigated using scanning electron microscopy and energy dispersive X-ray spectroscopy. The ammonium perchlorate (AP) grains had a scraggy surface and were difficult to disperse uniformly. The compatibility between the AP grains and the polymer binder was poor, especially for large grains. The size distribution range of the AP and octogen (HMX) grains in propellants varied from several to several hundreds μm for the former while for the latter from several to several tens μm. Contrasting images before and after dissolution the propellant in trichloromethane showed that the degree of crosslinking of the polymer binder was low since non-crosslinked binder on the surface areas was easily removed by the solvent, and that the plasticizer was near the HMX grains and contributed more O to the element analysis of HMX

A study on the microstructure of a nitrate ester plasticized polyether propellant dissolved in HCl and KOH solutions

Understanding of how the properties and performance of nitrate ester plasticized polyether (NEPE) propellants relate to microstructure is complicated by numerous components that have different characteristics. One approach to alleviating these complications is to observe a microstructure that has lost one or several components. This article examines the dissolution process, mass loss and change of the ion concentration of propellants in acid and alkali solutions. A scanning electron microscope was used to observe the dissolved residual of the propellants. The results revealed that the main constituents of NEPE propellant have different dissolving properties in solutions of HCl and KOH. By monitoring the dissolution process of NEPE propellant in HCl and KOH solutions, it was found that the microstructure of the propellant is generally compact and the polymer binder not only binds all the other components, but also protects the inner part of the propellant in solution

JSCS–4024 Original scientific paper

A study on the microstructure of a nitrate ester plasticized polyether propellant dissolved in HCl and KOH solution

Recent Advances in Self-Assembly and Application of Para-Aramids

Poly(p-phenylene terephthalamide) (PPTA) is one kind of lyotropic liquid crystal polymer. Kevlar fibers performed from PPTA are widely used in many fields due to their superior mechanical properties resulting from their highly oriented macromolecular structure. However, the “infusible and insoluble” characteristic of PPTA gives rise to its poor processability, which limits its scope of application. The strong interactions and orientation characteristic of aromatic amide segments make PPTA attractive in the field of self-assembly. Chemical derivation has proved an effective way to modify the molecular structure of PPTA to improve its solubility and amphiphilicity, which resulted in different liquid crystal behaviors or supramolecular aggregates, but the modification of PPTA is usually complex and difficult. Alternatively, higher-order all-PPTA structures have also been realized through the controllable hierarchical self-assembly of PPTA from the polymerization process to the formation of macroscopic products. This review briefly summarizes the self-assembly methods of PPTA-based materials in recent years, and focuses on the polymerization-induced PPTA nanofibers which can be further fabricated into different macroscopic architectures when other self-assembly methods are combined. This monomer-started hierarchical self-assembly strategy evokes the feasible processing of PPTA, and enriches the diversity of product, which is expected to be expanded to other liquid crystal polymers