مجله پژوهش و توسعه فناوری پلیمر ایران
سال هشتم شماره 3 (پیاپی 31، پاییز 1402)

One of the main applications of nitrocellulose polymer is producing propellants. The propellant production process includes mixing nitrocellulose with solvents and other additives and converting it from a fibrous to a non-fibrous state during gelatinization and physical gel formation. This gel is subsequently subjected to shaping processes using ram or screw extrusion. One of the main problems in producing propellant based on nitrocellulose is the lack of uniformity and product quality control. Despite the high capability of rheology knowledge as a powerful tool for measuring the quality control of raw materials and the production process of propellant based on nitrocellulose, this knowledge has received less attention from researchers and manufacturers in this field. This article reviewed the use of rheology in different parts of the production of nitrocellulose-based propellants, from the quality control of the incoming raw materials to the final mixing and extrusion. At first, the rheological behavior of nitrocellulose mixtures was discussed. Next, the effect of nitrocellulose polymer microstructure on the rheological behavior of its solution was discussed. Phenomena affecting the measurement of the rheological behavior of the mixture, such as wall slippage, were among the other cases investigated. Finally, a review of the quality control methods of nitrocellulose-based propellant products using appropriate material functions and production process modification was discussed.

In the past decades, porous materials have attracted a lot of attention in physics, chemistry and materials science. Among various compounds, metal-organic frameworks (Metal organic frameworks, MOFs) and covalent organic frameworks (COFs), as crystalline porous materials, were developed at a very high speed. MOFs are a subgroup of porous compounds in which organic ligands are connected together with metal cations. COFs are two- or three-dimensional organic solids with extended structures in which the building blocks are connected by strong covalent bonds. These compounds have unique advantages including well-defined and tunable structures, large surface area, high porosity, and ease of framework modification, which make them ideal host substrates for various guests including polymers, metal oxide nanoparticles, and semiconductors to create Converts MOF or COF-based multistructures. Compared to single-component compounds, polycomposites always show new properties due to their synergistic effects. Therefore, to further improve their performance and expand their applications, many efforts have been made to design and fabricate various MOF or COF-based multi-structures. Therefore, in this study, the integration of MOFs and COFs, their manufacturing methods, and the applications of these multiple structures will be investigated. Moreover, the capability of the prepared sorbents in various fields such as sorbent, catalysis and other format will be discussed. Metal–organic frameworks (MOFs) are a class of compounds consisting of metal clusters (also known as SBUs) coordinated to organic ligands to form one-, two-, or three-dimensional structures.

In the last three decades, many researches have been conducted in the field of shape memory polymers, and in the past few years, the interest in research in this field has received a lot of attention. In this study, a comprehensive and complete review of the structure, mechanism, model and applications of this category of polymers has been done. In general, the mechanisms of shape memory polymers are divided into three groups: direct thermal induction, indirect thermal induction, and optical induction, and each has its own switch unit that controls the shape structure. These switches have amorphous and semi-crystalline phase, which are defined in two phase and molecular levels. Also, increasing the mechanical properties, including the strength and toughness of shape memory polymers, is of great importance, which can increase their efficiency. Shape memory polymers can be used in medical, aerospace, textile and other industries. In the textile industry, the electrospinning process is used as a simple and efficient method for the preparation of shape memory polymer fibers and the development of their structure, and the mechanism and method of preparation of these fibers will be investigated. In the last three decades, many researches have been conducted in the field of shape memory polymers, and in the past few years, the interest in research in this field has received a lot of attention. In this study, a comprehensive and complete review of the structure, mechanism, model and applications of this category of polymers has been done.

Advances in the synthesis and industrial production of carbon nanomaterials, particularly carbon nanotubes (CNTs) have been widely used in the polymer materials industry in the past few decades, leading to the creation of a group of carbon nanotube-reinforced polymer composites that exhibit the potential to be used in several applications, such as military, transportation, aerospace, automotive, and sports equipment. The advantageous thermal, electrical, and mechanical properties of CNTs, in conjunction with their low density, which encourages researchers to use them in making polymer composites. Polymeric composites have been welcomed by many researchers and industrialists due to their special properties including low weight, favorable mechanical properties and diverse production processes compared to other types of composites and other engineering materials. On the other hand, CNTs are unique as mechanical reinforcement components for structural applications due to their nanometer dimensions and extraordinary strength. Therefore, in this review study, an attempt has been made to examine the researches carried out in the field of mechanical properties of polymer composites reinforced with CNT. The implications of several factors affecting mechanical properties of CNT reinforced polymer composites such as amount, shape, and contact area of the reinforcing agents with the polymer matrix, have been highlighted.

Chitosan has been widely used as a natural biopolymer. The modification of chitosan for various applications can be easily achieved due to the abundant active groups (NH2 and OH) in the main chain. Controlled drug release makes the drug release rate predictable and repeatable for prolonged release drugs. Drug delivery systems prepared from nanoparticles show several advantages, including improved efficiency and reduced toxicity. Using drug delivery systems based on nanoparticles loaded with anti-cancer agents is an effective method for targeting cancer cells. These systems, with the ability to penetrate better inside the cells, combine the drug in a targeted way in the cells. Also, due to the enhanced permeability and retention (EPR), the possibility of better accumulation of drugs in the tumor site is provided. In most researches, the suitable particle size for the targeted release of drug nanocarriers has been reported to be less than 300 or 200 nm. This amount is suitable for the application of drug release for diffusion among tissues and causes the effect of increasing permeability. In this study, for the first time, it examines and analyzes the particle size and zeta potential (surface charge) of chitosan-based nanocarriers through dynamic light scattering and electron microscope tests in improving the release of the antitumor drug, 5-fluorouracil.

Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are formed through the self-assembly of metal nodes and organic bonds, resulting in a nanoporous crystalline framework. High porosity, high specific surface area, adjustable pore size and good stability are some of their most significant attributes. Hybridization with flexible materials like polymers is an emerging trend in MOF research. Polymers possess distinctive characteristics, including softness, thermal and chemical stability, suitable optical properties, and ease of processing. These properties can be combined with MOFs to produce hybrid structures with intricate architecture and distinctive characteristics. Among the most important novel applications of the polymer/MOF hybrids are gas separation and adsorption, ion exchange membranes and nanofiltration, sensors, catalysts, biomedical, etc. The objective of this article is to investigate the hybridization technique of MOFs and polymers, as well as the attractive applications of these hybrid materials. Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are formed through the self-assembly of metal nodes and organic bonds, resulting in a nanoporous crystalline framework. High porosity, high specific surface area, adjustable pore size and good stability are some of their most significant attributes. Hybridization with flexible materials like polymers is an emerging trend in MOF research. Polymers possess distinctive characteristics, including softness, thermal and chemical stability, suitable optical properties, and ease of processing. These properties can be combined with MOFs to produce hybrid structures with intricate architecture and distinctive characteristics.