مجله پژوهش و توسعه فناوری پلیمر ایران
سال هفتم شماره 2 (پیاپی 26، تابستان 1401)

Every year, an enormous amount of 2.5 million tons of plastic enter the oceans. On land, plastic also accumulates in landfills, beaches and other sensitive ecosystems around the world which has been a huge concern through the years. Recent research has been conducted to show us that one type of worm may help us solve the huge problem of plastic waste. Scientists have discovered that the larvae of a type of worm, Mealworm called Tenebrio Molitor, can include styrofoam and other polystyrenes as well as polyethylene in their diet. Not only do worms go on a styrofoam diet, they say, but the microorganisms in their gut can break down plastics during their digestive process, turning it into carbon dioxide and eventually use it as the nutrients that their bodies need. Biodegradable materials disposed by worms also seem to be used as fertilizer to fertilize and impregnate agricultural soil. We are looking for solutions to implement this discovery in a way that eliminates plastic waste therefore can be a solution to clearer oceans, rivers and the entire environment from the inevitable consequences of plastic accumulation. In this review study, narrations from articles related to the biodegradation of polyethylene, polystyrene and polypropylene have been reviewed.

Molecular self-assembly is the spontaneous aggregation of molecules or macromolecules into supramolecular structures with non-covalent interactions. This phenomenon is an interdisciplinary research topic that has a lot of potential applications in various fields. One of the main driving forces of molecular self-assembly is the existence of molecular amphiphilicity in the system which can cause microphase separation and create complex and stable nanostructures. Self-assembling peptides are one of the most important classes of molecules with the ability to self-assemble. The rich self-assembly behavior is observed in systems of peptides, due to the simultaneous presence of different interactions (such as electrostatic interaction, hydrophobicity and hydrogen bond) in systems consisting of them and the diversity of their molecular configuration. Better understanding of peptides self-assembly enables the better design of peptides to form functional nanostructures. In this review article, at first, peptide self-assembly and its importance are stated. Then, some examples of self-assembling peptides which have attracted the interest of scientists for various reasons, such as cyclic peptides, amphiphilic peptides, ionic complementary peptides and some other examples, are explained. Also, some important applications and benefits of peptides self-assembly, which include nanoscale construction, tissue engineering, drug delivery, applications in biosensors, and the study of conformational diseases, are reviewed.

Shape memory polymers (SMPs) represent a highly special class of materials. As one representative of the intelligent polymeric systems, these materials gained significant interest in recent years. SMPs are stimuli-responsive polymers, which act as stimulants like light, temperature, PH changes, solvent changes, electrical fields or magnetic fields, and their output is strain. Also, these polymers are highly regarded as essential for fundamental research and technological innovation. The present review will provide a short overview with particular attention to structure, mechanisms and applications of SMPs, shape memory effects and, as well as the current developments and concepts for shape memory polymers. The applications of shape memory polymers can be noted in medical industries, commercial industries, S hape memory polymers (SMPs) represent a highly special class of materials. As one representative of the intelligent polymeric systems, these materials gained significant interest in recent years. SMPs are stimuli-responsive polymers, which act as stimulants like light, temperature, PH changes, solvent changes, electrical fields or magnetic fields, and their output is strain. Also, these polymers are highly regarded as essential for fundamental research and technological innovation. The present review will provide a short overview with particular attention to structure, mechanisms and applications of SMPs, shape memory effects and, as well as the current developments and concepts for shape memory polymers. The applications of shape memory polymers can be noted in medical industries, commercial industries, aerospace industries, self-healing polymers, etc. aerospace industries, self-healing polymers, etc.

The Flory-Huggins interaction parameter (χ) is a crucial factor affecting the miscibility and morphology of components in polymer mixtures and their final properties and applications. The reliable measurement of the interaction parameter is worthwhile in fundamental understanding and quantitative determination of structure-performance relation and finally in practical applications of polymers in different fields. Different methods are used for evaluation of this parameter. In this study, six semi-experimental methods are reviewed: measurement of melting point depression, equilibrium swelling, contact angle, phase separation points, vapor pressure, and inverse gas chromatography. In these methods, equilibrium melting temperatures of pure polymer and its mixtures, degree of equilibrium swelling of the cross-linked polymer in the presence of swelling agent, surface energy of components in the polymeric mixtures, equilibrium components composition in the two-phase system, the ratio of partial vapor pressure of solvent to its saturated one and retention volume are experimentally measured, respectively. Then a proper equation is fitted on the data and the interaction parameter is obtained. In some methods, such as measurement of contact angle, only a positive interaction parameter at temperature of the test is obtained. But in some others, such as measurement of melting point depression, there is no constraint for the sign of interaction parameter. In addition, some methods can determine the composition dependency of the interaction parameter, such as determination of phase separation points.

Common terminology is essential for accurate communication among researchers, scientists, engineers, and other decision makers. To assist manufacturing process characterization, a common understanding of terminology is imperative for efficient and effective communication in industry; it can also facilitate automation and interoperability of software tools. Manufacturing process characterization enables the assessment and improvement of unit manufacturing processes, products, and systems from a sustain- ability perspective. To develop and implement sustainability-related standards and best practices in industry, naming conventions and definitions of common terms are needed. Presently, many terms used are ill-defined, vague, or overlap in meaning. Although there are ongoing standards efforts related to terminology identification and definition, an identified common set is yet to be developed. The objective of this work was to facilitate ongoing standards development efforts by harmonizing the varied array of terms used to describe production processes. As a result of a review of the literature, a concise set of 47 terms focusing on process characterization and able to describe sustainable production was generated; terms unique to individual production processes were omitted. The terms were orga- nized into six categories to define the overarching concepts: Scope, Boundary, Material, Measurement, Model, and Flow. Definitions of the terms were then derived from the literature in sustainable manufacturing and chemical and process industries, process characterization and planning, organization standards, and life cycle assessment and management. The reported terms and definitions are not unique to sustainable production, and could foster wide- spread use of the concepts to improve the economic, environmental, and social performance of industry. In the future, the terminology described could be standardized through international standards orga- nizations.

Common terminology is essential for accurate communication among researchers, scientists, engineers, and other decision makers. To assist manufacturing process characterization, a common understanding of terminology is imperative for efficient and effective communication in industry; it can also facilitate automation and interoperability of software tools. Manufacturing process characterization enables the assessment and improvement of unit manufacturing processes, products, and systems from a sustain- ability perspective. To develop and implement sustainability-related standards and best practices in industry, naming conventions and definitions of common terms are needed. Presently, many terms used are ill-defined, vague, or overlap in meaning. Although there are ongoing standards efforts related to terminology identification and definition, an identified common set is yet to be developed. The objective of this work was to facilitate ongoing standards development efforts by harmonizing the varied array of terms used to describe production processes. As a result of a review of the literature, a concise set of 47 terms focusing on process characterization and able to describe sustainable production was generated; terms unique to individual production processes were omitted. The terms were orga- nized into six categories to define the overarching concepts: Scope, Boundary, Material, Measurement, Model, and Flow. Definitions of the terms were then derived from the literature in sustainable manufacturing and chemical and process industries, process characterization and planning, organization standards, and life cycle assessment and management. The reported terms and definitions are not unique to sustainable production, and could foster wide- spread use of the concepts to improve the economic, environmental, and social performance of industry. In the future, the terminology described could be standardized through international standards orga- nizations.