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Charles Nekrasov
Charles Nekrasov

Polymers, Polymer Blends, Polymer Composites An... _VERIFIED_

Abstract:This paper presents a water footprint assessment of polymers, polymer blends, composites, and biocomposites based on a standardized EUR-pallet case study. The water footprint analysis is based on life cycle assessment (LCA). The study investigates six variants of EUR-pallet production depending on the materials used. The system boundary included the production of each material and the injection molding to obtain a standardized EUR-pallet of complex properties. This paper shows the results of a water footprint of six composition variants of analyzed EUR-pallet, produced from biocomposites and composites based on polypropylene, poly(lactic acid), cotton fibers, jute fibers, kenaf fibers, and glass fibers. Additionally, a water footprint of applied raw materials was evaluated. The highest water footprint was observed for cotton fibers as a reinforcement of the analyzed biocomposites and composites. The water footprint of cotton fibers is caused by the irrigation of cotton crops. The results demonstrate that the standard EUR-pallet produced from polypropylene with glass fibers as reinforcement can contribute to the lowest water footprint.Keywords: water footprint; environmental impact assessment; biocomposites; natural fibers

Polymers, Polymer Blends, Polymer Composites An...

Contemporary microscopes can magnify almost everything that is invisible to the naked eye, down to the atomic level. Current classifications include optical microscopy, electron microscopy, and scanning probe microscopy, in which optical one focuses on microscale while electron and scanning probe ones focus on the nanoscale. Microscopy is an indispensable technique of characterization for shape memory polymers (SMPs), including optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), infrared microscopy, fluorescence microscopy, and laser scanning confocal microscopy (LSCM). In this chapter, the micro- and nanostructures of different shape memory polymers, blends, and composites will be discussed. The applications of these microscopical techniques will be outlined. A brief account of various types of morphologies and their impact on shape memory effects will be provided.

The details of polymer behavior are of importance in a variety of fields -- for example, in aerospace or nanotechnology, as demonstrated by the increasing use of polymer composites as strong, light-weight building materials. The study of polymer fluids lends itself well to computational methods, as indicated by the vast number of successful studies which have already been performed to this day, using numerical methods such as Molecular Dynamics, Monte Carlo, self-consistent field theory, dynamic density functional theory, Ginzburg-Landau theory, and Dissipative Particle Dynamics (DPD).

This chapter provides an overview of shape-memory polymers and their blends and composites. The history of shape-memory polymers, their advantages, shape-memory cycles, classification and the molecular mechanism of the shape-memory effect are briefly discussed. The characterisation techniques such as dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical and polarized optical microscopy (OM and POM), atomic force microscopy (AFM), laser scanning confocal microscopy (LSCM), universal testing machine (UTM), nanoindentation technique, etc., are powerful techniques to investigate the shape-memory mechanism and shape-memory performance. Shape-memory polymers have myriad of potential applications in automobile, sports products and textile, aerospace and medical fields.

Self-assembly in polymeric systems, physics of confined polymers, thermodynamics of polymer blends, architectural design of polymers, lithographic materials, coatings, thin film membranes, x-ray scattering methods

  • Matt's thesis work focused on the measurement of local, nanoscale mechanical and fracture properties of polymers, polymer blends, and polymer composites using characterization tools such as atomic force microscopy, nanoindentation, quasi-static toughness testing, dynamic mechanical analysis, and high-frequency rheometry.

  • Currently, he researches the mechanical properties of ring-functionalized carbon nanotube polymer composites at IMDEA Nanocienca as a postdoctoral researcher in order to develop high performance polymer composites.

Eaton, M.D., Brinson, L.C., Shull, K.R., "Temperature Dependent Fracture Behavior in Model Epoxy Networks with Nanoscale Heterogeneity," Polymer 221 (2021), p. 123560. DOI: 10.1016/j.polymer.2021.123560

Polymers are essential components of many drug delivery systems and biomedical products. Despite the utility of many currently available polymers, there exists a demand for materials with improved characteristics and functionality. Due to the extensive safety testing required for new excipient approval, the introduction and use of new polymers is considerably limited. The blending of currently approved polymers provides a valuable solution by which the limitations of individual polymers can be addressed.

Polymer blends combine two or more polymers resulting in improved, augmented, or customized properties and functionality which can result in significant advantages in drug delivery applications. This review discusses the rationale for the use of polymer blends and blend polymer-polymer interactions. It provides examples of their use in commercially marketed products and drug delivery systems. Examples of polymer blends in amorphous solid dispersions and biodegradable systems are also discussed. A classification scheme for polymer blends based on the level of material processing and interaction is presented.

The use of polymer blends represents a valuable and under-utilized resource in addressing a diverse range of drug delivery challenges. It is anticipated that new drug molecule development challenges such as bioavailability enhancement and the demand for enabling excipients will lead to increased applications of polymer blends in pharmaceutical products.

There are a variety of polymers currently available with unique properties which have been used in marketed drug and healthcare products. Due to this precedent of use, these polymers may be used in the development of new pharmaceutical products, provided that the amounts used are within the limits for which safety has been established. Despite the availability of these polymers, there is a demand for new and improved materials. While synthesis of new polymers to obtain desired functionalities is possible, the extensive safety testing requirements for new materials are often a limiting barrier to their use in new drug products. Considering the time and resources required to obtain regulatory approval when a new excipient is to be utilized, polymer blends present an attractive alternative means by which to address various formulation and drug delivery challenges.

The goal of blending polymers from a functionality standpoint is to improve, customize, or maximize material performance [1]. Table 1 lists applications of polymer blends in pharmaceutical dosage forms. Various mechanisms of drug release from polymer-based dosage forms are possible depending on the type of delivery system (Fig. 1). The scientific literature on the application of polymer blends in pharmaceutical products, excipients, and drug delivery systems has mostly focused on specific properties or applications of polymer blends such as miscibility [35, 36], film coating [37, 38], orally disintegrating films [39], matrix tablets [40,41,42], solid dispersions [43,44,45], biodegradable systems [46, 47], transdermal drug delivery [48], environmentally responsive systems [49, 50], and modifying or improving the performance of natural polymers [51,52,53,54,55]. Polymer blends have been used in recently emerging pharmaceutical processing techniques such as 3D printing [56,57,58] and electrospinning [59,60,61]. These techniques have also been used to prepare polymer blends for use in tissue engineering and wound dressings [62, 63]. Although most studies reported in the literature have focused on binary polymer blends, there has been some work performed on blends with more than two polymers such as ternary polyvinyl alcohol/poly(vinylpyrrolidone)/chitosan blends [64].

Mechanism of drug release from the polymer-based drug delivery systems discussed in this paper. IR, immediate release; SR, sustained release. Spheres represent drug molecules. In the matrix and biodegradable systems shown, the polymer is uniformly distributed with the drug. Drug release occurs by diffusion through the matrix and gel erosion (e.g., hypromellose-based tablets) or biodegradation (e.g., poly(lactide-co-glycolide)-based systems). In coated or encapsulated systems, a polymer forms a film or shell around drug particles. In coated IR systems, the film dissolves rapidly, while in coated SR systems, drug release occurs gradually by diffusion through an insoluble polymer film

Despite the potential advantages of polymer blends, there is an absence of comprehensive reviews on their use and application in marketed products. Furthermore, the currently available literature on polymer blends in pharmaceuticals is very product specific and is highly fractured across many scientific journals, publications and patents. This paper therefore reviews the applications of polymer blends in excipients and drug delivery systems across a broad range of different dosage forms with an emphasis on commercialized products and technologies. Applications of polymer blends in drug solubility enhancement are also addressed.

Noncovalent polymer-polymer interactions may range from van der Waals forces in physical mixtures to stronger intermolecular interactions such as hydrogen bonding, ionic interactions, and hydrophobic interactions that may occur during processing. Many experimental techniques are available for the characterization of polymer blends depending on the state of the material being studied [65]. Widely used methods include molecular weight characterization, spectroscopy, light and x-ray scattering, diffraction, microscopy, imaging techniques, thermal analysis, rheology, and mechanical testing in conjunction with evaluation of long term product stability. 041b061a72


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