Polymers matrix interactions, chemical

Xe-NMR spectroscopy [6]. This method evaluates the chemical shift of xenon-129, dissolved in the polymer matrix. The chemical shift of the Xe atoms depends on the interaction of the electron cloud with those of the atoms in the surrounding polymer. This interaction is stronger the smaller the size of the FVE in which the Xe probe is located. 

However, the mentioned model does not explain the causes of extreme reduction of the melt viscosity of HDPE/EP nanocomposites. Therefore for explanation of this effect the authors [11] used another treatment. As it is known [13], the extreme change of properties of blends in the case of their interaction (both chemical and physical) is realised at equimolar (stoichiometric) component contents. Since for the considered nanocomposites the extremum is reached at 2.0-3.0 mass percentage EP, then this means that the polymer matrix interacts not with the entire epoxy polymer, but only a part of it consisting of 4-6 mass percentage HOPE. In this case for estimation of rig (further designated as Tjo) the relationship applied for description of the chemical reaction kinetics of two components can be used [14] ... 

Chemical Approaches to Promote Natural Fiber-Polymer Matrix Interactions... 

With further understanding how molecular rotors interact with their environment and with application-specific chemical modifications, a more widespread use of molecular rotors in biological and chemical studies can be expected. Ratiometric dyes and lifetime imaging will enable accurate viscosity measurements in cells where concentration gradients exist. The examination of polymerization dynamics benefits from the use of molecular rotors because of their real-time response rates. Presently, the reaction may force the reporters into specific areas of the polymer matrix, for example, into water pockets, but targeted molecular rotors that integrate with the matrix could prevent this behavior. With their relationship to free volume, the field of fluid dynamics can benefit from molecular rotors, because the applicability of viscosity models (DSE, Gierer-Wirtz, free volume, and WLF models) can be elucidated. Lastly, an important field of development is the surface-immobilization of molecular rotors, which promises new solid-state sensors for microviscosity [145]. 

CNT can markedly reinforce polystyrene rod and epoxy thin film by forming CNT/polystyrene (PS) and CNT/epoxy composites (Wong et al., 2003). Molecular mechanics simulations and elasticity calculations clearly showed that, in the absence of chemical bonding between CNT and the matrix, the non-covalent bond interactions including electrostatic and van der Waals forces result in CNT-polymer interfacial shear stress (at OK) of about 138 and 186MPa, respectively, for CNT/ epoxy and CNT/PS, which are about an order of magnitude higher than microfiber-reinforced composites, the reason should attribute to intimate contact between the two solid phases at the molecular scale. Local non-uniformity of CNTs and mismatch of the coefficients of thermal expansions between CNT and polymer matrix may also promote the stress transfer between CNTs and polymer matrix. 

Nanocarbon structures such as fullerenes, carbon nanotubes and graphene, are characterized by their weak interphase interaction with host matrices (polymer, ceramic, metals) when fabricating composites [99,100]. In addition to their characteristic high surface area and high chemical inertness, this fact turns these carbon nanostructures into materials that are very difficult to disperse in a given matrix. However, uniform dispersion and improved nanotube/matrix interactions are necessary to increase the mechanical, physical and chemical properties as well as biocompatibility of the composites [101,102]. 

Hybrid polymers are composites containing one organic component (e.g polymer) and another part, distinct in nature to the matrix (e.g. the nanomaterial), and these parts interact through chemical bonding so that the polymer layer bonded to the filler is distinct from the polymer matrix. The properties of these materials are improved by the introduction of the nanomaterial into the polymer matrix. Some of the properties that can be enhanced include the Young s modulus, resistance to flammability, low permeability to gases, and increased heat resistance. 

Spent resins are generally compatible with the polymer matrix material. Generally, the polymer and the resin do not interact chemically. The immobilization of spent ion-exchange resins in polymers is a common application all over the world. Epoxy resins, polyesters, polyethylene, polystyrene and copolymers, polyurethane, phenol-formaldehyde, and polystyrene are among the polymers used (IAEA, 1988). Inorganic materials are generally not immobilized using polymers because they are more acceptable to other immobilization matrices such as cement. 

Additives are used for a variety of purposes to improve processing, to modify performance or appearance, to prevent or retard aging, to reduce cost. They are normally incorporated into the polymer matrix during compounding and may constitute a major or minor part of the final product. For this reason it is not always useful to define additives in terms of the amount of that ingredient present. Additives may, or may not, interact chemically with the... 

PEBBLEs are water-soluble nanoparticles based on biologically inert matrices of cross-linked polymers, typically poly(acrylamide), poly(decylmethacrylate), silica, or organically modified silicates (ORMOSILs), which encapsulate a fluorescent chemo-sensor and, often, a reference dye. These matrices have been used to make sensors for pH, metal ions, as well as for some nonionic species. The small size of the PEBBLE sensors (from 20 to 600 nm) enables their noninvasive insertion into a living cell, minimizing physical interference. The semipermeable and transparent nature of the matrix allows the analyte to interact with the indicator dye that reports the interaction via a change in the emitted fluorescence. Moreover, when compared to naked chemosensors, nanoparticles can protect the indicator from chemical interferences and minimize its toxicity. Another important feature of PEBBLEs, particularly valuable in intracellular sensing applications, is that the polymer matrix creates a separate... 

Although the approach of covalent functionalization of CNT surface is an effective means to obtain a homogeneous dispersion of CNTs in polymer matrix and a strong interfacial interaction with the polymer, it inevitably destroys the intrinsic properties of CNTs such as the unique ji-electron system of pristine CNTs is affected due to formation of covalent bonds and shortening of length of CNTs during chemical treatments (70). 

---