Polymers between

The scalping of flavor and aroma by a package can be minimised by placing a barrier material as near as possible to the food. The ingress of undesirable permeants from the environment can be minimised by placing a barrier polymer between the food and the environment, not necessarily near the food. 

I. Webman, J. L. Lebowitz, M. H. Kalos. Monte-Carlo studies of a polymer between planes, crossover between dimensionalities. J Physique 47 579-583, 1980. 

Below Tg tensile strengths are usually at least as strong for crystalline polymers as for amorphous polymers. Between and T, the strength and rigidity will be very dependent on the degree of crystallinity and... 

For crystalline polymers between and the diffusion rate is very dependent on the degree of crystallisation. 

Details are given of the successful construction of a novel reversible system of network polymers between bifunctional monomers by utilising the equilibrium polymerisation system of a spiro orthoester. Molecular structures were determined by NMR and IR spectroscopy. 9 refs. 

We test the permeability of polymer films or sheets to various vapors and gases by mounting the polymer between chambers that contain different concentrations of the migrant molecules. We can determine the permeability from pressure changes, volumetric changes, or by microanalytical techniques that measure the concentration of the migrant molecules in a stream of gas flowing across the low concentration side of the barrier. 

The band gap in substituted PPPs can be tuned to some extent by diluting the substituted phenylene rings with unsubstituted phenylenes. A bathochromic shift in absorption was observed for copolymer 473 (Eg = 2.95 eV) compared to the all-substituted homopolymer 472k (Eg = 3.1 eV) [581]. Sandwiching this polymer between ITO and Ca electrodes afforded a... 

Since most of our observations on the reacting systems were made by means of conductivity measurements it is necessary to remember that in these systems the only factor which increases conductivity is an increase in the concentration of ions, but that a decrease of conductivity could be due to any or all of the following effects increase of size of cation by polymerisation, increase of viscosity of solvent due to polymer, occlusion of ions in precipitated polymer, trapping of polymer between the electrodes. A similar list was given by Matyska in one of the earliest applications of conductivity measurements to a cationic polymerisation, that of isoprene by aluminium bromide in toluene solvent [19]. 

Fig. 8.11 (a) Schematic of the hierarchical structure of a composite with multiple CNT fibers, where each fiber is a composite itself [77]. (b) The intercalation of small amounts of polymer between CNTs during CNT fiber production is a promising method to fabricate structural composites based on nanocarbons [81], With kind permission from Elsevier (2011) and Taylor and Francis (2012). 

In terms of reinforcement, hydrocalumite/polymer nanocomposites may also be considered as promising in the field of cement-related materials. The so-called macro-defect-free (MDF) cements are based on the filHng by polymer of the macroscopic voids responsible for the breakdown of cement. The hydrocalumite phase is formed during the hydration of cement and is known to readily incorporate polymers between its layers [71-75]. 

The rheometer most often used to measure viscosity at low shear rates is the cone and plate viscometer. A schematic of a cone and plate rheometer is found in Fig. 3.24. The device is constructed with a moving cone on the top surface and a stationary plate for the lower surface. The polymer sample is positioned between the surfaces. Two types of experiments can be performed the cone can be rotated at a constant angular velocity, or it can be rotated in a sinusoidal function. The motion of the cone creates a stress on the polymer between the cone and the plate. The stress transferred to the plate provides a torque that is measured using a sensor. The torque is used to determine the stress. The constant angle of the cone to the plate provides an experimental regime such that the shear rate is a constant at all radii in the device. That is, the shear rate is independent of the radial position on the cone, and thus the shear stress is also independent of the position on the cone. 

The blending of short glass fibres results in an increase of the E-modulus to e g. its threefold over the whole temperature region. If the slope of the log E - T curve is small, such as with semi-crystalline polymers between Tg and T, a vertical shift causes a considerable horizontal shift (see MT 8.1.2.), so a strong increase of the softening points, which are of importance in applications at higher temperatures. 

One of these has already been mentioned, namely, that all the intermolecular forces involved (between plasticizer and plasticizer, between polymer and polymer, between plasticizer and polymer) be of the same order of magnitude. 

Removal of about half of the linear polymer by solvent extraction left individual zeolite crystals containing the remaining polymer. Scanning electron micrographs showed there was essentially no polymer between or on the zeolite (observable before the extraction), and resembled micrographs of the pure zeolite. All linear polymer could be removed on extended solvent extraction. 

Articles in which glass fibers are imbedded to improve impact strength often are made by mixing the fibers with an ethenylbenzene (styrene) solution of a linear glycol (usually l,2-propanediol)-butenedioic anhydride polyester and then producing a cross-linked polymer between the styrene and the double bonds in the polyester chains by a peroxide-induced radical polymerization (Section 29-6E). 

Gram-negative organisms Have outer semi-permeable structure of lipopolysacharide with inner structure of muramic polymer, between these structures there is a space containing protein. 

Flow in a circular channel with a significant relative length 1/H (here 1 — is the length of circular head H = R2 — Rt is the width of clearance, i.e., the difference between the inner radius of the outer cylinder, the tip, and the outer radius of the inner cylinder, the core) was simulated by the flow of a polymer between two parallel plates removed from one another to a distance H (see Fig. la). The resultant flow occurs due to the pressure difference AP = P, — P2 and motion of the upper plate with velocity U0 in the direction transverse to the axial flow. In this case boundary conditions in the Cartesian system of coordinates are ... 

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