NEAT polymer

Transesterification. There has been renewed interest in the transesterification process for preparation of polycarbonate because of the desire to transition technology to environmentally friendly processes. The transesterification process utilizes no solvent during polymerization, producing neat polymer direcdy and thus chlorinated solvents may be entirely eliminated. General Electric operates a polycarbonate plant in Chiba, Japan which produces BPA polycarbonate via this melt process. 

Inherently Conducting Polymers. Conducting polymers are polymers with a pi-electron backbone capable of passing an electrical current. These polymers generally are not sufficiently conductive as neat polymers but require the inclusion of an oxidi2ing or reducing agent (dopant) to render them conductive. 

For example, the increment in maximum stress over the neat polymer is 100% and 53% in the case of the unmodified- and the modified-clay-fiUed samples, respectively. The extraordinary results obtained with the unmodified clays were explained with the help of thermodynamics and surface energetics. They explained it as follows. 

Addition of layered nanoclays to a neat polymer restricts the permeability due to the following two phenomena ... 

When nanoclays are added to the system, we may assume that the clay layers are randomly placed in the matrix. The diffusion of the solvent will detour around the impermeable clay layers. Diffusion will be diverted to pass a clay platelet in every layer and, hence, the solvent must have to travel a longer path d in the filled system compared to that d( for the neat polymer. 

As a result, the permeability of nanocomposites (Pf) is reduced from that of the neat polymer... 

When a solvent diffuses across a neat polymer, it must travel the thickness of the sample (do). When the same solvent diffuses through a nanocomposite film with nanoclays, its path length is increased by the distance it must travel around each clay layer it strikes. According to Lan et al. [99] the path length of a gas molecule diffusing through an exfoliated nanocomposite is... 

FIGURE 15 Weight loss of polymer discs prepared from 3,9-bis(methylene-2,4,8,10-tetraoxaspiro[ 5,5 jundecane) and 1,6-hexanediol at pH 7.4 and 37°C. (o) neat polymer, (v) polymer with 10 wt% Na2C03,... 

Polarization of the Emission. We have sought support for the weakly interacting chain segment model from measurements of room temperature fluorescence polarization (19) on dilute solutions of 1 in 3-methylpentane. An independent preliminary report of similar measurements on a dilute glassy solution at 77K and on a neat polymer has also appeared (21). In the latter case, the analysis is complicated by inter-chain energy transfer. 

Metals are characterized by their low coefficients of thermal expansion and their strong thermal and electric conductivities, whereas wood (except where there is excessive moisture), and neat polymers have high coefficients of thermal expansion and are electrical and thermal insulators. 

Table 3.4 shows some examples of the modulus and the strength reinforcement ratios for various reinforced thermoplastics and thermosets. The reinforcement ratio is the performance of the reinforced polymer divided by the performance of the neat polymer. 

Compared to neat polymer and glass fibre reinforced polymer ... 

These results are of the same order as those in Table 3.5 for mineral-filled polypropylene. Versus neat polymer ... 

For an industrial example (see Table 3.8), the reinforcement ratios obtained with a loading of nanosilicate as low as 2% are attractive. The reinforcement ratio is the ratio of the nanocomposite performance versus that of the neat polymer. 

Table 3.17 Properties of EMI grades compared to neat polymers...

General chemical properties are subject to the compatibility of the fillers and reinforcements with the ambient conditions. If the fillers are well adapted, the chemical properties are the same for filled and neat polymers. 

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