Continuous poly

The resistance of the polymer to oils and organic solvents can be direcdy attributed to the hydroxyl fiinctionahty and the fihn-forrning properties of the polymer. Treated paper substrates display a significant amount of oil resistance, which make them valuable for packing papers and food-grade paperboard containers. This performance improvement is achieved despite the fact that the 1—3 wt % add-on level, typical of size press appHcations, is too low to provide a continuous poly(vinyl alcohol) film. 

Continuous cultivation, which needs permanent multiplication of cells, seems not to be appropriate for poly(3HB) synthesis because the product is mainly formed during the stationary growth phase. But there are three opportunities, discussed below, that make continuous poly(3HB) synthesis possible. 

Laubriet et al. 111 Continuous Poly condensation, finisher Tube reactor, disc type... 

In HIPS, desirably the PS is the continuous phase including a discontinuous phase of rubber particles. The size and distribution of the rubber particles in the continuous PS phase can affect the properties of the HIPS. In blends of PS with other materials, the distribution of the noncontinuous phase in the continuous poly(styrene) phase is often similarly important (2). The impact strength of HIPS can go up to sevenfold of that of general purpose PS. 

Cationic polymerization of XII may therefore be visualized in terms of Figure 9 according to which the ir complex initially formed between the active site and the monomer is converted into a carbocation with rupture of a C—C bond in the cyclopropane. This cation may be Xlla, b, or c, but only the latter can give rise to Structure M, alone compatible with the experimental data. This change necessitates the transfer of a hydride ion to transform the primary cation XIIc into the more stable tertiary cation Xlld. On this assumption, the termination reaction probably occurs as the result of the displacement of a proton in the alpha position with respect to the C+, which is relatively easy, whereas the steric hindrance around the active site does not favor continued poly-... 

Polycarbonates (continued) Poly [2,2-pentane bis(4-phenyl)carbonate] 282.3 >1.13 ... 

Figure 5 shows the influence of IPN component ratio on Tg. Each sample was of IPN 1 type, prepared by the simultaneous method. Increasing the amount of 23G lowered the Tg of the IPN. This result also suggests that these IPNs show a good ability to mix. The Tg of IPN containing 70% of 23G was shown to be about 0 C, just like IPN 2 synthesized by the sequential method. The structure of 70%-23G-IPN can be considered to be cured phenolic resol in a continuous poly 23G phase. So, the loss tangent peak of IPN 2 at 0°C was attributed to the structure of 23G rich IPN such as 70%-23G-IPN. 

The change of a continuous poly stochastic model into its numerical form is carried out using the model described by Eq. (4.71) rewritten in Eq. (4.146). The solution of this model must cover the variable domain 0 z z, 0 t T. In accordance with the previous discussion, the following univocity conditions must be attached to this stochastic model. Here, fk(z),g (T) and h(t) are functions that must be specified. 

CNC CHEMICAL CORP. Special Purpose Products(Continued) POLY-COUPLER, IMP, RFB-X353 ... 

Petro M, Svec F, and Frechet JMJ. Molded continuous poly(styrene-co-divinylbenzene) rod as a separation medium for the very fast separation of polymers. J. Chromatogr. A 1996 752 59-66. 

Fig. 12.4. Continuous poly-Si film formed by the ALILE process on a 3-in substrate (To obtain this figure the Al on top of the poly-Si film was sele, removed by wet chemical etching), (from [28])...

The crystallized fraction, which was defined as the ratio of the dark area to the total area in the optical micrographs, is shown in Fig. 12.7 as a function of the tx for different annealing temperatures T (from 500 to 530°C). The tx necessary to form a continuous poly-Si layer (i.e., to reach a crystallized fraction of 100%) becomes shorter with increasing annealing temperature. For example, at 530°C a continuous poly-Si film was formed after 19 min. Whereas, it took 90 min to form a continuous poly-Si film at 500°C. The time necessary to finalize the ALILE process can be separated into the above... 

The permeable membrane (barrier layer) plays a crucial role for the ALILE process. Usually, the barrier layer is formed by exposure of the Al-coated glass substrate to air. The thickness of this barrier layer (A1 oxide), which is on a nanometer scale, can be influenced by the variation of the exposure time. With increasing exposure time, the thickness of the barrier layer increases. The thicker the barrier layer, the lower is the nucleation density and the longer is the process time necessary to form a continuous poly-Si film [19]. By X-ray photoelectron spectroscopy (XPS) measurements it was shown that the barrier layer stays in place during the whole ALILE process. 

In order to demonstrate the importance of the barrier layer for the layer exchange process, an initial glass/Al/a-Si stack without a barrier layer was prepared [50]. To prevent the formation of a barrier layer the a-Si was deposited directly onto the A1 (without vacuum break). The SEM images in Fig. 12.11 make the influence of the barrier layer clear. Two samples are shown - one with barrier layer (by exposure to air for 2 h) (left hand side) and one without barrier layer (right hand side). Both samples were annealed for 45 min at 480° C. After the annealing step, the A1 was etched off chemically. To show the cross section as well as the surface, the samples were tilted by 30° for the SEM measurements. The sample with barrier layer (left) shows a continuous poly-Si film with Si islands on top (similar to what is shown in Fig. 12.5), whereas the sample without barrier layer (right) does not show a continuous poly-Si film but a porous film structure. The former interface between the A1 layer and the a-Si layer is not visible. In some parts, the... 

Fig. 12.11. SEM images of a sample with barrier layer (left) and a sample without barrier layer (right). The samples were annealed at 480°C for 45min. After the annealing step, the A1 was etched off. The samples were tilted by 30° to show both cross section and surface. The sample with barrier layer (left) features a continuous poly-Si film with Si islands on top. The sample without barrier layer (right) features a porous structure, (from [50])...

In addition to the experiments with very thin barrier layers, rather thick barrier layers have also been investigated [51]. The thick barrier layers were formed by thermal oxidation of the Al surface (e.g., for 2h at 560°C). With such a thick barrier layer, an estimated average grain size of above 200 pm was reached. But at the corresponding Ta of 450°C, it took days to form a continuous poly-Si film. The influence of a barrier layer formed by thermal oxidation on the preferential orientation of the poly-Si surface was already described (see Fig. 12.10). 

Continuous Poly(vinyl Acetate) Emulsion Polymerization Reactors... 

For both designs a microphase separated morphology was found with 20-50 nm peptide domains dispersed in a continuous poly(ethylene glycol) phase. Furthermore, a 100-150 nm superstructure was observed in cast films, which was explained to result from the polydispersity and multiblock character of the polymers. The mechanical properties of fibers and films made from these block copolymers could be modulated by manipulating the length and nature of the constituent blocks. Similar work was reported by Shao et al. [47]. 

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