Conventional polymer-processing

The easy processibility of hydroxyproline-derived polyesters is in marked contrast to the unfavorable material properties of most conventional poly (amino acids) that cannot usually be processed into shaped objects by conventional polymer-processing techniques (7). Furthermore, since the synthesis of poly(N-acylhydroxyproline esters) does not require the expensive N-carboxyanhydrides as monomeric starting materials, poly(N-acylhydroxyproline esters) should be significantly less expensive than derivatives of conventional poly(hy-droxyproline). 

The first member of this series, poly(CTTE), was a high-melting and virtually insoluble polymer that could not be processed into shaped objects by any one of the conventional polymer-processing techniques. In this respect, poly(CTTE) was highly reminiscent of conventional poly(L-tyrosine). 

S. Kharchenko, K.B. Migler, and S. Hatzikiriakos. Conventional polymer processing additives. In S.G. Hatzikiriakos and K.B. Migler (Eds.), Polymer Processing Instabilities—Control and Understanding, Dekker, New York, 2005. 

PFSs can be fabricated into films, shapes, and fibers using conventional polymer-processing techniques. The dimethylderivative 73 (R = R =Me), which has been studied in the most detail, is an amber, film-forming thermoplastic (Figure 11), which possesses a Tg at 33 °C and melt transitions (T in the range of 122-150 °C. The multiple melt transitions arise from the presence of crystallites of different sizes which melt at slightly different... 

It should be soluble and/or fusible, so that it can be processed by conventional polymer processing procedures. 

Polyferrocenylsilanes can be fabricated into films, shapes, and fibers using conventional polymer processing techniques. The dimethyl derivative 3.22 (R=R = Me), which has been studied in the most detail, is an amber, film-forming thermoplastic (Fig. 3.7a) which shows a Tg at 33°C and melt transitions (T ) in the range 122-145 °C. The multiple melt transitions arise from the presence of crystallites of different size, which melt at slightly different temperatures [65, 100). Poly(ferrocenyldimethylsilane) 3.22 (R=R =Me) can be melt-processed above 150°C (Fig. 3.7b) and can be used to prepare crystalline, nanoscale fibers (diameter 100 nm to 1 pm) by electrospinning. In this method, an electric potential is used to produce an ejected jet from a solution of the polymer in THF, which subsequently stretches, splays, and dries. The nanofihers of different thickness show different colors due to interference effects simUar to those seen in soap bubbles... 

Solid-state extrusion has been practiced with coextrusion of different polymers [93]. Despite the large amount of research on solid-state extrusion and the outstanding mechanical properties that can be obtained, there does not seem to be much interest in the polymer industry. The main drawbacks, of course, are that solid-state extrusion is basically a discontinuous process, it cannot be done on conventional polymer processing equipment, and very high pressures are required to achieve solid-state extrusion. Also, one should keep in mind that very good mechanical properties can be obtained by taking a profile (fiber, film, tube, etc.) produced by conventional, con-... 

Polyetherketone-based nanocomposites can be produced by conventional polymer processing techniques such as extrusion and compression molding, frequently combined with preprocessing stages such as mechanochemical treatments in organic solvents. In order to further increase their properties, nanofiller addition has been considered but dispersion and improved load transfer ability from the matrix to the nanoreinforcement must be achieved and different routes have been developed to efficiently incorporate nanofillers into these matrices. 

Side-chain substitutions are now routinely used to enhance solvent solubility and fusibility so that various conventional polymer processing methods may be used. Some of these polymeric materials, e.g., the poly(3-al-kylthiophenes), may contain only a small volume fraction of electrically active regions (i.e., the 7r-conjugated main chain). Still these materials can exhibit extremely high dc conductivities (7) after doping (or more precisely, intercalation) by a guest species. This intercala-... 

Addition of flexible side chains to the stiff 7r-conjugated polymer backbone of the host polymer has proven to be an extremely effective procedure for obtaining tractable and fusible materials. This approach is not limited to conducting polymers but has also attracted considerable attention in more conventional rigid-rod-like polymers [96-99] including various polyimides and polyamides and in other novel polymers such as the polysilanes [100]. Not only does this modification enable the utilization of conventional polymer processing methods, it can also, in some cases, create new materials that exhibit enhanced electronic properties in comparison to the linearly unsubstituted parent polymer. These side-chain-substituted conducting polymers also exhibit properties that do not exist in the unsubstituted hosts discussed in... 

Starch processing is much more complicated and difficult to control than conventional polymer processing due to its unique phase transitions, high viscosity, water evaporation and fast retrogradation. However, with proper formulation development (plasticizer selection, etc.) and suitable processing conditions, many of these challenges can be overcome. ... 

The results demonstrate that ECAP technique is an effective methodology to consolidate raw WS or WG powder into bulk plastic materials without using any additional plasticizers at relatively low temperatures. This is impossible to achieve by any other conventional polymer processing method. 

The radical-mediated grafting modification of polyolefins is a technique practiced on the industrial scale. It is a solvent free process with relatively inexpensive reagents, and is readily adapted to conventional polymer processing equipment [1-2]. The twin-screw extruder is widely used in the grafting modification of polymers due to its unique features, such as modular screw configuration, excellent mixing, and independent feeding operation. 

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