Moldings, microstructure

As the number of technological applications of MIPs continues to increase, there is a growing demand for MIPs tailored to specific physical forms. Polymerization methods to yield the MIPs in the form of size-defined spherical particles at the micro- or nanoscale, monoliths, thick and thin films and molded microstructures have all been published in the last few years [Biffis et al., 2012]. 

Bardhan N., Roy S., Jena A. K. and Bhargava P., Influence of plaster of paris mold microstructure on sintered slip cast compacts, presented at International Seminar on Ceramics - CeraTec 2007, Vishakhapatnam, India. 

In the following discussion, different injection molding techniques and some molded microstructures will be presented. 

Microstructure (see also Stereochemistry and Tacticity) 114,115.128.138,139 Miscibility (see also Compatibility) 12, 53, 68 Model networks 163 Modification of a polymer, chemical 154 Mold release 71, 74 Molecular weight, control 147. 154... 

Re-entrant foam provides a counter-intuitive demonstration of processing (5). Polyurethane can be isotropically compressed in a mold and heated to about 170 °C. The microstructure of the resulting solid yields a material that bulges in cross section when stretched More information on polymers will be available from John Droske s complementary NSF-funded project (described in the preceding section). 

Karger-Kocsis J. (1991). Microstructural aspects of fracture and fatigue behavior in short fiber-reinforced, injection-molded PPS-, PEEK- and PEN-composites. Poiym. Bulletin 27, 109-116. 

Karger-Kocsis J. and Friedrich K. (1987). Microstructural details and the effect of testing conditions on the fracture toughness of injection molded poly(phenylene sulphide). J. Mater. Sci. 22, 947-961. 

The facts that the LCST of PNIPAAm is only 32 °C and the polymerization reaction is highly exothermic can also lead to problems with reproducibility of the gel synthesis. If the solution is deliberately warmed above the LCST during polymerization, an opaque gel with a permanently phase separated microstructure is formed [65]. Depending upon the initial solution temperature, initiator concentration and type, and heat transfer characteristics of the gel mold, the solution temperature can rise substantially during polymerization and alter the gel s properties. 

Microfabrication was achieved by UV-lithography with a negative photoresist SU-8 2035 based on a nickel plate [163], By means of electroforming of the exposed and developed resist structure, a nickel mold was prepared (see Figure 1.182). By hot embossing, the final polymer mixer structures were prepared. Holes for fluid connectors were drilled. The microstructured substrate was joined with a blank polymer plate by thermal fusion bonding. 

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