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In rubber-assisted hot embossing, a softened thin thermoplastic film is pressurized between a hard mold surface and a rubber pad. The rubber pad, as a soft counter-tool, deforms conformably to the hard mold surface, allowing feature transfer from the hard surface and formation of shell-type structures on the polymer film. This two-article sequence was aimed to understand the basic mechanisms affecting the pattern uniformity and replication in rubber-assisted hot embossing. In Part I, a series of rubber-assisted embossing experiments involving parametric studies of the effects of different processing conditions, as well as material selections, on the pattern thickness uniformity and replicated pattern height were conducted. The difference in film thickness uniformity in different experiments was explained using the mechanical and rheological behavior of the polymer film and the rubber counter-tool under different processing conditions. Based on the experimental results, strategies for determining a feasible process window for achieving uniform shell patterning by rubber-assisted embossing were proposed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This two-article sequence on rubber-assisted embossing was aimed to understand the basic mechanisms affecting the pattern uniformity and replicability and to determine a process window for achieving uniform patterning and faithful replication. In Part I, the effects of major process and material parameters were identified and studied, and strategies for successful hot embossing with rubber as a pressure medium were proposed. In Part II, the rubber-assisted embossing process was analyzed considering the unique rheological behavior of the materials involved to develop useful predictive capabilities for this new process. Specifically, a finite-strain hyperelastic formulation was used for simulating the isothermal embossing stage, and a generalized Maxwell model was used to study the stress relaxation during the holding stage and to predict the elastic recovery after demolding. The rheological properties obtained in Part I were fitted to the constitutive models and implemented in the simulation procedures. The simulation results agreed with the major findings in the experimental work and provided a more quantitative insight into the process. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The article focuses on the experimental study involving a two-station embossing strategy for enhancing the fabrication of surface microstructures on thermoplastic polymers. The two-station embossing process uses contact heating and cooling for rapid thermal cycling of embossing molds. Based on the results of the study, good replication fidelity including local replication of sharp edges and mold surface defects can be attained with an embossing time of less than several seconds.

The article discusses the single-polymer composites based on slowly crystallizing polymers. An approach of using slowly crystallizing polymers to form single polymer composites was examined which demonstrates the method using polyethylene terephthalate as a model system. The method was used the to observed the difference in melting temperature between high density polyethylene (HDPE) matrix and its reinforcement to construct a HDPE homocomposite.

Discusses the experimental results of cold forging for replicating high-aspect-ratio microchannels on polytetrafluoroethylene (PTFE). Room-temperature mechanical properties of PTFE; Replicability of microchannels in cold forging experiments with varied forging displacement and force; Deformation behavior of PTFE during forging.