Thermoplastic elastomers solution casting

Cakmak M. and Wang M.D., Structure development in the tubular blown film of PP/EPDM thermoplastic elastomer, Antec 89, 47th Annual Tech. Conference of SPE, New York, May 1, 1989, 1756. Hashimoto T., Todo A., Itoi H., and Kawai H. Domain boundary structure of styrene-isoprene block copolymer films cast from solution. 2. Quantitative estimation of the interfacial thickness of lamellar microphase systems. Macromolecules, 10, 377, 1977. 

It was found that when the solution-cast films are stretched at temperature greater than Tg, liquid crystalline microdomains can support part of the elastic extension and, at the same time, deform to result in a long-range orientation of azobenzene mesogens. The liquid crystal orientation is retained in the relaxed film at r < Tg, which creates a thermoplastic elastomer whose glassy micro-... 

S. Hui, T.K Chaki, S. Chattopadhyay, Effect of sihca-based nanofillers on the properties of a low-density polyethylene/ethylene vinyl acetate copolymer based thermoplastic elastomer. Journal of Applied Polymer Science 110 (2) (2008) pp. 825-836. https //en.wikipedia.org/wiki/Polymer Solution Casting. 

Solution casting is a very convenient method when thin films of the blends are required. The elastomer and the thermoplastic are dissolved in a suitable common solvent or a mixture of solvents and then cast on a glass plate. 

A significant advantage of thermoplastic rubber solutions is their faster drying rate in film form compared to solutions of conventional elastomers. When 1 mil films (dry basis) were cast from 10%w toluene solutions, a t> pical S-I-S polymer reached a given level of residual solvent in 90% of the time required for natural rubber. The films were dried in an 86 %F recirculating air oven. If the comparisons were made between solutions of the same solution viscosity (a more practical case), the drying times for the thermoplastic rubbers would be roughly half those for SBR or natural rubber. 

Polyurethane thermoplastic elastomers may also be produced in fibrous form to give elastic fibres (spandex fibres). Such fibres are made either by solution spinning or by reaction spinning. In the first process, a hydroxyl-terminated polyester (e.g. an adipate) or polyether (e.g. poly(oxy-tetramethylene) glycol) is treated with an excess of diisocyanate (e.g. diphenyl-methane diisocyanate) to give an isocyanate-terminated pre-polymer similar to those used for cast elastomers (section 16.6.1). The pre-polymer is dissolved in a strongly polar solvent (e.g. dimethylformamide) and treated with an... 

Like all thermoplastic elastomers, thermoplastic polyurethane (TPU) is elastic and melt-processable. Further, it can be processed on extrusion as well as on injection, blow and compression molding equipments. It can be vacuum-formed or solution-casted and is well suited for a wide variety of fabrication methodologies. TPU can even be colored through a number of processes. But more... 

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