@article { ISI:000233400500005, title = {Crystallization of polymers from stressed melts}, journal = {Journal of Macromolecular Science-Polymer Reviews}, volume = {C45}, number = {4}, year = {2005}, month = {OCT}, pages = {375-397}, publisher = {TAYLOR \& FRANCIS INC}, type = {Article}, address = {325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA}, abstract = {

In the last decade, there have been several investigations into the route by which a polymer melt that has been subjected to flow transforms into a crystalline state. Crystallization of polymers from flowing or stressed melts is a technologically important problem since most thermoplastics are subjected to intense flow fields during normal processing operations. The renewed interest in this problem is due to the availability of new experimental tools that, coupled with advances in modeling and simulations, are beginning to yield insights into the molecular characteristics that control the crystallization pathways adopted by a stressed polymer melt. Recent evidence conclusively implicates the high molecular weight tail in promoting crystallization on shearing. It appears that the formation of oriented nuclei in polydisperse melts is controlled by chain orientation of a small fraction of high molecular weight chains in a melt. Thus, it is the theological criteria for {\textquoteleft}{\textquoteleft}critical{\textquoteright}{\textquoteright} chain orientation that govern flow-induced acceleration and orientation in polymer crystallization. This review summarizes the literature on the effect of shearing on polymer crystallization, and focuses on recent advances in understanding the role of molecular parameters that couple polymer crystallization to flow and melt orientation.

}, keywords = {flow, polymer crystallization, processing, shear}, issn = {1532-1797}, doi = {10.1080/15321790500304171}, author = {Kumaraswamy, Guruswamy} } @article {43871, title = {Capillary uptake in macroporous compressible sponges}, journal = {Soft Matter}, volume = {13}, year = {2017}, month = {SEP}, chapter = { 5731-5740}, abstract = {

The capillarity-driven uptake of liquid in swellable, highly porous sponges is of significant industrial importance. Sponges prepared using polymers and their composites with carbon nanotubes and graphene have been reported, with extraordinary solvent uptake capacities and with the ability to separate oil from water. However, the effect of systematic variation of sponge characteristics on solvent uptake has not been investigated. Here, we report experiments that study capillary uptake in a variety of flexible, centimetre-sized macroporous cylindrical sponges. We used ice-templating to prepare a series of model macroporous sponges in which the porosity, modulus and composition were systematically varied. We investigated two kinds of sponge: (a) those composed purely of cross-linked polymers and (b) those prepared as composites of inorganic particles and polymers. Both kinds of sponge are flexible and exhibit elastic recovery after large compressive deformation. All sponges were characterized thoroughly with respect to their pore microstructure and elastic modulus. When one end of a sponge is plunged into a large reservoir, water rises through capillary action against gravity. We observed a transition from an inertial capillary regime, where the liquid column height rose linearly with time, t, to a viscous capillary regime, where the liquid height rose with time t(0.5). We showed that these results can be rationalized using analyses developed for rigid sponges. We combined differential momentum balance equations for uptake in rigid capillaries with the phenomenological Ergun-Forchheimer relations to account for the effect of the sponge microstructure. This approach works remarkably well in the viscous capillary regime and shows that capillary uptake is governed primarily by the total porosity and pore dimensions of soft sponges.

}, keywords = {aerogels, Building blocks, Catalyst Supports, Contact-angels, Dynamics, flow, Organic Liquids, Porous-Media, Rise}, issn = {1744-683X}, doi = {10.1039/c7sm00826k}, author = {Chatterjee, Soumyajyoti and Doshi, Pankaj and Kumaraswamy, Guruswamy} }