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Permanent Shape (permanent + shape)
Selected AbstractsShape Memory Effect of Bacterial Poly[(3-hydroxybutyrate)- co -(3-hydroxyvalerate)],MACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2005Young Baek Kim Abstract Summary: A bacterial poly[(3-hydroxybutyrate)- co -(3-hydroxyvalerate)] biosynthesized by Pseudomonas sp. HJ-2 was found to be a shape memory polymer. Permanent shapes were set by annealing at room temperature the samples that had been pre-treated above 95,°C in specified shapes. The temporary shapes were set by stretching and holding the elongated samples. Thermal shrinkage began at 45,°C and stopped at 75,°C to recover to their permanent shapes. Apparently, the orientation induced the formation of hard segments that were responsible for setting the temporary shapes. The shape memory effect of this polymer was explained based on the DSC and XRD results at different phases. The recovery of a coil shape upon heating a strip of HJ-2 PHB35V, demonstrating the polymers shape memory effect. [source] Triple-Shape Polymeric Composites (TSPCs)ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Xiaofan Luo Abstract In this paper, the fabrication and characterization of triple-shape polymeric composites (TSPCs) that, unlike traditional shape memory polymers (SMPs), are capable of fixing two temporary shapes and recovering sequentially from the first temporary shape (shape 1) to the second temporary shape (shape 2), and eventually to the permanent shape (shape 3) upon heating, are reported. This is technically achieved by incorporating non-woven thermoplastic fibers (average diameter ,760 nm) of a low- Tm semicrystalline polymer into a Tg -based SMP matrix. The resulting composites display two well-separated transitions, one from the glass transition of the matrix and the other from the melting of the fibers, which are subsequently used for the fixing/recovery of two temporary shapes. Three thermomechanical programming processes with different shape fixing protocols are proposed and explored. The intrinsic versatility of this composite approach enables an unprecedented large degree of design flexibility for functional triple-shape polymers and systems. [source] Polymers Move in Response to LightADVANCED MATERIALS, Issue 11 2006Y. Jiang Abstract Significant advances have recently been made in the development of functional polymers that are able to undergo light-induced shape changes. The main challenge in the development of such polymer systems is the conversion of photoinduced effects at the molecular level to macroscopic movement of working pieces. This article highlights some selected polymer architectures and their tailored functionalization processes. Examples include the contraction and bending of azobenzene-containing liquid-crystal elastomers and volume changes in gels. We focus especially on light-induced shape-memory polymers. These materials can be deformed and temporarily fixed in a new shape. They only recover their original, permanent shape when irradiated with light of appropriate wavelengths. Using light as a trigger for the shape-memory effect will extend the applications of shape-memory polymers, especially in the field of medical devices where triggers other than heat are highly desirable. [source] Melt spun thermoresponsive shape memory fibers based on polyurethanes: Effect of drawing and heat-setting on fiber morphology and propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Jasmeet Kaursoin Abstract Thermoresponsive shape memory (SMP) fibers were prepared by melt spinning from a polyester polyol-based polyurethane shape memory polymer (SMP) and were subjected to different postspinning operations to modify their structure. The effect of drawing and heat-setting operations on the shape memory behavior, mechanical properties, and structure of the fibers was studied. In contrast to the as-spun fibers, which were found to show low stress built up on straining to temporary shape and incomplete recovery to the permanent shape, the drawn and heat-set fibers showed significantly higher stresses and complete recovery. The fibers drawn at a DR of 3.0 and heat-set at 100°C gave stress values that were about 10 times higher than the as-spun fibers at the same strain and showed complete recovery on repeated cycling. This improvement was likely due to the transformation brought about in the morphology of the permanent shape of the SMP fibers from randomly oriented weakly linked regions of hard and soft segments to the well-segregated, oriented and strongly H-bonded regions of hard-segments. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2172,2182, 2007 [source] Shape Memory Effect of Bacterial Poly[(3-hydroxybutyrate)- co -(3-hydroxyvalerate)],MACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2005Young Baek Kim Abstract Summary: A bacterial poly[(3-hydroxybutyrate)- co -(3-hydroxyvalerate)] biosynthesized by Pseudomonas sp. HJ-2 was found to be a shape memory polymer. Permanent shapes were set by annealing at room temperature the samples that had been pre-treated above 95,°C in specified shapes. The temporary shapes were set by stretching and holding the elongated samples. Thermal shrinkage began at 45,°C and stopped at 75,°C to recover to their permanent shapes. Apparently, the orientation induced the formation of hard segments that were responsible for setting the temporary shapes. The shape memory effect of this polymer was explained based on the DSC and XRD results at different phases. The recovery of a coil shape upon heating a strip of HJ-2 PHB35V, demonstrating the polymers shape memory effect. [source] | ||||||||||||||||||||||