Executive Summary :
Objective: 1. Development of Multifunctional shape memory composite using SMPs and SMAs – Acronym as Smart-SMPCs. 2. Design and Development of Smart And Multifunctional Polymeric Composites For Shape Memory, Self-Healing And Biomedical Applications – S-H-Biomedical-SMPCs. 3. Shape-recoverable Polymeric Cellular Material for Thermal insulating Applications – S-PCM
Summary: The abstracts for individual work-packages are as follows:
The advantages of SMPs over SMAs are evident in its lower cost, lower density, easier processing, biodegradability, lower deformation loads and larger attainable strains. SMAs rule over SMPs in their recoverable force ranges, recoverable speeds, precision control and heat conductivity. Thermally responsive Shape memory alloys (SMA) and Shape Memory Polymers (SMP) can be combined to form a Multifunctional Smart Material system. Such a multifunctional system that involves the combination of SMA and SMP not only improves these properties but also results in a MSMS with a new set of response characteristics that would be quite different than the original two materials.
Thermo-sensitive shape memory polymer composites were developed Under the 12th FYP project, using shape memory polyurethane with different loadings of CNT to improve recovery stresses in the composites. The further work in this area of material is to provide application oriented modification such as formation of an inter-connected conductive network of nano-tubes/particles in the SMP matrix to further enhance mechanical as well as thermal properties that might result in trigger shape memory effect of polymer composites by either means; electrical as well as thermal actuation. Characterization with respect to their thermal electrical, mechanical properties is needed. Dispersion of functional fillers or reinforcing materials in thermoplastics is a challenge due to very high viscosities of thermoplastics having narrow working range of temperature in which melt mixing is possible. CSIR AMPRI Bhopal has facility of micro-compounder that can effectively deal with mixing of thermoplastics with other thermoplastics to make blends as well as fine dispersions. Melt mixing is superior to the solution casting methods employed in thermoplastics processing.
High Recovery Stress shape memory polymer composites have potential applications in Automobile, Engineering, Aviation and Aerospace, sealing & packaging industries. This technology could find possible applications in Shape Memory Fastener, Deployable housing in space, Foldable housing and Deformable sandwich panels.
Polymeric foams have become a part of comfortable life and an important component of industrial growth of modern world; with applications as catalysts for uniform reaction efficiency, sudden shock absorption, housing chemicals in cells, thermal insulations etc. Polymeric foams are made all over the world by a variety of techniques ranging from leaching a soluble filler phase, providing an internally generated gas-producing phase, utilizing emulsion-derived phase separation techniques etc. The most popular technology uses blowing agents in polymer gels, which on heating to a certain temperature liberate gases to form bubbles and foaming takes place. The foamed gel is then stabilized.
Contrary to universally adopted method of production of polymeric foam, the proposed POLYMERIC CELLULAR MATERIAL would be formed using naturally available gaps and voids by virtue of geometry and shape of elementary constituents (No need to create bubble or voids by chemicals vapors). These elementary constituents can be of different shapes, however, must have good adhesion with adjacent elements by suitable mechanism to make a network which will be termed as POLYMERIC CELLULAR MATERIAL. The Polymeric cellular material can regain its shape repeatedly on removal of applied load and can be tailored for different load-bearing capacity.
Polymeric cellular materials were also worked out using elementary constituents of polymers which were assembled to form a porous structure containing randomly distributed elementary constituents. This porous structure is not only breathable but provides excellent thermal insulation, and shows shape-memory characteristics. The density varies from 0.35 to 0.80 g/cc with compressive modulus more than 2.0 MPa depending on types of materials and size of constituent elements.
This semi rigid foam would provide a better alternative to thermal insulation to buildings so as to make them more energy efficient at competitive cost. The process neither uses any imported raw material, foaming agent or sophisticated equipment/controls to make uniform porosity in the material as is required in the conventional foam production. It uses natural voids and almost any material (that could be converted to elementary constituent by conventional industrial processes) so that thermal conductivity, compressive strength, shapes recovery can be tailored to desired value. Panels and board of different thicknesses have been made and characterized at lab-scale for several properties.
It is now aimed to carry forward the findings for making panels and boards of different size at CSIR-AMPRI, Bhopal and its trials at different locations to have data useful for its commercialization. It is also proposed to laminate this foam so as to replace honey comb structure. This would involve making (i) panels of different sizes and thickness (ii) Mechanical, & Thermal characterization (iii) Parameter optimization for specific compositions, (iv) Field trials with the help of industry.