SSM''s ( Shape memory Materials) Shape shifting polymers have the ability to shift shapes in accordance to a stimuli, which can be thermal, photonic, electronic, magnetic or Ph. They are engineered to have a reactive range on which a mechanical change will occur; the material can hold two or three forms which it will transition between on occurrence of its stimuli.
Shape memory alloys are materials which possess the same characteristic; however they are based on alloys which often require a more extreme stimulus range, such as a high temperature so the usefulness of such in textile applications is restricted.
To be useful in textile applications the trigger temperature needs to be around that of body temperature and the application potential in garments is wide ranging. Some possibilities include that of a shape memory polyurethane coating, which when activated by body heat would shape to remove wrinkles and creases. The possibility is further extended into garments such as sportswear or PPE? of which air permeability is necessary for water vapour transfer, heat reactive materials within the fabric structure would allow the structure to expand, thus opening the interstices allowing further air/vapour transfer. Anti counterfeit measures such as labels which display text upon encountering heat is an area being used in brand protection.
Shape memory materials have a range of applications within the medical and hygiene sector, for example, implants can be put in the body through smaller incisions, such as stents to open arteries, or plates to bring bones back into alignment.
Anti counterfeit label video
The Science behind Shape Memory Materials
The shape change properties are possible because of the atomic modelling of the material. The 3 states of matter include, gas, liquid and solid, however there are two models of atomic structuring in a solid;
Martensite; occurs at a lower temperature, is more flexible, atoms can change position from pressure, allowing for deformity.
Austenite; Occurs at a higher temperature, is harder and more rigid.
Materials can be set in the required shape at the Austenite stage, at an extreme level not encountered under normal conditions, then revert into the martensite stage appearing to loose its shape. When encountering the temperature required for Austenite structure it will remember its set shape and revert to this, however this temperature is at a much lower level than that required to set it.
To understand the science behind Shape memory materials, view the video.
The science behind Shape Memory materials.