Why is the acrylic memory process only possible with thermo plastics?
The acrylic memory process refers to the ability of certain thermo plastics, like acrylic, to undergo a reversible deformation when exposed to heat. This phenomenon allows the plastic to return to its original shape once it cools down.
To understand why this process is only possible with thermo plastics, it's important to first understand the properties of thermo plastics compared to other types of plastics.
Thermo plastics are a type of polymer that can be heated and molded, and then cooled and solidified repeatedly without undergoing significant chemical change. This is because thermo plastics have linear or branched polymer chains that are entangled but not cross-linked. This molecular structure allows the plastic to soften when heated and become more malleable, allowing it to be shaped into various forms. When it cools, the chains become rigid again, locking the shape in place.
On the other hand, there are other types of plastics, such as thermosetting plastics, that undergo a permanent chemical change when heated and cooled. These plastics have cross-linked polymer chains that form a three-dimensional network, making them less pliable upon heating and irreversibly setting their shape upon cooling. Once these plastics are heated and molded, they cannot return to their original shape upon cooling.
So, the unique molecular structure of thermo plastics, with their linear or branched chains and lack of cross-links, allows them to undergo the acrylic memory process. The chains can move and rearrange when heated, leading to temporary deformation, and then return to their original arrangement when cooled. This property makes them useful in applications where shape memory and reversible deformations are required, such as in certain medical devices or flexible electronics.