Expandable microspheres are microscopic spheres comprising a
thermoplastic
A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.
Most thermoplastics have a high molecular weight. The polymer chains associat ...
shell encapsulating a low boiling point liquid
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
. When heated to a temperature high enough to soften the thermoplastic shell, the increasing pressure of the hydrocarbon will cause the microsphere to expand. The volume can increase by 60 to 80 times.
Expandable microsphere
The expandable microsphere is a material that can act as a blowing agent when mixed in a product and subsequently heated to cause expansion within the matrix.
The expandable microspheres are off-white, can be 6 to 40 micrometers in average diameter and have a density of 900 to 1400 kg/m
3.
The expandable microspheres are used as a blowing agent in products like e.g. puff ink, automotive underbody coatings or injection molding of thermoplastics.
["New developments with expandable microspheres", Klas Elfving, Expancel. The Fifth International Conference Blowing agents and Foaming Processes 2003, Rapra.] Here the product must be heated at some point in the process for the expandable microspheres to expand.
Expanded microsphere
The expanded microsphere is a material that has been heated to cause expansion. The product acts as a light weight filler in many products.
The expanded microspheres are white, can be 15 to 90 micrometers in average diameter and can have a density of 15 to 70 kg/m
3.
The expanded microspheres are used as a lightweight filler in composite materials such as
cultured marble, in waterborne paints and crack fillers/
joint compound
Joint compound (also known as drywall compound, drywall mud, or mastic) is a white powder of primarily gypsum dust mixed with water to form a paste the consistency of cake frosting, which is used with paper or fiber ''joint tape'' to seal jo ...
.
Characteristics
Characteristics that make expandable microspheres unique,
* Ability to expand
* Resilient
* Ultra-low density when expanded
* Closed cells that can be distributed evenly
* Can introduce a pressure in the production process
References
{{reflist
See also
*
Cenosphere
A cenosphere is a lightweight, inert, hollow sphere made largely of silica and alumina and filled with air or inert gas, typically produced as a coal combustion byproduct at thermal power plants. The color of cenospheres varies from gray to almos ...
*
Glass microsphere
Glass microspheres are microscopic spheres of glass manufactured for a wide variety of uses in research, medicine, consumer goods and various industries. Glass microspheres are usually between 1 and 1000 micrometers in diameter, although the ...
*
Microbead
Microbeads are manufactured solid plastic particles of less than one millimeter in their largest dimension. They are most frequently made of polyethylene but can be of other petrochemical plastics such as polypropylene and polystyrene.
They are u ...
*
Microplastics
Microplastics are fragments of any type of plastic less than in length, according to the U.S. National Oceanic and Atmospheric Administration (NOAA) and the European Chemicals Agency. They cause pollution by entering natural ecosystems from a v ...
*
Plastic particle water pollution
Plastic pellet pollution is a type of marine debris originating from plastic particles utilized in manufacturing large-scale plastics. These pre-production plastic pellets, sometimes referred to as nurdles with reference to plastic pollution, are ...
Thermoplastics
Hydrocarbons