Absolutely! All materials fall somewhere in the
spectrum of heat conductors and insulators. For a
container that is intended for insulation, you
want a material that has a low thermal
conductivity (i.e. it can sustain large
temperature gradients). To understand how to
retain heat, you'll need to know how heat travels.
You can see the table below
for a range of thermal conductivities in various
materials. This table was taken from the link
here to read it.
The units of thermal conductivity are Watts (or
Joules per second) per meter Celsius. It's a
measure of how much heat (i.e. energy) is
transferred per unit time across each unit of area
per unit temperature. Note that these are only for
25 C. Thermal conductivity is temperature
dependent! In fact, at high enough temperatures,
you can insulating materials conducting.
How does heat travel?
From everyday intuition (and many years of
thermodynamics), we know that heat tends to travel
from hot to cold. There are several mechanisms
that heat is transferred between two bodies of
different temperatures. The modes of heat transfer
- advection: transport by fluid via fluid motion
- conduction: transfer by physical contact
- convection: transfer by contact between physical
object and environment via fluid motion
- radiation: generated by thermal motion of
charged particles into light
The one you may be most familiar with is
conduction (e.g. when Convection could technically
be seen as a form of conduction if you view the
gas as a collection of particles that transfer
energy via collisions with itself and the physical
What makes an insulator an insulator?
It turns out that materials that are good
electrical insulators also tend to be good thermal
insulators. Metals are good conductors mainly due
to the fact they have essentially free electrons,
which carry heat with them when conducting. The
reason for this can be roughly traced back to what
you learn in chemistry- metals tend to want to
give up electrons to achieve a stable octet, so
they tend to hang on to valence electrons less
strongly. It's pretty surprising how much
intuition you can have about a material simply
from its position on the periodic table. In
contrast, insulators have very localized electrons
that do not conduct well; heat travels through
insulators via lattice vibrations, also known as
A cool application is a vacuum-insulated thermo.
Most thermos containers are just insulated with a
layer of air, so why a vacuum? A vacuum has
nothing in it- no particles, not even dust- so
heat exchange can't happen through conduction or
convection! But of course, this would have to be a
perfect vacuum, which is pretty hard (and
expensive) to achieve. What would happen if
thermos were instead insulated with wood? Would
you still expect your hot drink to be as hot a few
hours later? For reference, the thermal
conductivity of a vacuum is nearly zero.
Another interesting thing to muse about: Why is it
that tile, such as in your bathroom or kitchen,
feels cooler than the carpet, even though they are
at the same temperature? Think about it, and then
watch this video
about the nuances between heat and temperature to
find out more.
Hope this helps!