question

[kat05]

Hi,
Why does biodiesel sourced from plants have lower melting point and less cloud flow problems than biodiesel sourced from animals? Is the cloud point of biodiesel lower or higher than petroldiesel?

Thank you.

[interessant]

Triglycerides produced from plants form unsaturated esters, and triglycerides produced from animals form saturated esters. Unsaturated esters contain at least one carbon-carbon double to triple bond, whereas saturated esters contain only carbon-carbon single bonds. Because unsaturated esters have double bonds, there are kinks in the molecule which make it difficult to pack together. This then makes the dispersion forces weaker, and so therefore has a lower melting point, which is why biodiesel sourced from plants have a lower melting point.

[Evolio]

Hey!
Also, the cloud point of biodiesel is higher than that of petrodiesel. This is because of the strong intermolecular bonds that biodiesel molecules can form with each other, that is the presence of the dipole-dipole bond and the stronger dispersion forces due to its greater molar mass.
Since the cloud point is higher, this means that the biodiesel will freeze or specifically gel in colder temperature which is not good because then the biodiesel will not flow easily along fuel lines in car engines for example.