The melting point corresponds to the thermal energy which is required for overcoming the energy maintaining the crystal lattice. If this energy is exceeded, the crystal is destroyed and melting therefore occurs. As the fillers are not miscible with polymers, i.e. are just dispersed inside, the crystals are formed in a completely independent way when the polymer is cooled. The same is true when the temperature increases, i.e. crystals melt at the same temperature, whether fillers are present or not, as polymer and fillers behave separately. This is true, as far as equilibrium is reached. However, effects can be observed on Tg, because interactions between polymer and fillers may change the mobility of the polymer chains, and therefore the Tg.
Alain
you can find a suitable answer in the following article:
http://onlinelibrary.wiley.com/doi/10.1002/pc.20830/abstract
The melting point corresponds to the thermal energy which is required for overcoming the energy maintaining the crystal lattice. If this energy is exceeded, the crystal is destroyed and melting therefore occurs. As the fillers are not miscible with polymers, i.e. are just dispersed inside, the crystals are formed in a completely independent way when the polymer is cooled. The same is true when the temperature increases, i.e. crystals melt at the same temperature, whether fillers are present or not, as polymer and fillers behave separately. This is true, as far as equilibrium is reached. However, effects can be observed on Tg, because interactions between polymer and fillers may change the mobility of the polymer chains, and therefore the Tg.
Alain
Fillers tend to influence rather crystallization (by nucleation) thus the crystalline size ditribution, long periods and spherulite diameter distribution. They may also influence the degree of crystallinity. Melting point is influencedy by additives which get incorporated in the crystal lattice. As, however, crystalline size distribution influences the shape of the DSC melting curve you may observe a slight shift in the melting minimum.
Dear Ba,
Let's make it easier... if there is no interaction between the filler and the polymer matrix, then all thermal properties are unaffected by the presence of the filler. Thus, microphase separation will occur and aggregation of the filler particles into big clusters.
But, if there are physical or chemical interactions, and the filler is well dispersed and with enough amounts, the first and second order transitions of the polymer will definitely be affected; specially those polymer chains in the vicinity of the interface.
Please, check our recent paper...
“Two Glass Transition Behaviour of Polyurea Networks: Effect of the Segmental Molecular Weight”, Soft Matter 2014, 10, 5729-5738
SALUT!
Tony
when mixing polymer with fillers ther is no chemical or intermolecular bonding that occurs
therefore thermal properties are not affected,hence no change in melting point
most answers (re melting point, degree of crystallinity) fit with what I would say. One comment to Antoni: there is always interaction between a filler and the polymer matrix (otherwise the filler would not be dispersed).
The major effect is that a monomolecular layer is adsorbed on the filler particle surface. Please look here:
https://www.researchgate.net/publication/229816762_Electrical_conductivity_in_heterogeneous_polymer_systems._V_%281%29_Further_experimental_evidence_for_a_phase_transition_at_the_critical_volume_concentration
Therefore, one can find changes in glass transition point.
Article Electrical conductivity in heterogeneous polymer systems. V ...
Thermally, carbon black act as thermal antioxidant behavior due to carbons absorbed large amounts of bound oxygen. These carbons are also acidic and decompose peroxides by the ionic mechanism.([1]) But it increased the brittle point and stress without effect on tensile.
[1]Antioxidant properties of carbon black in unsaturated elastomers. Studies with cis-polybutadiene
J. T. Gruver, K. W. Rollmann journal of applied polymer Volume 8, Issue 3 May/June 1964 Pages 1169–1183
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