What are Heckel plots?
What are Heckel plots?
In 1961 Heckel postulated a linear relationship between the relative porosity (inverse density) of a powder and the applied pressure. Large values of the Heckel constant indicate susceptibility to plastic deformation at low pressures, when the tablet strength depends on the particle size of the original powder.
What is the Heckel equation?
The Heckel and Walker equations. Heckel (1961a) developed his equation by assuming similarity to a first-order chemical reaction, where the concentration is substituted with porosity and the time with pressure. (1) d D/ d P=K ∗ (1 − D) where P is the pressure, D the relative density of the compact and K is a constant.
What is the importance of Heckel plot?
Heckel Plots Heckel plot is density v/s applied pressure Follows first order kinetics As porosity increases compression force also increases Thus the Heckel’s plot allows for the interpretation of the mechanism of bonding.
What is difference between compaction and compression?
Compression is a process of compressing, or increase in density or lessening in the bulk volume of granules or powder. Compaction is the transformation of powder into an intact compact with measurable strength and defined shape by the application of compression pressure.
What is Heckel analysis?
Abstract. The Heckel equation is one of the most useful equations for describing the compaction properties of pharmaceutical powders. Important material properties (e.g., yield strength) of powders can be derived using Heckel analysis. Two types of Heckel analysis are in common use.
What is solid deformation?
A change in shape due to the application of force is known as deformation. Even small forces are known to cause some deformation. Objects under the actions of external forces undergo deformation. This may be squashing, twisting, ripping, or pulling apart the object.
What is compaction profile?
Definition › Compaction profiles are hysteresis curves that establish the relationship between axial pressure and radial pressure. › In the compaction cycle, two forces are considered 1. Axial force: This vertical component is applied by the upper punch during compression.
What compression means?
The definition of compression is the action or state of being squished down or made smaller or more pressed together. When a pile of material is squished together and made smaller and more dense, this is an example of compression.
What is Heckel equation in physical pharmaceutics?
Heckel Equation: The Heckel equation is one of the most useful equations for describing the compaction properties of pharmaceutical powders. Heckel measured that decline in the voids follows the first order kinetics connection with applied pressure.
What is compaction force?
COMPACTION It is the compression & consolidation of two phases (solid & gas) system due to applied force. 4. Itis defined as the reduction in volume of a powder owing to the application of a forces.
What are the two types of deformations?
Types of deformations include:
- Elastic deformation – This can be reversible.
- Plastic deformation – This may be irreversible.
- Metal fatigue – This occurs primarily in ductile metals.
- Compressive failure -This is applied to bars, columns, etc., which leads to shortening.
- Fracture – This may be irreversible.
What are types of deformation of solids?
Types of deformation
- Elastic deformation.
- True stress and strain.
- Plastic deformation.
- Fracture.
Why is the Heckel plot important at high pressure?
At high pressures, where the Heckel plot is linear, the punch movement is very small. This makes accurate measurement of distance and precise correction for deformation of tools and machine parts extremely important.
Which is part of the Heckel plot is linear?
The region where the Heckel plot is linear is only accounting for a small portion of the total densification ( Huffine, 1953, Birks, 1990, Konkel and Mielck, 1997 ). Some investigators were unable to define any linear part of the Heckel plot ( Rue and Rees, 1978, York, 1979, Celik and Marshall, 1989 ).
How did Heckel come up with the Heckel equation?
Heckel (1961a) developed his equation by assuming similarity to a first-order chemical reaction, where the concentration is substituted with porosity and the time with pressure. (1) d D/ d P=K ∗ (1 − D) where P is the pressure, D the relative density of the compact and K is a constant. Eq.
Why are Heckel plots an error prone method?
As obvious from the data, Heckel Plots are an error-prone method describing deformation behaviour of powders, due to the difficulties in measuring the in-die tablet height sufficiently accurately. Therefore, it might be difficult to evaluate literature data of Heckel Plots properly.
