Parts per hundred rubber

In the rubber-chemical industry, parts per hundred rubber (phr) is used to describe the mass proportions of the individual mixture components in a recipe for an elastomer mixture . This information is based on 100 parts (by mass) of the base polymer or base polymers (in the case of polymer blends ).

Similar to baking cakes, this specification of the recipe ingredients is particularly suitable when preparing the mixture (" mixing ") itself. On the other hand, the phr proportions only say something about the density of the respective mixture ingredient about its volume ratio : ${\displaystyle i}$ ${\displaystyle \Phi _{vol}}$

${\displaystyle \Phi _{vol}={\frac {V_{i}}{V_{ges}}}={\frac {\frac {{\rm {phr}}_{i}}{\rho _{i}}}{\sum _{i}{\frac {{\rm {phr}}_{i}}{\rho _{i}}}}}}$

Recipe example of a rubber compound

component ${\displaystyle i}$	phr	Density / g / cm³	Volume / cm³	${\displaystyle \Phi _{vol}}$
Polymer 1	80	1.1	72,727	70.3%
Polymer 2	20th	0.95	21,053	20.4%
Filler - carbon black	8th	1.9	4.211	4.1%
Aggregate 1 - crosslinker	1	0.99	1.010	1.0%
Aggregate 2 - accelerator	3	1.3	2,308	2.2%
Additive 3 - anti-aging	2	0.95	2,105	2.0%
total	114		103.413	100.0%

literature

• John S. Dick: Rubber Technology: Compounding and Testing for Performance. Hanser
• struktol.com: Rubber Handbook. (PDF; 2.3 MB)