份 in a scientific context

[Kenny同志]

So again my teacher asks me to translate an abstract of a thesis of polymer science for her. And I ran into 份. For example, a rubber recipe goes like this

天然橡胶 100份、 氧化锌 5份、硬脂酸 2份、防老剂PBN 1份、促进剂MBTS 1份、 硫磺 2.5份

天然橡胶 natural rubber

氧化锌 zinc oxide

硬脂酸 stearic acid

防老剂 anti-ager

促进剂 vulcanization accelerator

硫磺 sulfur

What is the English term for 份?

Thanks a lot.

[zhwj]

Instead of any specific unit, the recipe gives proportions of each ingredient in "parts" -- 100 parts natural rubber, 5 parts zinc oxide, etc. The paper ought to specify parts-by-weight or parts-by-volume.

[Kenny同志]

Thanks zhwj. I assume it’s parts-by weight.

PS: I got the term by googling "rubber recipe". seems like phr is also okay.