What does paraffin penetration index represent in industrial production?

What does paraffin penetration index represent in industrial production?

The Penetration Index (PI) of paraffin wax is a key indicator for measuring its temperature sensitivity, with specific implications as follows:

I. Definition and Calculation

‌Physical Significance‌

PI is calculated by correlating penetration data at different temperatures (typically ≥3 temperature points) with the softening point, reflecting the rate at which paraffin wax viscosity changes with temperature.

Calculation formula: $ PI = frac{20 - 500A}{1 + 50A} $, where $ A $ is the temperature sensitivity coefficient, determined by the linear regression slope of penetration logarithm versus temperature.

‌Colloidal Structure Classification‌

‌Sol-type (PI < -2)‌: Low paraffin content, prone to softening at high temperatures and brittleness at low temperatures.

‌Gel-type (PI > +2)‌: Forms a network structure, exhibiting strong high-temperature stability but poor low-temperature ductility.

II. Engineering Application Impact

‌Temperature Adaptability‌

Higher PI indicates lower sensitivity to temperature changes (e.g., PI>2 ensures stable high-temperature performance but may cause low-temperature hardening).

High-PI paraffin (e.g., PI=0~+2) is suitable for wide-temperature environments, but requires balancing high-temperature fluidity and low-temperature toughness.

‌Performance Correlation‌

PI has no direct relationship with penetration, but it can predict the viscosity-temperature curve characteristics of paraffin.

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