The chemical resistance of thermoplastics is influenced by several key factors including the chemical concentration, temperature, exposure time, and the specific formulation of the plastic material.

Thermoplastic Material Reference

The following table provides a quick reference for common thermoplastic piping materials and their general chemical resistance properties.

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General chemical resistance characteristics of common thermoplastic piping materials.
Material	Common Abbreviation	General Chemical Resistance Notes
Acrylonitrile Butadiene Styrene	ABS	Good resistance to many acids, alkalis, & salts.
Chlorinated Polyvinyl Chloride	CPVC	Excellent resistance to most acids, bases, salts, & aliphatic hydrocarbons.
Polypropylene	PP	Excellent resistance to most organic solvents, fats, & oils. Limited resistance to strong oxidizing acids.
Polyvinyl Chloride	PVC	Good resistance to acids, alkalis, salts, & many alcohols. Poor resistance to ketones, aromatics, & chlorinated hydrocarbons.
Polyethylene	PE	Good resistance to most acids, alkalis, & aqueous solutions. Swelled by some organic solvents.
Polybutylene	PB	Good resistance to acids, alkalis, & salt solutions. Common in hot/cold water distribution.
Polyvinylidene Fluoride	PVDF	Exceptional chemical resistance to most acids, aliphatics, aromatics, alcohols, & halogenated solvents.
Cross-linked Polyethylene	PEX	Enhanced resistance to creep & chemical attack compared to standard PE. Good for water & radiant heating.

Source: plasticpipe.org/pdf/tr-19_thermoplastic_pipe_for_transport_of_chemical.pdf

Key Calculation Formulas

When evaluating chemical resistance, two fundamental quantities are often calculated: the chemical's permeation rate through the pipe wall and the diffusion coefficient.

The chemical permeation rate ( $J$ ) can be estimated using Fick's first law for steady-state diffusion:

$J = -D \frac{\Delta C}{\Delta x}$

Where:

$J$ is the permeation flux (kg/m²·s).
$D$ is the diffusion coefficient (m²/s).
$\Delta C$ is the concentration difference across the wall (kg/m³).
$\Delta x$ is the pipe wall thickness (m).

The diffusion coefficient ( $D$ ) itself is often temperature-dependent and can be modeled with an Arrhenius-type equation:

$D = D_0 \exp\left(-\frac{E_a}{RT}\right)$

Where:

$D_0$ is the pre-exponential factor (m²/s).
$E_a$ is the activation energy for diffusion (J/mol).
$R$ is the universal gas constant (8.314 J/mol·K).
$T$ is the absolute temperature (K).

References

Original Source

Source: engineeringtoolbox.com