Oxygen Transmission Rate Calculator

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Oxygen Transmission Rate (OTR) Calculator

The material's inherent ability to let oxygen pass through.
Standard air is 0.21 atm (21% oxygen).
Note: 1 mil = 0.001 inch = 25.4 microns.

Calculation Results

Unit: cc / (m² · day)

function calculateOTR() { var perm = parseFloat(document.getElementById('permCoeff').value); var pressure = parseFloat(document.getElementById('pressureDiff').value); var thick = parseFloat(document.getElementById('thickness').value); var resultContainer = document.getElementById('otrResultContainer'); var resultValue = document.getElementById('otrResultValue'); if (isNaN(perm) || isNaN(pressure) || isNaN(thick) || thick <= 0) { alert("Please enter valid positive numerical values for all fields."); resultContainer.style.display = "none"; return; } // OTR Formula: (Permeability Coefficient * Partial Pressure Difference) / Thickness var otrResult = (perm * pressure) / thick; resultValue.innerHTML = otrResult.toFixed(4) + " cc/m²/day"; resultContainer.style.display = "block"; }

Understanding Oxygen Transmission Rate (OTR)

Oxygen Transmission Rate (OTR) is a critical measurement used in the packaging industry to determine the amount of oxygen gas that passes through a plastic film or barrier over a specific period. This metric is vital for food shelf-life, pharmaceutical stability, and electronics protection.

The OTR Formula

The mathematical relationship used in this calculator is based on Fick's Law of Diffusion, simplified for barrier packaging materials:

OTR = (P × Δp) / L
  • P: Permeability Coefficient of the material.
  • Δp: Partial pressure difference of oxygen across the film.
  • L: Thickness of the material (often measured in mils or microns).

Why Does OTR Matter?

Oxygen is a primary cause of food spoilage through oxidation. High OTR materials allow more oxygen to enter a package, leading to:

  • Rancidity: Fats and oils reacting with oxygen.
  • Color Change: Discoloration in fresh meats or dried goods.
  • Nutrient Loss: Degradation of vitamins like Vitamin C.
  • Microbial Growth: Encouraging the growth of aerobic bacteria and molds.

Factors Affecting OTR Results

While the formula provides a theoretical value, real-world OTR is heavily influenced by external factors:

  1. Temperature: Permeability generally increases as temperature rises. Most OTR tests are conducted at 23°C (73°F).
  2. Relative Humidity (RH): For certain materials like EVOH or Nylon, moisture significantly increases oxygen transmission. Tests are often standardized at 0% RH or 90% RH.
  3. Coating and Laminations: Multi-layer structures are designed to combine the mechanical strength of one polymer with the high barrier properties of another.

Example Calculation

Imagine you have a packaging film made of Low-Density Polyethylene (LDPE).

  • Permeability (P): 450 cc·mil / (m²·day·atm)
  • Pressure (Δp): 0.21 atm (ambient air)
  • Thickness (L): 1.5 mil
Calculation: (450 × 0.21) / 1.5 = 63 cc/m²/day.

Common Material OTR Comparison

Material Typical Barrier Quality
EVOH Excellent (High Barrier)
PET (Polyester) Good (Medium Barrier)
LDPE / HDPE Poor (Low Barrier)

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