What Is ASTM D7399 PP LDPE Blend Ratio Ir?
ASTM D7399 describes a standard test method for determining the amount of polypropylene (PP) in binary mixtures of polypropylene and low-density polyethylene (LDPE) using infrared spectrophotometry (FTIR). Knowing the composition of polyolefin blends is essential for quality control, recycled content verification, and material identification in the plastics industry.
This method provides a quantitative, non-destructive analytical tool for characterizing PP/LDPE blend composition from pressed film specimens, supporting material identification in recycling streams and quality assurance in compound production.
Applications and Benefits of ASTM D7399 PP LDPE Blend Ratio Ir Testing
Scope
ASTM D7399 applies to PP/LDPE binary blend systems and determines:
- Weight percent PP in the PP/LDPE mixture
- FTIR spectrum-based quantitative analysis using characteristic absorption bands
- Accuracy across the full 0–100% PP composition range
- Applicability to both virgin and recycled polyolefin blends
Applications
- Recycled polyolefin stream composition verification
- Polyolefin compounding blend ratio quality control
- Contamination detection in PP or LDPE production streams
- Sorting and identification of mixed polyolefin recyclates
- Raw material specification compliance for PP/LDPE blend products
Benefits
- Non-destructive analysis of a small pressed film specimen
- Rapid quantitative result without dissolution or separation
- Applicable to both production compounds and recycled material streams
- Builds on widely available FTIR instrumentation in plastics laboratories
- Simple calibration and good precision across the full composition range
Our ASTM D7399 Testing Procedure
Specimen Preparation
A small amount of PP/LDPE blend material is hot-pressed into a thin film of uniform thickness for IR analysis.
1FTIR Spectrum Acquisition
The pressed film is analyzed by transmission FTIR; the full mid-IR spectrum from 4000–650 cm⁻¹ is recorded.
2Absorbance Measurement
Characteristic absorbance bands for PP (e.g., ~998 cm⁻¹) and LDPE (e.g., ~720 cm⁻¹) are integrated or measured from the spectrum.
3PP Concentration Calculation
The PP/LDPE absorbance ratio is applied to a calibration curve to determine PP wt%.
4ASTM D7399 Test Parameters and Requirements
| Parameter | Details |
|---|---|
| Standard | ASTM D7399 |
| Test Principle | Transmission FTIR of pressed film specimen |
| Applicable Materials | Binary PP/LDPE blends (0–100 wt% PP) |
| Key Absorbance Bands | PP: ~998 cm⁻¹; LDPE: ~720 cm⁻¹ |
| Measured Output | PP content (wt%) in PP/LDPE blend |
| Calibration | Gravimetrically prepared PP/LDPE reference standards |
- FTIR spectrometer with transmission accessory
- Hot press for thin film preparation (approximately 0.1–0.3 mm thickness)
- Polished metal or KBr windows for film pressing
- Calibration standards (PP/LDPE blends at known compositions)
- FTIR data analysis software with absorbance integration capability
Equipment and Instrumentation Used for ASTM D7399 Testing
What You Receive: Test Report, Data, and Certification
- PP content (wt%) in the tested PP/LDPE blend sample
- FTIR spectrum with marked analytical bands
- Calibration curve and linearity data
- Measurement uncertainty and precision
- Analytical certificate for material identification or specification compliance
ASTM D7399 PP LDPE Blend Ratio Ir FAQs
PP exhibits a distinctive absorption band near 998 cm⁻¹ (CH₃ rocking) while LDPE has characteristic bands near 720–730 cm⁻¹ (CH₂ rocking); the ratio of these band intensities is used for quantification.
ASTM D7399 is specifically validated for PP/LDPE binary mixtures; HDPE has different crystallinity and band intensities, so separate validation would be needed for PP/HDPE blends
The method is designed for blends across the full composition range; detection of very low PP levels (below ~2–5 wt%) may require more sensitive spectroscopic approaches or chemometric analysis.
Yes — for quantitative transmission FTIR, specimen thickness must be controlled and consistent; absorbance values must fall within the linear response range of Beer's Law (typically A < 1.5 absorbance units).
ASTM D7399 specifies transmission FTIR with pressed films; ATR-FTIR is a surface measurement with different penetration depth and may require separate calibration validation for quantitative PP/LDPE determination.
CIPP (Cured-In-Place Pipe) spectral analysis uses infrared spectroscopy to evaluate the resin in a cured pipe liner. The sample’s infrared spectrum is compared with a reference spectrum to verify resin identity and assess whether the installed liner matches the specified resin system. This helps support quality control and compliance with applicable requirements.
Infrared (IR) spectroscopy identifies polypropylene (PP) by measuring how the material absorbs infrared light at characteristic molecular vibration frequencies. The resulting spectrum is compared with reference spectra to identify PP and distinguish it from other plastics, such as polyethylene (PE). This method supports polymer identification and material quality control.
Why Choose Infinita Lab for PP LDPE Blend Ratio Ir Testing?
When your PP LDPE Blend Ratio Ir results have to hold up - for compliance, a customer audit, or an engineering decision - ASTM D7399 accuracy and an unbiased third-party report matter more than price. Infinita Lab routes your ASTM D7399 PP LDPE blend ratio ir testing to ISO/IEC 17025-accredited U.S. partner labs with hands-on method experience, so you get defensible data, transparent reporting, and turnaround times built around your project deadline - not ours.
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