In most labs, developing a full thermal and rheological profile for polypropylene (PP) samples means coordinating between three instruments, multiple operators, and a multi-day test queue.
One tool measures dynamic viscosity, another registers thermal transitions such as glass transition and melt point temperature (Tg/Tm), and a third logs physical properties. Each tool has its own prep, calibration, and quirks.
But what if you could measure all three – physical properties, Tg/Tm, and dynamic viscosity – in a single, closed-cavity test?
Alpha Technologies’ Premier™ ESR with Sub-Zero™ Technology condenses that workflow. A single closed-cavity run delivers Tg, Tm, and a full frequency-sweep viscosity curve from the same pellet in less than 30 minutes.
The Traditional Way: Time-Consuming and Fragmented
Here’s what a typical characterization sequence looks like:
• Physical properties via DMA: Time-intensive and typically takes 1–2 days to schedule and run.
• Tg/Tm via DSC: Provides heat-flow data but lacks precision in capturing subtle mechanical shifts, especially in filled or blended PP grades.
• Viscosity via Rotational Rheometer: Limited to low shear rates and subject to edge fracture.
Multiply that cadence across dozens of blends and the hands-on time, cost, and data-management effort escalate quickly.
One Instrument. One Run. Under 30 minutes.
In our recent study, we used the ESR with Sub-Zero to evaluate three types of polypropylene without liquid nitrogen or special sample prep:
• PP Homopolymer (PP HP)
• PP Block Copolymer (PP BcP)
• PP Random Copolymer (PP RcP)
A single test sequence produced:
• Glass Transition Temperature (Tg) from the peak in loss modulus (G”)
• Melting Point (Tm) confirmed by concurrent pressure rate drops and die gap traces
• Shear viscosity captured through a frequency sweep modeled with the Cross equation
No liquid nitrogen. No reloading samples. No handoffs between departments.
Here’s What We Measured:
Compared to DSC (which reported all Tg values as ~ -35°C), the ESR data revealed meaningful transitions and formulation differences that align with real-world mechanical performance.
The rheometer resolved real grade-to-grade differences that DSC masked.
Tg shifted from 8.36 °C in PP HP to –4.75 °C in PP BcP and –14.68 °C in PP RcP, while Tm ranged from 127.95 °C to 139.71 °C depending on copolymer architecture.
Zero-shear viscosity for PP HP, derived from two frequency sweeps, matched six-hour low-shear benchmarks in roughly 15 minutes
Why It Matters
For compounders, QA labs, and R&D teams working with polypropylene, this all-in-one approach offers three decisive advantages:
• Speed: Complete thermal and rheological profile in under 1 hour
• Sensitivity: Detects mechanical transitions that thermal-only tools often miss
• Efficiency: Consolidates equipment, fewer samples to prep, calibrate, and archive; streamlined data management
Whether you’re qualifying a new copolymer, validating recycled content, or benchmarking suppliers, capturing Tg, Tm, and viscosity in one pass streamlines decision-making and reduces risk.
See the Full Data for Yourself
Download the white paper “Pinpointing Polypropylene Glass Transition Temperatures Using Sub-Zero Rheology” for detailed methods, side-by-side DSC vs. ESR comparisons, and implementation guidance.