DMTA Measurement Protocols¶

This page maps standard DMTA/DMA measurement protocols to RheoJAX test_mode parameters, following ISO 6721 and ASTM D4065 conventions.

Protocol-to-Test-Mode Mapping¶

DMTA Protocol	Standard	RheoJAX `test_mode`	`deformation_mode`
Frequency sweep (isothermal, tensile)	ISO 6721-4	`oscillation`	`tension`
Temperature sweep (\(T_g\) determination)	ISO 6721-11	`oscillation`	`tension`
Multi-frequency temperature sweep	ASTM D4065	`oscillation`	`tension`
Creep / recovery (tensile)	ISO 899-1	`creep`	`tension`
Shear vibration (sandwich geometry)	ISO 6721-6	`oscillation`	`shear`
Parallel plate rheometry	ISO 6721-10	`oscillation`	`shear`

Note

The ISO 6721 series covers dynamic mechanical properties only. Static tests (stress relaxation, creep) fall under separate standards. For tensile stress relaxation on plastics, no single ISO standard exists; use instrument vendor protocols or ASTM E328.

Instrument Geometry Mapping¶

Clamp / Geometry	Measures	`DeformationMode`	Poisson Needed?
Film tension clamp	\(E^*\)	`TENSION`	Yes
3-point bending	\(E^*\)	`BENDING`	Yes
Single/dual cantilever	\(E^*\)	`BENDING`	Yes
Compression clamp	\(E^*\)	`COMPRESSION`	Yes
Shear sandwich	\(G^*\)	`SHEAR`	No

Note

All tensile-family geometries (tension, bending, compression) produce \(E^*\) data and require Poisson’s ratio for \(E^* \to G^*\) conversion. See DMTA Theory & Conversion for recommended values by material class.

Temperature Sweep + TTS Pipeline¶

The most common DMTA experiment is a multi-temperature frequency sweep at 2–5 frequencies, followed by time–temperature superposition:

Collect isothermal frequency sweeps at 10–20 temperatures spanning \(T_g \pm 50\) °C (finer spacing near \(T_g\))
Build master curve using Mastercurve with WLF or Arrhenius shift factors
Fit the master curve with GMM or fractional models
Extract WLF parameters \(C_1, C_2\) and activation energy \(E_a = 2.303\,R\,C_1 C_2\)

from rheojax.transforms import Mastercurve

mc = Mastercurve(reference_temp=T_ref, method='wlf')
master, shifts = mc.transform(datasets)

# Or use auto-shift (no manual shift factors needed)
mc_auto = Mastercurve(reference_temp=T_ref, auto_shift=True)
master, shifts = mc_auto.transform(datasets)

Recommended Heating Rates¶

Material Type	Rate (°C/min)	Rationale
Amorphous polymer	2–3	Standard; captures \(T_g\) accurately
Semi-crystalline	1–2	Avoid melting kinetics artefacts
Vitrimer / CAN	1–2	Resolve \(T_v\) transition from \(T_g\)
Elastomer (above \(T_g\))	3–5	Broad rubbery plateau, less sensitive to rate

Important

Faster heating rates shift apparent \(T_g\) to higher values (~2 °C per doubling of rate). Always report the heating rate alongside \(T_g\).

Creep Compliance Protocol¶

Some DMTA instruments can measure tensile creep compliance \(D(t) = 1/E(t)\):

model.fit(
    t, E_relax,
    test_mode='relaxation',
    deformation_mode='tension',
    poisson_ratio=0.5,
)

# For creep compliance, use test_mode='creep'
# (available for models with creep support)

Usage Example¶

from rheojax.models import FractionalZenerSolidSolid

model = FractionalZenerSolidSolid()

# Frequency sweep from DMTA (tension clamp)
model.fit(
    omega, E_star,
    test_mode='oscillation',
    deformation_mode='tension',
    poisson_ratio=0.40,  # semicrystalline polymer
)

# Temperature sweep — same API, just different x-axis
# (pre-process with Mastercurve to get master E*(ω) first)