Polymer Glass Transition Temperature (Tg) Lookup

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Chemistry & Materials

Tranche

tranche-7

Evidence ID

t7-034

Ledger rows

1

No ledger note is attached.

Review findings

The arithmetic and stated Fox formula are standard under the listed assumptions. Verdict is NEEDS_REVIEW because the spec names 'Polymer Handbook' without an edition or exact table convention, and it does not define how grade, tacticity, crystallinity, measurement method, or missing Tm values are handled. The displayed table values are widely tabulated reference values, not guaranteed values for every commercial specimen.

Formula and scope findings

• The Fox equation is standard for an ideal, miscible polymer blend when w_i are nonnegative mass fractions summing to 1 and all Tg_i are absolute temperatures in kelvin; these applicability constraints are not stated.
• The lookup-table specification does not identify a Polymer Handbook edition, polymer grade, tacticity, molecular-weight range, crystallinity, or measurement method, all of which can change reported Tg and Tm values.
• Tm is a lookup value only for polymers or grades having a meaningful crystalline melting transition; amorphous polymers should report Tm as not applicable rather than inventing a value.

Unit assumptions

• Fox-equation Tg_i and the calculated blend Tg must be in kelvin; Celsius values must be converted using T_K=T_C+273.15 before reciprocal calculations.
• Blend fractions w_i are dimensionless mass fractions, not percentages; they must be nonnegative and sum to exactly 1 within a stated tolerance.
• Lookup outputs are reported here in both degrees Celsius and kelvin, with exact conversion offset 273.15.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The Fox equation has an undefined-result failure at a zero-kelvin component Tg. The instrument must reject that input; accepting it or propagating a numeric value would be a break. The specification also does not explicitly state the required kelvin convention for Fox arithmetic, creating a unit-convention failure risk.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "polymer": "high-density polyethylene (HDPE)",
    "operation": "lookup"
  },
  "expected_outputs": {
    "Tg_C": -125,
    "Tg_K": 148.15,
    "Tm_C": 130,
    "Tm_K": 403.15
  },
  "reference_data": {
    "HDPE_Tg_C": {
      "value": -125,
      "source_convention": "widely tabulated standard value; Polymer Handbook-style reference table"
    },
    "HDPE_Tm_C": {
      "value": 130,
      "source_convention": "widely tabulated standard value; Polymer Handbook-style reference table"
    },
    "temperature_conversion": {
      "value": 273.15,
      "unit": "K per degree Celsius",
      "source_convention": "SI temperature-scale definition"
    }
  },
  "working": "Tg_K = -125 + 273.15 = 148.15 K. Tm_K = 130 + 273.15 = 403.15 K. The lookup outputs are therefore Tg = -125 °C (148.15 K) and Tm = 130 °C (403.15 K)."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json