Source: https://guthlabs.ai/docs/instruments/polymer-glass-transition-temperature-tg-lookup/implementation/

instrument implementation / implementation-contract

# Polymer Glass Transition Temperature (Tg) Lookup implementation

A source-bound implementation contract for Polymer Glass Transition Temperature (Tg) Lookup; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-034

**Effect**: Computation or source lookup only

## Input and validation requirements

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.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "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)."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/polymer-glass-transition-temperature-tg-lookup/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/polymer-glass-transition-temperature-tg-lookup/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/polymer-glass-transition-temperature-tg-lookup/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche7/tranche7-results.json`