01 MATERIAL-IDENTITY EVIDENCE
Use FTIR, DSC and density as separate identity clues—not proof of an exact film grade
A supplier name, resin acronym or single spectrum is not enough to approve a delivered film. Start with a traceable approved reference, require a specimen surface and layer map, and ask a responsible laboratory to report each applicable method as a separate clue. The buyer then decides whether the combined evidence is sufficient for hold, investigation, trial or requalification.
02 DECISION FRAME
The answer is a controlled consistency check—not an exact-grade certificate
FTIR can support qualitative spectral comparison, DSC can add transition-temperature and enthalpy context, and density can add a separate bulk-property observation. Their usefulness depends on the exact specimen, exposed surface or isolated layer, preparation, method, reference and report. None alone or together establishes a commercial grade, every layer, an additive package, recycled content, food-contact status or finished-film performance.
- A delivered lot or complaint sample that needs comparison with an approved retained reference
- A supplier, grade or construction change that needs a documented identity-evidence plan before qualification
- An unknown optical event or suspected mix-up that needs a separately owned analytical investigation
- That a surface FTIR spectrum represents every layer of a coated, printed, metallized or laminated construction
- That a library match identifies an exact commercial grade, manufacturer, additive package or recycled-content source
- That one DSC transition or density result uniquely identifies a polymer or proves a construction
- That material-identity evidence establishes food contact, performance, conformity or lot release
03 COMPARISON MAP
Keep nine identity-evidence records attached to the same specimen decision
Each row has a different role. Preserve the original report and unresolved differences; do not merge the outputs into a fabricated universal score.
Swipe or scroll horizontally to review every evidence column.
| Evidence record | What it can contribute | What must remain attached | What it cannot establish alone |
|---|---|---|---|
| Approved commercial reference | The buyer-controlled identity expected for the comparison | PO, supplier, manufacturer, grade, TDS or COA revision, lot and retained-reference ID | Analytical identity, delivered-lot conformity or future supply |
| Required specimen surface and layer map | Which roll location, side, exposed surface or separated layer was actually examined | Sample ID, lot and roll, web position, side labels, layer order, preparation and images | That one exposed surface represents every layer or the complete construction |
| FTIR qualitative spectrum | A qualitative spectral comparison within the reported infrared technique and reference basis | Acquisition mode selected by the laboratory, specimen state, spectrum, reference and interpretation | Exact commercial grade, supplier identity, every layer or additive package |
| Polyolefin structural FTIR context | Reported polyolefin structural-feature evidence when ASTM D5576 is applicable | Exact method and edition, specimen, spectrum, calculation or report basis and stated limitations | A universal polymer-identification route or an ISO-equivalent result |
| DSC transition and enthalpy record | Reported thermal-transition, melting or crystallization context for the identified specimen | Method and edition, specimen preparation and history, instrument record, curve, units and interpretation | A unique resin, exact grade, formulation, layer or performance result |
| Density or specific-gravity record | A separate bulk-property observation for the exact tested specimen | Method and edition, specimen preparation, test conditions, result, unit and uncertainty if reported | Polymer identity where crystallinity, fillers, voids, moisture or layers can affect the result |
| Controlled reference comparison | A difference record against an approved retained sample, supplier reference or controlled library basis | Reference provenance, age, storage, preparation, comparison owner and declared match criteria | Automatic acceptance, cross-method equivalence or a supplier-wide conclusion |
| Orthogonal follow-on investigation | A route for microscopy, layer separation or another approved method when the first evidence is ambiguous | Investigation question, specimen chain, responsible laboratory, method and original output | A root cause, composition or layer identity unless the separate route establishes it |
| Buyer disposition and requalification record | The controlled hold, retest, concession, supplier question, trial or requalification decision | Decision rule, evidence gaps, risk owner, approval, affected lots and change triggers | Certification, regulatory approval, product performance or permanent supplier approval |
04 SELECTION SEQUENCE
Move from a broad comparison to an approvable decision.
Require the specimen map first
Identify the exact lot, roll, web position, tested side, exposed surface and layer order. If a layer is separated, retain how it was obtained and which interfaces may remain. An unmapped spectrum or thermal curve cannot safely be extended to the whole film.
Keep each method in its published role
Ask the responsible laboratory to select the applicable current licensed method and report its original output. Do not convert FTIR, DSC and density into one universal identity score or treat ASTM and ISO routes as interchangeable.
Make the buyer own the disposition
Compare the combined record with the approved reference and the named commercial risk. Hold, retest, investigate or requalify through controlled quality processes; the page supplies no pass/fail rule or material approval.
05 RFQ INPUTS
Plastic-film FTIR, DSC and density identity-evidence RFQ checklist
Send all 20 fields as one fixed brief. Leave a field unresolved for the responsible buyer, supplier or laboratory instead of inventing a material conclusion.
Open the RFQ brief builder ↗- 01
Exact buyer decision: incoming consistency, complaint investigation, suspected mix-up, supplier change or requalification
- 02
Candidate and approved-reference sample identities with the intended comparison stated
- 03
Supplier, manufacturer, commercial grade or order code and controlled document revisions
- 04
Complete film, coating, print or laminate construction with layer order and nominal gauges
- 05
Sample type and stage: resin, monofilm, coated film, printed film, laminate, retained roll or finished package
- 06
PO, batch, lot, roll, report, complaint and chain-of-custody traceability
- 07
Required specimen surface and layer map: locations, tested side, exposed surface, layer identity and separation record
- 08
Processing, conversion, storage, ageing, conditioning and contamination history
- 09
Exact suspected substitution, contamination, mix-up or consistency question without assuming its cause
- 10
FTIR evidence role and laboratory-selected acquisition mode, specimen state and applicability record
- 11
FTIR reference basis: approved retained sample, controlled library, supplier reference or another declared comparison
- 12
DSC transition or property requested and the reporting basis without prescribing a thermal procedure
- 13
Density or specific-gravity method applicability, exact specimen identity and preparation record
- 14
Current method, edition, laboratory-confirmed applicability and every reported deviation
- 15
Laboratory and report owner, competence or accreditation scope where applicable, without treating accreditation as product certification
- 16
Original spectra, curves, observations, results, units, uncertainty statements and raw-record references
- 17
Reference-match, uncertainty and buyer decision criteria with the responsible owner named
- 18
Images, microscopy, layer-separation record and any separately approved orthogonal evidence
- 19
Buyer hold, retest, concession, supplier escalation, lot disposition and qualification owner
- 20
Supplier, formulation, process, layer or site change triggers, requalification owner and complete deliverable pack
06 EVIDENCE BOUNDARY
Public scopes support separate clues; they do not create an identity certificate
ASTM E1252-98(2021) is active and publicly describes general techniques for obtaining infrared spectra for qualitative analysis. ASTM D5576-00(2021)e1 is active and addresses FT-IR structural features in polyolefins and polyolefin copolymers; its public page lists no known ISO equivalent. ASTM D3418-21 is active and addresses DSC transition temperatures and enthalpies; ASTM's public page calls it similar to, but not equivalent to, ISO 11357-1, ISO 11357-2 and ISO 11357-3. ISO 11357-1:2023 and ISO 11357-3:2025 are published; the former gives DSC general principles and the latter addresses melting and crystallization temperatures and enthalpies for crystalline and partially crystalline plastics, excluding fast DSC. ASTM D792-20 is active and addresses density and specific gravity of solid plastics by displacement; its public page says it is not equivalent to ISO 1183-1 Method A. ISO 1183-1:2025 is published and addresses three density methods for void-free non-cellular plastics while noting specimen-preparation effects. This page reproduces no paid procedure, spectral band, sample-preparation instruction, instrument setting, calibration, thermal cycle, heating or cooling rate, specimen dimension, immersion liquid, formula, match score, threshold or acceptance rule. It infers no cross-method or cross-standard equivalence. It establishes no LayerSource FTIR, DSC, density, microscopy, spectroscopy, thermal-analysis, laboratory, testing, inspection, identification, authentication, certification, conformity, exact-grade, additive, layer, recycled-content, food-contact, performance, material or supply capability or result. The buyer, supplier and responsible laboratory must select the applicable current licensed method and control the specimen map, references, interpretation, decision rule and disposition.
07 BUYER QUESTIONS
Resolve the assumptions that make quotes diverge.
01Can FTIR identify the exact commercial film grade?+
No. A qualitative spectrum can support comparison within its reported specimen, acquisition and reference context. It does not by itself identify the exact manufacturer, commercial grade, additive package, processing history or every layer of a construction.
02Can a surface FTIR spectrum represent every film layer?+
No. The observed surface and sampling depth depend on the reported technique and specimen. Coatings, inks, metal, adhesives and adjacent polymers can change what is observed, so the tested side, exposed surface and layer or separation map are required.
03Does one DSC melting peak prove polymer or grade identity?+
No. Thermal history, crystallinity, blends, copolymers, additives and specimen preparation can affect a DSC record. Preserve the curve and interpretation, then compare it with a controlled reference and other evidence.
04Are ASTM D3418 and ISO 11357 interchangeable?+
No equivalence is inferred. ASTM's public D3418 page describes it as similar to, but not equivalent to, ISO 11357-1, ISO 11357-2 and ISO 11357-3. Keep the exact method, edition and original result with the specimen.
05Are ASTM D792 and ISO 1183-1 interchangeable?+
No. ASTM's public D792 page states that it is not equivalent to ISO 1183-1 Method A. Preserve the selected method, specimen preparation, conditions, result and unit rather than converting between standards.
06Can one density result identify a plastic film?+
Not uniquely. Crystallinity, fillers, voids, moisture, coatings and multilayer construction can affect density. It is one separately reported clue for the exact specimen, not a polymer or grade certificate.
07Can combined FTIR, DSC and density evidence prove PCR, food contact or film performance?+
No. Recycled-content claims, food-contact status, barrier, sealing, mechanical behavior and conversion performance each require their own traceable evidence, applicable rules and responsible approval route.