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department of polymers, plastics & composites

Polymers, plastics & composite failure analysis.

A cracked housing, a delaminated laminate, a bond that let go — plastics and composites fail in ways that look identical on the surface and are not. We determine the actual mechanism from the physical evidence.

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What failed?

Start a conversation with our AI Research Concierge, already scoped to polymers, plastics & composites. Select a specialization to prompt it, or describe your situation directly.

AI Research Conciergepolymers, plastics & composites · triage, not a substitute for an expert
Tell me what failed and I'll help scope it — the likely mechanisms, what to preserve, and which expert fits. I won't give the formal analysis here.

Polymers behave unlike metals, and that difference is exactly where an investigation goes wrong when it is handled by someone trained on the wrong material. A thermoplastic housing can craze and fracture at a fraction of its rated strength if the wrong chemical touches it while it is under stress; a composite laminate can look pristine on the surface while harboring a delamination that guts its compression strength; an adhesive bond can fail cohesively through the glue line or adhesively at the interface, and those two outcomes point to entirely different root causes. This department covers the failure modes specific to polymers, plastics, and fiber-reinforced composites — from a single cracked part to a delaminated structural laminate — using the spectroscopy, thermal analysis, and fractography that actually distinguish one mechanism from another.

specialization areas

Specialization areas in this department.

Each specialization area covers a distinct failure mechanism with its own physics, examination protocol, and governing standards. Start with the one that matches your incident.

methodology

How this department investigates.

Polymer and composite investigations depend on sequencing chemical, thermal, and mechanical analysis so that each step preserves the evidence the next one depends on.

FTIR spectroscopyInfrared analysis identifying the base polymer, additive depletion, oxidation, and chemical contamination on a fracture or degraded surface.
DSC & thermal analysisDifferential scanning calorimetry and TGA establishing glass transition, crystallinity, cure state, and thermal history against the specification.
SEM fractographyHigh-magnification imaging of fracture surfaces to distinguish brittle, ductile, fatigue, and environmental crack morphologies.
CT & ultrasonic imagingNon-destructive detection of voids, delaminations, and internal defects before any part is sectioned.
Mechanical & fracture testingTensile, impact, and fracture-toughness testing of exemplar and failed material against specification and design allowables.
Optical & polarized-light microscopyStress birefringence, craze morphology, and surface degradation imaging under polarized and standard optical light.
news & insights

News & insights from this department.

Technical briefings and case analyses on polymer, plastic, and composite failures — written by the people who investigate them.

What accelerated weathering testing can and cannot predict

Laboratory weathering compresses years into weeks by intensifying specific stresses. It ranks materials and confirms mechanisms reliably; converting its hours into calendar years is where it gets misused.

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Premature or expected? Rating exposure against service life

All outdoor plastics degrade eventually, so degradation alone establishes nothing. The question is whether it happened faster than the material, as specified and as installed, should have allowed.

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The carbonyl index and how far the degradation has gone

Photooxidation is measurable rather than merely visible. Depth-profiling oxidation from the exposed surface inward turns a faded, chalky part into a quantified degradation front.

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Degraded before it was moulded: regrind, heat and residence time

A part can be measurably brittle while the resin certificate reads entirely normal. Thermal history in the barrel, moisture at the hopper and regrind content all degrade material before the tool sees it.

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Design defect or moulding defect? Ask the population

A defect built into the geometry appears in every part from the tool. A process defect varies between lots and cavities. How failures distribute across a production population separates the two.

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Weld lines: the plane a moulded part was always going to break on

Where two melt fronts meet, the polymer never fully re-entangles. That plane is weaker than the material around it, its location is predictable, and it is a recurring source of field cracking.

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all polymers, plastics & composites insights
common questions

Polymer & composite failure analysis — the questions we hear.

How do you tell whether a plastic or composite part failed because of a defect or the environment it was in?

The physical evidence usually separates the two. Defects tend to be intrinsic and geometric — a weld line, a void, an under-cured bondline, a manufacturing-induced delamination — and show up as as-molded or as-laid-up conditions under microscopy, independent of what the part was exposed to in service. Environmental causes leave their own chemical or physical fingerprint: measurable oxidation from UV, chain scission or swelling from a chemical agent, or the specific craze morphology of environmental stress cracking. Reading which signature is present, and comparing failed parts against unused ones from the same production run, is how the distinction gets made.

What is the difference between environmental stress cracking and chemical attack?

Environmental stress cracking requires a sustained tensile stress plus a surface-active agent, and it proceeds with almost no measurable chemical change to the polymer. Chemical attack changes the polymer’s chemistry directly — measurable chain scission, swelling, or a new chemical species detectable by FTIR and GPC — and can occur with or without significant applied stress. The two are easy to confuse visually and straightforward to separate analytically, and the distinction routinely decides where liability falls.

Can you tell whether a composite delamination happened during manufacturing or in service?

Usually, yes. Manufacturing-induced delamination is typically associated with elevated void content and a distribution that follows the ply layup and process, not an impact site. Service-induced delamination from impact typically shows a localized, roughly conical damage pattern centered on an identifiable impact location. Non-destructive imaging — CT and ultrasonic C-scan — followed by cross-section microscopy is what distinguishes the two reliably.

Which standards apply to polymer and composite investigations?

It depends on the failure. Mechanical property work commonly references ASTM D638 for tensile properties and D256 for impact resistance. Environmental stress cracking is evaluated under ASTM D1693 and related bent-strip protocols. Chemical resistance follows ASTM D543. Adhesive bond testing references ASTM D1002 for lap-shear strength and D5573 for classifying fracture-surface failure modes. Composite delamination work references ASTM D5528 and D7905 for Mode I and Mode II interlaminar fracture toughness. UV and weathering work references ASTM G154 and G155 for accelerated exposure. The applicable set is chosen based on the specific mechanism in question.

A polymer, plastic, or composite part failed. Find out why.

Describe the incident. We will scope it and connect you with the right expert — usually within one business day.

failure-analysis assistanttriage · not a substitute for an expert
Tell me what failed and I'll help scope it — the likely mechanisms, what to preserve, and which expert fits. I won't give the formal analysis here.