Polymer Failure Analysis — Cracking, Aging & Process Evidence
Cracked, embrittled or distorted polymer parts require the formulation, processing and service environment to be considered together. Material identification alone cannot distinguish incorrect resin, environmental stress cracking, thermal history or an overloaded design.
Record the combination of stress and exposure
Provide molding conditions, weld lines, residual stress, additives, joining processes and contact with cleaners or lubricants. Mark fracture origins and service orientation before cutting. A chemical exposure that is harmless to an unstressed coupon may behave differently in a loaded assembly. Retain original surfaces and do not clean away residues until the investigator has agreed how they will be sampled.
Pair chemistry with structure and thermal behaviour
FTIR can compare polymer chemistry or oxidation indicators; DSC, TGA or DMA may explore thermal transitions, composition or mechanical response under temperature. Microscopy and fracture examination help connect these results to local failure features. Each method has limitations and preparation effects, so compare failed and appropriate unaffected specimens under equivalent conditions. A matching polymer identity does not establish matching molecular history or processing quality.
Verify a mechanism before redesigning
Request a staged investigation with explicit hypotheses and decision points. If environmental stress cracking or aging is suspected, define a separate representative exposure/loading experiment rather than assuming accelerated temperature alone reproduces the mechanism. A useful report explains supported factors and unresolved alternatives, and proposes targeted verification of corrective actions. Confirm whether the lab's experience covers your polymer, assembly and failure environment.
Sample considerations
- Provide resin grade, available formulation, molding history, service stress, temperature and chemical contacts.
- Send failed parts with orientation marks and unaffected production comparators; avoid cleaning fracture surfaces.
- Agree destructive preparation, representative exposure studies and retained evidence.
Questions to ask a laboratory
- How will processing effects be distinguished from chemistry and service exposure?
- What control makes the thermal or spectroscopic comparison meaningful?
- What experiment would verify the suspected mechanism without introducing a new one?
Laboratories with relevant capabilities
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Frequently asked questions
- Can a laboratory identify an unknown plastic?
- Techniques such as infrared spectroscopy and thermal analysis usually identify the polymer family and often the grade characteristics, though a precise commercial grade cannot always be confirmed.
Sources and scope references
Related testing briefs
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