Polymer Failure Analysis

Compared to some traditional construction materials, polymers typically have shorter life expectancy than well established materials that have been in use for hundreds of years. Lack of understanding about how polymers behave also means that sometimes in construction applications polymers are used near to or beyond the limits of their properties, leading to premature failure.

Failures can sometimes be catastrophic, resulting in fatality or serious personal injury. A failure in a structural sealant or fixing material can lead to falling masonry or glass. A defect in a polymer floor, such as a curled edge of a vinyl or rubber tile or an uneven surface in a cast epoxy floor, can lead to a slipping or tripping accident.

More commonly, failures in construction applications lead to an unacceptable deterioration in product performance. Examples include: Clear ethylene vinly acetate (EVA) used as an encapsulant in solar panels becoming opaque due to hydrolysis, leading to reduced efficiency; Distortion of sealants used above their softening point in a glazing unit resulting in moisture ingress; Failure in polybutylene terephthalate (PBT) water pipe joints; Environmental stress cracking in polyethylene oil storage tanks resulting in oil leakage and extensive damage to property.

Aesthetic failures can also be a serious problem, and the most common aesthetic failures are related to colour, including: staining, fading, colour variation and colour not conforming to the specification. Classic examples include pinking in polyvinylchloride (UPVC) window profiles, phenolic yellowing in flooring and foams, and cladding panels not conforming to the architects expectations.

Whatever the type of failure, the financial implications can be high, so it is important to understand the cause of failure as early as possible in order to manage corrective action and damage limitation, and to prevent re-occurrence.

A failure investigation can range from a single test to establish fitness for purpose relating to a particular performance feature to an extensive and complex investigation, particularly where the failure is subject of a litigation.

Questions that are typically addressed include:

• Was the specified material fit for purpose?
• Did the product performance specification adequately consider the known and foreseeable performance requirements?
• Did the material conform to the requirements of applicable standards or regualtions?
• Was the specified material used?
• Did contamination or interaction between materials result in a deterioration in performance?
• Is there any evidence of migration or diffusion?
• Was the design stress exceeded?
• Is the failure an isolated incident, or are a large number of products likely to be affected?
• Are defects present arising from the manufacturing process?
• Did poor workmanship result in a deterioration in properties?
• Is a product recall or a building closure necessary?

Sandberg staff have considerable experience in carrying out failure investigations and providing an expert witness service where required.