When it comes to selecting materials for your next innovative product, the material specification sheet is likely the first place that you will turn. This document provides core properties measured by the manufacturer and serves as an essential tool for supplier verification and new product development. However, while these sheets are reliable and provide a standard method for comparison, they often fail to tell the whole story.

For successful material selection, product performance, failure prevention, it is important to go beyond the spec sheet and conduct in-house testing. This proactive approach will save you both time and money by facilitating informed material choices and enhancing product design.

A material specification sheet provides a snapshot of a material’s key properties as measured by the manufacturer. These properties are typically measured using standardized methods such as ASTM or ISO standards, offering some consistency and comparability across different materials. The spec sheet can be used for various purposes:

• Supplier Verification: Ensuring that the material provided by a supplier meets the necessary criteria for production.
• New Product Development: Aiding in the selection of new materials during the design phase of a product.

While spec sheets provide a foundational understanding, relying solely on them can be risky; they often provide incomplete information to know the material’s performance or predict lifetime of a product, especially in real-world application conditions.

Spec sheets are foundational for understanding general material properties, but they often lack detailed information about how a material will behave under specific conditions, such as the effects of different temperatures, prolonged stress or stress cycles, or exposure to harsh environments. Uncovering these blind spots is necessary for improving processing conditions, understanding material lifespan, and ultimately selecting the right material at the start of your development process.

To fully understand a material’s properties and ensure it meets your specific requirements, additional testing is required. Here are some critical aspects to consider:

Environmental Impacts

Materials can perform differently under various environmental conditions, such as UV exposure, or humidity. Due to the impracticality of inspecting materials in active use, such as polymer coatings on wires embedded in walls, a quick test lasting only a few minutes to hours is conducted to estimate the long-term stability of these materials over decades.¹

Differential scanning calorimetry (DSC) with oxidative induction time (OIT) analysis helps predict the aging and degradation of polymers, guiding material selection for longevity and reliability. For instance, polymers exposed to heat, oxygen, or light degrade faster, and OIT provides insights into their lifespan.

A variation of the OIT test, known as high-pressure OIT (HPOIT), is becoming increasingly popular. Proponents argue that oxidative data obtained under high pressure and temperature conditions align more closely with results from traditional, accelerated aging tests. The HPOIT test offers two primary advantages: high pressure raises the boiling points of additives, reducing their volatility, and it increases the concentration of the reacting oxidizing gas. This enables the use of lower test temperatures or significantly reduces test durations at comparable temperatures.²

Alternatively, high-pressure thermogravimetric analysis (HP-TGA) simulates extended exposure to harsh environments by using a combination of heat and elevated pressure. It is particularly useful for materials used in industrial applications, such as cabling for electrical or fiber optic systems. Safeguarding polymers against catastrophic degradation when exposed to direct sunlight or buried underground is crucial for these applications.³

Mechanical Behavior

Understanding the mechanical properties of materials beyond the scope of the datasheet is essential for nearly every application. For example, the following should be considered:

• Temperature Effects: Materials can exhibit drastically different properties at varying temperatures. Datasheets typically only list tensile properties at room temperature, but materials are frequently expected to perform under higher or lower temperatures.
• Long-Term Loading: What happens if a material is subjected to a load for weeks, months, or even years? Will it deform over time, i.e., creep? Will it crack under prolonged stress, i.e., creep rupture? For example, a clothing hanger may perform well under normal use, but storing a heavy coat over winter could cause the neck to elongate and eventually break. In this example, the clothing hanger began failing to perform its function (holding up clothes) due to creep and fell off the rod. Had it not fallen due to deformation, it would have eventually cracked due to creep rupture.

• Repeated Loading: In a process known as fatigue, repeated loading can cause accumulating damage, leading to fracture. It is important to know the stress levels and number of loading cycles a material can withstand before failure. Polymers exhibit fatigue in a very different way than metals and fatigue life estimates cannot be extrapolated from tensile strength as easily. Additionally, the usage temperature can have a significant impact on fatigue life at much lower temperatures than metals.

Mechanical test instruments evaluate durability and mechanical characteristics under various stresses (forces), frequencies, and environmental conditions. Specifically, Electroforce load frame instruments measure a sample’s response to force, whether it is a single push or pull (tensile test), repetitive load (fatigue), or creep/stress-relaxation test. Mechanical testing also accounts for environmental effects by testing in temperature-controlled air, gas, or fluid submersion.

Material testing is crucial in manufacturing and product development because it minimizes the risk of product failure, which can have costly and even dangerous consequences. Unexpected material behavior can lead to malfunctions, product recalls, and reputational damage.

For example, a woven fiberglass composite had a manufacturer’s recommended operating temperature up to 130°C. However, Dynamic Mechanical Analysis (DMA) testing revealed that the material’s storage modulus and loss modulus began to change around 100°C.⁴ Further fatigue testing data revealed that the material had a 90% reduction in its fatigue life at 100°C.⁵ Manufacturers could have mistakenly put this material into products used at high temperatures, such as baking, without realizing that it was highly likely to break.

Conducting thorough testing upfront provides higher confidence in material choices, ultimately saving time, money, and resources. Moreover, comprehensive material testing contributes to better long-term product reliability and performance. By thoroughly examining how a material responds to factors like fatigue, creep, and environmental degradation, manufacturers can design products that not only meet initial requirements but also maintain integrity throughout their life cycle. This proactive approach fosters innovation in product design, as engineers gain a deeper understanding of the material’s limits and capabilities, allowing for the creation of more efficient, safer, and longer-lasting products.

Going beyond the spec sheet is not just a recommendation; it is a necessity. By investing in additional testing, such as OIT using DSC and HP-TGA, you can uncover profound insights about material performance. By adding DMA and Electroforce fatigue testing to your testing suite, you can better predict material properties at various temperature conditions and repeat loading. These insights will ensure you make informed decisions that save time, money, and valuable resources by selecting the proper material for your application conditions. TA Instruments is here to support you with precision instruments and technical expertise, ensuring you have the tools needed to expertly evaluate materials and make the best decisions for your projects.