There is far more to the world of packaging than meets the eye. Every type of packaging material comes with pros and cons that can only be fully understood by analyzing the logistics from every possible angle.
Some of the most important packaging features fall into the category of barrier properties, which help us determine certain materials’ physical strengths and weaknesses. It’s not just about pure strength, however. Many other attributes come into play to ensure a package meets requirements and delivers a satisfactory product overall.
Let’s investigate what makes barrier properties so important, what key terms are needed to see the complete picture, and which materials give manufacturers the best barriers when it comes to packaging.
What Are Barrier Properties?
If a material can be used as a barrier, it will have certain properties that make it distinct from other materials in that category. This unique set of attributes and capabilities are referred to as barrier properties, and the possibilities are endless, given the infinite availability of synthetic and natural materials.
More specifically, we’re talking about barrier properties in the specific application of packaging systems, which demand a certain type of functionality to achieve an end goal.
This means that barrier properties are highly specialized and never universal. One company’s ideal packaging material may have complete opposite barrier properties to another’s since their product specifications are on opposing ends of the spectrum.
Therefore, choosing a material should always be an informed decision taking into account all variables – not only how it looks or feels, but how these protective attributes combine to make a better, more resilient product to succeed in the marketplace.
Moisture Vapor Transmission Rate (MVTR) or Water Vapor Transmission Rate (WVTR)
Before we get into some specific barrier properties and why they matter, let’s explore two of the main performance metrics that matter to manufacturers, retailers, and suppliers across all major industries.
From ingredients and food products to pharmaceuticals and construction materials, the MVTR or WVTR are both considered to be critical barrier property metrics.
According to regulators like the American Society for Testing and Materials, the scientific community uses the measurement of grams per square inch per day (g/in²/day) when looking at MVTR.
Testing for MVTR involves using infrared detectors to measure relative humidity on various films and seeing how much moisture is absorbed over a 24-hour period. Materials are tested in heat, cold, and tough conditions, including 100% humidity.
The strongest modern barrier materials allow less than 0.02 grams of moisture per square inch per day, which allow for fantastic shelf life and resilience.
Oxygen Transmission Rate (OTR)
We don’t think protecting against oxygen is so important as moisture protection, but when it comes to highly sensitive materials, oxidation is the enemy. The risk of microbes and other issues can come with too much oxygen, especially in perishable food products.
This means barriers must be designed to prevent oxygen transmission through the films and ensure minimal exposure to the products within, expressed as the OTR.
Similar to MVTR, this measurement is expressed as cubic centimeters of oxygen penetrating square meters of material in a 24-hour period. The highest-capacity barriers allow for less than 0.1 cubic centimeters of oxygen to get through the material in this timeframe.
What Do Barrier Properties Do?
We have a basic idea of what barrier properties are and some common metrics we encounter, but what are some real-world functions of these properties when creating packaging systems?
Water, moisture, and oxygen are the main metrics we look at when considering barrier properties since these are universal problem areas for manufacturers across industries.
These forms of barrier protection are valued most highly because they pose a threat to products at every stage of the supply chain, from the moment materials are packaged all the way to the hands of the consumer.
Water, for example, may come in the form of precipitation, cleaning functions, or accidents during shipping. Moisture isn’t as common but may be an issue in high-humidity biomes and certain seasons, especially closer to the equator.
Of course, oxygen is one of the few constants in our atmosphere, making it even more pernicious compared to water. We also can’t forget about light, heat, and various gasses and microbes that may find their way into products and cause irreversible harm.
In review, manufacturers must ask themselves what their top priorities are in terms of barrier properties before even reviewing their options. It’s common for certain materials to have unexpected properties and be a better option than anticipated.
Thankfully, there is a vast range of materials to choose from among modern packaging systems, complete with full assessments of barrier properties and their pros and cons. Manufacturers can therefore expedite their packaging process, reduce the need for trial and error, and get their products to market faster and more assured.
Barrier Packaging Materials
From naturally occurring elemental materials to the most advanced modern synthetics, there are barrier packaging choices with properties of all kinds.
Let’s look at some of the most common packaging materials and assess their properties as they pertain to popular consumer products.
With metals like tin, iron, and aluminum alloys, you get a ton of flexibility and quality protective attributes for a wide range of applications.
From cans to trays and even stand-up pouches with child-resistant features, metals mix the old-school appeal of sturdy packaging with strong protections and a clean user experience.
Most notably, metals are great at preventing intrusive microbes and oxygen and being nearly 100% light-blocking. Metals can be extremely thin and lightweight and maintain these exceptional barrier properties.
One possible downside is corrosion; certain materials do not interact well with metals over longer durations.
With strong protection against water, oxygen, and gaseous elements, glass is still one of the best materials in terms of well-rounded barrier properties.
With access to different types of seals used to maintain interior conditions, manufacturers have more control over glass packaging than ever. Even light can be blocked with colored glass, while transparent glass is a clear branding advantage.
The incredible versatility of plastic makes it a top option for the current generation of manufacturers as they seek a blend of barrier properties and customer appeal.
Plastics can be customized to an extreme degree, including the exact amount of permeability for oxygen, moisture, and even molecule type. Temperature maintenance remains an issue for some plastics on supply chain journeys, but this is also being addressed and improved.
Mixing various forms of plastic, paper, metal, and other materials, laminates offer the best of all worlds and exceptional barrier properties.
These custom materials are used commonly in beverage distribution in which precise conditions must be maintained to maximize freshness and flavor.
However, many products don’t require the complexity or the cost of laminates and can accomplish packaging goals with simpler solutions.
Additives and Enhanced Packaging
Advanced nanotechnologies are on the horizon to improve packaging in a responsive, intelligent way. This may involve packages that change and shift under certain conditions to maintain optimal barrier properties and eliminate the need for tradeoffs.
From the simplest materials to next-gen composites, barrier properties can’t be ignored for packaging systems at any level.
Discover what’s available, weigh your options, and select the best materials to deliver winning products every time.