What should I consider when choosing Polyester strapping or Polypropylene strapping for my packaging requirement.
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A guide to choosing the best poly strapping: polyester strap, polypropylene strap, or both?
Introduction
Both polyester strap and polypropylene strap are equally good at strapping loads of products. The basic material used is plastic (polymer), a synthetic material made from 100% recycled resins. From a sustainability point of view, that’s really important in today's society where businesses in different industries are doing their best to be more eco-friendly, help the environment in one way or another, and ultimately live up to the expectations of the end customer. In terms of quality, neither of the two is any better than the other because it all comes down to the application.
Main differences between polypropylene strap and polyester strap
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Polypropylene strapping is more affordable than polyester strapping. The material can be easily recycled, just like polyester, it’s lightweight, and it features high stretch or elongation, as well as elongation recovery. The downsides of polypropylene strapping are the low retained tension and splitting risk. That’s why polypropylene is best used to tie light packages or loads like newspaper bundles.
Polyester strapping is not necessarily better, but stronger. It is recommended for heavy-duty applications, like strapping and securing skids, loads, and other heavy products. Out of the three main strapping options - polypropylene, steel, polyester PET) - polyester has less elongation, making it a more rigid option. In simple terms, it means that it retains tension for extended periods of time. The tension retained is greater than when using polypropylene strapping.
Compared to steel strapping, although the tension strength is similar, polyester is safer than steel. When cutting a steel band under tension, the springback could cut through. It could spring back because it’s a stronger force. But with polyester, the springback relaxes almost immediately. It’s not that dangerous, not to mention that it’s more conveniently-priced than steel. Leaving aside the performance characteristics, polyester straps are easy to recycle and dispose of and are available in both hand grade and machine grade. In terms of applications, polyester strapping is ideal for lumber, heavy pallet loads, cans, bottles, and more.
Main benefits of polyester strapping over steel & polypropylene
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Steel strapping used to be a go-to choice for lumber loads. However, given that lumber shrinks and dries over time, the steel straps become loose. For that reason, polyester is a better option for heavy loads. One of its core benefits is that it comes with a “wrapping memory”. Although it’s not an elastic band that molds perfectly after a certain load, it’s better than steel because it stays tight enough to hold the load in place over time.
Polypropylene is not advised for heavy product shipping either because of its lack of recoverability. It relaxes too much. The more it stretches, the looser it gets and it doesn’t come back. With polyester, the whole concept is that it needs to be elongated so that it recovers. And this is where semi-automatic and automatic machines come in. If you just strap it as it is, that's all you're going to get. For extraordinary performance, polyester straps work best when stretched because it has stronger residual tension when doing that.
Main benefits of polypropylene strapping over polyester
Polypropylene straps come with their fair share of benefits, too. They’re meant for different applications, namely products that are more sensitive that simply need to remain steady. Shipping foam, for example, would be better when using polypropylene strapping because the product is lighter and doesn’t need the strapping tension offered by polyester.
But then again, it all comes down to the characteristics of the load itself. For example, polypropylene straps would do just fine when moving or transporting 5 table chairs that weigh 200 pounds from Home Depot. In this case, the goal is to just keep them together since the load is not that heavy. But moving 5 luxurious, hand-made table chairs that weigh 1000 pounds is a whole different story. While you can take a risk with polypropylene, you won’t because of the value paid for the chairs.
Applications for using polyester strapping & polypropylene strapping
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Both polyester and polypropylene come with pros and cons. Prior to making a choice, it is important to determine the application. First, it is important to look at the size and weight of the product. Second, look at the dollar worth of that product. And third, don’t forget about safety.
Polyester straps have excellent holding power, great elongation, and perfect tension for heavy-duty packages and loads like lumber and other packages and materials that shrink after they’ve cooled down. If stored outside, polyester straps are resistant to ultraviolet degradation, meaning that they won’t weaken like steel that usually rusts if it rains. For lighter loads that don’t need the tension offered by polyester straps, polypropylene would be a more convenient option. Also, the strapping is easier to customize and print, thus boosting the marketing value of the product shipped or transported.
Whether polyester or polypropylene, it’s equally important to pay attention to the strapping tools. Some can easily be used with both, but others have specific applications and can only work on one type. Regardless of choice, most of them come with limitations in terms of thickness or width.
Manual strapping tools (link)
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One of the most common options of strapping is via manual tools. It’s a viable option if low volume strapping is required and has a lower entry cost for the equipment. An example of this application would be strapping required for a few loads a day.
Battery-powered strapping tools (link)
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Available in both polyester and polypropylene strapping, such tools consolidate all functions into a single, efficient tool that’s also portable. Also, they combine sealing, tensioning, and cutting, at the same time providing different strengths to the product or load that needs to be tightened.
Pneumatic strapping tools
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Pneumatic tools have all the benefits offered by battery tools. An added benefit would be that they’re more durable and cannot be lost or misplaced since they’re attached to a compressed source of air.
Semi-automatic & automatic strapping machines
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Strapping machines come in all shapes and sizes. For business purposes (e.g. factories, warehouses), they’re the ideal choice because they save time, money, and labor force. From table-top strapping all the way to customized automatic machines, they can consolidate different strapping functions extremely fast and efficient. Also, they integrate with conveyor systems or assembly lines, allowing specific tension on different loads, products, and materials.
Conclusion
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When it comes to strapping and straps, there’s no best and worst. Both polyester and polypropylene are excellent materials because each serves a different purpose. Before making a choice, it is important to assess the load at hand - the shape, size, material, and weight. Polypropylene strapping typically has lower breaking strength than PET. PP has less recoverability, so when used in heavy-duty loads like lumber, they will loosen up. However, polypropylene is great on loads like paper, cartons, and other materials that just need to be kept in place. Polyester strapping offers excellent stretch and is ideal for heavy-duty shipments or loads that need to be held really tight. Also, they provide abrasion resistance and durability over time. Regardless of choice, the most important parameter to consider before making a choice is application.
- Recommended Applications for PET strapping: Brick and block, lumber, PET bottles, corrugated, printed materials, steel coils, aluminum extrusions
- Recommended Applications for PP Strapping: bundling, produce, meat and fish packaging, cartons, newspapers, flyers, furniture packaging, cabinets.