PLA vs. PP vs. PHA Straw Machines: How Material Choice Affects Production

While two factories might operate identical straw extruders at the same line speed, they might have drastically different results when it comes to their output, scrap rate, and the quality of product. Most often, it is not the machine but the resin that is the culprit.

PLA, PP, and PHA process in unique ways in terms of melting and cooling processes, and their tolerance for errors in manufacturing. Apart from price and eco-friendly label, resin selection determines what drying, extrusion, and cooling equipment you will need.

This guide breaks down how PLA, PP, and PHA behave during production, what each material demands from your equipment, and how to evaluate your true cost per straw.

Quick comparison table

Why material choice drives machine setup

The processing stages of interest in this case include: feeding and drying, extruder screw, die, cooling and sizing, haul-off, and cutting. After that, straws may be transported to bending or packaging.

Each of these stations depends on melting properties of the resin, its rate of cooling and humidity sensitivity. By using a different type of the resin, you change the temperature curve, cooling bath arrangement and screw design.

If you want the full picture of how a straw goes from pellet to finished product, Sunrise's guide on how to manufacture straws walks through the extrusion process step by step.

PLA straws: what the straw machine has to handle

Full Automatic PLA Straw Extrusion Machine

PLA is the material most people picture first when they hear "biodegradable straw." It's plant-based, it's well established in the market, and buyers generally know what it is. Running it efficiently is a different story.

• Processing behavior: PLA absorbs moisture from the environment and presence of moisture results in hydrolysis inside the barrel and thus weakening of the melt resulting in bubbles, brittleness and poor surface appearance of the straw. Also, it crystallizes slowly and the straw must cool slowly to maintain its form before hardening.

• Equipment implications:  Dehumidifying dryer at the hopper is a must when working with PLA otherwise you will fight against the resin right from the beginning. Moreover, it requires stable barrel temperature with proper zoning and properly set-up cooling and vacuum sizing.

• Common production issues: The most frequent complaints are oval straws instead of round ones, diameter drift along the length, a wavy or uneven wall, and reduced strength at the wall. Most of these trace back to either drying or temperature control. Sunrise's team has published a detailed breakdown of this exact problem in their article on PLA straw deformation and temperature control troubleshooting, worth reading if you already run a PLA line.

• Product trade-offs: PLA straws feel rigid and close to a traditional plastic straw, and the material has strong name recognition with consumers. The catch: PLA softens in hot drinks over time, and it needs industrial composting conditions to actually break down; it won't do much in a backyard compost pile. 

PP straws: the speed and stability option 

Polypropylene isn't biodegradable, but it's the material most operators describe as "easy." If your priority is volume and consistent output, PP is usually where you start.

• Processing behavior: PP straws run at higher melt temperatures than PLA straws and barely react to ambient moisture.

• Equipment implications: What PP really requires is adequate cooling. The material contracts when curing, and if you lack proper and consistent control of the cooling process, there will be distortions despite the excellent behavior of the material. Proper wall thickness adjustment and control of the line speed will help more than playing with temperatures.

• Throughput and yield: The density of PP is lower than that of PLA, which implies that one kilogram of PP resin will give more straws than one kilogram of PLA at the same dimensions. For instance, for a drinking straw of the standard size, this difference can amount to about 8-10 percent per kilogram. Do the math for your specific straw sizes and thicknesses prior to using this information in a quote.

• Product trade-offs: The advantages of PP straws include high heat resistance, flexibility, and cheaper price per kilogram than that of PLA or PHA. 

Sunrise's PP straw making machine line is built around this kind of high-speed, stable-resin operation.

PHA straws: the premium, demanding option 

PHA is the newest of the three to most factories, and it's the one that gets oversold on marketing and undersold on process difficulty.

• What PHA is and why buyers ask for it:  PHA is manufactured through microbial fermentation rather than chemical synthesis, and based on the particular grade and certifications, it may have compostability claims, as well as marine biodegradation claims in certain cases. The latter is critical for food service and hospitality industry customers who require solutions for straws to deal with when they fall into the ocean. But be aware about using such words in your marketing efforts: claims differ by grade, and only the results of certification may be claimed as facts.

• Processing behavior: And here lies the challenge of PHA. The material features a narrow processing temperature range – the temperature range between "properly melting" and "degrading already" is rather limited. Besides, it crystallizes slowly and possesses low melt strength. Therefore, the melted tube deforms even before cooling to form.

• Equipment implications: Effective processing of PHA includes good temperature control in all barrel zones, careful management of residence time for the resin in the barrel, use of a less aggressive screw design to prevent degradation through shear, and accurate cooling and sizing. Often, producers add PHA and PLA in order to make the processing easier and lower the material cost. It’s a quite common and logical practice, not a trick to be ashamed of.

• Cost reality: PHA resin is often more expensive than both PLA and PP, even much more. This means that scraps are valuable in the way they aren’t with PP. Good stability of the production line is not a luxury in PHA processing, but necessity.

If your machine supplier offers compatible biodegradable raw materials, sourcing a known-good grade alongside the equipment removes one variable from an already tight process.

How the materials compare in daily production

• Line speed and output: PP works best. PLA is good once drying and cooling are optimized. PHA is always slower, with tighter tolerances, particularly in the initial phase of learning the material.

• Scrap and start-up waste: PLA and PHA generate more scrap and have higher start-up costs, because both of them are less forgiving than PP. Scrap from PHA burns a lot because of the high price of the resin.

• Energy use:  PLA and PHA require extra energy costs for drying; PP does not have the drying process, but it requires extra cooling capacity.

• Downstream effects: Straw stiffness, surface finish, and consistency all carry into bending and packing. A straw with dimensional drift causes more jams at the bending or packing stage, not just more rejects at the extruder. If you're running or adding a straw bending machine, straw conveyor, or straw packing machine, a stable upstream material choice makes those downstream machines run smoother too.

For a broader look at matching machine capability to your production goals, Sunrise's article on how to choose a high-speed straw making machine covers the factors beyond raw speed.

The Real Cost Picture

Price per kilogram is the figure which everyone pays attention to, and price per kg is probably the one which deceives most of people. The lowest price for the resin doesn't always mean the lowest price for the straw when all other factors are considered.

To actually compare materials, you need to look at:

• Resin cost per kilogram: the sticker price, and the easiest number to compare, which is exactly why it's not enough on its own

• Straws produced per kilogram: determined by the density of the material and wall thickness, this factor may give the advantage to PP

• Scrap rate: percentage of loss associated with the start-up, adjusting processes and rejects; this rate is dynamic and is likely to grow for PLA and PHA

• Energy cost: drying adds to the cost of production for PLA and PHA; PP has the cooling capacity costs

• Downtime: each pause caused by the deformation and jams costs more than the material itself.

Put those into a simple cost-per-1,000-straws spreadsheet rather than comparing resin prices alone, and the picture often looks different from what the initial quote suggests.

Can one machine run all three materials?

Some of the aspects in the process are constant regardless of moving to a different material: the extruder frame, the haul off system and cutter system can all stay the same. Other components usually need to be changed. The screw, die and the cooling system are usually optimized for a particular material or group of materials. A dryer designed for PLA/PHA would become useless when producing PP.

Changing from one material to another (e.g., PLA to PP) means the time for changeover, the material needed for cleaning the barrel and potentially cross-contamination in case of improper changeover procedure.

When you hear that a supplier provides a "multi-material line," make sure to ask about which materials, what needs to be changed during the changeover, how much time it takes and whether you would have to have spare dies/screws ready. These answers would give you much more than the words "multi-material" alone.

How to choose: a simple decision checklist

Work through three questions before you commit to a material:

1. Who's buying, and what do they require? Some buyers may require special certification, hot drink compatibility, or compliance with local regulations regarding single-use plastics. Let the customer's requirement set boundaries first.

2. What margin and scrap tolerance can your business handle? PHA requires the strictest process control and punishes any mistakes with serious financial losses. PP provides you with the maximum margin for errors.

3. What's your team's process control experience? Younger company which hasn't gained enough process discipline will not be able to work with PHA even if they have excellent equipment.

As a general starting point: PP will be the best choice for those operations which value productivity and stability, PLA is an entry level bio-based straws material, and PHA will suit companies targeting high-end buyers.

Conclusion

Material choice isn't a side decision in straw production; it's the decision that sets the ceiling on your output, your scrap rate, and your production costs. PP gives you speed and forgiveness. PLA gives you a familiar, recognizable bio-based option with a manageable process. PHA gives you the strongest sustainability story, at the cost of the tightest process control.

If you are trying to decide on the material that will be best for your production needs, our expert team at Sunrise can assist with configuring the line to suit the material and production requirements. Contact us now for more information and prompt assistance.

FAQs

Why do PLA straws soften in hot drinks?

PLA (polylactic acid) straws become soft when exposed to hot drinks due to the low glass transition temperature of PLA (usually 55 to 60°C, or 131 to 140°F). When the temperature of a hot drink exceeds this point, the polymer chains become loose and slide over each other.

Do I need a dryer for PLA or PHA straws?

A dryer is not needed for processed PLA or PHA straws, although PLA absorbs moisture when kept as raw 3D-printing filament.

Is PHA harder to extrude than PLA?

Yes, Polyhydroxyalkanoate (PHA) is definitely more difficult to extrude than polylactic acid (PLA). Although PLA is one of the most easily processable bioplastic materials, pure PHA and a lot of its derivatives create a much higher entry barrier because of the narrow operating window, thermal instability, and slow crystallization.

Can I switch from PP to PLA on the same processing line?

Yes, you can swap from polypropylene (PP) to polylactic acid (PLA) on the same processing line, yet you should bear in mind that they have incompatible chemical composition and different thermal regimes, hence you can not simply feed one type right after another.