Plastic Packaging & Resin: What You Actually Need to Know
If you're sourcing rigid plastic packaging—whether from Amcor's Orlando facility, the Bellevue, Ohio plant, or any other supplier—you've probably run into a few confusing terms. ABS. Thermoset. Thermoplastic. Resin grades. Plastic strainers.
This covers the questions I get most often. Not the textbook definitions. The real-world stuff that matters when you're trying to avoid a $22,000 redo or 8,000 units ruined in storage. (Yes, both have happened.)
1. Is ABS plastic thermoset or thermoplastic?
Thermoplastic. Period.
ABS stands for Acrylonitrile Butadiene Styrene. It's a thermoplastic polymer, meaning it melts when heated and hardens when cooled—repeatedly. Thermoset plastics, on the other hand, undergo a chemical change during curing and can't be remelted.
Why does this matter for rigid packaging? Because ABS can be injection molded, extruded, and even recycled. If you're specifying rigid plastics for a project that may need rework or secondary operations (drilling, bonding, painting), you want a thermoplastic. Thermoset is for permanent shapes, like the handle on a frying pan. Not for packaging.
I've had vendors try to argue both sides. One insisted ABS was thermoset because "it feels rigid." No. Rigidity doesn't equal thermoset. Check the datasheet. Every ABS resin supplier lists thermoplastic.
Standard reference: Underwriters Laboratories (UL) 94 flammability classification for ABS lists it as a thermoplastic. Any resin supplier's technical data sheet confirms this. Always verify with the manufacturer.
2. What's the difference between plastic resin and plastic strainers?
This sounds basic. But I've seen spec sheets where the buyer confused the two. Easy mistake if you're new to plastics.
Plastic resin is the raw material. Pellets or granules. The thing that gets melted and molded. Think of it as flour for baking. You buy resin by the ton. It comes in different grades (ABS, PET, polypropylene, etc.), each with specific properties for different applications.
Plastic strainer is a finished product. A filter or sieve—usually made from polypropylene or nylon—used in cooking, industrial filtration, or lab work. It's made from plastic resin. Not the same thing.
I've seen a buyer at a food processing company ask for "plastic strainer" when they actually needed resin for injection molding. Their supplier sent them kitchen strainers. That was an awkward phone call. (Should mention: the supplier should have clarified. But still.)
3. When I'm sourcing from Amcor Rigid Plastics (Orlando or Bellevue), what should I ask about resin?
Three things, specifically.
First: Resin grade and supplier. Don't just say "PET." Ask for the exact grade. Bottle-grade PET (like Eastman 9921) differs from sheet-grade PET. The processing temperature varies. The impact resistance varies. If you're using this for a product that'll sit on a refrigerated shelf, and the resin grade isn't cold-temperature rated, you're asking for cracking.
Second: Recycled content percentage. Most rigid plastics facilities, including Amcor's, offer post-consumer recycled (PCR) content options. But 'recycled content' means different things. Is it post-industrial scrap (clean, consistent) or post-consumer (variable)? The difference matters for color consistency and mechanical properties.
Third: Compliance documentation. If your product goes to food contact or pharmaceuticals, you need more than a data sheet. You need a letter of compliance—FDA 21 CFR 177.1520 for olefin polymers, or EU 10/2011 if you're dealing with European customers. The compliance manager at your supplier should be able to provide this. If they can't, that's a red flag.
Note: As of January 2025, FDA's food contact substance notifications (FCNs) are the standard for new resins. Verify current FCN numbers at accessdata.fda.gov for the specific grade.
4. How do I evaluate plastic resin quality for rigid packaging?
I have mixed feelings about this. On one hand, the industry has standard tests. On the other, I've seen people over-rely on one metric and miss the bigger picture.
Here's what I actually check:
- Melt Flow Index (MFI) — Every resin has a spec. If MFI is outside the range by more than 10%, the processing behavior changes. I've rejected batches where MFI was 15% over spec because it caused flashing in the mold.
- Tensile strength — ASTM D638. Important for any packaging that'll bear weight. I once ran a test on a $3,000 order that came back completely wrong—the resin had half the expected tensile strength. The vendor claimed it was 'within industry standard.' We rejected it.
- Color & clarity — For PET packaging, haze and yellowness index (ASTM D1003) matter. Clear bottles shouldn't look like they've been in the sun for 10 years before filling.
The vendor failure in March 2023 changed how I think about this. We received a batch where the resin looked fine. Passed basic checks. But in storage conditions, 8,000 units developed stress cracks at the base. Turned out the resin's environmental stress crack resistance (ESCR) wasn't spec'd for that application. Now I check ESCR on anything that'll contact oils, detergents, or cold environments.
5. Should I use ABS or polypropylene for a rigid plastic strainer?
Depends on the use case. Which sounds like a cop-out. But it's the truth.
ABS: Better for structural rigidity. Higher impact resistance. Looks better—you can polish ABS to a high gloss. But it's not as heat-resistant as polypropylene. And it's more expensive. If the strainer is for industrial use where aesthetics matter less and heat resistance matters (like straining hot liquids), ABS might not be the best choice.
Polypropylene: Lighter. Cheaper. Better chemical resistance. Can handle boiling water. But it's less rigid—a polypropylene strainer will flex more. And it's harder to bond or paint if you need secondary operations.
The question isn't which is better. It's what your application needs. I've seen companies pay 30% more for ABS when polypropylene would have done the job. And I've seen polypropylene strainers fail in cold environments where ABS would have held up.
Rapid insight: Look at the resin's heat deflection temperature (HDT). For hot-fill applications (sauces, syrups), you need HDT above 100°C. Most polypropylene grades handle this. Most ABS grades don't. Simple.
6. How do I calculate total cost for rigid plastic packaging, so I'm not just looking at unit price?
The $500 quote turned into $800 after shipping, setup, and revision fees. The $650 all-inclusive quote was actually cheaper. I now calculate TCO before comparing any vendor quotes.
Here's what I include:
- Resin price — Negotiable per ton. Usually the biggest line item.
- Tooling & mold costs — Amcor and other rigid plastics suppliers charge for mold creation. Get this quoted separately. Some vendors bury it in unit price.
- Shipping — A Bellevue, Ohio plant shipping to the Midwest is cheaper than Orlando shipping to the Pacific Northwest. Factor in distance.
- Minimum order quantities — A low unit price with a 50,000-unit minimum isn't cheap if you need 5,000.
- Rejection & rework rate — If the vendor's first-pass yield is 90%, you're paying for 10% waste. That's not their cost. It's yours.
- Testing & compliance — Third-party testing for food contact adds cost. Some vendors include it in the price. Others charge per batch.
I get why procurement teams go with the lowest quote—budgets are real. But the hidden costs add up. That quality issue I mentioned earlier—the one that cost us a $22,000 redo? We went with the cheapest vendor to save $2,000 on the initial order. Not worth it.
Standard reference: For food contact materials, FDA 21 CFR part 177 covers the requirements for resin compliance. This isn't optional. Verify at accessdata.fda.gov for the specific resin grade.
7. What's one question about plastic resin or rigid plastics that most buyers don't ask—but should?
Here it is: "What's the environmental stress crack resistance (ESCR) of your resin for my specific application?"
Because resin vendors test ESCR under standard conditions: typically with a known chemical (like Igepal) at a specific temperature. Your product may contain a different chemical. Oil. Citrus. Ammonia. The ESCR varies dramatically.
I learned this the hard way. We'd sourced ABS for a container that would store a cleaning solution. The datasheet said 'good chemical resistance.' But in practice, the container cracked within 2 weeks. The strainer of the container actually held up fine—interesting. But the body failed. We'd have caught it with an application-specific ESCR test.
Ask your Amcor rigid plastics rep or any supplier: "Can you run ESCR testing with my actual product formulation?" Some will. Some won't. The ones that do are usually the ones who've been burned too. A lesson learned the hard way.
Done.