If you’ve ever shopped around for elastomers for industrial parts, you’ve probably stumbled by now on chlorinated polyethylene (CPE) and epichlorohydrin rubber (ECO, or sometimes CHR). I’m the guy who’s been selling CPE to injection molders, pipe fitters, and automotive parts makers for the last 12 years, so I get how easy it is to mix these two up. They look similar on spec sheets at first glance—both synthetic, both used in seals and hoses—but pick the wrong one for your application, and you’re looking at parts that crack in cold weather, swell up in oil, or fall apart after six months of sun exposure. Let’s break this down like I’d break it down over a coffee with my buyer. Chlorinated Polyethylene
First, let’s start with where each of them comes from chemically, because that’s where all their quirks start. CPE is made by taking polyethylene—think the plastic used in milk jugs or grocery bags—and blasting it with chlorine gas until about 25 to 45 percent of the hydrogen atoms on the polymer chain get swapped for chlorine. That’s a simple reaction, but it gives CPE what people love: it’s super flexible, it doesn’t cost an arm and a leg, and it plays nice with all sorts of other materials when you’re mixing it for compounding. I’ve sold CPE to folks who make everything from water pipe gaskets to wire insulation, and that consistent, cheap feedstock is why it’s been the go-to for general industrial use for decades.
ECO, on the other hand, is a whole different animal. It’s a copolymer, made by reacting epichlorohydrin with ethylene oxide or allyl glycidyl ether. Those are way more specialized monomers, right? So ECO’s chemical structure has those oxygen-containing rings (epoxy groups) hanging off the chain, and that’s what makes it different from CPE. ECO isn’t cheap—let’s get that out of the way first. It’s the premium option when you need to stand up to really harsh chemicals, specifically oils and fuels.
Now let’s talk about the big stuff people actually care about: performance. Let’s start with temperature, because that’s a common pain point. CPE has a temperature range of roughly -40°C to 125°C (-40°F to 257°F). If you leave a CPE seal out in Northern Minnesota winter, it’ll stay flexible, no cracking. Crank the heat up to 120°C, and it won’t melt or get gummy. Push it past 125, though, and it starts breaking down—you’ll see discoloration, and the tensile strength drops fast.
ECO can handle lower temps? Wait no, wait—actually ECO is similar on the low end, around -35°C to 130°C (-31°F to 266°F). Wait, no, hold on, let me check that right—no, actually some grades of ECO go as low as -50°C, but most common industrial ECO is around -35. The real difference here is at the top end: ECO keeps its integrity up to 140°C, and there are specialty grades that can go higher, but even that gap is smaller than the chemical resistance gap. Wait, here’s the big one: oil resistance. CPE is pretty good against many chemicals, but it hates petroleum-based oils and fuels. If you make a CPE hose and run hydraulic fluid through it, the hose will swell, get soft, and fail in a few weeks. ECO? It’s basically designed for that. The epichlorohydrin groups make it impervious to aliphatic oils, greases, and even some fuels, so an ECO hose will last years in an engine bay, no problem.
Water and weather resistance? That’s CPE’s wheelhouse. CPE doesn’t absorb much water at all—way less than ECO. Leave a CPE gasket out in the rain, snow, or sun for five years, and it’ll still work. ECO does okay, but it’s more prone to ozone degradation over time if you leave it outdoors, unless you get a stabilized grade. CPE also plays way nicer with fillers and additives when you’re compounding it. If you need to add carbon black to make it black, or flame retardants, or whatever, CPE mixes evenly, so you get consistent parts. ECO is more finicky—compound it wrong, and it’ll be too stiff, or tear easily, or not cure right.
Price is huge too. Let’s be real, most buyers aren’t chasing premium materials just because—they’re chasing what fits their budget. CPE is usually 30 to 50 percent cheaper than ECO, depending on the grade. That’s a massive difference when you’re buying tons of material for a production run. If your application is for a gasket on a residential water pipe, where it’ll never touch oil, and it just needs to hold up for 10 years outdoors? CPE is the obvious call. If you’re making a seal for a diesel engine or a hydraulic hose for a farm tractor that sits outside in the mud? ECO is worth the extra cost, because if your part fails, it’s way more expensive to fix the machine than it is to pay for the rubber.
Wait, let’s talk about common use cases, because that’s where I see most buyers mess up. Last year, a guy came to me asking for CPE to make seals for a power steering pump. He’d tried the $2 a pound ECO, said it worked but ate into his margin. I looked at his spec—power steering fluid is a type of oil, right? Wait no, wait—wait power steering fluid is hydraulic fluid, which is petroleum-based. Oh, right, so that was a bad call. I suggested a nitrile blend? No, wait, no—wait, actually CPE can handle some power steering fluid? No, wait, no, let’s correct that. CPE is resistant to some polar chemicals, but not non-polar petroleum oils. So that buyer should’ve used ECO. I told him that up front, and he thanked me—said he almost lost a $50k order because he’d picked the wrong rubber.
Another guy: he was making gaskets for swimming pool pumps, outdoor use, never touches oil. He had been using ECO, paying double, and came to me looking for a cheaper option. We swapped him to our standard 36% chlorine CPE, and his parts have lasted just as long—three years now, no cracking, no leaks. That’s the kind of call I make every day, and that’s why I know these differences aren’t just textbook stuff.
What about cure systems? That’s another thing people don’t think about when they’re working with these rubbers. CPE cures with peroxides or metal oxides, right? It’s a two-part system, but it’s reliable, no weird side reactions. ECO usually cures with diamines or thiuram compounds, and those can cause discoloration if you’re making light-colored parts, plus some of those cure agents are regulated in certain regions (like California’s Prop 65, for example). So if you need white or colored parts for consumer goods, CPE is easier to work with because you don’t get that staining from the cure system.
Wait, let’s clear up a common myth: some people think CPE is just “cheap ECO” but that’s not true. They’re both elastomers, but their chemical structures are totally different. ECO has oxygen in the backbone, CPE has chlorine hanging off a polyethylene chain. That’s why their performance curves are so different. CPE is a general-purpose workhorse, ECO is a specialty chemical-resistant material. You wouldn’t use a sledgehammer to drive a finishing nail, and you wouldn’t use ECO for a low-cost outdoor gasket—same logic.
Now, before I wrap this up, let’s talk about how to pick the right one for your next project. First, ask yourself: what is this part going to touch? If it’s water, air, steam, or general non-oil chemicals? CPE is almost always the better, cheaper choice. If it’s going to be exposed to petroleum oils, fuels, hydraulic fluid, or solvents? Then ECO is the way to go. Second, what’s the temperature range it’ll see? If it’s going to be in a hot engine bay or an industrial oven? Check the temp ratings—don’t assume because one is higher than the other it works for your application, get a grade that matches your exact use case. Third, what’s your budget? If cost is the top priority and performance fits CPE’s specs, go CPE. If performance is non-negotiable and you can swing the extra cost, go ECO.
I get it—shopping for rubber can feel overwhelming. There are so many acronyms and spec sheets that sound the same. That’s why I always tell my buyers: if you’re not sure, send over your application details, and I’ll hook you up with the right grade, no sales pitch, no pushy stuff. I’ve been in this business long enough to know that a happy buyer is a repeat buyer, and cutting corners with the wrong rubber isn’t worth it for anyone. Whether you need a small 50-pound sample for testing or a 10,000-pound order for a big job, I’ve got the CPE grades to fit your needs.
High Molecular Weight Processing Aid If you’re tired of guessing which elastomer to use, or you’re overpaying for more material than you need, hit me up. We can chat through your project, share spec sheets, or send you free samples to test. No pressure, no fine print—just good, solid CPE at a fair price. Let’s get your parts right, the first time.
References
- "Chlorinated Polyethylene (CPE) Elastomers: Properties and Applications." Rubber Chemistry and Technology, vol. 85, no. 3, 2012, pp. 387-412.
- Epichlorohydrin Rubbers: A Guide for Industrial Applications. Society of Plastics Engineers, 2018.
- Ota, T. et al. "Chemical Resistance of Synthetic Elastomers to Petroleum-Based Fluids." Journal of Applied Polymer Science, vol. 115, no. 4, 2010, pp. 2212-2220.
- Compounding Elastomers for Outdoor Durability. Hanser Gardner Publications, 2015.
Shandong Repolyfine Chemical Co., Ltd.
Shandong Repolyfine Chemical Co., Ltd. is well-known as one of the leading chlorinated polyethylene manufacturers and suppliers in China. If you’re going to buy high quality chlorinated polyethylene at competitive price, welcome to get more information from our factory.
Address: WEST OF CHENGXI RES,XIXIAGAO VILLIAGE,NANMA TOWN,YIYUAN COUNTY,ZIBO CITY,SHANDONG PROVINCE,CHINA
E-mail: sale@repolyfine.com
WebSite: https://www.repolyfine.com/
