ABS is stiffer and more heat-resistant and holds tighter tolerances; HDPE is lighter, cheaper per kilogram and resists acids, alkalis and water. Producer datasheets contradict one common claim: injection-molding grades of HDPE are not tougher than ABS on a notched impact test.
What Is HDPE
HDPE is polyethylene at the dense end of the range: ASTM’s density types, originally in ASTM D1248, class polyethylene from 0.941 g/cm³ upward as high density.
Polyethylene at this density is sold in process-specific HDPE grades for injection molding, blow molding, pipe and film, separated mainly by melt flow rate: low for pipe and blow molding, higher for injection. Typical parts are caps and closures, crates, pallets, pails, chemical and detergent bottles, and gas and water pipe.
What Is ABS
ABS is a two-phase material. A rigid styrene–acrylonitrile copolymer forms the continuous phase, and polybutadiene rubber particles are dispersed through it.
Producers sell ABS in grade families: general-purpose, high-impact, high-flow, platable, transparent, flame-retardant and high-heat. ABS is used largely for automotive parts and electrical and electronic equipment.
The Difference Between HDPE and ABS
Most of the differences trace back to structure: HDPE is semi-crystalline and ABS is amorphous. HDPE’s chains pack into crystals as the melt cools, which makes it shrink more and resist most polar chemicals. ABS’s glassy styrene–acrylonitrile matrix keeps it stiff and dimensionally steady up to its softening point, and the rubber particles give it impact strength.
Stiffness and Strength
ABS is the stiffer and stronger of the two. On the same ISO 527 tensile test, the general-purpose ABS grade Terluran GP-22 has a tensile modulus about 1.5 to 2.4 times that of HDPE injection grades.
Yield strength follows the same order. Terluran GP-22 ABS yields at 45 MPa against 26 MPa for the HDPE injection grade Rigidex HD5211EA, both on ISO 527 at 23 °C.
HDPE gives more before it yields: the HDPE grades BorPure MB7541 and Hostalen GC 7260 yield at 7 to 9.6 % strain, the ABS grades Terluran GP-22 and HI-10 at 2.6 to 2.8 %.
Impact Resistance
At room temperature, injection-molding grades of ABS take a notched impact several times better than injection-molding grades of HDPE: on notched Charpy (ISO 179/1eA, 23 °C), Terluran GP-22 ABS absorbs 22 kJ/m² against 4 kJ/m² for Hostalen GC 7260 HDPE.
HDPE’s notched impact depends on its melt flow rate. Across INEOS’ Rigidex injection range, notched Charpy at 23 °C falls steadily as melt flow rate rises. Only a low-flow pipe compound, SABIC P6006 (PE100), reaches ABS’s notched values, and it is made for pipe extrusion.
Cold-Temperature Toughness
ABS loses about two-thirds of its notched impact strength between 23 °C and −30 °C, while the injection-grade HDPE Hostalen GC 7260 loses none, yet ABS still ends higher. At −30 °C, Terluran GP-22 ABS absorbs 8 kJ/m² on notched Charpy (ISO 179/1eA), against 4.5 kJ/m² for Hostalen GC 7260. The producer sheets stop at −30 °C, so there is no like-for-like comparison below it.
Heat Resistance
ABS handles heat better. At the same 0.45 MPa load (ISO 75, method B), Terluran GP-22 ABS deflects at 99 °C, 33 to 38 °C above Borealis’ HDPE molding grades. The ABS specimens were annealed for 4 hours at 80 °C and the HDPE sheets do not say theirs were.
On Vicat B (ISO 306, 50 N), Terluran GP-22 ABS softens at 96 °C against 74 °C for Hostalen GC 7260 HDPE.
HDPE’s crystalline melting point, about 135 °C for homopolymer by DSC, does not mean an HDPE part carries load at higher temperatures. A loaded HDPE part creeps and deflects well below that melting point.
Chemical Resistance
HDPE resists more of the chemicals a molded part usually meets. Acids, alkalis and alcohols are rated satisfactory on HDPE at room temperature, apart from concentrated nitric and sulfuric acid.
Acetone, rated satisfactory on HDPE at both 21 °C and 60 °C, dissolves the ABS surface; with methyl ethyl ketone, ethyl acetate and cyclohexanone, it is one of the solvents used to bond ABS parts.
HDPE is not solvent-proof either:
- Hydrocarbon and chlorinated solvents: hexane, toluene, xylene and chlorinated solvents are rated unsatisfactory on HDPE already at 21 °C.
- Fuels and oils: gasoline, fuel oil and mineral oils are rated satisfactory on HDPE at 21 °C but unsatisfactory at 60 °C.
Both resins can also crack without chemical attack when a stressed part meets the wrong agent. Surfactants such as soaps and alcohols crack stressed HDPE, and resistance to this varies by grade. ABS cracks where residual molding stress meets an aggressive solvent.
Density and Part Weight
An ABS part weighs about 7 to 11 % more than the same part molded in HDPE, comparing general-purpose, high-impact, high-flow and platable ABS grades with HDPE molding grades on ISO 1183 densities.
Flame-retardant ABS grades make the same part about 21 to 25 % heavier than in HDPE.
Shrinkage and Dimensional Stability
ABS holds its dimensions far better: Terluran GP-22 ABS shrinks 0.4 to 0.7 % in the mold (ISO 294-4), while HDPE molding grades shrink 1 to 2 % on producer sheets. The HDPE sheets state no test method.
How much HDPE shrinks depends on wall thickness and molding conditions, so HDPE parts are also more prone to warp. After molding, HDPE moves more with temperature too: HDPE’s coefficient of linear thermal expansion is about 120 × 10⁻⁶/°C, against 80 to 110 × 10⁻⁶/°C for Terluran GP-22 ABS.
A mold cut to ABS shrinkage will not produce HDPE parts to the same dimensions, so moving a part between the two resins in an existing tool means requalifying its dimensions.
Painting, Printing and Bonding
ABS can be painted, printed, metallized and solvent-bonded as molded; HDPE needs its surface treated before paint, ink or adhesive will hold.
The HDPE surface is treated by flame, corona or plasma, and HDPE parts are more often joined by welding than by glue.
Which Processes Each Suits
Both resins injection mold well; beyond that, HDPE is sold in grades for blow molding, pipe and film extrusion, while ABS is sold mainly as injection grades, with some high-impact grades for extrusion and blow molding.
Do not set the two resins’ flow figures side by side. ABS sheets print melt volume rate at 220 °C/10 kg in cm³/10 min; HDPE molding-grade sheets print melt flow rate at 190 °C/2.16 kg in g/10 min.
Drying Before Molding
ABS needs drying before molding; HDPE does not.
Terluran GP-22 ABS takes up 0.22 % moisture at equilibrium in air at 23 °C and 50 % RH. Drying Terluran GP-22 pellets for 2 to 4 hours at 80 °C brings them below 0.1 % residual moisture; a vented screw with adequate venting makes predrying unnecessary unless the pellets have become very wet in storage.
HDPE takes up about 0.03 % water in 24 hours’ immersion.
How To Choose The Right One
Choose by what the part has to do: ABS when it needs stiffness, heat resistance, tight dimensions or a decorated surface; HDPE when it must resist chemicals and water, stay light and cheap, or be blow-molded or extruded into pipe.
Sunlight degrades both resins, so outdoor HDPE is stabilized with carbon black or UV stabilizers, outdoor ABS with stabilizers or paint.
Both can be recycled. HDPE comes back through collected packaging such as bottles, while ABS is recovered mainly from scrapped electronics and vehicles.
Both are sold in food-contact grades, but in the US the prior-sanction rule covering general-purpose ABS, 21 CFR 181.32, limits rigid ABS articles to food piping and repeated-use items, while polyethylene under 21 CFR 177.1520 has no such use restriction.
Neither self-extinguishes unmodified.
When neither fits, polypropylene is the usual next candidate: stiffer than HDPE and lighter than both, with the same polyolefin chemical resistance, though less tough than ABS. Polycarbonate is the next resin to consider when a part needs more heat and impact resistance than ABS gives.
Price
HDPE is the cheaper resin per kilogram. In modeled monthly market assessments from March 2025 to March 2026, ABS cost more than HDPE in every month, in both Northwest Europe and China.
In Northwest Europe, the ABS price ran 1.51 to 1.75 times the HDPE injection-grade price in every month from March 2025 to February 2026. In March 2026 the HDPE injection-grade price in Northwest Europe rose 35 % in one month, and the ABS-to-HDPE price ratio fell to 1.26. In China, ABS ran 1.18 to 1.37 times the price of yarn-grade HDPE over the same thirteen months.
The European ABS series is a contract price and the HDPE series a spot price, and the data provider labels its free series illustrative, so quote any ratio with its month and region. Per part, the gap is wider than per kilogram, because the same part in ABS weighs 7 to 11 % more.