SMA HMA
Grade
HMA = high-MA compatibilizer / coupling resin
Additive grade (flake/pellet/powder) used at 1–10% to compatibilize ABS/PC, PA blends and to couple glass or mineral fillers — not for standalone molding.
Values for the HMA condition
Other SMA grades and fills
SMA is listed in 10 conditions; see the grade overview at SMA.
Compare all 10 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified | Choose for automotive instrument-panel substrates and housings needing ABS-like toughness with higher heat resistance. | 36 | 36 | 25 | 105 HRR |
HMAThis page High-MA compatibilizer / coupling resin | Additive grade (flake/pellet/powder) used at 1–10% to compatibilize ABS/PC, PA blends and to couple glass or mineral fillers — not for standalone molding. | 42 | 42 | 1 | 87 Shore D |
Mineral / talc filled SMA | Low-warpage, low-cost stiffening for large flat panels where isotropic shrinkage beats fiber strength. | 45 | 45 | 1.5 | 87 Shore D |
Flame-retardant compound | Use where UL 94 V-0 at 1.5–3 mm is required in heat-exposed electrical housings; slight loss of impact and flow. | 45 | 45 | 2 | 85 Shore D |
Low-MA transparent grade | Pick when optical clarity and easy flow matter more than maximum heat resistance. | 48 | 48 | 3 | 84 Shore D |
UFDefault Unfilled / Natural | Default choice for rigid, heat-resistant, dimensionally stable molded parts where impact loads are low. | 50 | 50 | 2.5 | 85 Shore D |
Heat-stabilized / high-heat molding grade | Select when HDT above ~130 °C is needed from an unreinforced styrenic, e.g. lighting bezels near lamps. | 52 | 52 | 2 | 86 Shore D |
20% glass-fiber reinforced SMA | Mid-level stiffness/heat upgrade for structural brackets and IP carriers with moderate warpage. | — | 90 | 1.8 | — |
30% glass-fiber reinforced SMA | The workhorse reinforced grade — highest stiffness/HDT combination for load-bearing heat-exposed parts. | — | 110 | 1.5 | — |
40% glass-fiber reinforced SMA | Maximum stiffness / lowest CTE version for rigid metal-replacement structures; very brittle and abrasive to tooling. | — | 125 | 1.3 | — |
What is SMA HMA?
SMA HMA is SMA in the HMA grade — additive grade (flake/pellet/powder) used at 1–10% to compatibilize ABS/PC, PA blends and to couple glass or mineral fillers — not for standalone molding. SMA HMA has a yield strength of 42 MPa (6.09 ksi) and a tensile strength of 42 MPa (6.09 ksi) — weaker than 62% of polymer grades. Elongation at break is 1% and the elastic modulus is 3.6 GPa (0.522 Msi). SMA HMA has a density of 1.11 g/cm³ (0.0401 lb/in³), lighter than 65% of polymer grades. Its glass-transition temperature is 165°C (329 °F). UF is the default condition FabDigit quotes; HMA is available on request or by drawing note.
Advantages
- Stiff — 3.6 GPa (0.522 Msi), better than 84% of polymer grades
- Low, predictable mold shrinkage — 0.4%, better than 82% of polymer grades
Limitations
- Limited ductility — 1%, worse than 98% of polymer grades
- Needs corrosion protection — 45/100, worse than 98% of polymer grades
- Low fracture toughness — 1 MPa·√m (0.91 ksi·√in), worse than 87% of polymer grades
- Limited formability — 10/100, worse than 87% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
SMA HMA properties
Typical room-temperature values for SMA HMA; 29 are specific to this condition. Other listed values are SMA reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
SMA HMA has a density of 1.11 g/cm³ (0.0401 lb/in³), lighter than 65% of polymer grades. Its glass-transition temperature is 165°C (329 °F).
Mechanical17
SMA HMA has a yield strength of 42 MPa (6.09 ksi) and a tensile strength of 42 MPa (6.09 ksi) — weaker than 62% of polymer grades. Elongation at break is 1% and the elastic modulus is 3.6 GPa (0.522 Msi).
Thermal11
SMA HMA is rated for continuous service to 120°C (248 °F). It conducts heat at 0.17 W/m·K (0.0982 BTU/hr·ft·°F), worse than 75% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical7
SMA HMA is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 98% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of SMA HMA takes about 95 MJ of energy and emits 3.6 kg of CO₂ — less than 70% of polymer grades. Typical recycled content is 0%.
Manufacturability8
SMA HMA's machinability is fair (50/100, worse than 73% of polymer grades); weldability fair (40/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SMA HMA
Is SMA easy to machine?
Machines like SAN/PS — sharp carbide tools, high speed, light feed, air cooling; brittle so avoid sharp internal corners and pre-drill before tapping.
Can SMA be welded?
Ultrasonic, vibration and hot-plate welding work well; solvent bonding with MEK/methylene chloride blends; adhesives should be epoxy or cyanoacrylate, avoid amine-cured systems that react with anhydride.
Can SMA be formed, bent or molded?
Dry 2–4 h at 80–90 °C, mold at 230–270 °C melt / 55–90 °C tool with generous gates; keep residence time short as anhydride can hydrolyse and outgas, causing splay.
What surface finishes work on SMA?
Takes paint and hot stamping readily; can be vacuum metallized after base coat; polishes to a glossy surface but stress-cracks in aggressive solvent-based primers.
SMA chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| styrenemonomer, backbone | 68 – 92 | 85 |
| maleic anhydrideMA content sets Tg/HDT and reactivity | 8 – 32 | 15 |
| butadiene/acrylic rubberonly in impact-modified terpolymer grades | 0 – 20 | 0 |
| glass fiberreinforced grades only | 0 – 40 | 0 |
SMA HMA — frequently asked
What is SMA HMA used for?
SMA HMA is typically used for automotive interior trim, appliance housings needing higher HDT, PC/ABS compatibilizer and instrument panel components. In short: highest-HDT styrenic copolymer; PC/ABS compatibilizer resin; glass-reinforced to 40 %.
What is the yield strength of SMA HMA?
SMA HMA has a typical yield strength of 42 MPa (6.09 ksi) and a tensile strength of 42 MPa (6.09 ksi) — weaker than 62% of polymer grades. Strength varies by condition: see the 10 listed tempers.
Is SMA HMA easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 73% of polymer grades). Machines like SAN/PS — sharp carbide tools, high speed, light feed, air cooling; brittle so avoid sharp internal corners and pre-drill before tapping.
Can SMA HMA be welded?
With care — weldability is rated fair (40/100). Ultrasonic, vibration and hot-plate welding work well; solvent bonding with MEK/methylene chloride blends; adhesives should be epoxy or cyanoacrylate, avoid amine-cured systems that react with anhydride.
What surface finishes work on SMA HMA?
Takes paint and hot stamping readily; can be vacuum metallized after base coat; polishes to a glossy surface but stress-cracks in aggressive solvent-based primers.
Can SMA HMA be formed, bent or molded?
Dry 2–4 h at 80–90 °C, mold at 230–270 °C melt / 55–90 °C tool with generous gates; keep residence time short as anhydride can hydrolyse and outgas, causing splay.
What is the maximum service temperature of SMA HMA?
SMA HMA is rated for continuous use to about 120°C (248 °F), and briefly to 130°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SMA UF and SMA IM?
UF is the default condition — default choice for rigid, heat-resistant, dimensionally stable molded parts where impact loads are low. IM: choose for automotive instrument-panel substrates and housings needing ABS-like toughness with higher heat resistance. Yield strength is 50 MPa in UF versus 36 MPa in IM.
Sources
- XIRAN SMA copolymer and compound datasheets — Polyscope Polymers (2023)
- Dylark SMA resin technical data — NOVA Chemicals (2005)
- CAMPUS / UL Prospector styrenic copolymer datasets — CAMPUS Plastics (2024)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- ISO 527 / ISO 178 / ISO 75 / ISO 306 test methods — ISO (2019)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.