MPR A55
Hardness band
A55 = shore A 55
Softest standard grade for soft-touch grips, low-durometer seals and flexible hose covers.
Values for the A55 condition
Other MPR grades and fills
MPR is listed in 9 conditions; see the grade overview at MPR.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
A55This page Shore A 55 | Softest standard grade for soft-touch grips, low-durometer seals and flexible hose covers. | 2 | 6 | 360 | 14 Shore D |
Shore A 60 | Balanced soft grade for gaskets, bellows and overmoulded soft-touch surfaces. | 2 | 7 | 330 | 17 Shore D |
Low-temperature flexible grade | Pick for cold-climate hose and seals needing flexibility below −40 °C. | 2 | 7 | 340 | 19 Shore D |
Overmould / bondable grade | Formulated for two-shot bonding to rigid PVC, PA and ABS substrates without adhesive. | 3 | 8 | 320 | 19 Shore D |
Oil / fuel resistant grade | Choose for continuous contact with engine oils, ATF, diesel and gasoline where low swell is required. | 3 | 9 | 280 | 24 Shore D |
Flame-retardant grade | Use where UL 94 V-0 or low-flame-spread cable/hose jacketing is specified. | 4 | 9 | 230 | 28 Shore D |
A70Default Shore A 70 | Default workhorse hardness for fuel-hose covers, seals and industrial tubing. | — | 9 | 300 | 70 Shore A |
Shore A 80 | Higher-modulus grade for hose covers needing abrasion/kink resistance and semi-rigid seals. | — | 11 | 280 | 30 Shore D |
Shore D 40 | Hardest MPR grade for rigid-flex hose jackets, wear strips and structural soft parts. | — | 15 | 240 | 40 Shore D |
What is MPR A55?
MPR A55 is MPR heat treated to A55 — softest standard grade for soft-touch grips, low-durometer seals and flexible hose covers. MPR A55 has a tensile strength of 6 MPa (0.798 ksi), weaker than 82% of polymer grades. Elongation at break is 360% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi). MPR A55 has a density of 1.16 g/cm³ (0.0419 lb/in³), lighter than 55% of polymer grades. Its glass-transition temperature is -25°C (-13 °F). A70 is the default condition FabDigit quotes; A55 is available on request or by drawing note.
Advantages
- Forms and bends easily — 90/100, better than 91% of polymer grades
- Good UV / weathering resistance — 80/100, better than 86% of polymer grades
- Ductile — tolerates forming and impact — 360%, better than 85% of polymer grades
- Readily welded — 78/100, better than 84% of polymer grades
Limitations
- Difficult to machine — 26/100, worse than 90% of polymer grades
- Low stiffness — 0.01 GPa (7.25×10⁻⁴ Msi), worse than 89% of polymer grades
- High mold shrinkage — 2%, worse than 81% of polymer grades
- Absorbs moisture — dry before molding — 0.6%, worse than 75% of polymer grades
MPR A55 properties
Typical room-temperature values for MPR A55; 22 are specific to this condition. Other listed values are MPR reference data and may not represent this condition. Bars are the position among polymer grades.
Physical3
MPR A55 has a density of 1.16 g/cm³ (0.0419 lb/in³), lighter than 55% of polymer grades. Its glass-transition temperature is -25°C (-13 °F).
Mechanical9
MPR A55 has a tensile strength of 6 MPa (0.798 ksi), weaker than 82% of polymer grades. Elongation at break is 360% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi).
Thermal8
MPR A55 is rated for continuous service to 110°C (230 °F). It conducts heat at 0.19 W/m·K (0.11 BTU/hr·ft·°F), worse than 68% of polymer grades. Thermal expansion is 190 µm/m·K (105.6 µin/in·°F).
Electrical4
MPR A55 is an electrical insulator with a dielectric strength of 18 kV/mm (457.2 V/mil) and a resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of polymer grades. UV resistance is very good.
Sustainability3
Producing a kilogram of MPR A55 takes about 95 MJ of energy and emits 4.2 kg of CO₂ — less than 70% of polymer grades. Typical recycled content is 10%.
Manufacturability6
MPR A55's machinability is poor (26/100, worse than 90% of polymer grades); weldability very good (78/100); formability excellent (90/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with MPR A55
Is MPR easy to machine?
Soft and gummy — machine only for prototypes with very sharp tools, high speed, low feed and support/freezing; die-cutting or waterjet is preferred for sheet.
Can MPR be welded?
Hot-plate, hot-gas, RF/HF and ultrasonic welding all work well thanks to the polar chlorinated backbone; solvent bonding and cyanoacrylate/polyurethane adhesives also bond well.
Can MPR be formed, bent or molded?
Injection mould and extrude at 150–190 °C melt with low shear, generous gates and full-round runners; dry 2–3 h at 70–80 °C, mould at 20–45 °C, allow 1.0–2.8 % shrinkage; regrind is re-usable.
What surface finishes work on MPR?
Takes matte or textured tool finishes directly; can be printed/painted with flexible PU or vinyl inks after solvent wipe — no plating or polishing.
MPR 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 |
|---|---|---|
| chlorinated polyethylene rubber (CPE)partially crosslinked elastomer phase | 40 – 60 | 50 |
| polyamide / chlorinated polyolefin hard thermoplastic matrix giving melt processability | 15 – 30 | 22 |
| plasticizer (ester type)sets durometer | 8 – 22 | 15 |
| fillers / pigments | 3 – 15 | 8 |
| stabilizers, acid scavengers, processing | 1 – 5 | 3 |
MPR A55 — frequently asked
What is MPR A55 used for?
MPR A55 is typically used for fuel line covers, hydraulic hose jackets, wire/cable jacketing and industrial tubing. In short: RF-weldable thermoplastic elastomer; fuel and oil resistant; rubber feel, thermoplastic processing.
What is the tensile strength of MPR A55?
MPR A55 has a typical tensile strength of 6 MPa (0.798 ksi) — weaker than 82% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is MPR A55 easy to machine?
Not especially — machinability is rated poor (26/100, worse than 90% of polymer grades). Soft and gummy — machine only for prototypes with very sharp tools, high speed, low feed and support/freezing; die-cutting or waterjet is preferred for sheet.
Can MPR A55 be welded?
Yes — weldability is rated very good (78/100). Hot-plate, hot-gas, RF/HF and ultrasonic welding all work well thanks to the polar chlorinated backbone; solvent bonding and cyanoacrylate/polyurethane adhesives also bond well.
What surface finishes work on MPR A55?
Takes matte or textured tool finishes directly; can be printed/painted with flexible PU or vinyl inks after solvent wipe — no plating or polishing.
Can MPR A55 be formed, bent or molded?
Injection mould and extrude at 150–190 °C melt with low shear, generous gates and full-round runners; dry 2–3 h at 70–80 °C, mould at 20–45 °C, allow 1.0–2.8 % shrinkage; regrind is re-usable.
What is the maximum service temperature of MPR A55?
MPR A55 is rated for continuous use to about 110°C (230 °F), and briefly to 145°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between MPR A70 and MPR FR?
A70 is the default condition — default workhorse hardness for fuel-hose covers, seals and industrial tubing. FR: use where UL 94 V-0 or low-flame-spread cable/hose jacketing is specified.
Sources
- Alcryn MPR melt-processible rubber grade datasheets (60A–40D series) — Advanced Polymer Alloys / Ferro (2019)
- Handbook of Thermoplastic Elastomers — Elsevier/William Andrew (2014)
- ASTM D412 / D2240 / D395 / D624 elastomer test methods — ASTM (2021)
- ISO 18064 Thermoplastic elastomers — nomenclature and abbreviated terms — ISO (2014)
- CAMPUS / UL Prospector TPE alloy property listings — CAMPUS, UL (2024)
- TPE/TPV (2026)
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.