CAP MP
Matrix · default condition
MP = medium-plasticizer standard injection-molding grade
General-purpose balance of stiffness, gloss and toughness for cosmetic caps, handles and housings.
Values for the MP condition
Other CAP grades and fills
CAP is listed in 4 conditions; see the grade overview at CAP.
Compare all 4 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
High-plasticizer soft/high-flow grade | Pick when maximum flow, deep-draw toughness and a soft warm feel matter more than heat resistance or stiffness. | 18 | 20 | 80 | 68 Shore D |
MPDefaultThis page Medium-plasticizer standard injection-molding grade | General-purpose balance of stiffness, gloss and toughness for cosmetic caps, handles and housings. | — | 32 | 50 | 95 HRR |
Pearlescent / transparent coloured eyewear & handle grade | Colour-matched, high-gloss compound for buffed eyewear frames, pen barrels and premium tool handles. | 32 | 34 | 45 | 79 Shore D |
Low-plasticizer rigid / high-heat grade | Pick for maximum rigidity, dimensional stability and the highest HDT available in CAP, at the cost of flow and notched impact. | 46 | 50 | 28 | 82 Shore D |
What is CAP MP?
CAP MP is CAP in the MP condition — general-purpose balance of stiffness, gloss and toughness for cosmetic caps, handles and housings. CAP MP has a yield strength of 30 MPa (4.35 ksi) and a tensile strength of 32 MPa (4.64 ksi) — weaker than 70% of polymer grades. Elongation at break is 50% and the elastic modulus is 1.4 GPa (0.203 Msi). CAP MP has a density of 1.21 g/cm³ (0.0437 lb/in³), heavier than 60% of polymer grades. Its glass-transition temperature is 142°C (288 °F).
Advantages
- Polishes to a fine finish — 92/100, better than 97% of polymer grades
- Easy to machine — 78/100, better than 81% of polymer grades
- Good UV / weathering resistance — 55/100, better than 77% of polymer grades
- Low, predictable mold shrinkage — 0.45%, better than 77% of polymer grades
- Forms and bends easily — 80/100, better than 75% of polymer grades
Limitations
- Absorbs moisture — dry before molding — 1.8%, worse than 95% of polymer grades
- Needs corrosion protection — 55/100, worse than 94% of polymer grades
- Limited service temperature — 60°C (140 °F), worse than 87% of polymer grades
CAP MP properties
Typical room-temperature values for CAP MP; 11 are specific to this condition. Other listed values are CAP reference data and may not represent this condition. Bars are the position among polymer grades.
Physical7
CAP MP has a density of 1.21 g/cm³ (0.0437 lb/in³), heavier than 60% of polymer grades. Its glass-transition temperature is 142°C (288 °F).
Mechanical12
CAP MP has a yield strength of 30 MPa (4.35 ksi) and a tensile strength of 32 MPa (4.64 ksi) — weaker than 70% of polymer grades. Elongation at break is 50% and the elastic modulus is 1.4 GPa (0.203 Msi).
Thermal11
CAP MP is rated for continuous service to 60°C (140 °F). It conducts heat at 0.21 W/m·K (0.121 BTU/hr·ft·°F), better than 55% of polymer grades. Thermal expansion is 130 µm/m·K (72.2 µin/in·°F).
Electrical7
CAP MP is an electrical insulator with a dielectric strength of 17 kV/mm (431.8 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 94% of polymer grades. UV resistance is good.
Sustainability4
Producing a kilogram of CAP MP takes about 100 MJ of energy and emits 4.5 kg of CO₂ — less than 61% of polymer grades. Typical recycled content is 0%.
Manufacturability8
CAP MP's machinability is very good (78/100, better than 81% of polymer grades); weldability good (60/100); formability very good (80/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CAP MP
Is CAP easy to machine?
Machines and turns easily with sharp positive-rake tools and coolant/air blast; keep speeds moderate to avoid smearing and plasticizer sweat-out.
Can CAP be welded?
Joins well by solvent cementing (acetone/MEK blends) and by ultrasonic or hot-plate welding; avoid overheating which causes acid odour and discolouration.
Can CAP be formed, bent or molded?
Dry 2–3 h at 65–75 °C before molding; melt 185–240 °C, mold 35–75 °C, low-to-moderate injection pressure with generous gates — over-shear causes brown streaks and burnt-sugar odour.
What surface finishes work on CAP?
Ash-buffs to an exceptional mirror gloss; accepts hot stamping, vacuum metallising and printing after suitable priming, but avoid ketone/ester based paints and cleaners.
CAP 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 |
|---|---|---|
| propionyl contentprimary ester substituent (per ASTM D817 assay) | 39 – 48 | 45 |
| acetyl contentminor ester substituent | 0.5 – 3.5 | 2 |
| hydroxyl contentfree OH, governs polarity and moisture pickup | 1 – 3 | 1.8 |
| plasticizer (e.g. DOA / DEP / citrate essets LP / MP / HP grade class per ASTM D1562 | 0 – 20 | 10 |
| stabilizers, UV absorbers, colourants | 0 – 2 | 0.5 |
| cellulose backbone (anhydroglucose unitswood pulp / cotton linter derived | ≥ 45 (balance) | — |
CAP MP — frequently asked
What is CAP MP used for?
CAP MP is typically used for cosmetic packaging, pens and styluses, eyewear components, toothbrush handles and decorative moldings. In short: highest gloss cellulosic; low odour and taste; between CA and CAB.
What is the yield strength of CAP MP?
CAP MP has a typical yield strength of 30 MPa (4.35 ksi) and a tensile strength of 32 MPa (4.64 ksi) — weaker than 70% of polymer grades. Strength varies by condition: see the 4 listed tempers.
Is CAP MP easy to machine?
Yes — machinability is rated very good (78/100, better than 81% of polymer grades). Machines and turns easily with sharp positive-rake tools and coolant/air blast; keep speeds moderate to avoid smearing and plasticizer sweat-out.
Can CAP MP be welded?
Yes — weldability is rated good (60/100). Joins well by solvent cementing (acetone/MEK blends) and by ultrasonic or hot-plate welding; avoid overheating which causes acid odour and discolouration.
What surface finishes work on CAP MP?
Ash-buffs to an exceptional mirror gloss; accepts hot stamping, vacuum metallising and printing after suitable priming, but avoid ketone/ester based paints and cleaners.
Can CAP MP be formed, bent or molded?
Dry 2–3 h at 65–75 °C before molding; melt 185–240 °C, mold 35–75 °C, low-to-moderate injection pressure with generous gates — over-shear causes brown streaks and burnt-sugar odour.
What is the maximum service temperature of CAP MP?
CAP MP is rated for continuous use to about 60°C (140 °F), and briefly to 90°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CAP MP and CAP LP?
MP is the default condition — general-purpose balance of stiffness, gloss and toughness for cosmetic caps, handles and housings. LP: pick for maximum rigidity, dimensional stability and the highest HDT available in CAP, at the cost of flow and notched impact. Yield strength is 30 MPa in MP versus 46 MPa in LP.
Sources
- ASTM D1562 — Standard Specification for Cellulose Acetate Propionate Molding and Extrusion Compounds — ASTM International (2021)
- ASTM D817 — Test Methods for Cellulose Acetate Propionate and Cellulose Acetate Butyrate — ASTM International (2020)
- Tenite Propionate molding and extrusion compounds — property and processing data — Eastman Chemical Company (2022)
- Engineered Materials Handbook Vol. 2: Engineering Plastics (cellulosics section) — ASM International (1988)
- CAMPUS / UL Prospector cellulose ester grade data — CWFG / UL Solutions (2024)
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.