CTA MEMB
Grade
MEMB = membrane grade
High-purity, tightly controlled DS/molecular-weight flake for asymmetric RO, NF and dialysis hollow-fibre casting; chlorine tolerant but pH-limited (4–7).
Values for the MEMB condition
Other CTA grades and fills
CTA is listed in 3 conditions; see the grade overview at CTA.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
MEMBThis page Membrane grade | High-purity, tightly controlled DS/molecular-weight flake for asymmetric RO, NF and dialysis hollow-fibre casting; chlorine tolerant but pH-limited (4–7). | 6 | 10 | 30 | — |
Plasticized injection-moulding / extrusion grade | Plasticizer-modified compound (usually with CA/CAB blending) when melt processing rather than solvent casting is required. | — | 45 | 40 | 100 HRR |
Optical polarizer protective film grade | Choose for LCD polarizer protective film and optical compensation film where retardation must be near zero and haze <0.5 %. | 75 | 105 | 20 | 70 HRM |
What is CTA MEMB?
CTA MEMB is CTA in the MEMB grade — high-purity, tightly controlled DS/molecular-weight flake for asymmetric RO, NF and dialysis hollow-fibre casting; chlorine tolerant but pH-limited (4–7). CTA MEMB has a yield strength of 6 MPa (0.87 ksi) and a tensile strength of 10 MPa (1.45 ksi) — weaker than 94% of polymer grades. Elongation at break is 30% and the elastic modulus is 0.8 GPa (0.116 Msi). CTA MEMB has a density of 1.3 g/cm³ (0.047 lb/in³), heavier than 69% of polymer grades. Its glass-transition temperature is 185°C (365 °F).
Advantages
- Polishes to a fine finish — 80/100, better than 89% of polymer grades
Limitations
- Limited service temperature — 35°C (95 °F), worse than 100% of polymer grades
- Absorbs moisture — dry before molding — 2.5%, worse than 98% of polymer grades
- Low strength — 6 MPa (0.87 ksi), worse than 94% of polymer grades
- Poor heat conductor — 0.1 W/m·K (0.0578 BTU/hr·ft·°F), worse than 83% of polymer grades
CTA MEMB properties
Typical room-temperature values for CTA MEMB; 13 are specific to this condition. Other listed values are CTA reference data and may not represent this condition. Bars are the position among polymer grades.
Physical7
CTA MEMB has a density of 1.3 g/cm³ (0.047 lb/in³), heavier than 69% of polymer grades. Its glass-transition temperature is 185°C (365 °F).
Mechanical13
CTA MEMB has a yield strength of 6 MPa (0.87 ksi) and a tensile strength of 10 MPa (1.45 ksi) — weaker than 94% of polymer grades. Elongation at break is 30% and the elastic modulus is 0.8 GPa (0.116 Msi).
Thermal11
CTA MEMB is rated for continuous service to 35°C (95 °F). It conducts heat at 0.1 W/m·K (0.0578 BTU/hr·ft·°F), worse than 83% of polymer grades. Thermal expansion is 80 µm/m·K (44.4 µin/in·°F).
Electrical7
CTA MEMB is an electrical insulator with a dielectric strength of 16 kV/mm (406.4 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
UV resistance is fair.
Sustainability4
Producing a kilogram of CTA MEMB takes about 105 MJ of energy and emits 4.5 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 2%.
Manufacturability7
CTA MEMB's machinability is good (65/100, better than 66% of polymer grades); weldability good (60/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CTA MEMB
Is CTA easy to machine?
Machines like acrylic with sharp positive-rake tools and air cooling; avoid water-soluble coolants (moisture pickup) and any chlorinated/ketone cutting fluids that will craze or dissolve the surface.
Can CTA be welded?
Not weldable by hot-gas in practice — join by solvent bonding (dichloromethane/acetone blends) or pressure-sensitive/acrylic adhesives after corona or saponification treatment.
Can CTA be formed, bent or molded?
Predominantly solvent cast from dichloromethane–methanol dope; melt processing needs plasticizer and a narrow 220–265 °C window with pre-drying to <0.05 % moisture, since the polymer degrades and yellows above ~280 °C.
What surface finishes work on CTA?
Takes high-gloss polish and vacuum-deposited hardcoats/AR stacks; alkaline saponification is used to make TAC film surfaces hydrophilic for PVA polarizer lamination — avoid strong alkali on load-bearing parts.
CTA 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 |
|---|---|---|
| cellulose triacetate (acetyl content)wt % combined acetic acid basis ≈ 60–62.5 %; degree of substitution 2.8–3.0 | 43 – 44.8 | 43.9 |
| plasticizer (triphenyl phosphate / diethfilm-base and moulding grades only; optical TAC film uses low or non-phthalate plasticizer | 0 – 15 | 10 |
| residual free acid / moisture | 0 – 1 | 0.3 |
| cellulose backbone (biobased, wood/cottobalance of the anhydroglucose repeat unit | balance | — |
CTA MEMB — frequently asked
What is CTA MEMB used for?
CTA MEMB is typically used for photographic/motion-picture film base, polarizer protective film, optical filters and textile fibers. In short: highest-clarity cellulosic; low-birefringence optical film; solvent-cast, not moulded.
What is the yield strength of CTA MEMB?
CTA MEMB has a typical yield strength of 6 MPa (0.87 ksi) and a tensile strength of 10 MPa (1.45 ksi) — weaker than 94% of polymer grades. Strength varies by condition: see the 3 listed tempers.
Is CTA MEMB easy to machine?
Reasonably — machinability is rated good (65/100, better than 66% of polymer grades). Machines like acrylic with sharp positive-rake tools and air cooling; avoid water-soluble coolants (moisture pickup) and any chlorinated/ketone cutting fluids that will craze or dissolve the surface.
Can CTA MEMB be welded?
Yes — weldability is rated good (60/100). Not weldable by hot-gas in practice — join by solvent bonding (dichloromethane/acetone blends) or pressure-sensitive/acrylic adhesives after corona or saponification treatment.
What surface finishes work on CTA MEMB?
Takes high-gloss polish and vacuum-deposited hardcoats/AR stacks; alkaline saponification is used to make TAC film surfaces hydrophilic for PVA polarizer lamination — avoid strong alkali on load-bearing parts.
Can CTA MEMB be formed, bent or molded?
Predominantly solvent cast from dichloromethane–methanol dope; melt processing needs plasticizer and a narrow 220–265 °C window with pre-drying to <0.05 % moisture, since the polymer degrades and yellows above ~280 °C.
What is the maximum service temperature of CTA MEMB?
CTA MEMB is rated for continuous use to about 35°C (95 °F), and briefly to 140°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Engineered Materials Handbook Vol. 2: Engineering Plastics (cellulosics section) — ASM International (1988)
- Polymer Handbook, 4th ed. (cellulose ester thermal/optical data) — Wiley (1999)
- Cellulose ester product literature (cellulose acetate / triacetate flake) — Eastman Chemical (2022)
- ASTM D871 — Testing Cellulose Acetate (acetyl content, viscosity) — ASTM (2020)
- ISO 1875 / GB/T 1043, D638, D790, D256, D648 test methods referenced for typical values — ISO/ASTM/GB (2021)
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.