UP
GB GB/T 8237 · ISO 3672
UP is a styrene-cured unsaturated polyester thermoset (GB/T 8237) offered as orthophthalic, isophthalic, DCPD and BPA-fumarate resins, cast, gel coat, flame-retardant and mineral-filled grades, glass-reinforced laminate and SMC/BMC molding compounds.
Reference datasheet — UP is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Cast condition
UP grades and fills
UP is supplied in 11 conditions, soft to hard. Cast is the default FabDigit quotes; the values on this page are for it.
Compare all 11 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Highly mineral-filled casting | 60–80% ATH/quartz/CaCO₃ filled casting resin for sinks, countertops, window sills and machine bases. | 25 | 0.4 | ||
Flexible / rubber-modified (impact-modified) resin | Blend or grade with higher elongation for buttons, encapsulation, patching and shock-loaded laminates. | 25 | 30 | 25 | 65 Shore D |
BMC/DMC | For injection/compression-molded electrical parts — breakers, lamp holders, motor housings — needing arc resistance and dimensional stability. | 40 | 0.6 | ||
Flame-retardant resin/compound | Specify for rail, building panels, ducting and electrical parts needing V-0 / EN 45545 / low smoke performance. | 45 | 1.2 | 88 Shore D | |
Dicyclopentadiene modified, low-shrink / low styrene emission | Pick for low-shrink, low-VOC spray-up and thin bathware/marble parts where surface quality and styrene emission matter. | 50 | 1.5 | 86 Shore D | |
CastDefault As cast | Baseline low-cost orthophthalic (191-type) resin cured with MEKP/Co — casting, putty, tooling and general hand-layup matrix. | 55 | 2 | 85 Shore D | |
Bisphenol-A fumarate corrosion-resistant resin | For FRP tanks, ducts and scrubbers handling bleach, dilute alkali and hot chemicals where ortho/iso resins hydrolyse. | 60 | 2 | 88 Shore D | |
Sheet molding compound | Pick for high-volume compression-molded panels, electrical enclosures, water-tank panels and automotive body parts. | 75 | 1.2 | ||
Vinyl ester resin | Highest chemical/blister resistance and toughness of the family — corrosion FRP linings, pipe, marine skin coats. | 80 | 5 | ||
GF30 | The standard fiberglass laminate for tanks, boats, panels and enclosures made on open molds. | 110 | 1.8 | ||
GF60 | Use for structural profiles, gratings, rebar and pipe where high axial stiffness and strength are needed. | 600 | 2 |
Supply forms, finishes and certifications
Ways UP is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
GELCOAT | Thixotropic pigmented surface coat | Surface finish |
ISO | Isophthalic (and NPG) resin | Certification |
What is UP?
UP is a styrene-cured unsaturated polyester thermoset (GB/T 8237) offered as orthophthalic, isophthalic, DCPD and BPA-fumarate resins, cast, gel coat, flame-retardant and mineral-filled grades, glass-reinforced laminate and SMC/BMC molding compounds. It is the default low-cost matrix for hand lay-up, spray-up, pultrusion, RTM and compression molding, with 55 MPa tensile strength, 2% elongation and 85 °C service temperature. Limits are 7–9% volumetric cure shrinkage, styrene emissions, brittleness and only moderate chemical resistance; vinyl ester is the obvious step up for acids, solvents and blister resistance. UP has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 90°C (194 °F). UP has a tensile strength of 55 MPa (7.98 ksi), stronger than 61% of polymer grades. Elongation at break is 2% and the elastic modulus is 3.4 GPa (0.493 Msi).
What is UP used for?
- Fiberglass boat hulls
- SMC/BMC molded parts
- Composite panels
- Bathroom fixtures (tub/shower)
Advantages
- Stiff — 3.4 GPa (0.493 Msi), better than 82% of polymer grades
- Low embodied carbon — 3.4 kg CO₂/kg, better than 76% of polymer grades
Limitations
- Low fracture toughness — 0.5 MPa·√m (0.455 ksi·√in), worse than 99% of polymer grades
- Needs corrosion protection — 50/100, worse than 97% of polymer grades
- Limited ductility — 2%, worse than 95% of polymer grades
- Limited formability — 5/100, worse than 95% of polymer grades
- Difficult to weld — 5/100, worse than 89% of polymer grades
UP properties
Typical room-temperature values for UP-Cast; bars are the position among polymer grades.
Physical6
UP has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 90°C (194 °F).
Mechanical15
UP has a tensile strength of 55 MPa (7.98 ksi), stronger than 61% of polymer grades. Elongation at break is 2% and the elastic modulus is 3.4 GPa (0.493 Msi).
Thermal10
UP is rated for continuous service to 85°C (185 °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 100 µm/m·K (55.6 µin/in·°F).
Electrical7
UP 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 fair (50/100), worse than 97% of polymer grades. UV resistance is fair.
Sustainability4
Producing a kilogram of UP takes about 70 MJ of energy and emits 3.4 kg of CO₂ — less than 93% of polymer grades. Typical recycled content is 0%.
Manufacturability6
UP's machinability is good (55/100, worse than 64% of polymer grades); weldability not recommended (5/100); formability not recommended (5/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. UP is highlighted; hover a dot for its name, or open the interactive family chart.
Working with UP
Is UP easy to machine?
Trim and drill cured laminate with carbide or diamond tooling, high speed / low feed, backing to prevent chipping; glass dust and styrene fumes require extraction and PPE.
Can UP be welded?
Not weldable — repair and join by secondary lamination (grind, wet out with CSM), or bond with polyester putty, MMA or epoxy adhesives.
Can UP be formed, bent or molded?
Cured by peroxide/cobalt at 20–30 °C (hand lay-up, spray-up, RTM, casting) or at 140–165 °C for SMC/BMC compression and injection; gel time 10–30 min, post-cure 60–80 °C for full Tg; control exotherm and 7–9% volumetric shrink.
UP 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 |
|---|---|---|
| unsaturated polyester (maleic/fumaric + backbone polyester; iso-, NPG-, DCPD- or BPA-fumarate variants change acid/glycol | 55 – 70 | 65 |
| styrene (reactive diluent/crosslinker)LSE/DCPD grades run lower; MMA used in some castings | 28 – 45 | 35 |
| MEKP initiatoradded at use; BPO/TBPB for hot-cure SMC/BMC | 0.8 – 2 | 1.5 |
| cobalt octoate acceleratorwith DMA co-promoter for RT cure | 0.1 – 0.5 | 0.25 |
| hydroquinone/TBC inhibitorstorage stabilizer | 0.01 – 0.03 | 0.02 |
| glass fiber0% for cast resin; 25–30% SMC, 15–25% BMC, 55–70% pultrusion | 0 – 70 | 30 |
| mineral filler (CaCO3 / ATH / quartz)40–50% in SMC/BMC, 60–80% in cultured marble; ATH also gives FR/low smoke | 0 – 80 | 0 |
What surface finishes work on UP?
Gel coat in the mold gives the finished colour/gloss; otherwise sand and spray 2K PU/acrylic, or wet-sand and buff cast surfaces — never anodize/plate directly without conductive primer.
Equivalent designations
Standards and trade names that resolve to UP in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ISO
- 3672
- GB (China)
- GB/T 8237
How much does UP cost?
UP is a budget-cost polymer ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
UP — frequently asked
What is UP used for?
UP is typically used for fiberglass boat hulls, SMC/BMC molded parts, composite panels and bathroom fixtures (tub/shower). In short: cheapest FRP matrix; standard SMC/BMC resin; 85 °C service limit.
What is the tensile strength of UP?
UP has a typical tensile strength of 55 MPa (7.98 ksi) — stronger than 61% of polymer grades. Strength varies by condition: see the 11 listed tempers.
Is UP easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Trim and drill cured laminate with carbide or diamond tooling, high speed / low feed, backing to prevent chipping; glass dust and styrene fumes require extraction and PPE.
Can UP be welded?
Not readily — weldability is rated not recommended (5/100). Not weldable — repair and join by secondary lamination (grind, wet out with CSM), or bond with polyester putty, MMA or epoxy adhesives.
What surface finishes work on UP?
Gel coat in the mold gives the finished colour/gloss; otherwise sand and spray 2K PU/acrylic, or wet-sand and buff cast surfaces — never anodize/plate directly without conductive primer.
Can UP be formed, bent or molded?
Cured by peroxide/cobalt at 20–30 °C (hand lay-up, spray-up, RTM, casting) or at 140–165 °C for SMC/BMC compression and injection; gel time 10–30 min, post-cure 60–80 °C for full Tg; control exotherm and 7–9% volumetric shrink.
What is the maximum service temperature of UP?
UP is rated for continuous use to about 85°C (185 °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 UP Cast and UP Tough?
Cast is the default condition — baseline low-cost orthophthalic (191-type) resin cured with MEKP/Co — casting, putty, tooling and general hand-layup matrix. Tough: blend or grade with higher elongation for buttons, encapsulation, patching and shock-loaded laminates.
How much does UP cost?
UP is a budget-cost polymer ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM D1201 / D2583 (Barcol hardness) and ISO 3672 Unsaturated-polyester resins — designation & basis for specifications — ASTM / ISO (2000)
- Engineered Materials Handbook Vol.2: Engineering Plastics / Vol.1 Composites — ASM International (1988)
- Unsaturated polyester & vinyl ester resin datasheets (AOC, Reichhold/Polynt, Ashland/INEOS Derakane, / / ) — various resin producers (2024)
- CAMPUS / UL Prospector entries for UP-GF, SMC and BMC moulding compounds — CAMPUS / UL (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.