Quick facts
- Catalogue code
- SPR 401 PT
- Chemistry
- Non-thixotropic terephthalic unsaturated polyester
- Production cure
- Heat-activated peroxide blend, 1.0–2.0% total
- Production MEKP / cobalt
- 0% / 0%
Pultrusion in one paragraph
Pultrusion pulls continuous reinforcement through a resin bath and then through a heated die, where the resin cures in seconds and emerges as a finished profile of constant cross-section — rods, angles, channels and structural sections. Because the cure happens in the hot die, the resin is run on a heat-activated initiator system rather than the room-temperature MEKP and cobalt system used for hand lay-up.
Reading the published values
SPR 401 PT is described as a high-strength terephthalic grade with strong mechanical properties for continuous pultrusion. The catalogue lists a clear, light-straw to amber liquid of 300–600 cPs at 25 °C, a specific gravity of 1.10–1.14 and 36–42% styrene by weight, supplied non-accelerated and non-thixotropic.
Two gel times are published and they mean different things. The hot-die gel time, 40–80 seconds at 130–140 °C, describes the resin in production. The ambient gel time, 15–25 minutes at 25 °C, is a quality-control test, not the production cure. Production uses a heat-activated peroxide blend at a total dosage of 1.0–2.0%, added separately during processing, with production MEKP at 0% and production cobalt at 0%.
Limitations and alternatives
A profile’s strength comes from its fibre content, fibre architecture, die design, line speed and cure as much as from the resin; resin data does not state a profile’s structural capacity. For pultrusion in more aggressive chemical service, the existing guide on vinyl ester resin for pultrusion covers that route. For wound pipes and tanks rather than profiles, see the filament-winding grade SPR 301 FW.
Source, roles and the Nepal enquiry path
The values on this page are the typical specification printed for SPR 401 PT in the supplier’s 2026 product catalogue. Samrat Poly Resins has since published a Technical Data Sheet for this grade, linked from the product page; its figures and the catalogue’s agree, and the catalogue is the source named beside every figure here.
Samrat Poly Resins, India manufactures the grade and issues its technical information. Samrat FRP Traders is the Nepal supplier and importer and handles enquiries; price, packaging, lead time and stock in Nepal are confirmed on enquiry.
Key properties
| Property | Typical value |
|---|---|
| Appearance | Clear, light-straw to amber liquid |
| Viscosity | 300–600 cPs at 25 °C |
| Hot-die gel time | 40–80 seconds at 130–140 °C |
| Ambient QC gel time | 15–25 minutes at 25 °C |
| Specific gravity | 1.10–1.14 |
| Styrene content | 36–42% by weight |
| Supply condition | Non-accelerated · non-thixotropic |
| Production cure | Heat-activated peroxide blend, total dosage 1.0–2.0% — added separately during processing |
| Production MEKP | 0% |
| Production cobalt | 0% |
Source: Samrat Poly Resins, India — product catalogue, 2026 edition (typical specification). Typical values describe the grade; they are not batch guarantees or acceptance limits.
Frequently asked questions
Can SPR 401 PT be cured with MEKP and cobalt?
Not in production. The catalogue lists production MEKP at 0% and cobalt at 0%; production runs on a heat-activated peroxide blend of 1.0–2.0% in total.
Why are there two gel times?
The hot-die gel time (40–80 s at 130–140 °C) describes production; the ambient gel time (15–25 min at 25 °C) is a QC test.
Is it a vinyl ester?
No. SPR 401 PT is a terephthalic polyester. Vinyl Ester Resin is a separate chemistry, also used for pultrusion where the service calls for it.