Ateva 1821A EVA Copolymer Resin,18% VA,3 MI,Wire & Cable Grade (LSZH)

Technical documentation for Ateva 1821A identifies an ethylene-vinyl acetate copolymer carrying 18 wt% vinyl acetate and a melt flow rate of 3 g/10 min when measured at 190 °C under 2.16 kg load in accordance with ASTM D1238. The resin is supplied as pelletized material for compounding and extrusion in low-smoke zero-halogen wire and cable formulations. The 18 wt% vinyl acetate content reduces polyethylene crystallinity, increases polar filler wetting, and improves low-temperature flexibility relative to 12 wt% VA grades. The 3 g/10 min melt flow rate is positioned between high-flow injection grades and low-flow high-melt-strength extrusion grades, providing a compromise between thin-wall flow and jacket melt strength during cable sheathing operations. Table 1 lists nominal physical data associated with this VA/MFI combination.

What Distinguishes Ateva 1821A Within Vinyl Acetate Copolymer Grades?

Relative to a 12 wt% vinyl acetate grade, Ateva 1821A shows a measurable reduction in crystallinity and a corresponding decrease in room-temperature modulus. The higher polar comonomer content increases the resin’s ability to wet and encapsulate mineral fillers such as alumina trihydrate and magnesium dihydrate, which is essential in low-smoke zero-halogen compounds where filler loadings frequently reach 50–65 wt%. The trade-off is a lower tensile yield and greater surface tack than lower-VA grades. Relative to a 28 wt% vinyl acetate grade, the 18 wt% level provides higher modulus, lower surface blocking, and better dimensional stability, but lower rubber-like flexibility and slightly reduced filler acceptance. In cable jacket applications, this intermediate position allows the compound to retain enough flexibility for installation while avoiding the blocking and pellet-agglomeration problems often associated with high-VA EVA resins during warm-weather storage.

The melt flow rate of 3 g/10 min distinguishes the resin from lower-flow 0.7 g/10 min and 1.5 g/10 min EVA grades used in heavy-wall sheathing and from higher-flow 6 g/10 min grades used in thin-wall insulation. The 3 g/10 min value reduces extrusion head pressure compared with lower-MFI grades when compounds contain high filler concentrations, while still preserving sufficient melt strength to reduce sag on large-diameter cables. The combination of 18 wt% VA and 3 g/10 min melt flow rate is therefore common in thermoplastic LSZH sheathing compounds where mineral filler dispersion, low smoke release, and processability must be balanced without crosslinking.

Low-smoke zero-halogen performance is not provided by the base resin alone. Ateva 1821A functions as the polymer matrix in a formulated compound containing halogen-free flame retardants, stabilizers, processing aids, and coupling agents. In such compounds, the resin contributes filler compatibility, mechanical elongation, and low-temperature flexibility, while the flame retardant system contributes the heat-release and smoke-suppression behavior. The resin itself does not contain halogenated flame retardants and is not an inherently flame-retardant polymer; final fire performance must be verified on the finished cable construction.

Where cable designs demand greater low-temperature flexibility but not the aggressive surface tack of 28 wt% VA grades, Ateva 1821A occupies an intermediate position. In filled compounds, the resin’s polar acetate group interacts with hydrated mineral surfaces through dipole interactions and hydrogen bonding, reducing filler agglomeration and distributing the mineral phase more uniformly. This interaction helps maintain elongation at break after compounding, which is important because high filler loadings can otherwise reduce elongation to below 150% in an unfilled polymer. Processors may select 18 wt% VA over 12 wt% VA when elongation, stress-crack resistance, and filler dispersion are limiting the cable jacket’s cold-bend performance, while selecting it over 28 wt% VA when pellet blocking, screw feeding, and high-temperature dimensional stability are greater concerns.

When 3 g/10 min Melt Flow Rate Governs LSZH Compounding Stability

In production-scale compounding, the 3 g/10 min melt flow rate is commonly evaluated on a co-rotating twin-screw extruder with an L/D ratio between 36:1 and 44:1. The resin is fed in the main feed throat; mineral fillers are introduced through a downstream side feeder to limit peak torque and reduce localized melt-temperature rise. Screw configurations typically alternate kneading blocks and reverse-conveying elements to disperse alumina trihydrate or magnesium dihydrate without excessive shear heating. Barrel set points are often staged from 140 °C in the feed zone to 180 °C in the transition and mixing zones, with the final melt temperature held below 200 °C to limit vinyl acetate deacetylation.

The processing window above 200 °C should be approached with caution. Prolonged residence time or high shear at elevated melt temperature can liberate acetic acid from the vinyl acetate segments, producing an acidic volatile stream that corrodes downstream vacuum pumps, pelletizer water systems, and metal tooling. The presence of acetic acid is often identified by reduced melt pH and increased volatile condensate acidity. Atmospheric venting or vacuum degassing in the downstream barrel section is used to remove volatiles; a vacuum level below -0.07 MPa is typical when compounding filled LSZH formulations. Batch-to-batch variation in filler moisture must be controlled because hydrated mineral fillers release water at temperatures above 200 °C, and residual moisture above 0.1 wt% can generate porosity, surface roughness, and reduced tensile properties in the pelletized compound.

In cable jacket extrusion, the 3 g/10 min melt flow rate influences die swell, drawdown, and sag resistance. The resin is compatible with standard single-screw extruders equipped with barrier screws and Maddock mixers, although grooved-barrel extruders used for polyolefin sheathing may require adjusted barrel temperatures because the lower melt viscosity of EVA can reduce pressure stability. Melt pressure at the die is a function of compound viscosity, which rises sharply with filler content; operators may record head pressure in the range of 80–180 bar depending on formulation and die diameter. A 3 g/10 min melt flow rate generally permits thin-wall extrusion at line speeds above those attainable with 0.7 g/10 min resin without requiring the high temperatures and shorter residence times associated with 6 g/10 min resin.

Pre-drying of the base resin is not normally required when pellets are stored in closed containers at ambient conditions. However, compounds containing hydrophilic fillers may require 70–80 °C drying of the mineral phase or the final compound before extrusion if moisture exceeds 0.1 wt%. Moisture-related defects in filled EVA compounds include microvoids, surface sharkskin, and tensile strength loss. Processors encountering intermittent bubbles in the extrudate should first quantify filler moisture by Karl Fischer titration rather than increasing melt temperature, because elevated temperature accelerates both water release and deacetylation.

Material Boundaries, Additive Interactions, and Quality Control Records

Ateva 1821A is neither a thermoset nor an XLPE resin. It is a thermoplastic ethylene-vinyl acetate copolymer and can be reprocessed as part of a closed-loop regrind stream when the regrind fraction is controlled and contamination is excluded. The resin is not designed for continuous operating temperatures above 90 °C without crosslinking or without a compound-level thermal stabilizer package. In LSZH sheathing compounds, continuous conductor temperature ratings are determined by the finished cable design, not by the base resin alone.

Additive compatibility should be verified by torque rheometry and melt pH because certain acidic processing aids, chlorinated flame retardants, or amine-based stabilizers can accelerate deacetylation or interfere with filler coupling. Standard LSZH formulations based on Ateva 1821A commonly incorporate aminosilane or vinylsilane coupling agents to improve mineral filler adhesion and maintain elongation after thermal aging. Antioxidant packages are selected to survive the high filler surface area and the mildly acidic local environment generated during processing; phenolic antioxidants blended with phosphite secondary antioxidants are typical.

Table 2 provides a compliance matrix of test standards frequently requested for finished LSZH cable compounds in which Ateva 1821A may serve as the polymer phase. The base resin cannot itself be certified against cable fire, smoke, or halogen-acid requirements because those tests apply to the complete compound and cable construction after formulation, extrusion, and aging.

Quality control for Ateva 1821A incoming lots typically includes melt flow rate, vinyl acetate content, density, and visual pellet cleanliness. Variations in melt flow rate beyond ±0.5 g/10 min can alter extrusion pressure and cable wall thickness, especially on high-speed lines with narrow die gaps. Variations in vinyl acetate content beyond ±1 wt% can shift filler dispersion, hardness, and low-temperature flexibility. In high-filler LSZH production, lot-to-lot drift is compensated by adjusting downstream filler feed rate or extruder barrel temperature, but mechanical and flame properties should be re-en confirmed on the finished compound because small changes in polymer phase polarity can affect the dispersion of the mineral flame retardant system.

For processors comparing Ateva 1821A with a 6 g/10 min grade of the same vinyl acetate content, the lower melt flow rate of Ateva 1821A provides greater melt strength and reduced sag but may require slightly higher die temperatures or lower line speeds on very thin constructions. Conversely, compared with a 1 g/10 min grade, the 3 g/10 min melt flow rate reduces screw torque and permits higher filler loadings before viscosity limits are reached. Published data for every specific filled formulation is limited; therefore, pilot-scale trials on production equipment are required to establish the exact processing window for a given LSZH compound. The selection of Ateva 1821A is most appropriate when a cable compound requires high filler acceptance, reliable pellet feeding, and a balance between low-temperature flexibility and surface non-blocking in an un-crosslinked polymeric sheathing material.