Plastic Antioxidant 1010 vs 168 vs 1076: Molecular Weight, Volatility and Thermal Stability Data

Overview #

The specification parameter that most procurement teams get wrong when sourcing plastic antioxidants from China is not the active content assay — it’s volatility at processing temperature, which determines whether the antioxidant survives the compounding step and actually protects the polymer. Antioxidant 1010, 168, and 1076 are the three most widely sourced hindered phenolic and phosphite antioxidants in global polymer processing, and they are frequently treated as interchangeable by buyers who focus on price per kilogram rather than molecular weight and the thermal stability data that actually predicts field performance. The selection decision between these three grades is driven by four measurable parameters: molecular weight, melting point, volatility loss at processing temperature, and compatibility with the target polymer matrix. Getting this wrong at the specification stage costs more in scrap and reprocessing than the price differential between grades ever saves.

Molecular Weight, Volatility and Thermal Stability: The Three Parameters That Drive Grade Selection #

The single most important differentiator between Antioxidant 1010, 168, and 1076 is molecular weight — not because higher is always better, but because molecular weight directly controls volatility during melt processing, and volatility determines how much active antioxidant remains in the polymer after extrusion or injection molding at temperatures above 200°C.

Antioxidant 1010 (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) has a molecular weight of 1177 g/mol and a melting point of 110–125°C. Its high molecular weight gives it a volatility loss of less than 0.5% after 2 hours at 200°C under standard thermogravimetric conditions — making it the preferred primary antioxidant for polyolefins processed above 220°C. Antioxidant 1076 (octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) has a molecular weight of 531 g/mol and a melting point of 50–55°C. Its lower molecular weight results in measurably higher volatility — typically 2–4% loss under the same 200°C/2h TGA conditions — which limits its use to lower-temperature processing applications or systems where bloom resistance is less critical. Antioxidant 168 (tris(2,4-di-tert-butylphenyl) phosphite) is a secondary phosphite antioxidant with a molecular weight of 647 g/mol, functioning as a hydroperoxide decomposer rather than a radical scavenger, and is almost always used in combination with a primary hindered phenolic rather than as a standalone stabilizer.

The table below summarizes the specification data that should appear on any supplier TDS before you commit to a qualification trial:

Most procurement teams over-specify purity (requesting >99% assay) and under-specify the parameter that actually matters in high-temperature compounding: volatility loss at processing temperature. A supplier who delivers 99.2% purity but cannot provide TGA data at 220°C is giving you a number that tells you nothing about performance in your extruder.

These grades are governed under ASTM International test methods for thermal analysis (ASTM E1131 for TGA) and are subject to REACH registration requirements for import into the EU above 1 tonne/year — a compliance checkpoint that a significant number of Chinese suppliers cannot satisfy for all three grades simultaneously.

For buyers sourcing into food-contact or medical polymer applications, FDA Guidelines 21 CFR 178.2010 governs antioxidant use in polyolefins, and not all Chinese-sourced grades carry the necessary documentation. This is a qualification gate, not a paperwork formality.

Selection Criteria and Application Performance: When Each Grade Is the Right Answer #

The decision between 1010, 168, and 1076 is not a matter of preference — it is determined by processing temperature, polymer type, and whether you are stabilizing against processing degradation, long-term thermal aging, or both.

Criterion 1 — Processing Temperature Above 240°C: If your compounding or molding process runs above 240°C (engineering plastics, glass-filled PP, PA blends), Antioxidant 1010 is the only hindered phenolic of the three with sufficient thermal stability to survive the process intact. At 260°C, 1076 shows volatility losses that can exceed 8% in a 30-minute residence time — meaning a significant fraction of the antioxidant load is gone before the part is formed. We have seen qualification failures in glass-filled PP compounds where the formulator specified 1076 at 0.15 phr and the compounder was running barrel temperatures at 255°C. The OIT (oxidative induction time) on finished pellets was 40% below the target value, and the root cause was not dosage error — it was grade selection.

Criterion 2 — Synergistic Blending with Phosphite: Antioxidant 168 is almost never used alone. Its function is to decompose hydroperoxides formed during processing before they generate free radicals — a mechanism that is complementary to, not competitive with, the radical-scavenging function of 1010 or 1076. The standard industry blend ratio is 1010:168 at 1:1 to 1:2 by weight, with total antioxidant loading typically between 0.1 and 0.5 phr depending on polymer sensitivity. Buyers who source 168 without specifying a paired primary antioxidant in the same TDS request are missing half the stabilization system.

Criterion 3 — Bloom and Migration in Film Applications: In thin-film polyolefin applications (BOPP, LLDPE stretch film, agricultural film), 1076’s lower melting point (50–55°C) and higher volatility are actually liabilities. Bloom — the migration of antioxidant to the film surface — is directly correlated with molecular weight and compatibility with the polymer matrix. In our supplier qualification program, we require OIT testing per ASTM International ASTM D3895 at 200°C/oxygen atmosphere as a pass/fail gate: minimum OIT of 20 minutes for PP homopolymer film compounds using 1010 at 0.1 phr. Batches that fall below 15 minutes are rejected regardless of COA assay values.

Criterion 4 — Long-Term Thermal Aging vs. Processing Stabilization: This is the distinction that most formulation briefs fail to make explicit. Processing stabilization requires an antioxidant that survives the thermal shock of melt processing (favoring 1010 for high-temperature systems). Long-term thermal aging protection in the finished article requires an antioxidant that does not volatilize or migrate out of the matrix over months of service at elevated ambient temperatures. For outdoor applications (automotive under-hood, agricultural film, pipe), the combination of 1010 + 168 at a 1:2 ratio with a HALS co-stabilizer is the standard approach — and the HALS selection is a separate specification decision that buyers frequently omit from their initial TDS request.

These materials fall within the broader category of rubber-plastic-additives and their performance is closely linked to the base polymer and processing aid package — buyers sourcing antioxidants alongside carrier resins or masterbatch systems should cross-reference the specialty-additives category for compatible co-stabilizer and UV absorber grades.

Supplier Qualification and Lot Consistency: Where Chinese Sourcing Risk Is Concentrated #

The biggest quality risk when sourcing Antioxidant 1010, 168, or 1076 from China is not the initial sample — it is lot-to-lot consistency of the active content and the impurity profile after production volume begins.

In our supplier qualification program, we have seen suppliers pass initial sample approval with COA values showing >99% assay and correct melting point, then deliver production batches where the melting point of 1076 had shifted to 44–47°C — a 6–8°C depression that indicates either a different raw material source or incomplete purification. A melting point shift of this magnitude in 1076 correlates with increased volatility at processing temperature and measurably reduced OIT in the finished compound. The standard COA that most buyers accept — assay, melting point, ash content — will not catch this without incoming DSC (differential scanning calorimetry) spot-testing on each lot.

Three out of six Chinese suppliers we evaluated for Antioxidant 1010 over an 18-month qualification cycle could not provide six consecutive batch COAs with melting point data within ±3°C of the specification midpoint. Two of those suppliers were ISO 9001 certified. Certification status is not a substitute for lot consistency data.

Most Western buyers do not realize that SAC China Standards GB/T standards governing antioxidant purity in China specify a minimum assay of 98.0% for commercial grades — which is 1 full percentage point below the 99.0% minimum that most European and North American polymer processors specify on their incoming material standards. A Chinese supplier delivering “GB/T compliant” material is not necessarily delivering material that meets your engineering specification. This gap is not disclosed on most Chinese supplier COAs unless you ask for it explicitly.

For buyers who require REACH compliance documentation, request the full SVHC declaration and the REACH registration number for each substance. Antioxidant 168 (CAS 31570-04-4) and Antioxidant 1010 (CAS 6683-19-8) are both registered under REACH, but the registration holder is typically the European importer, not the Chinese manufacturer — which means the Chinese supplier’s COA may reference a registration that does not cover their specific production site or synthesis route.

Practical Guidance for Buyers #

When sourcing Antioxidant 1010, 168, or 1076 from China, the first specification to request from any supplier is not purity assay — it is TGA volatility data at your actual processing temperature, measured per ASTM E1131 or equivalent, with the test temperature matching your compounding conditions. Most buyers request assay and melting point because those are the easiest values to produce. Volatility at 220°C or 260°C is the value that predicts whether the antioxidant survives your process.

The most common sourcing mistake we see is selecting Antioxidant 1076 for a high-temperature compounding application because it is 15–20% cheaper per kilogram than 1010. At processing temperatures above 240°C, 1076’s volatility loss can exceed 8% in a 30-minute residence time — meaning you are paying for antioxidant that is not in your product. The cost differential disappears entirely when you account for the increased loading required to compensate for volatility losses, and the OIT shortfall in finished parts creates downstream warranty exposure that no price saving justifies.

Before committing to volume order, require three consecutive batch COAs with DSC melting point data, TGA volatility data at your processing temperature, and — for food-contact or regulated applications — a current FDA 21 CFR 178.2010 compliance letter or EU 10/2011 migration test report. For any supplier you have not previously qualified, run incoming OIT testing per ASTM D3895 on the first three production lots before releasing material to your compounding line.

Decision Matrix: Antioxidant Grade Selection by Application #

What to Specify on Your TDS Request: Checklist #

When requesting a Technical Data Sheet from a Chinese antioxidant supplier, the following parameters must be explicitly listed — not assumed to be included in a standard COA:

For all three grades (1010, 168, 1076):
– CAS number and IUPAC name (to confirm you are receiving the correct substance, not a structural isomer or blend)
– Assay (minimum 99.0% by HPLC, not titration — specify the method)
– Melting point range by DSC (not capillary tube — specify DSC per ASTM International ASTM E794 or equivalent)
– Ash content (maximum 0.1% for polymer-grade material)
– Heavy metals content (maximum 10 ppm total, with individual limits for Pb, Cd, Hg per REACH SVHC thresholds)

For processing stability verification:
– TGA volatility data at your specified processing temperature (e.g., 220°C/2h or 260°C/30min), measured per ASTM E1131
– OIT data on a reference PP compound at 0.1 phr loading, measured per ASTM D3895 at 200°C — minimum 20 minutes for 1010, minimum 12 minutes for 1076

For compliance-sensitive applications:
– REACH registration number and SVHC declaration
– FDA 21 CFR 178.2010 compliance letter (food-contact applications)
– SAC China Standards GB/T grade designation and the specific standard number — so you can compare the Chinese specification tolerance against your own incoming material standard

For lot consistency qualification:
– Six consecutive batch COAs (not cherry-picked samples) showing melting point, assay, and volatility data
– Supplier’s raw material source declaration (the compounder supplying the antioxidant intermediate, not just the repackager)

The difference between a supplier who can provide all of the above and one who cannot is not a paperwork issue. It is a signal about process control capability that will show up in your incoming inspection rejection rate within the first three production lots.

Frequently Asked Questions #

Q1: What is the most important specification to verify when sourcing Antioxidant 1010 from China?

A: TGA volatility at your processing temperature — not purity assay. A COA showing 99.2% assay tells you nothing about whether the antioxidant survives your 250°C compounding step. Request volatility loss data at your actual processing temperature per ASTM E1131 before approving any supplier.

Q2: Can Antioxidant 168 be used as a standalone antioxidant in polypropylene?

A: No. Antioxidant 168 is a secondary phosphite antioxidant that decomposes hydroperoxides — it does not scavenge free radicals. Used alone, it provides inadequate processing stabilization. The standard approach is a 1010:168 blend at 1:1 to 1:2 by weight, with total loading between 0.1 and 0.5 phr depending on the polymer and processing conditions. Specifying 168 alone is one of the most common formulation errors we see in buyer TDS requests.

Q3: Why did our finished PP compound fail OIT testing even though the antioxidant COA showed correct assay values?

A: This is where most sourcing decisions go wrong. The threshold is 20 minutes OIT per ASTM D3895 at 200°C for a standard PP homopolymer compound at 0.1 phr 1010 loading. If you are falling below 15 minutes, the most likely causes are: (1) grade substitution — 1076 delivered instead of 1010, which you will catch by DSC melting point (1076 melts at 50–55°C, 1010 at 110–125°C); or (2) volatility loss during processing because the supplier’s 1010 has a lower-than-specified molecular weight, indicating an impure or adulterated batch.

Q4: What compliance documentation should I require for antioxidants going into food-contact polyolefin applications?

A: Request a current FDA Guidelines 21 CFR 178.2010 compliance letter specific to the grade and CAS number, plus a REACH SVHC declaration with the registration number. For EU food-contact applications, also require an EU Regulation 10/2011 migration test report. Do not accept a generic “food grade” statement on a COA — it has no regulatory standing.

Q5: Is Antioxidant 1076 a lower-quality substitute for 1010, or a legitimate alternative?

A: It is a legitimate alternative for low-temperature processing applications below 220°C — not a lower-quality substitute. The distinction is processing temperature. Above 240°C, 1076’s volatility loss makes it the wrong choice regardless of price. Below 200°C, it performs adequately at a lower cost. The problem is that buyers often select 1076 based on price without checking whether their processing temperature is within the grade’s thermal stability window.

Published by sinoraw.com Technical Team | Request a sourcing consultation