Technical Specifications
This grade family is available as 5 CheMost grades — the differences are in the columns below.
| Property | Unit | PIB680 | PIB950 | PIB1300 | PIB2400 | PIB3500 (indicative) | Test Method |
|---|---|---|---|---|---|---|---|
| Molecular Weight (Mn) | g/mol | 680 | 950 | 1300 | 2400 | 3500 | GPC |
| Viscosity at 100°C | mm²/s | 80 | 230 | 650 | 4500 | 8000 | ASTM D445 |
| Flash point | °C | 175 | 205 | 225 | 270 | 290 | ASTM D92 |
| Density at 20°C | kg/m³ | 890 | 890 | 900 | 910 | 920 | ASTM D4052 |
| Appearance | Colourless to pale-yellow viscous liquid | Colourless to pale-yellow viscous liquid | Colourless to pale-yellow viscous liquid | Colourless to pale-yellow viscous liquid | Colourless to pale-yellow viscous liquid | Visual |
* Typical values from batch production. Batch-specific COA available on request.
Technical content reviewed by the CheMost additives team · Specifications last reviewed
Molecular Structure
Molecular structure · polyisobutylene (PIB)
–[CH₂–C(CH₃)₂]ₙ–
Repeat unit of polyisobutylene; the chain length n sets the molecular weight (Mn 680–3500) and the viscosity.
What Is Low-Molecular-Weight Polyisobutylene (PIB)?
Low-molecular-weight polyisobutylene (PIB), also called polybutene, is a colourless, non-toxic, non-drying liquid polymer made by polymerising isobutylene. It is one of the most versatile additives in the lubricant industry: a tackifier that makes oil cling to metal, a viscosity and thickening agent, and a clean-burning base-fluid component — all from a single, chemically inert hydrocarbon polymer that resists oxidation and UV and volatilises without leaving residue.
PIB is supplied across a ladder of molecular-weight grades. The number-average molecular weight (Mn) sets almost everything that matters: lower-Mn grades are light, free-flowing liquids that add modest tack and viscosity, while higher-Mn grades are very viscous, stringy polymers that give strong adhesion and “anti-fling” cling. CheMost supplies five grades — PIB680, PIB950, PIB1300, PIB2400 and PIB3500 — spanning Mn 680 to 3500, set out grade-by-grade in the Technical Specifications table above.
Because PIB is a standardised commodity polymer rather than a CheMost-proprietary additive, the table shows typical values for each nominal grade; the figures for PIB680–PIB2400 follow published polybutene datasheets, while the highest grade, PIB3500, is shown with indicative values. Exact specifications for any grade are confirmed by Certificate of Analysis on each shipment. CheMost supplies and sources these grades worldwide as a manufacturing and sourcing partner.
How Polyisobutylene Works
Tackiness & anti-migration
Long polyisobutylene chains entangle in the oil and form a cohesive, stringy network that keeps the lubricant adhering to the metal surface instead of slinging off or migrating away. This “stick-on-metal” tack is why PIB is the standard tackifier for open gear, chain, wire-rope and slideway oils — covered in depth on the dedicated PIB tackifier page; this page focuses on its viscosity and thickening role.
Viscosity & thickening
PIB builds viscosity by a purely physical mechanism — the dissolved coils thicken the fluid and contribute to its viscosity index. It is the older viscosity-modifier and thickening route, used where simple body-building and tack matter more than the high shear stability of an olefin copolymer; for severe-shear multigrade engine oils, an OCP or PMA modifier is the better tool.
Clean, residue-free volatilisation
PIB is chemically inert and decomposes completely on burning, leaving no carbon residue or ash. That clean burn-off is the reason low-Mn grades are valued in two-stroke engine oils (low smoke, clean combustion) and in applications such as electrical insulating oil and cable fillers where purity and inertness are essential.
The molecular-weight ladder
Tack, viscosity and adhesion all rise with molecular weight, while flowability and ease of handling fall. Lower-Mn grades (PIB680/950) are easy-handling liquids for light tack and VI; higher-Mn grades (PIB2400/3500) give the strongest stringiness and anti-fling for heavy-duty open gears. As with all long-chain polymers, the higher-Mn grades that tack most strongly are also the most susceptible to breakdown under sustained high shear.
Choosing Between the PIB Grades (Mn 680–3500)
All five grades are the same polyisobutylene chemistry; the choice is set by molecular weight, which drives the trade-off between tack/viscosity and handling. The numbers are in the Technical Specifications table above — here is how to read them:
PIB680 & PIB950 (Mn 680–950) — light, free-flowing grades. Low-viscosity liquids that blend and pump easily, adding defined tack and a modest viscosity uplift. Suited to chain and chainsaw bar oils, light open-gear formulations, two-stroke engine oils and sealant/adhesive uses where handling ease and clean volatilisation matter.
PIB1300 (Mn 1300) — the dual-function middle grade. The sweet spot of strong tackiness plus a meaningful viscosity-index contribution. Used in wire-rope lubricants, open-gear greases, electrical-insulation compounds and quenching-oil brighteners where both adhesion and viscosity build are needed.
PIB2400 & PIB3500 (Mn 2400–3500) — high-tack, anti-fling grades. The highest chain entanglement and the most pronounced stringiness, for heavy-duty open-gear lubricants on kilns and mills, high-load wire-rope compounds and specialty adhesives demanding maximum fling-off resistance. They contribute the most viscosity per unit and the strongest cling, at the cost of higher handling viscosity and greater sensitivity to high shear.
As a rule of thumb, climb the Mn ladder for more tack, more viscosity and stronger anti-fling, and step down it for easier handling, cleaner volatilisation and better shear durability. If you are unsure which grade fits your formulation, our technical team can advise on request.
Applications
This polyisobutylene is used as the tackifier, thickener and clean base-fluid component in formulations targeting the categories below; it adds adhesion and viscosity but carries no detergency, dispersancy or antiwear of its own.
Open gear, chain & wire-rope oils
The classic use: PIB1300–PIB3500 give the tack and stringiness that keep heavy, high-viscosity compounds clinging to kiln, mill and ring-gear teeth, chains and wire ropes under rotation and high load — the “anti-fling” function.
Two-stroke & small-engine oils
Low-Mn grades (PIB680/950) burn cleanly with low smoke and minimal residue, making them well suited to two-stroke and small-engine lubricants where complete, low-ash combustion is required.
Greases, slideway & metalworking fluids
Small additions improve the body, water resistance and adhesion of greases and slideway oils, and add controlled tack and viscosity to metalworking and quenching oils (PIB1300/2400 are used as quench-oil brighteners).
Adhesives, sealants & insulation
Beyond lubricants, PIB is a binder and tackifier in pressure-sensitive adhesives, sealants and waterproofing compounds, and an inert filler in electrical insulating oils and cable compounds, exploiting its impermeability to moisture and gases.
Finished-product OEM and industry approvals are held by the fully formulated oil, grease or compound, not by an individual tackifier or base-polymer component.
Treat Rate & Formulation Notes
Because PIB is a standardised commodity polymer used across very different applications, there is no single TDS dosage; the right level is set by the function and the grade. As an indicative guide grounded in typical formulating practice:
light tack / VI → lower end · strong anti-fling open-gear cling → higher end (with the higher-Mn grades)
For a defined tack in chain and gear oils a low addition is often enough, while heavy open-gear and wire-rope compounds use more of a higher-Mn grade to build both viscosity and stringiness; as a thickener or base fluid the proportion can be considerably higher. Remember the shear trade-off: the higher-Mn grades that tack most strongly also break down fastest under sustained high shear, so in high-shear service the grade and dose are balanced against the durability you need. Match the grade to the base oil as well — PIB is broadly compatible with mineral (Group I–III) and many synthetic stocks.
The figures above are indicative typical values, not a fixed dosage from a datasheet; the correct grade and level depend on your application, base fluid and performance target. CheMost can provide grade-selection and treat-rate support on request.
Formulating With PIB — Complementary Additives
PIB provides tack and viscosity only; a finished tacky gear, chain or grease formulation pairs it with the additives that cover the rest of the performance envelope:
Extreme-pressure additives
Open-gear and wire-rope compounds carry very high, shock loads, so sulfur-phosphorus EP additives are combined with PIB’s tack to protect the tooth and rope contacts that adhesion alone cannot.
Antioxidants
Although PIB is itself oxidation-resistant, the base oil it tackifies still ages; aminic and phenolic antioxidants extend the service life of hot, long-drain open-gear and chain oils.
Rust & corrosion inhibitors
Open gears, wire ropes and slideways are frequently exposed to weather and washdown, so PIB’s water-resistant film is paired with rust inhibitors to protect the steel underneath.
Olefin-copolymer viscosity modifiers
Where shear-stable, high-VI viscosity control is the goal rather than tack, an OCP viscosity modifier is the modern alternative to PIB; the two are sometimes used together to combine tack with stay-in-grade viscosity.
Documentation, Qualification & Regulatory Support
A Certificate of Analysis (COA) confirming the typical grade properties is provided per shipment, together with the Technical Data Sheet (TDS) and Safety Data Sheet (SDS, GHS/CLP) on request rather than as a public download. Additional support is available on request:
Regulatory documentation
REACH, TSCA and country-specific market-registration documentation support available on request.
Third-party inspection
SGS / Intertek / BV pre-shipment inspection can be arranged on request.
Grade sourcing & packaging
Sourcing of specific Mn grades and packaging on request.
Formulation support
Grade selection, treat-rate and base-oil-compatibility guidance from our technical team.
Packaging & Supply
This polyisobutylene is stocked and shipped worldwide, with a typical lead time of 1–15 days. Samples and quotations are answered within 12 hours.
Packaging
Metal drum (typically ~180 kg) · IBC · ISO tank, by grade and viscosity.
Minimum order
1 drum or 1 IBC — no minimum order value.
Incoterms
FOB · CIF · EXW, to suit your freight arrangement.
Loading ports
All major Chinese ports.
Frequently Asked Questions
What is polyisobutylene (PIB) used for in lubricants?
Polyisobutylene is used mainly as a tackifier — it makes oil cling to metal and resist fling-off, which is essential in open gear, chain, wire-rope and slideway lubricants. It also works as a viscosity and thickening additive and, in low-molecular-weight grades, as a clean-burning component of two-stroke oils. Beyond lubricants it is used in adhesives, sealants, electrical insulation and cosmetics.
What is the difference between PIB and polybutene?
In the lubricant trade the terms are used interchangeably: “polybutene” and “polyisobutylene (PIB)” both refer to the low-molecular-weight liquid polymer of isobutylene supplied here. CheMost’s PIB680–PIB3500 grades are this material, classified by number-average molecular weight (Mn).
How do I choose between PIB680, 950, 1300, 2400 and 3500?
Choose by molecular weight: lower-Mn grades (PIB680/950) are easy-handling liquids for light tack, VI and two-stroke uses; PIB1300 balances strong tack with viscosity build for wire-rope and open-gear greases; higher-Mn grades (PIB2400/3500) give the most tack and anti-fling for heavy-duty open gears, at the cost of higher handling viscosity and lower shear durability. The grade-by-grade specs are in the table above.
Is polyisobutylene toxic?
No — low-molecular-weight polyisobutylene is a non-toxic, chemically inert, non-drying polymer, which is why it is used not only in lubricants but also in cosmetics, gum base and food-contact-grade applications by various producers. Always follow the Safety Data Sheet for the specific grade and handling conditions.
Is PIB a viscosity index improver like olefin copolymer?
PIB does build viscosity and viscosity index, and it is an older VM route, but it works mainly by thickening and tack rather than the shear-stable, temperature-responsive behaviour of a modern olefin copolymer (OCP) or PMA viscosity modifier. For severe-shear multigrade engine oils, OCP/PMA are preferred; PIB is chosen where tack and body are the priority, sometimes alongside an OCP.