FX PEROX® — Peroxide Masterbatch for Polypropylene Visbreaking

FX PEROX®, a brand of FX Flow Xpress®, is Polytechs’ range of peroxide masterbatches on PP carrier designed for controlled polyolefin modification. Through precise chain scission (visbreaking), FX PEROX® VM PP grades increase the Melt Flow Index (MFI) of virgin and recycled polypropylene, narrow the molecular weight distribution, and deliver consistent rheology batch after batch.

Four active grades — VM PP 2,5X / 5X / 10X / 20X — cover every dosage need from fine MFI tuning on virgin PP to demanding recycled PP upgrade.

For recyclers and converters specifically focused on rPP and rPE applications, explore our dedicated FX PEROX® microsite for polyolefin recycling.

Recycling

Upgrade rPP MFI from flakes to spec-compliant pellets

Textiles

High-flow PP for meltblown and spunbond

Glass-Filled PP Compounds

Improved flow during impregnation

Compounding

PP grades rationalization, tailored MFI

Plastic baskets on the shelf in the store

Injection
Molding

Optimized mold filling, thin-wall parts

The mechanism

How peroxide visbreaking works

PP visbreaking is a controlled β-scission reaction of polypropylene chains, initiated by free radicals generated through the thermal decomposition of an organic peroxide during melt processing. The result: a higher MFI, a narrower molecular weight distribution, and more predictable flow behavior.

PART 1: Active ingredient
Peroxide structure & radicals generation

The active peroxide (typically 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) decomposes above 160 °C, releasing tert-butoxy and methyl radicals.

PART 2: The vis breaking or reaction of free radicals with PP chains

Free radicals abstract tertiary hydrogens on the PP backbone, triggering β-scission. Long chains are split into shorter ones, MFI increases, and MWD narrows.

MFI evolution regarding % of VM PP5X

On virgin PP copo: MFI ×5 at 0,1% / ×6 at 0,2% / ×18 at 0,5% / ×45 at 1% — predictable, dose-driven, fully reproducible.

RECYCLED PP UPGRADE

Recycled PP (rPP) MFI upgrade — the FX PEROX^® performance

Recycled PP flakes typically show low and inconsistent MFI (3–15 g/10min), making it hard to meet downstream customer specifications. FX PEROX^® VM PP grades restore controlled rheology with industrial reliability.

Reference case — rPP block copolymer, starting MFI 4,9 g/10min, target 30–38 g/10min:

VM PP 10X dosage	Final MFI (230°C, 2.16kg)	MFI uplift
0,8%	22,1 g/10min	×5
1,2%	26,1 g/10min	×5
1,6%	34,9 g/10min	×7

8-hour extrusion trial on rPP >95% purity (230°C, 2,3 t/h throughput):

VM PP 20X (300 ppm active peroxide): >95% of output within customer MFI specifications
40% BIBP on CaCO₃ compacted (250 ppm active peroxide): 40–50% of output OFF-SPEC

FX PEROX^® delivers a narrow, repeatable MFI window where compacted peroxide alternatives fail to hold tolerance.

👉 Looking for in-depth performance data, application case studies and direct technical support for your recycling line? Get full datasets on rPP visbreaking and rPE crosslinking.

FX PEROX® landing page dedicated to PP and PE recycling →

The grades

The FX PEROX® VM PP range

VM PP 2,5X

Active peroxide: 2,5%
Application: Fine MFI tuning on virgin PP, sensitive applications
Typical use: PPh, fiber, compounding

VM PP 5X

Active peroxide: 5%
Application: Recycled PP, Virgin PP, fiber & nonwoven, textile, face mask meltblown
Typical use: PPh, high-flow grades for spunbond/meltblown ; Controlled MFI Reaction in Recycling

VM PP 10X

Active peroxide: 10%
Application: PP, PP copo, recycled PP, GMT/thermoforming, glass-filled compounds
Typical use: Compounding, injection molding, recycling