Technical Features


RFF has >=94% of renewable carbon content, certified according to ASTM D6866

Renewable carbon originates from alternative non-fossil sources like biomass or CO₂  and circulates between the atmosphere and biosphere. It contains a well-characterized amount of C14 isotopes that enable differentiation from fossil carbon materials by radiocarbon analysis. ASTM D6866 quantifies the biobased content relative to the material’s total organic content and does not consider the inorganic carbon and other non-carbon-containing substances present. UPM’s Renewable Functional Fillers are “DIN-tested” and certified to belong to the highest biobased material class. Their renewable carbon contents, according to ASTM D6866, are greater or equal to 94%.

RFF is lightweight, featuring a lower material density of only 1.3 g/cm³ compared to the traditional fossil-based fillers used in the rubber and plastics industry

In contrast to heavy CO₂  intensive traditional functional fillers used by the rubber and plastics industry, UPM’s RFFs feature a much lower material density. Determination by volumetric gas pycnometery according to ISO 21687 yields values of only 1.3 g/cm³, which, compared to carbon black and precipitated silica, is more than 25% and 35% lower, respectively. Inactive, inorganic white fillers like kaolin, talcum, or siliceous earth are even twice as heavier. This unique natural feature of RFF allows reducing the overall rubber weight signiticantely.

Depending on the compound design (i.e., rubber type, filler to be replaced, and actual filler loading), final weight savings of up to 25% can be achieved. Lightweight materials have always been an essential topic in product design across several industries. Nowadays, the concept has been most important, especially in the automotive industry, for better fuel economy. Focusing on automotive, the critical driver for lightweight materials is to compensate for the heavyweight of the batteries in electric vehicles and plug-in hybrid vehicles.


RFF is 100% electrically non-conductive

UPM’s Renewable Functional Fillers are characterized by high specific resistivity of greater than 1010 Ω in a dry state. The corresponding electrical conductivity in an aqueous solution has been determined to be less than 1500 µS/cm according to ISO 787. In contrast to carbon black and similar to precipitated silica or other inorganic white fillers, rubber compounds applying RFF maintain their electrical insulating performance at any filler concentration. This feature effectively prevents electrochemical corrosion when in direct contact with light metal alloys like magnesium and aluminium and improves the lifetime of the metal parts. Similarly, electrochemical degradation of rubber parts in direct contact with water and other cooling liquids are effectively avoided.


RFF is a PAH free product – the absence of carcinogenic substance banned by regulations

In contrast to many fossil-based materials, UPM’s Renewable Functional Fillers contain no or deficient PAH levels. The related content for each of the eight different EU PAHs determined by GC/MS analysis is well below 0.1 mg/kg after Soxhlet extraction with toluene for 48 hours. In compliance with Commission Regulation (EU) No. 1272/2013, UPM’s RFF are ideally suited to be used even at very high concentrations in plastic or rubber parts of consumer goods as no PAHs are added by their introduction. Due to the absence of hazardous PAHs, UPM’s fillers can be even applied for category 1 materials of the voluntary “Tested Safety” Mark (Geprüfte Sicherheit, GS-Mark) of German Product Safety Committee (Ausschuss für Produktsicherheit, AfPS) without concentration limits.


RFF meets the highest purity requirements 

UPM’s Renewable Functional Fillers offer high cleanliness: zero grit in the form of coke and refractory materials, sulphur levels of less than 0.2wt%, traces of heavy metals like Cr, Cu, Ni, Pb, Zn well below 10 ppm, and a residual ash content of less than or equal to 1wt%.


Surface functionalities enable chemical bonding of RFF to polymer matrices

Driven by a total oxygen content of greater than 25wt%, UPM’s Renewable Functional Fillers are polar. Surface OH-groups in phenolic and aliphatic functionalities are available for chemical modification and reaction, further expanding the range of possible applications.