APPLICATION INFORMATIONMODIFIERS FOR GLASS FIBER REINFORCED POLYPROPYLENE

TP-A 2

02Modifiers for glass fiber reinforced polypropylene

Content
03 Introduction
04 Application fields
05 SCONA modifiers in glass fiber reinforced polypropylene
06 Chemistry of the modifiers
07 Mode of action
08 Advantages of SCONA modifiers
10 Labeling-free coupling agents
11 Product overview

03

Introduction
Polypropylene (PP) is among the most significant thermoplastic materials interms of quantity. This is due, firstly, to the diverse application possibilities
and secondly, to the extremely attractive manufacturing costs. In the past,
polypropylene was mainly used for inexpensive tasks which were notparticularly demanding. But for some time now this interesting material has
tapped into more and more fields of application which were previously
reserved for the so-called technical thermoplastics, such as polyamides (PA),acrylonitrile butadiene styrene (ABS), etc. This has been made possible byfactors including the use of functional fillers and fibers such as talc andglass fibers. Now that glass fibers are being used, we also see more andmore coupling agents being used today, enabling the chemical bonding of
the sized glass fibers to the polymer matrix. This has given rise to a substantial
improvement in the mechanical property profile of the resulting compounds,
which have been able to replace technical thermoplastics in the most diverse
applications as a result of their continuously increasing level of properties.

For additional information onadditives and technical topics,
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Thermoplastics.BYK@altana.com

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04

Modifiers for glass fiber reinforced polypropylene

Application fields
A key field of application for glass fiber reinforced
polypropylene is automotive engineering. The picture showsa typical example of the induction manifold of a combustion
engine which was previously manufactured out of metal.
Later, technical thermoplastics (polyamide/GF) were used.
Due to the ongoing trend towards lightweighting (e.g. intransportation applications), such parts are nowadays madefrom the considerably cheaper and, equally important,lighter polypropylene glass fiber (PP/GF) solution.

Induction manifold ofa combustion engine asa typical example of acomponent made fromglass fiber reinforced
polypropylene

05

Modifiers for glass fiber reinforced polypropylene

SCONA modifiers in glass fiber
reinforced polypropylene
Coupling agents are used in glass fiber reinforced compounds
to increase the adhesion of the fibers to the polymer matrix,
thereby significantly improving the compound‘s mechanicalproperties. The improved fiber-matrix adhesion results in aparticularly significant increase of the charpy (notched) impact
strength of the material. Consequently, the coupling agent
ensures an efficient load transfer from the matrix to thereinforcing fiber. A modifier concentration as low as 1 wt%
or even less already ensures such a significant improvement.
Better incorporationin the polypropylene
matrix when using
SCONA couplingagents

Glass fibers inpolypropylene

06

Modifiers for glass fiber reinforced polypropylene

Chemistry of the modifiers

Polymer backbone (multiple: e.g. PE, POE, PP, SEBS, EBA, EVA, PLA, ...)  

Grafted monomers (multiple: e.g. MAH, GMA , AA, …)

G. 01

HighSCONA coupling agents for reinforced polypropylene:Melt flow rate versus grafting level

SCONA 20097SCONA 20098
SCONA TSPP 22113 GA

Melt flow rate (MFR)

BYK´s product portfolio of SCONA modifiers covers a broad
spectrum of products for reinforced polypropylene
composites. One feature that all the products have incommon is that they exhibit a substantially higher degree offunctionalization compared to most conventional modifiers.
A high degree of functionalization will result in a betteroverall performance and/or in cost advantage as lessmodifier is needed to achieve the same level of properties.
Due to the unique design of BYK´s grafting processes,a broad range of melt flow rates can be covered to ensureextensive fiber wetting in the different processes. At thesame time, a broad range of grafting levels can be achieved
as illustrated in G. 02.

Chemistry of the SCONA coupling agents

SCONA TSPP 10213 GB

Conventional graftedproducts

SCONA TPPP 8112 GA
SCONA TPPP 9112 GA
Low

BYK offers a broad portfolio of polymeric modifiers under
its SCONA brand for different applications to the market.
The SCONA modifier consists in general of a base polymer –a polymer backbone. These base polymers are functionalizedwith different monomers in a grafting process. By doing so,reactive moieties can be attached to the polymer backbone.
Typical examples of the grafting moieties are monomers
like maleic anhydride (MAH), acrylic acid (AA), glycidyl
methacrylate (GMA) but are not limited to those (see G. 01).
There is also a broad selection of base polymers suitable forthe grafting process – from polyolefins (PP, PE), elastomers(POE, SEBS, ...), acrylic copolymers (EBA, EVA, ...) topolyester (PLA, ...). The modifiers employed as coupling
agents in glass fiber reinforced polypropylene are usuallybased on polypropylene co- or homopolymers
functionalized with maleic anhydride.

SCONA TPPP 9212 GA

SCONA TPPP 9012 GA
LowMediumHigh

Grafting level
Polypropylene homopolymer (hPP)  

Polypropylene copolymer (cPP)

G. 02

07

Modifiers for glass fiber reinforced polypropylene

Mode of action
As already mentioned, the coupling agent brings about astronger adhesion of the glass fibers to the polymer matrix.
To achieve this, it must interact with the glass fibers. In fact,
this interaction does not take place directly with the glasssurface, but rather with the surface treatment of the glass
fibers – called sizing. Specifically in the present case, thismeans a reaction of the maleic anhydride groups of thecoupling agent with the amino groups of the silane of thesizing. The reaction results in an extremely stable imide.
As illustrated in G. 04, multiple reaction sites on the surfaceof the glass fiber as well as on the polymeric backbone of
the SCONA modifier result in strong adhesion of the glass
fiber to the polypropylene matrix.

Schematic coupling mechanism of grafted SCONA modifier to solid particles/fibers

SCONA modifier

Solid particle/fiber

Reactive group (e.g. hydroxy, amine)  

G. 03

Reactive group (e.g. anhydride, acidic)

Reaction of the coupling agent with the glass fiber sizing
OO
HCO+HCNSCONA modifierCNNHCCPPO

PP

OO

O

NH

PP

C

H+ O HO

Glass fiberwith sizing

G. 04

08

Modifiers for glass fiber reinforced polypropylene

Advantages of SCONA modifiers
One of the most important fields of application for PP/GF
is automotive structural parts. For years now, it has been
increasingly important to reduce volatile organic compound(VOC) emissions.
A significant contribution to reducing these emissions is madeby PP/GF compounds and, in particular, the coupling agentsused. Coupling agents can contain large quantities of lowmolecular by-products resulting from chain-scissioning anddecomposition of the base polymer at the elevated processtemperature. Furthermore, the degradation products of
the initiator system are another source of organic volatiles.
The initiator system is needed for the grafting reaction.
As a result of BYK´s sophisticated grafting technologies andthe underlying process design, the SCONA modifiers havea significantly reduced VOC content in comparison tocompetitive materials (T. 01).

T. 02 shows a comparison of SCONA TPPP 9012 FA withdifferent competitive products. All products are used ascoupling agents for the manufacture of PP/GF compounds.
The high effectiveness of the SCONA product results fromthe high content of bound MAH.

Comparison of different coupling agents for glass fiber reinforced polypropylene
Modifier

MFR g/10 min(190 °C/2.16 kg)

MAH content %Yellowness index

totalfreeboundCompetitive sample 12600.95

0.240.71

32.0

Competitive sample 22800.90

0.30

0.60

22.0

Competitive sample 3

380

0.80

0.20

0.69

28.1

SCONA TPPP 9012 FA

123

0.98

0.02

0.96

6.8
T. 02

Comparsion of VOC content of coupling agents
Polymer

VOC (mean value) µg/g*1

SCONA TPPP 9012

88

SCONA TPPP 8112 GA

127

Competitive MAH-g-PP

158

Polypropylene (non-grafted)

34*1 based on VDA 277

T. 01

Modifiers for glass fiber reinforced polypropylene / Advantages of SCONA modifiers

The lower yellowness index is also a consequence of thegentle process conditions of BYK‘s grafting processes. Harshprocess conditions (e.g. high temperature, short dwell times,etc.) can generally give fluctuating results in terms of theMAH content and the molecular weight.
Thanks to BYK‘s unique process design, it can be assured
that the SCONA modifiers have very high grafting levels for
maximum performance and efficiency in conjunction with areliable and constant product quality.
G. 05 also shows that there is an optimum for themechanical properties. Higher coupling agent dosages do
not lead to any improvement, or a slight deterioration iseven observed. Nevertheless, it may sometimes be necessary
to use a higher modifier dosage in certain applications, suchas suds containers in washing machines, in order to achieve
the required alkaline resistance (G. 06).

Better impact strength as a result of the coupling agent
having a higher MAH content
60
55
50
454035
30
25
20
0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Coupling agent content (%)

SCONA TPPP 9012 FA  

Charpy notched impact strength (kJ/m2)

G. 05 illustrates this once again by means of the impact
strength and notched impact strength in a 30 % glass fiber
polypropylene composite. The high content of free MAH in
the competitive product is responsible for the high VOCemissions of these products. Furthermore, the free MAH
also naturally reacts with the sizing of the glass fiber,
thereby coating the surface of the glass fiber without
contributing to the adhesion between the glass and thepolymer matrix.

Charpy impact strength (kJ/m2)

09121110
98
765
4
0

0.4

0.8

1.2

1.6

Coupling agent content (%)

G. 05

Competitive sample 2

Effect of coupling agent dosage on the properties of the PP/GF compoundIncreasing coupling agent loading
No coating

Partial coating

Virtually total coverage

Total coverage

Poor mechanicalproperties

Significantly improved
mechanical properties

Maximum mechanicalproperties

Possible slight decline in themechanical properties, but
excellent alkaline resistance

G. 06

10Modifiers for glass fiber reinforced polypropylene

Labeling-free coupling agents
Changing environmental regulations are a continuous driverfor new innovative products. The 13th Adaptation to
Technical Progress (ATP) to the regulation on classification,labeling and packaging of substances and mixtures (CLP)
was published by the European Union at the end of 2018.
Compounders and processors of thermoplastic materials ofsuch glass fiber reinforced polypropylene are now impacted
by changes in the product classification for maleic anhydride(MAH). Products containing a free residual MAH content ofas low as 10 ppm (0.001 %) now need to be classified asskin sensitizing (T. 03). This is currently a topic with relevancein Europe but might become also of relevance in otherregions in the course of changing regulations.
As outlined up to now, maleic anhydride is the mostfrequently used functional group of grafted polyolefin
polymers. BYK has developed a labeling-free alternative tomeet the changing market requirements. Such an innovative
product is SCONA TSPP 8219 GA, using alternativemonomers. The functionality remains very similar andcompared to state-of-the-art MAH-grafted products, such
as SCONA TPPP 9112 GA, there is no drawback in terms of
mechanical performance when using the labeling-freealternative SCONA TSPP 8219 GA at the same dosage level(G. 07). While there is no loss in physical properties thereis a significant benefit in regulatory and environmental“friendliness” as the new product requires no special
labeling, which results in the key benefit for the customer,that no precautionary measures need to be taken to meetthe hazardous potential of the coupling agent. At the sametime there is no drawback in terms of efficiency andperformance.

Comparison of standard coupling agents and innovative labeling-freecoupling agents according to European legislation

Grafted monomer

Standard coupling agent

Labeling-free coupling agent

Maleic anhydride

Labeling-free alternative

Hazard pictograms

NoneH317: May cause an allergic skin reaction*2T. 03*2 Labeling necessary if free residual MAH content is larger than 10 ppm

Mechanical performance of labeling-free SCONA modifier in glass fiber reinforced(30 %) polypropylene compounds in comparison to state-of-the-art modifier
Charpy notched impact strength

Flexural strength

Charpy impact strength

Tensile strength

Control  

0.8 % SCONA TPPP 9112 GA  

0.8 % SCONA TSPP 8219 GA

G. 07

11Modifiers for glass fiber reinforced polypropylene

Product overview
ProductBasepolymer

Deliveryform

MFR/MVR

Grafting
functionalization

Graftinglevel (%)

GraftinglevelDosageApplication/benefit

SCONA TPPP 8112 GA*3

hPP

Pellet80–140 g/10 min(190 °C/2.16 kg)

Maleic anhydride

1.4 %*4high0.8 % –3.0 %Very suitable for long glass fiber reinforced polypropylene compounds

SCONA TPPP 9012 GA*3

hPP

Pellet50–110 g/10 min(190 °C/2.16 kg)

Maleic anhydride> 0.9 %*4medium

0.5 % –2.0 %Standard grade for short glass fiber reinforced polypropylene compounds

SCONA TPPP 9112 GA*3

hPP

Pellet70–120 g/10 min(190 °C/2.16 kg)

Maleic anhydride> 1.0 %*4medium

0.5% –2.0 %Standard grade for lowest impact on discoloration

SCONA TPPP 9212 GA*3

hPP

Pellet80–140 g/10 min(190 °C/2.16 kg)

Maleic anhydride> 1.8 %*4

very high

0.5 % –2.0 %Very highly functionalized grade for maximum efficiency and performance

SCONA TSPP 8219 GA

hPP

Pellet

100 g/10 min(190 °C/2.16 kg)

Proprietary

2.0 %*4very high

0.5 % –3.0 %Free of maleic anhydride

SCONA TSPP 10213 GBcPP

Pellet40–100 cm³/10 min(170 °C/1.2 kg)

Maleic anhydride

2.0 %*4very high

0.5 % –5.0 %Especially suitable for polypropylene composites based on recycled carbon fiber
reinforced polypropylene due to its extraordinary high grafting level

SCONA TSPP 22113 GA

hPPPellet130–220 cm³/10 min(170 °C/1.2 kg)

Maleic anhydride> 1.8 %*4

very high

0.5 % –2.0 %Very high flow and highly functionalized grade for extensive fiber wetting andmaximum efficiency; especially suitable for processes with low dwell time

SCONA 20097

hPP

Pellet25–30 g/10 min(190 °C/1.2 kg)*5

Maleic anhydride(> 0.9 %*4) medium> 0.4 %*6

1.0 % – 4.0 %Very high flow grade for extensive fiber wetting; especially suitable for processes
with low dwell time

SCONA 20098

hPPPellet

15–35 g/10 min(190 °C/1.2 kg)*5

Maleic anhydride(> 1.3 %*4) high> 0.5 %*6

1.0 % – 4.0 %Very high flow grade for extensive fiber wetting; especially suitable for processes
with low dwell time

*3 also available as a powder (FA-version)   *4 according to BYK titration method    *5 measured with a die 8/1   *6 according to BYK FT-IR method

09/2022
TP-A 2BYK-Chemie GmbH
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GermanyTel +49 281 670-0
Fax +49 281 65735

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The information herein is based on our present knowledge and experience. The information merely describes the properties of our products but noguarantee of properties in the legal sense shall be implied. We recommend testing our products as to their suitability for your envisaged purpose
prior to use. No warranties of any kind, either express or implied, including warranties of merchantability or fitness for a particular purpose, are maderegarding any products mentioned herein and data or information set forth, or that such products, data or information may be used without infringing
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