APPLICATION INFORMATIONIMPROVED PHYSICAL PROPERTIES IN POLYAMIDE APPLICATIONSUSING BYK-MAX CT 4275
TP A-9

02

Improved physical properties in polyamide applications using BYK-MAX CT 4275

Contents
03 The challenge
04 Our solution
05 Increased heat deflection temperature
07 Improved tensile strength and modulus
08 Reduction in density compared to other mineral fillers
11 Conclusion

03

The challenge
Polyamide is used in many industries due to its excellent physical properties,ease of processing, relatively low density, and reasonable cost. There iscontinuous pressure to improve these benefits further to continue efforts inmetal replacement and offer an alternative to higher cost engineering
polymers. Additionally, PA6.6 must be used in a variety of applications due
to its heat resistance compared to PA6. However, PA6 is less costly andmany times more available than PA6.6.
Automotive and other applications require improved physical properties inpolyamide compounds as well as improvement of HDT (heat deflectiontemperature) in neat PA6 to replace PA6.6.

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04Improved physical properties in polyamide applications using BYK-MAX CT 4275

Our solution
BYK has developed BYK-MAX CT 4275 specifically toincrease the physical properties of polyamides while nothaving a significant effect on density. BYK-MAX CT 4275
is highly miscible in polyamides, especially PA6, requiringno special processing considerations.

Key benefits• Increased HDT, especiallyin neat PA6• Improved tensile strengthand tensile modulus• Reduction in density
compared to other mineralfillers

05

Improved physical properties in polyamide applications using BYK-MAX CT 4275

Increased heat deflection temperatureThis data demonstrates that adding either one of
two organoclay types (BYK-MAX CT 4255 or
BYK-MAX CT 4275) has a much larger effect on HDT
than electrophile hardening technologies when dosedat recommended levels. While BYK-MAX CT 4255 has apositive impact on physical properties as well, it wasoriginally developed to improve barrier properties.
In contrast, BYK-MAX CT 4275 has been specificallydeveloped to improve physical properties of engineering
thermoplastics, especially polyamides. BYK-MAX CT 4275
in PA6 was able to match the HDT performance of PA6.6
with a loading of approximately 2.0 % to 2.5 %. In addition,
this additive dosage will have only a very marginal effecton density.

Options to increase PA6 heat deflection temperature
Temperature (°C)

The effect of adding BYK-MAX CT 4275 in PA6 wasinvestigated with respect to HDT and density in more detail(G. 02). By using BYK-MAX CT 4275 it is possible to matchthe HDT of PA6.6 by using PA6. The required amount to be
added is between 1.5 % to 2.5 %, depending on specificgoals. Using this amount of additive, the resulting density
increase in PA6 would only be between 0.5 % to 1.1 %.

Heat deflection temperature change depending on
BYK-MAX CT 4275 addition

160

140
Neat PA6.6
0.9 MPa goal
120

Temperature (°C)

PA6.6 is used in many applications due to its higher HDT
compared to PA6. There are multiple approaches to increase
HDT properties, especially in neat PA6. Either reactive
chemistry or compatibilized clay offer the possibility ofsuccess. However, clay products have proven more effectivethan other alternatives (G. 01).

180160140
Neat PA6.60.9 MPa goal

12010010080
Neat PA6.6
1.8 MPa goal

80
Neat PA6.6
1.8 MPa goal

60
60
4040202000PA6 neat resin

1.8 MPa  

0.9 MPa

BYK-MAX CT 4255 BYK-MAX CT 4275
2.5 %2%

Electrophile 1
0.1 %Electrophile 2
0.1 %0G. 01

1.8 MPa  

0.50.9 MPa

11.52
2.5
3BYK-MAX CT 4275 dosage (%)

3.544.5

G. 02

Improved physical properties in polyamide applications using BYK-MAX CT 4275 / Increased heat deflection temperature

It is very popular to use kaolin as a mineral filler inpolyamides for reinforcement. Using kaolin is cost effective
and does increase the stiffness and surface quality of PA6and P6.6. It was tested whether the HDT of 20 % kaolinfilled PA6.6 can be achieved by adding BYK-MAX CT 4275
to 20 % kaolin-filled PA6. The effect at 0.9 MPa is very

marginal, while the effect at 1.8 MPa is more significant(G. 03). But neither achieves the goal up to an addition levelof 6 %. Nevertheless, it can be expected that an addition of
8–10 % BYK-MAX CT 4275 in 20 % kaolin-filled PA6 could
match the 1.8 MPa HDT of 20 % kaolin-filled PA6.6.

Temperature (°C)

Effect of adding BYK-MAX CT 4275
to 20 % kaolin-filled PA6 on HDT

Fiberglass is also a popular reinforcement for polyamides.
As expected, addition of BYK-MAX CT 4275 provides
only marginal increase in HDT as the fiberglass plays thedominant role of reinforcement. The levels achieved do
not approach those of similar PA6.6.

HDT change with addition of BYK-MAX CT 4275
to 30 % glass-fiber-filled PA620 % kaolin
in PA6.6
0.9 MPa
load

200

180

160

30 % glass-fiber-filled PA6.6:
0.9 MPa HDT = 247 °C
1.8 MPa HDT = 256 °C
Temperature (°C)

06

215

210

20 % kaolin
in PA6.6
1.8 MPa
load

140

205

120

100

200

80

60

195

40

20019020 % kaolin

1.8 MPa  

20 % kaolin +2 % BYK-MAX CT 4275

0.9 MPa

20 % kaolin +4 % BYK-MAX CT 4275

20 % kaolin +6 % BYK-MAX CT 4275

30 % glass fiber

G. 03

1.8 MPa  

0.9 MPa

30 % glass fiber +2 % BYK-MAX CT 4275

30 % glass fiber +4 % BYK-MAX CT 4275

30 % glass fiber +6 % BYK-MAX CT 4275

G. 04

07

Improved physical properties in polyamide applications using BYK-MAX CT 4275

Improved tensile strength and modulus
Similar to the positive effect of BYK-MAX CT 4275 on HDT,
it can be used to boost other physical properties of PA6,
such as tensile strength and tensile modulus, without asignificant increase in density. An increase in tensile strengthof 23 % and in tensile modulus of 29 % is possible whenadding 6 % of BYK-MAX CT 4275. This addition increases
the density by only 1.8 %. Further increases out to at least
10 % addition levels are expected and predicted below(G. 05).

1105000

1004500
90

Tensile strength (MPa)Tensile modulus (MPa)

Increase in physical properties by addition ofBYK-MAX CT 4275

80

4000

70
3500

60503000
40

30

2500
0%2%4%6%8%

10 %

BYK-MAX CT 4275 dosage (%)

Tensile modulus  Tensile strength

G. 05

08

Improved physical properties in polyamide applications using BYK-MAX CT 4275

Reduction in density compared to other mineral fillers
Another interesting study is replacing kaolin used in
mixed-reinforcement systems. One common combination
is using kaolin with glass fiber. Starting with a baseline
formulation of 17 % glass fiber and 21 % kaolin in PA6,
the kaolin was removed and replaced with varying amountsof BYK-MAX CT 4275 and fiberglass to match similar
properties. (The difference in amounts between kaolin
and BYK-MAX CT 4275 was accommodated by addingPA6.) The test matrix is shown in T. 01.
The use of BYK-MAX CT 4275 initially results in an increaseof both tensile modulus and strength (Formula PA6 #2). This
provides significant improvements in modulus and strength
but does not quite reach the level of PA6.6 (G. 06). Further
testing was completed by adding in a small amount of glass
fiber, with further increases in modulus and strength(PA6 #3 and PA6 #4 below). Similar results can be seen inPA6.6 formulations.

PA6 formulation tested for replacing kaolin in mixed-reinforcement systems
FormulaBYK-MAX CT 4275

Glass fiberKaolin

Total ash*

PA6 #10%

17 %

21 %

38 %

PA6 #25%

17 %0%

20.5 %

PA6 #33%

22 %0%

24.1 %

PA6 #42%

25 %0%

26.4 %* Total ash is slightly less than the sum of glass fiber and BYK-MAX CT 4275 because BYK-MAX CT 4275 contains
an organic coating that burns during the ash test.

T. 01

Improved physical properties in polyamide applications using BYK-MAX CT 4275 / Reduction in density compared to other mineral fillers

The flow improvement is not limited to the single-point melt
flow measurement but is also evident in the shear versus
viscosity curves (G. 08).

Density and processability changes due to use ofBYK-MAX CT 4275
12Equivalent
PA6.6 tensile
modulus160

140
Equivalent
PA6.6 tensile
strength120

108Tensile modulus (GPa)Tensile strength (MPa)

Kaolin replacement with BYK-MAX CT 4275 in
PA6 MF grade

100
680

60

4

1.5

4035
1.45

Density (g/cm³)

The use of BYK-MAX CT 4275 not only improves physicalproperties, but it also decreases density and improves melt
flow rate (G. 07). If used in the same mold, a 10 % weight
reduction can be realized. Due to the improved flow, it may
be possible to mold thinner parts, thus improving weight
reduction further.

Melt flow rate at 250 °C (g/10 min)

0930
1.425
1.35

20

15

1.3

1040
2

1.25
52000
PA6 #1

Tensile modulus  

PA6 #2Tensile strength

PA6 #3

1.2

0

PA6 #4PA6 #1

G. 06

MFR  Density

PA6 #2

PA6 #3

PA6 #4

G. 07

10Improved physical properties in polyamide applications using BYK-MAX CT 4275 / Reduction in density compared to other mineral fillers

Processing improvement
example in mixed
reinforcement system:shear versus viscosity andspiral flow improvements* (Pa s)

Physical property optimization with processability improvement
108

MFR at 280 °C = 28107

106

105

104

103
MFR at 280 °C = 32

102
10-3

Physical property equivalent systems with optimized density:

10-2

10-1

PA6.6/17 % glass fiber/21 % mineral filler  

100

101

PA6.6/21 % glass fiber/2 % BYK-MAX CT 4275

102103 (rad/s)
G. 08

11Improved physical properties in polyamide applications using BYK-MAX CT 4275Conclusion
Polyamide is used in many industries due to its excellent
physical properties, ease of processing, relatively low density,and reasonable cost, but there is continuous pressure toimprove these benefits further. BYK-MAX CT 4275 can provide
improvements in physical properties and processability at areasonable cost. In many instances, it can enable the use ofPA6 in place of PA6.6. It also offers progress in the continuous
struggle to reduce density and weight.

05/2022
TP A-9BYK-Chemie GmbH
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GermanyTel +49 281 670-0
Fax +49 281 65735

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