Cellasto. A microcellular polyurethane elastomer

September 22, 2018 | Author: Raymond Dalton | Category: N/A
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1 Cellasto A microcellular polyurethane elastomer2 When NVH BASF The Chemical Company BASF is the world s leading chemic...

Description

Cellasto® A microcellular polyurethane elastomer

When NVH BASF The Chemical Company BASF is the world’s leading chemical company: The Chemical Company. Its portfolio ranges from oil and gas to chemicals, plastics, performance products, agricultural products and fine chemicals. As a reliable partner BASF helps its customers in virtually all industries to be more successful. With its high-value products and intelligent solutions, BASF plays an important role in finding answers to global challenges such as climate protection, energy efficiency, nutrition and mobility. At BASF, we create chemistry.

is critical Cellasto ® Cellasto

is

the

trade

name

for

BASF

The outstanding features are:

Polyurethanes’ high performance, microcellular

n Low compression set

polyurethane elastomer. Cellasto components

n High volume compressibility with minimum

have been used successfully for over 35 years as

lateral expansion

the NVH (Noise, Vibration, Harshness) solution for

n Excellent mechanical properties & durability

automotive chassis and suspension applications

n Highly versatile - noise isolation at small

such as jounce bumpers, shock absorber top

amplitude

&

high

frequency;

vibration

mounts and coil spring isolators. Cellasto is also

isolation at large amplitude & low frequency

used in many other applications outside of

n Abrasion resistant

automotive such as: elevator safety buffers; paper

n Resistant to ozone, oils, greases and other

conveying components; friction dampers; subframe, motor & body mounts; and more.

aliphatic hydrocarbons

Progressive load deflection behavior Cellasto components are based on a microcellular

The maximum compression of a Cellasto molded

polyurethane elastomer. The molded components

component depends on its density. The spring

are produced in a closed-mold foaming process.

deflection increases with decreasing density,

Depending on the amount of the material used, the

and can reach up to 80% of the original length

molded

of the component.

components

have

densities

of

350 to 650 kg/m . The pore volume accounts for 3

50 – 63% of the molded volume.

Large spring deflection and low block height characterize

The pore diameters are in the range of a tenth of a

molded

components

made

from

Cellasto material.

millimeter and are partially closed. For Cellasto components, a compressive stress of During compression loading, the pore volume is the

4 MPa represents the dynamic continuous load limit.

first to compress followed by material compression.

However, the material is not destroyed by a single

As compression increases, the material gains

impact generating stresses of up to 20 MPa.

rigidity

and

transitions

from

flexible/soft

to

rigid/stiff. This non-linear or progressive load4

deflection behavior is depicted in Figure A.

bulk density g/cm3 0.65 0.60 0.55 0.50 0.45 0.40 0.35 normal climate conditions

3

2

Compressive stress [MPa]

Figure A. Progressive pressurecompression behavior

1

0 0

10

20

Compression [%]

30

40

50

60

70

80

Low lateral expansion and high volume compressibility Compact elastomers show large lateral expansion when compressed. However, this is not the case with cellular

polyurethane

elastomers.

They

are

characterized by low lateral expansion. Cellasto spring elements are therefore suitable for applications where the surrounding structural space is confined or where the spring is located within an enclosure.

rubber

63%

P Cellasto rubber

100%

0%

P

Cellasto

Compression between two plates Compression in enclosed space

100 (45 Shore A) 80 rubber 60 Cellasto 3 0.35 g/cm 40 20 20 40 60 80 100 Compression [%]

Scale representation of the compression (compressive deformation of Cellasto and rubber between two plates)

Compressive stress

Figure B. Low lateral expansion and high volume compressibility

Increase in diameter [%]

120 rubber in a cylinder

Cellasto in a cylinder 20 60 100 Compression [%]

Material grades: Cellasto and rubber in the initial compression range (rubber 45 Shore A. 1.18 g/cm 3; Cellasto: 0.35 g/cm3)

Characteristic curves as a function of temperature The

mechanical

properties

of

plastics

are

temperature dependent, and are also subject to

They

are

then

suitable

for

applications

to

approximately -40°C (-40°F).

temperature limits. Cellasto Cellasto

components

decreasing

temperature

gradually and

stiffen

are

components

gradually

soften

with

with

increasing temperature. As demonstrated in Figure

for

C, the characteristic curve for Cellasto components

suitable

applications to about -30°C (-22°F).

changes only slightly up to a temperature of approximately

80°C

(176°F),

making

Cellasto

Cellasto components that must maintain their

suitable for use in ambient temperatures of up to

elasticity at low temperatures can be manufactured

80°C (176°F) without loss in elasticity performance.

from Cellasto specially formulated for cold flexibility.

4 bulk density 0.50 g/cm3

3

-30°C

2

-20°C Compressive stress [MPa]

Figure C. Characteristic curves as a function of temperature

0 - 80°C

1

0 0

10

20

Compression [%]

30

40

50

60

70

80

Temperature increase caused by damping The material dampens a portion of the mechanical

molded component temperature as a function of

energy input and converts it to heat. The dissipating

spring deflection and frequency. These conditions

heat thereby increases the temperature in the

are taken into consideration in the development

stressed molded component. This temperature

phase to determine if the critical temperature may

should not exceed 110°C (230°F).

be reached for a particular application.

An equilibrium temperature is reached for molded

Cellasto components which become stiffer at low

components subjected to stresses of constant

temperatures regain their elastic properties as the

frequency and constant spring deflection. The family

mechanical energy is converted to heat and the part

of curves depicted in Figure D is an example of the

temperature increases.

Temperature [°C]

Figure D. Temperature increase caused by damping

180 160 140 120 100 80 60 40 20 0

3.0

Fr

eq

n ue

cy

[H

z]

MH 24–50 60 50 Crit ≈ 110 ˚C

2.0

1.0 0.63

10 20

Sp rin

40

g de fle ct io n

60

[% ]

Static load-related creep When designing molded Cellasto components, the

The creep measurements shown in Figure E were

increased compression over time at constant load,

carried out over a period of years, and in this

or creep, must be considered from the outset. The

example,

scale of creep, in comparison with reversible

compression under constant load. In addition, the

compression, is extremely low and can generally be

linearity of the curves allow for extrapolation beyond

disregarded in standard applications.

the measurement period.

demonstrate

the

small

change

in

Dynamic load-related creep Under dynamic loading, deformation or compression

The curve in Figure F flattens out in the load

is determined by the load frequency and number of

controlled test. The low increase in compression

load cycles. Compression increases with increasing

equals the permanent set. At the end of the test, the

load frequency. The increasing frequency raises the

sample virtually recovers to its original height.

temperature of the Cellasto test specimen causing the material to become softer and more flexible.

Figure E. Static load-related creep

Figure F. Dynamic load-related creep

80

σ= 2.0 N/mm

20

Compression [%]

50

σ= 1.0 N/mm2

30 20

σ= 0.5 N/mm2

10 5 102 2

5 103 2

5 104 2

20

20 MH 24-65

50

σ= 1.5 N/mm2

40

0 0 10 2 5 101 2 Time [h]

60

7

70 2

Compression [%]

60

20

20

70

80

40

f=15 Hz

30 1/3 3 Hz ff=3 =3 3 1/ Hzz

20 f=15 Hz

10 0 2 5 103 2 5 104 2 10 2 Alternating load [cycles]

f=3 1/3 Hz

5 105 2

5 106 2

Amplitude dependent damping In order to provide optimum isolation performance

and

in the field of Noise, Vibration and Harshness (NVH),

contrasting requirements are met equally well with

materials need to have low damping properties at

the use of Cellasto.

high

frequencies.

At

those

frequencies

safe

driving

purposes.

These

seemingly

the

amplitudes are usually small. This is the opposite of

Figure G clearly shows the steep rise in “loss angle”

large movements at low frequencies where the

(a measurement of damping), with the increasing

material requirement is rapid damping for dynamic

amplitudes for all material densities.

Dynamic stiffening Cellasto exhibits a very low dynamic rate ratio even

amplitude of 0.1 mm is then applied. The dynamic

at high frequencies. Figure H shows the dynamic

rate ratio decreases with increasing density.

modulus values to a basis of 1 Hz. The data was This quality makes Cellasto an ideal material for

30% of its original height. A sinusoidal load with an

mounting elements to isolate noise and vibrations.

Figure G. Amplitude dependent damping

Figure H. Low dynamic rate ratio

10 Precompression: 30% Frequency: 10 Hz

MH 24-35 MH 24-45

Loss angle [˚]

8 6

MH 24-55 MH 24-65

4 Ø 30 mm

2 30 mm

Dynamic rate ratio [relative to 1Hz]

obtained by statically precompressing a cylinder by

1.4

MH 24-35 MH 24-45 MH 24-55 MH 24-65

Precompression: 30% Amplitude: 0.1 mm

1.35 1.3 1.25 1.2 1.15 1.1

Ø 30 mm

1.05

30 mm

1.0

0 0

1

2 3 Amplitude [mm]

4

5

1

20 40 60 80 100 120 140 160 180 200 Frequency [Hz]

Material characteristics Material designation: Cellasto MH24

Tested in accordance with

-35

-40

-45

-50

-55

-60

-65

Bulk density

ASTM D3574, A

350

400

450

500

550

600

650

kg/m 3

Tensile strength

ASTM D3574, E

3.0

3.5

4.0

4.5

5.5

6.5

7.0

MPa

Elongation at break

ASTM D3574, E

350

350

400

400

400

400

400

%

8.0

10.0

12.0

14.0

16.0

18.0

20.0

N/mm

deformation at 50%/70h/20°C ASTM D3574, D

3.5

3.5

3.5

3.5

3.5

3.5

3.5

%

deformation at 50%/22h/70°C ASTM D3574, D

5.0

5.0

5.0

5.0

5.0

5.5

5.5

%

Property

Tear Strength

Dimension

Compression set

Cellasto is the NVH

Our Commitment BASF can work with you to develop innovative solutions that address a multitude of performance attributes. BASF is committed to our customer's success, and delivers: n In-house technical expertise n Customized solutions n Collaboration between your engineering teams and BASF experts n Value added products through increased driving comfort, light weighting and noise reduction

To learn more, visit us at: basf.us/cellasto.com

solution

BASF Corporation 1609 Biddle Avenue Wyandotte, MI 48192 Phone: 734-324-6285 E-mail: [email protected] Follow us on:

facebook.com/basf

twitter.com/basf

For more information on Cellasto from BASF, scan the QR Code above, or visit: basf.us/cellasto.com

The statements in the product literature and label are guidelines only. Users should test this product in advance to verify suitability for particular uses. BASF Corporation neither makes nor authorizes to be made any express or implied representation or warranty with regard to this product concerning the performance, use, fitness for particular purpose, suitability for use on any surface or merchantability of this product, whether used alone or in combination with other products. The furnishing by us of information and products either as experimental samples or by sales, contains no recommendations respecting the use of these products or the lack of infringement of any patent nor does it grant a license under any patent owned by our company. BASF assumes no liability for any damage of any kind regardless of cause, including negligence. Cellasto ® is a registered trademark of BASF Polyurethanes GmbH. © 2011 BASF, Wyandotte, MI 48192. All rights reserved. CellastoCPE v1.0-09/15/11.

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