Flame Retardancy

Various flame-retardant agents can be blended to confer flame resistance to ABS and its alloy polymers. For consumer application plastic resins, the UL94 Flame Rating, established by the Underwriters Laboratories, is broadly recognized as a highly dependable flame retardancy standard.

Please click on the following link to view details of the test standards:

About UL94 HB

Any one of the following three ABC conditions must be met:

• A. When the specimen thickness is 0.12 to 0.125 (3.05 to 3.18 mm) (nominal 1/8”), the burn rate for a 3” (76 mm) span shall be 1.5” (38.1 mm)/min or less.
• B. The burn rate shall not exceed 3” (76.2 mm)/min over a 3” (76 mm) span when the specimen thickness is less than 0.12” (3.05 mm).
• C. Flames that do not comply with 94 V-0, 94 V-1 and 94 V-2 shall be extinguished before the flame reaches the 4” (101.6 mm) mark.

If the test reveals one of the three test pieces does not conform, the remaining pieces in the set must all conform.

• A. Draft-free chambers, enclosures and laboratory hoods.
• B. Use a Bunsen or Tirrill burner with a 4” (102mm) tube length and a 3/8” (9.5mm) ID. Do not attach a stabilizer like an end attachment.
• C. Ring stand with clamp.
• D. Industrial- grade methane gas (1000 BTU/ft³ (37 MJ/m³) can also be substituted), plus a regulator and flow meter.
• E. Wire mesh (20 mesh, 5 inch square).
• F. Stopwatch.
• G. Pretreatment chamber. However, the environment must allow the chamber to be maintained at 23+-2 ºC and 50+-5% PH.

Three 5” (127mm) long, 0.5” (12.7mm) wide and less than 0.125” (3.18mm) thick, also 5” (127mm) long, 0.5” (12.7mm) wide.
However, the maximum width shall be 0.52” (13.2mm), the edges shall be smooth and the corner radius shall not exceed 0.05” (1.27mm).
Test specimens representing available color, melt flow and reinforcement options should be provided. Representations should also illustrate the natural, light and dark color ranges, as well as the maximum and minimum for melt flow and reinforcement content and their respective ranges.
To evaluate combustion characteristics that might vary among specimens, limit materials by testing for color, melt flow and reinforcement content. Alternatively, generate additional specimens with intermediate values for color, melt flow and reinforcement content.

Process at 23+-2 ºC and 50%RH for 48 hours.

About UL94 V-0

All the following ABCDEF six conditions must be met.

• A. The flame must be extinguished no more than ten seconds after contact with any test specimen.
• B. For each set of five pieces, the flame duration after a total of ten exposures must be within 50 seconds.
• C. No flame or red heat may advance to the clamp location.
• D. Do not ignite cotton by burning or allowing red-hot sparks to drop that will ignite cotton below 1"” (305mm).
• E. The horizontal test of 94HB shall not burn up to the 4” (101.6mm) mark.
• F. The glow should not last more than 30 seconds after removing the second flame.

If any one of the five test specimens fails to meet the above requirements, or if the total flame duration of the five specimens is between 51 and 55 seconds, a further set of five specimens shall be tested. However, this second set must meet all the above requirements. 

• A. Draft-free chambers, enclosures and laboratory hoods.
• B. Use a Bunsen or Tirrill burner with a 4” (102mm) tube length and a 3/8” (9.5mm) ID. Do not attach a stabilizer like an end attachment.
• C. Ring stand with clamp.
• D. Industrial- grade methane gas (1000 BTU/ft³ (37 MJ/m³) can also be substituted), plus a regulator and flow meter.
• E. Stopwatch.
• F. Dry surgical cotton (size 2”*2”, thickness 1/4” freestanding).
• G. Desiccators containing anhydrous calcium chloride.
• H. Pretreatment chamber. However, the environment must allow the chamber to be maintained at 23+-2 ºC and 50+-5% PH.
• I. Pre-processing oven. However, it must be maintained at 70°C +-1ºC with an air ventilation circulation system.

5” (127mm) long, 0.5” (12.7mm) wide, with three thicknesses : minimum, maximum and intermediate. The maximum thickness shall be 0.5” (12.7 mm) and each specimen thickness between the minimum to maximum shall not exceed 0.125” (3.18 mm).
However, the maximum width shall be 0.52” (13.2mm), the edges shall be smooth and the corner radius shall not exceed 0.05” (1.27mm).
Test specimens representing available color, melt flow and reinforcement options should be provided. Representations should also illustrate the natural, light and dark color ranges, as well as the maximum and minimum for melt flow and reinforcement content and their respective ranges.
To evaluate combustion characteristics that might vary among specimens, limit materials by testing for color, melt flow and reinforcement content. Alternatively, generate additional specimens with intermediate values for color, melt flow and reinforcement content.

One set of five pieces was treated at 23+-2 ºC and 50% RH for 48 hours and the other set of five pieces was treated at 70 ºC for 168 hours, then placed in a desiccator containing anhydrous calcium chloride (room temperature) for four hours. Cool further.

Perform in a draft-free area, preferably using a laboratory hood. The relationship between the test piece and burner is shown below.
The burner is ignited away from the specimen and adjusted to a 3/4” blue flame height with no yellow chips.
Apply the test flame to the center portion of the bottom edge of the specimen for ten seconds remove it - leaving it at least 6” away - and record how long the specimen burns.
As soon as the specimen ceases to burn, the test flame is applied for ten seconds, removed and the duration of the flame and glow is recorded.
If the specimen melts and drips while in contact with the flame, or drips with the flame, tilt the burner up to 45 degrees or shift it slightly to prevent drips from entering the burner tube.
For specimens that have melted or flaming drips or those that burn out testing, the burner shall be supported by hand while the flame is on contact, keeping the burner tip and the bottom of the specimen 3/8” (9.5 mm) apart.
Ignore any melted threads of material and apply the flame to the main portion of the specimen.

About UL94 V-1

All the following ABCDE five conditions must be met :

• A. After contact with any test piece, the flame shall burn for 30 seconds or less.
• B. The total flame duration after ten flame contact times for a set of five pieces shall be within 250 seconds.
• C. No flame or red heat may advance to the clamp location.
• D. Do not ignite the cotton by dropping flames or sparks/embers that will ignite the cotton below 12” (305mm).
• E. After removing the second flame, the glow should not last more than 60 seconds.

If any one of the five test specimens fails to meet the above requirements, or if the total flame duration of the five specimens is between 51 and 55 seconds, a further set of five specimens shall be tested. However, this second set must meet all the above requirements.

• A. Draft-free chambers, enclosures and laboratory hoods.
• B. Use a Bunsen or Tirrill burner with a 4” (102mm) tube length and a 3/8” (9.5mm) ID. Do not attach a stabilizer like an end attachment.
• C. Ring stand with clamp.
• D. Industrial- grade methane gas (1000 BTU/ft³ (37 MJ/m³) can also be substituted), plus a regulator and flow meter.
• E. Stopwatch.
• F. Dry surgical cotton (size 2”*2”, thickness 1/4” freestanding).
• G. Desiccators containing anhydrous calcium chloride.
• H. Pretreatment chamber. However, the environment must allow the chamber to be maintained at 23+-2 ºC and 50+-5% PH.
• I. Pre-processing oven. However, it must be maintained at 70°C +-1ºC with an air ventilation circulation system.

5” (127mm) long, 0.5” (12.7mm) wide, with three thicknesses : minimum, maximum and intermediate. The maximum thickness shall be 0.5” (12.7 mm) and each specimen thickness between the minimum to maximum shall not exceed 0.125” (3.18 mm).
However, the maximum width shall be 0.52” (13.2mm), the edges shall be smooth and the corner radius shall not exceed 0.05” (1.27mm).
Test specimens representing available color, melt flow and reinforcement options should be provided. Representations should also illustrate the natural, light and dark color ranges, as well as the maximum and minimum for melt flow and reinforcement content and their respective ranges.
To evaluate combustion characteristics that might vary among specimens, limit materials by testing for color, melt flow and reinforcement content. Alternatively, generate additional specimens with intermediate values for color, melt flow and reinforcement content.

One set of five pieces was treated at 23+-2 ºC and 50% RH for 48 hours and the other set of five pieces was treated at 70 ºC for 168 hours, then placed in a desiccator containing anhydrous calcium chloride (room temperature) for four hours. Cool further.

Perform in a draft-free area, preferably using a laboratory hood. The relationship between the test piece and burner is shown below.
The burner is ignited away from the specimen and adjusted to a 3/4” blue flame height with no yellow chips.
Apply the test flame to the center portion of the bottom edge of the specimen for ten seconds remove it - leaving it at least 6” away - and record how long the specimen burns.
As soon as the specimen ceases to burn, the test flame is applied for ten seconds, removed and the duration of the flame and glow is recorded.
If the specimen melts and drips while in contact with the flame, or drips with the flame, tilt the burner up to 45 degrees or shift it slightly to prevent drips from entering the burner tube.
For specimens that have melted or flaming drips or those that burn out testing, the burner shall be supported by hand while the flame is on contact, keeping the burner tip and the bottom of the specimen 3/8” (9.5 mm) apart.
Ignore any melted threads of material and apply the flame to the main portion of the specimen.

About UL94 V-2

All the following ABCDEF six conditions must be met.

• A. After contact with any test piece, the flame shall burn for 30 seconds or less.
• B. The total flame duration after ten flame contact times for a set of five pieces shall be within 250 seconds.
• C. No flame or red heat may advance to the clamp location.
• D. You may ignite the cotton by dropping a flame or glowing drops that ignite the cotton below 12" (305mm).
• E. The horizontal test of 94HB shall not burn up to the 4” (101.6mm) mark.
• F. No more than 60 seconds of glow duration after removing the second flame.

If one of the five test specimens does not meet the above requirements, or if the total flame duration of the five specimens is between 251 and 255 seconds, another set of five shall be tested. . However, this second set of five must meet all the above requirements.
 

• A. Draft-free chambers, enclosures and laboratory hoods.
• B. Use a Bunsen or Tirrill burner with a 4” (102mm) tube length and a 3/8” (9.5mm) ID. Do not attach a stabilizer like an end attachment.
• C. Ring stand with clamp.
• D. Industrial- grade methane gas (1000 BTU/ft³ (37 MJ/m³) can also be substituted), plus a regulator and flow meter.
• E. Stopwatch.
• F. Dry surgical cotton (size 2”*2”, thickness 1/4” freestanding).
• G. Desiccators containing anhydrous calcium chloride.
• H. Pretreatment chamber. However, the environment must allow the chamber to be maintained at 23+-2 ºC and 50+-5% PH.
• I. Pre-processing oven. However, it must be maintained at 70°C +-1ºC with an air ventilation circulation system.

5” (127mm) long, 0.5” (12.7mm) wide, with three thicknesses : minimum, maximum and intermediate. The maximum thickness shall be 0.5” (12.7 mm) and each specimen thickness between the minimum to maximum shall not exceed 0.125” (3.18 mm).
However, the maximum width shall be 0.52” (13.2mm), the edges shall be smooth and the corner radius shall not exceed 0.05” (1.27mm).
Test specimens representing available color, melt flow and reinforcement options should be provided. Representations should also illustrate the natural, light and dark color ranges, as well as the maximum and minimum for melt flow and reinforcement content and their respective ranges.
To evaluate combustion characteristics that might vary among specimens, limit materials by testing for color, melt flow and reinforcement content. Alternatively, generate additional specimens with intermediate values for color, melt flow and reinforcement content.

One set of five pieces was treated at 23+-2 ºC and 50% RH for 48 hours and the other set of five pieces was treated at 70 ºC for 168 hours, then placed in a desiccator containing anhydrous calcium chloride (room temperature) for four hours. Cool further.

Perform in a draft-free area, preferably using a laboratory hood. The relationship between the test piece and burner is shown below.
The burner is ignited away from the specimen and adjusted to a 3/4” blue flame height with no yellow chips.
Apply the test flame to the center portion of the bottom edge of the specimen for ten seconds remove it - leaving it at least 6” away - and record how long the specimen burns.
As soon as the specimen ceases to burn, the test flame is applied for ten seconds, removed and the duration of the flame and glow is recorded.
If the specimen melts and drips while in contact with the flame, or drips with the flame, tilt the burner up to 45 degrees or shift it slightly to prevent drips from entering the burner tube.
For specimens that have melted or flaming drips or those that burn out testing, the burner shall be supported by hand while the flame is on contact, keeping the burner tip and the bottom of the specimen 3/8” (9.5 mm) apart.
Ignore any melted threads of material and apply the flame to the main portion of the specimen.

About UL94 5V

All three ABC conditions below must be met. Or meet D.

• A. The duration of both flame and red heat after 5 exposures to any test piece shall not exceed 60 seconds.
• B. There should be no drips on any specimen.
• C. There is no significant damage to any test piece in the area that came into contact with the test flame (significant damage in the area that came in contact with the test flame varies depending on the finish).
• D. 1Check the degree of influence by testing on a 6"*6" (152*152mm) plaque of the same thickness. Please refer to the plaque test method in the test method section.

If one set of five specimens does not meet this requirement, another set of five specimens shall be tested and all specimens shall comply with this requirement.

• A. Draft-free chambers, enclosures and laboratory hoods.
• B. Use a Bunsen or Tirrill burner with a 4” (102mm) tube length and a 3/8” (9.5mm) ID. Do not attach a stabilizer like an end attachment.
• C. Ring stand with clamp.
• D. Industrial- grade methane gas (1000 BTU/ft³ (37 MJ/m³) can also be substituted), plus a regulator and flow meter.
• E. Support burner at 20 degrees with mounting block.
• F. Stopwatch.
• G. Desiccators containing anhydrous calcium chloride.
• H. Pretreatment room or chamber that can be maintained at 23 degrees + - 2 degrees C and 50 + - 5% PH.
• I. Pre-processing oven. However, it must be maintained at 70°C +-1ºC with an air ventilation circulation system.

The length should be 5" (127mm) and the width should be 0.5" (12.7mm). There are three types of thickness: the minimum, maximum, and intermediate thickness. The maximum thickness shall be 0.5" (12.7 mm) and each specimen thickness increase from minimum to maximum shall not exceed 0.125" (3.18 mm).
However, the maximum width shall be 0.52” (13.2mm), the edges shall be smooth and the corner radius shall not exceed 0.05” (1.27mm).
Black should be 6"(152mm)*6"(152mm).
 
If color, melt flow, and reinforcement options are available, specimens and plaques representative of each option should also be provided. Also provided are representations of the natural, light, and dark color ranges, as well as maximum and minimum melt flow and reinforcement content, and representations of the ranges.
When evaluating combustion characteristics that vary from specimen to specimen, limit materials by testing color, melt flow, and reinforcement content. Alternatively, prepare additional specimens and plaques of intermediate color, melt flow and reinforcement content.

Test method using specimens: Each set is treated at 23+-2 ºC and 50%RH for 48 hours.
Plaque test method : Each set is treated at 121 ºC for 60 days, then cooled in a desiccator containing anhydrous calcium chloride (room temperature) for at least four hours.

5-1 : Test method using test pieces

5-2 : Test method using plaque

Do this in a well-ventilated place, preferably using a laboratory hood.
The burner is ignited away from the specimen and the total flame height is 5” (127 mm) and the height of the blue inner flame is adjusted to 1 1/2” (38 mm). Hold the burner at a 20 degree angle to the vertical and apply the tip of the blue flame to the plaque as follows.

A. The plaque should be vertical and at the bottom corner.
B. The plaque should be vertical and at the bottom edge.
C. The plaque should be vertical and centered on one side of the plaque.
D. Place the plaque horizontally and center the bottom of the plaque.
E. The plaque was held horizontally with the flame facing down onto the surface of the plaque.

Repeat the process of applying the flame for five seconds and then releasing it for five seconds until you have applied the flame five times.

After removing the flame for the fifth time, record the following observations :

A. Duration of flame and glow.
B. Distance at which the plaque was burnted or affected.
C. Is there any dripping from the plaque under test?
D. Observations of deformation and physical strength should be made immediately after combustion and after cooling.