Fig 4. Flat Fibers reduce the degree of warpage in molded products
The reduced anisotropy of mold shrinkage leads to lower warpage and does not depend on mold thickness.
Fig 5. 2FF and 4FF fibers show reduced shrinkage anisotropy as compared to conventional fibers due to their flatter shape.
Fig 6. Use of Nittobo’s Fine-FF produces a similar warpage reduction
as FF across a range of glass fiber weight percentage
Smooth Surface Finish
Flat Fiber composite materials show extraordinary surface smoothness, even with higher glass fiber content. The excellent surface finish is produced because fibers are oriented parallel to the mold surface. The lack of protrusions from the surface produces a smoother texture when compared to conventional glass fiber composites. The surface smoothness is important for applications like air intake components, where the smooth surface helps improve air intake efficiency.
Fig 7. Flat fibers show smaller protrusions at the surface producing a smooth finish
Nittobo’s Fine-FF, which has a flat ratio of 4 and a thickness of only 5µm, provides an even smoother finish. It is suitable for use in applications where surface smoothness is critical.
Fig. 8
Superior Mechanical Properties
Flat fiber produces a greater reinforcement effect, than conventional glass fiber, due to its wider specific surface area and aspect of major axis length. The enhanced reinforcement effect not only strengthens the material in the molding direction but also increases the strength in the transverse direction.
Fig 9. Flat fibers increase the tensile and flexural strength in both the molding and transverse directions (PA6/GF40%, Mold thickness: 3mm)
It is important to note that flat fibers show only a small improvement in the tensile strength and flexural modulus in the molding direction. However, in the transverse direction flat fibers show a 15 – 20 % higher modulus as compared to conventional fibers. This means that the anisotropy of physical properties is smaller and the overall modulus is larger.
Fig. 10 Tensile strength and flexural modulus for each orientation in the mold. 0° means the molding direction, in which the glass fiber is oriented, and 90° means the transverse direction of glass orientation. (Mold thickness: 3mm)
Fig 11. 2FF & 4FF flat fibers show similar reinforcement effect with
significant improvement over conventional glass fiber (Transverse direction, PA6/GF40%)
Reinforcement with Nittobo’s Fine-FF can further improve the mechanical properties of FRP’s for high-performance applications.
Fig 12. Fine-FF (blue) achieves even higher tensile and flexural strength than standard FF (Red) (Resin: PC)
A PP composite produced with long flat fiber technology shows higher tensile strength, improved flexural strength and superior impact strength with reduced warpage, when compared to conventional glass fiber reinforced PP.
| Property |
Method |
Unit |
Flat Fibers |
Conventional |
| Tensile strength |
ASTM
D638 |
Mpa |
145 |
135 |
| Flexural strength |
ASTM
D790 |
Mpa |
285 |
260 |
| Izod(Notched) |
ASTM
D256 |
kJ/m2 |
26 |
18 |
| Warpage |
- |
mm |
1.9 |
9.6 |
| Fiber length in reinforcement |
- |
µm |
930 |
720 |
Table 2. Flat fiber PP composites show superior mechanical
properties compared to conventional glass fiber (GC 50%)
Polyamide (PA6) is also an important polymer for the production of high-performance components. Long flat fiber technology, when applied to PA6, improves the physical properties of the composite material.
 |
Shape |
|
Flat Fiber |
|
Conv. |
| Diameter |
|
19 |
|
17 |
| GF Content (wt%) |
|
44 |
|
|
|
|
|
|
| Properties |
Method |
Unit |
|
|
|
|
| Tensile Strength |
ISO527 |
MPa |
|
250 |
|
250 |
| Flexural Strength |
ISO178 |
MPa |
|
400 |
|
380 |
| Flexural Modulus |
GPa |
|
14 |
|
13.5 |
| Charpy Impact |
Notched
Un-notched |
ISO179 |
kJ/m2 |
|
45
110 |
|
40
105 |
| Warpage |
- |
mm |
|
7 |
|
15 |
Table 3. Comparison of the physical properties of a PA6 composite made with long
flat fibers compared to those of a composite made with conventional glass fiber
Good Flowability
Flat fibers show good flowability, that improves processability and does not require use of any special processing equipment. Flat fibers with 2FF and 4FF flat ratios exhibit better molding flowability than conventional glass fiber, even with higher fiber content.
Fig 13. 2FF and 4FF flat ratio fibers exhibit better molding
flowability than conventional glass fiber (Thickness: 3mm)
Fig. 14 Nittobo’s Fine-FF shows the same improved
flowability exhibited by standard flat fibers
Low Dielectric Flat fiber
Flat fiber technology is not only useful for conventional applications, but also finds new applications in automotive C.A.S.E fields. Low dielectric performance is needed for car connectivity, autonomous or assisted driving and electrified powertrains and components. Nittobo’s low dielectric flat fiber shows similar performance with respect to warpage, physical properties, processability, as well as dielectric performance, as E-glass flat fiber.
Fig. 15 Low Dk Glass (30%) Flat fibers shows a lower dielectric constant as compared
to E-glass, with similar or superior physical properties (PBT/GF 30Wt%)