Plastics are ubiquitous in everyday life, from consumer goods to consumer durables. To increase the strength of plastics, thermoplastics are usually reinforced with glass or carbon fibers. In the face of impact stress under high load and high temperature and low temperature conditions, ordinary short glass fiber materials are often unable to match. In this case, the polymer begins to soften or become brittle, and long glass fiber reinforced polymers emerge as the times require. (The left is short glass fiber, the right is long glass fiber)

The production process of long glass fiber modified PP material is not complicated, and there are many material manufacturers on the market that are capable of realizing it.

However, the technical content of long glass fiber modified nylon is very high, even on a global scale, there are only a handful of them.

So what are the size differences and application advantages of long glass fiber and short glass fiber?

Size Difference

Nylon particles of ordinary glass fiber:

The size is about 3-4mm, the aspect ratio is 50-250

Long glass fiber nylon particles:

Size is about 10-12mm, aspect ratio > 400

In addition, the distribution of glass fibers in the two particles is also different.

Better base rigidity

As shown in the picture above, PA GF 50 natural (2916) is a 50% short glass fiber material based on PA66 alloy, and PA LGF 50 natural (5504) is a corresponding 50% long glass fiber material. It can be seen that the rigidity, strength and modulus have been improved to a certain extent, especially the notched impact performance has achieved a qualitative leap.

Better mechanical properties

As shown in the figure above, after 5000 hours of thermal aging at a high temperature of 150°C, the tensile strength of the long glass fiber material decreased from 290Mpa to 210Mpa, while the tensile strength of the short glass fiber decreased from 260Mpa to 125Mpa, and the long glass fiber material decreased from 260Mpa to 125Mpa. The rigidity retention rate is better than that of short glass fiber, and the ability of long glass fiber to resist thermal aging is stronger.

Lower creep

The factors affecting the creep performance are time, temperature and load. Under the load of 120℃ and 40Mpa, the creep of long glass fiber is obviously better than that of short glass fiber. This is very important for parts with long-term static pressure. When short glass fiber cannot meet the requirements, you can try long glass fiber.

Shock resistance

As shown in the figure above, after 5000 hours of thermal aging at a high temperature of 150°C, the tensile strength of the long glass fiber material decreased from 290Mpa to 210Mpa, while the tensile strength of the short glass fiber decreased from 260Mpa to 125Mpa, and the long glass fiber material decreased from 260Mpa to 125Mpa. The rigidity retention rate is better than that of short glass fiber, and the ability of long glass fiber to resist thermal aging is stronger.

less anisotropic shrinkage p>

The shrinkage rate is very important to the size of the part. The transverse shrinkage rate of the short glass fiber material is much higher than the longitudinal shrinkage rate, and the anisotropy is serious, which makes the size of the part difficult to control and the shrinkage is obvious. On the other hand, the lateral and longitudinal shrinkage of long glass fiber materials are very similar, showing isotropy, which improves the risk of part warpage and makes the size more controllable.