1. Influence of glass fiber filling specification on PA6 engineering plastics
We can find from the application and experiment that the content index is often one of the biggest influencing factors in fiber-reinforced composites.
With the increase in the glass fiber content, the number of glass fibers per unit area of the material will increase, which means that the PA6 matrix between the glass fibers will become thinner. This change determines the impact toughness, tensile strength, bending strength, and other mechanical properties of glass fiber-reinforced PA6 composites.
In terms of impact performance, the increase of glass fiber content will greatly increase the notched impact strength of PA6. Taking long glass fiber (LGF) filling PA6 as an example, when the filling volume increases to 35 percent , the notched impact strength will increase from the original 24.8J/m to 128.5J/m.
But the glass fiber content is not more is better, short glass fiber (SGF) filling volume reached 42 percent , and the impact strength of the material reached the highest 17.4kJ/㎡, but continuing to add will let the gap impact strength show a downward trend.
The above theory is verified by experiments. The data show that when the LGF (long glass fiber) is used to fill up to 35 percent , the bending elastic modulus increases to 4.99GPa. When the content of SGF (short glass fiber) is 42 percent , the bending elastic modulus reaches 10410MPa, which is about 5 times that of pure PA6.
2. Influence of glass fiber retention length on PA6 composites
The experimental results show that the tensile strength of the material increases from 154.8MPa to 164.4MPa when the glass fiber content is kept at 40 percent and the length of the glass fiber increases from 4mm to 13mm. The bending strength and notched impact strength were improved by 24 percent and 28 percent , respectively.
Moreover, the research shows that when the original length of the glass fiber is less than 7mm, the material performance increases more obviously. Compared with short glass fiber, long glass fiber reinforced PA material has better warping resistance, and can better maintain mechanical properties under high temperature and humidity conditions.
3. The influence of glass fiber types on PA6 composites
Among them, the glass fiber with higher monofilament strength has a stronger bearing capacity, and the experimental results show that the high-strength glass fiber-reinforced PA6 has better mechanical properties than the ordinary non-alkali fiber-reinforced PA6.
4. Influence of glass fiber addition process on PA6 composites
In the process of twin-screw modified granulation, the influence of the feeding position on the material properties in the blend of glass fiber and resin was studied. It was found that if the glass fiber was added earlier, the fiber would be easily destroyed and the length of the residual glass fiber would be smaller. When added late, the glass fiber is difficult to blend with the resin uniformly, and the combination is weak. Both of these conditions will make the overall performance of the material less than good results.
5. Influence of the extrusion process of modified granulation on glass fiber reinforced PA material
When the twin-screw extrusion mechanism is used to prepare glass fiber reinforced particles, the tensile modulus, tensile strength, bending strength, bending modulus and other indicators of the material are gradually increased with the increase of the host speed from 70r/min to 300r/min. When the host speed is increased to 450r/min, the properties of the material have little change or slightly decreased.
In addition, the feeding speed will affect the residence time of the material in the screw. The tensile modulus, tensile strength, flexural modulus, flexural strength and even impact strength of the composites gradually decrease with the feed speed increasing from 8r/min to 26r/min at the same speed of the main engine.
6. Effect of injection molding process on properties of glass fiber reinforced PA materials
It is found that the tensile strength of glass fiber reinforced PA6 material is directly proportional to the temperature of the feed port, and inversely proportional to the injection speed and screw speed. The fracture of glass fiber will be aggravated with the increase of injection speed. But generally speaking, the change of injection process has no great influence on the mechanical properties of glass fiber reinforced PA6 injection parts.
