High glass fiber Content modified nylon (PA) composite has the characteristics of mechanical properties (especially rigidity), excellent dimensional stability, long-term heat resistance, chemical resistance and oil resistance, and can be substituted for some metal materials (such as aluminum alloy materials) for automotive parts and mechanical parts and other structural parts.
With the increase of glass fiber content, the melt viscosity of PA matrix increases, glass fiber in the matrix is not easy to evenly dispersed, resulting in poor fluidity of the composite material and uneven, in the extrusion process prone to break the phenomenon, at the same time in the product surface easily caused by floating fiber.
Guangdong Wangzhongjiang New Material Co., Ltd. a method for improving the appearance of high glass fiber content (glass fiber mass fraction 55%) PA Composites was proposed. They found two functional resins from the PA family and modified the high glass fiber content PA composites.
The two functional resins are: copolymer of PA66 Salt and Caprolactam (PA66/6) and poly-bis (MXD6).
PA66/6 molecular chain has better flexibility and fluidity, which can effectively improve the dispersion degree of GF in matrix resin.
MXD6 contains a large space-resistance benzene ring structure, its crystallization rate is slow, can delay PA66 crystallization, is conducive to GF in the dispersion of resin.
In addition, there are carboxyl-containing hyperbranched polymers, acting as a surfactant-like role, the dosage of more than 0.4 will have a greater negative impact on the mechanical properties of composites, so the dosage is fixed to 0.2 parts.
PA66/6 PK MXD6
(1) Mechanical properties
The mechanical properties of the two functional resins, which were 10 parts, were added to the 55% glass fiber reinforced PA66 composites as shown in the table below.
The tensile strength and notched impact strength of composites added to PA66/6 were higher than that of composites with MXD6, and the flexural strength and modulus of composites added to MXD6 were higher than that of composites with PA66/6, but the notched impact strength of composites was not improved.
In terms of mechanical properties, the two functional resins are 2:2 flat.
(2) Fluidity and gloss
Both functional resins are used in 10 parts, and the melt flow rate and gloss after adding 55% glass fiber reinforced PA66 composites are shown in the table below.
The melt flow rate and gloss of the composites added to PA66/6 were increased significantly, and the increase was higher than that of the composites added to MXD6.
In terms of fluidity and appearance, the PA66/6 a victory.
(3) Cause analysis
PA66/6 chain segment is better compliant, can absorb more energy, and melt fluidity and molecular chain movement ability are better, while with PA66 belong to aliphatic pa, compatibility is relatively good, so in tensile strength, impact strength, fluidity and gloss more advantages.
MXD6 contains rigid benzene ring, resin rigidity is larger, so the bending strength and modulus of more advantages.
PA66/6 Complex with MXD6 As can be seen from the above PK process, PA66/6 in four aspects (tensile strength, impact strength, fluidity, gloss) wins, but the mechanical properties of composite materials to improve the range is small, and MXD6 in the flexural properties of composites significantly improved.
To this end, to maintain the total amount of functional resin 10 parts unchanged, the two ratios (5:5) of the complex (expressed in p1+m1), the results obtained are as shown in the table below.
It can be seen that the effect of the ratio (5:5) is not outstanding.
In order to enhance the effect of PA66/6 and MXD6, respectively, the amount of increase, but considering the MXD6 price of PA66/6 nearly twice times, so the two by the quality ratio of 10:8 (expressed in P10+M8), the results obtained are as shown in the table below.