Flame Retardant Formulations of Long Glass Fiber Reinforced Polypropylene
Publish Time: 2018-12-14 Origin: Site
Long glass fiber reinforced polypropylene (LGFPP) composite has excellent mechanical properties, good dimensional stability and high temperature resistance. It is considered to be an excellent material for replacing steel with plastic in the future. It can be used in automobiles, household appliances, tools, furniture, electronic and electrical fields, etc. Compared with the traditional short fiber reinforced composites, the long fiber reinforced thermoplastic composites have better comprehensive properties.
However, the limit oxygen index (LOI) of LGFPP is low, it is easy to burn, and the combustion process has a large amount of heat, which brings great fire hazards.
The flame retardant modification of LGFPP has important research value and practical application significance.
This article recommends two flame retardant LGFPP formulations.
Intumescent flame retardant LGFPP
Guizhou University, China National complex modified Polymer Engineering Center and others used pentaerythritol phosphate (PEPA) and melamine polyphosphate (MPP) as intumescent flame retardants (IFR) to flame retardant LGFPP composites. The composite of sepiolite (SP) and IFR was used as a synergistic flame retardant for LGFPP composites.
1. Formula
PP：45～70％；
LGF：30%；
IFR: 0～22％，PEPA／MPP =11／9；
SP：0～3％
2. Process
3. Flame retardant effect
Table 1 LOI and Combustion Grade of LFGPP Flame retardant Composites with different content of IFR
IFR mass fraction / % | LOI / % | Drip or not | Vertical combustion grade |
0 | 19.2 ± 0.1 | NO | 1） |
16 | 23.9 ± 0.2 | NO | V-2 |
18 | 25.2 ± 0.1 | NO | V-1 |
20 | 26.1 ± 0.3 | NO | V-1 |
22 | 28.8 ± 0.2 | NO | V-0 |
Note: 1) indicates that no combustion grade has been obtained.
When the mass fraction of IFR is 22%, the effect of adding SP is as shown in Table 2.
Table 2 LOI and vertical combustion grades of various composite systems under different SP content
System | LOI / % | Drip or not | Vertical combustion grade |
LGFPP | 19.2 ± 0.10 | NO | --- |
LGFPP / IFR | 28.8 ± 0.15 | NO | V-0 |
LGFPP / IFR / SP1 | 29.6 ± 0.10 | NO | V-0 |
LGFPP / IFR / SP2 | 28.1 ± 0.12 | NO | V-0 |
LGFPP / IFR / SP3 | 27.2 ± 0.11 | NO | V-1 |
Note: SP1, SP2 and SP3 respectively indicate that the mass fraction of SP is 1%, 2%, 3%.
4. Changes in mechanical properties
The mechanical properties of the composites decreased after the addition of IFR, and further decreased after the addition of SP.
The mechanical properties of the system with 1% SP content are relatively high. The tensile strength, flexural strength and notched impact strength of the system are reduced by 20.46%, 12.06% and 10.65%, respectively, compared with the flame retardant composite system of LGFPP/IFR.
Formulation 2 Bromine/ antimony flame retardant LGFPP