Abstract
In this study six new s-triazine bishydrazino and bishydrazido-based polymers were synthesized via condensation of bishydrazino s-triazine derivatives with terephthaldehyde or via nucleophilic substitution of dichloro-s-triazine derivatives with terephthalic acid hydrazide. The synthesized polymers were characterized by different techniques. The new polymers displayed good thermal behavior with great values in terms of limited oxygen indexed (LOI) 27.50%, 30.12% for polymers 5b,c (bishydrazino-s-triazine based polymers) and 27.23%, 29.86%, 30.85% for polymers 7a–c (bishydrazido-s-triazine based polymers) at 800 °C. Based on the LOI values, these polymers could be classified as flame retardant and self-extinguishing materials. The thermal results also revealed that the type of substituent groups on the triazine core has a considerable impact on their thermal behavior. Accordingly, the prepared polymers were mixed with ammonium polyphosphate (APP) in different proportions to form an intumescent flame-retardant (IFRs) system and were introduced into polypropylene (PP) to improve the flame-retardancy of the composites. The best results were obtained with a mass ratio of APP: 5a–c or 7a–c of 2:1, according to the vertical burning study (UL-94). In addition, the presence of 25% “weight ratio” of IFR in the composite showed great impact and passed UL-94 V-0 and V-1 tests.
Highlights
Polypropylene (PP) is considered as a vital commodity in the thermoplastic family, and has been extensively employed in numerous diverse usages like transportation, aviation, building and construction materials, the electrical and electronics field, and medical and consumer applications [1,2,3] as a consequence of its chemical and mechanical characteristics, its processability and machinability, cost price ratio, etc. [3]
Because of the flammability problem of PP due to its low limiting oxygen index (LOI value is around 17.5%), many scientists have displayed an interest in improving the fire retardancy of polypropylene
In continuation of our previous work [44,45], we describe the synthesis and characterization of two groups of charring agent based on polymers containing s-triazine with hydrazine and hydrazido linkage in their backbone chain
Summary
Polypropylene (PP) is considered as a vital commodity in the thermoplastic family, and has been extensively employed in numerous diverse usages like transportation, aviation, building and construction materials, the electrical and electronics field, and medical and consumer applications [1,2,3] as a consequence of its chemical and mechanical characteristics, its processability and machinability, cost price ratio, etc. [3]. Raising the fire-retardant activities of plastics material is a critical task for many forms of usage [4,5]. For this reason, employing flame-retardant (FR) material is essential [6,7]. Because of the flammability problem of PP due to its low limiting oxygen index (LOI value is around 17.5%), many scientists have displayed an interest in improving the fire retardancy of polypropylene. They performed intensive work to achieve retardancy of PP. The most popular efficient flame retardant is the one having halogens such as bromine (Br2 ) and antimony trioxide (Sb2 O3 ) synergistic systems
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