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<p>Three halogen-free phosphate-containing monomeric/oligomeric ester methacrylates (HFPOEMs) were synthesized, including a monomer without spacers (HFPOEM-1) and spacers incorporating either flexible aliphatic spacer (HFPOEM-2) or rigid aromatic spacer (HFPOEM-3). Phosphate groups and spacer units were successfully incorporated, according to structural investigations (FTIR and NMR). DSC data showed that processing behavior varied depending on the kind of spacer, with reactivity decreasing as steric limitations increased. According to thermogravimetric analysis, the aromatic spacer system had the highest thermal resistance (T5% = 279&#xa0;°C) and char yield (44.3 wt%), which were attributable to improved structural rigidity and carbonization. Compared with the spacer-free sample, the use of the flexible aliphatic spacer resulted in a significant improvement in flexural strength (49.47&#xa0;MPa), flexural strain at break (7.70%), and impact strength (17.68&#xa0;kJ/m²), due to increased segmental mobility and energy dissipation. In contrast to the flexible spacer, the rigid aromatic spacer increased strength (36.43&#xa0;MPa) and maintained high stiffness (2.16 GPa) but limited chain mobility, leading to decreased ductility and impact resistance. The Limited Oxygen Index (LOI) data demonstrate that samples with spacers had somewhat lower LOI values than samples without spacers, in the following order: HFPOEM-1 (LOI = 31.6) &gt; HFPOEM-2 (LOI = 30.5) &gt; HFPOEM-3 (LOI = 29.7). In addition, all HFPOEM samples achieved a V-0 rating in the UL 94 test.</p>

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Improving Mechanical Properties and Thermal Stability of Halogen-Free Flame Retardants Using di(hydroxyethyl methacrylate) Phosphate and Spacers

  • 期刊论文

  • 发表日期：

    2026年8月3日

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  • A. K. Al-Hamzawi,
  • Zahraa M. Gafil,
  • Hind Shabbani,
  • B. A. Buravov,
  • O. O. Tuzhikov,
  • O. I. Tuzhikov

摘要

Three halogen-free phosphate-containing monomeric/oligomeric ester methacrylates (HFPOEMs) were synthesized, including a monomer without spacers (HFPOEM-1) and spacers incorporating either flexible aliphatic spacer (HFPOEM-2) or rigid aromatic spacer (HFPOEM-3). Phosphate groups and spacer units were successfully incorporated, according to structural investigations (FTIR and NMR). DSC data showed that processing behavior varied depending on the kind of spacer, with reactivity decreasing as steric limitations increased. According to thermogravimetric analysis, the aromatic spacer system had the highest thermal resistance (T5% = 279 °C) and char yield (44.3 wt%), which were attributable to improved structural rigidity and carbonization. Compared with the spacer-free sample, the use of the flexible aliphatic spacer resulted in a significant improvement in flexural strength (49.47 MPa), flexural strain at break (7.70%), and impact strength (17.68 kJ/m²), due to increased segmental mobility and energy dissipation. In contrast to the flexible spacer, the rigid aromatic spacer increased strength (36.43 MPa) and maintained high stiffness (2.16 GPa) but limited chain mobility, leading to decreased ductility and impact resistance. The Limited Oxygen Index (LOI) data demonstrate that samples with spacers had somewhat lower LOI values than samples without spacers, in the following order: HFPOEM-1 (LOI = 31.6) > HFPOEM-2 (LOI = 30.5) > HFPOEM-3 (LOI = 29.7). In addition, all HFPOEM samples achieved a V-0 rating in the UL 94 test.