Imparting optical functionality to aromatic thermosetting copolyester by luminescent silicon nanoparticles cross-linked via in situ thermal polymerization reaction

Preparation and thermal cross-linking mechanism of co-polyester fiber with flame retardancy and anti-dripping by in situ polymerization

Extensive research has been conducted on polyester flame retardants and anti-droplet modifications in recent years. The conventional methods used to improve the effectiveness of the anti-droplet modifications usually involve improving the melt fluidity and the combustion char formation through reactive cross-linking. However, these methods, while reducing the droplets, may produce more smoke. This study proposes a combustion cross-linking method which avoids the droplet and flame retardancy synergistic modification problem. Based on the flame retardancy of polyester, anti-droplet properties were realized using a collaborative cross – linking structure formed by a phosphorus – containing flame – retardant group and acid silicon solvent to achieve a flame retardant and anti-droplets result. The results show that the phosphorus–silicon copolyester presents an enhancement effect for flame retardancy, confirmed by obvious reductions in the peak value of heat release rate (78.4%) and total heat release (44.2%). Meanwhile, the total smoke release and smoke product rate of phosphorus–silicon copolyester are decreased by 45.1% and 41.5%, respectively. And the phosphorus–silicon copolyester has a high LOI value of 34.8 ± 0.1% and UL-94 is V-0 rating with superior anti-dripping performance. Flame retardancy index (FRI) of the copolyesters containing phosphorus–silica are up to 4.3093 (good flame retardancy). Nonisothermal differential scanning calorimetry (DSC) was performed for qualitative analysis of network formation by the aid of Cure Index (CI) dimensionless criterion. It was observed that the acidic silica led to Excellent cure situation. The TG-DSC, XPS, and FTIR results validate the thermal cross-linking ability of the copolymer due to the synergistic cross-linking effect between the self-cross-linking characteristic of the catalysed acidic silica sol containing the phosphorus flame retardant. The SEM-EDX and Raman results further verify the effectiveness of the condensed-phase flame-retardant mechanism. Phosphorus–silicon copolyester has good spinnability, flame retardancy and anti-droplets properties. Which provides a simple method for preparing polyester by using this combustion synergistic crosslinking effect to achieve flame retardant and anti-dripping modification of copolymers.

Scheme of proposed thermal cross-linking mechanism.

Merging versatile polymer chemistry with multifunctional nanoparticles: an overview of crosslinkable aromatic polyester matrix nanocomposites

The current trend in the global advanced material market is expeditiously shifting towards more lightweight, multifunctional configurations, considering very recent developments in electrical aircraft, biomedical devices, and autonomous automobiles. Hence, the development of novel polymer nanocomposite materials is critical to advancing the current state-of-the-art of structural material technologies to address the pressing performance demands. Aiming at expanding the existing material design space, we have investigated crosslinkable aromatic polyester matrix nanocomposites. Aromatic polyesters, in the thermosetting form, are a prospective high-performance/high-temperature polymer technology, which is on a par with conventional epoxy-derivative resins and high-performance engineering thermoplastics in the range of their potential applications. The aromatic matrix-based thermosetting nanocomposites manifest greatly enhanced physical properties enabled by a chemistry-favored robust interfacial covalent coupling mechanism developed during the in situ polymerization reaction with various nanofiller particle configurations. Here, we provide a summary review of our recent efforts in developing this novel polymer nanocomposite material system. We highlight the chemical strategy, fabrication approach, and processing techniques developed to obtain various nanocomposite representations for structural, electrical, optical, biomedical, and tribological applications. The unique characteristic features emerging in the nanocomposite morphologies, along with their physicochemical effects on the multifunctional macroscale properties, are demonstrated. This unique matrix configuration introduces superior performance elements to polymer nanocomposite applications towards designing advanced composite materials.