Synergistic effect of mesoporous silica SBA‐15 on intumescent flame‐retardant polypropylene

Abstract

SUMMARYMesoporous silica SBA-15 synthesized from Pluronic P123 and tetraethoxysilane was used as a synergistic agent on the flame retardancy of polypropylene (PP)/intumescent flame-retardant (IFR) system. Limiting oxygen index (LOI), UL-94 rating and thermogravimetric analysis were used to evaluate the synergistic effect of SBA-15 on PP/IFR system. It showed that PP/IFR system could reach V-0 with loading of SBA-15 ranging from 0.5 to 3 wt%, while without SBA-15 it had no rating at UL-94 test. The LOI value increased from 25.5 to 32.2 when the loading of SBA-15 was 1 wt%. The thermal stability of PP/IFR was improved in the presence of SBA-15 and the amount of the char residue at 600 • C was increased from 8.96 to 16.42 wt% when loading of SBA-15 varied from 0.5 to 5 wt%. Laser Raman spectroscopy (LRS) and scanning electron microscopy were employed to study the morphology of the char residue of PP/IFR system with and without SBA-15.

Influence of modified mesoporous silica SBA‐15 on the flammability of intumescent high‐density polyethylene

“…This step has to be related to the catalyzed reactions of APP with the charring agent (PER). APP promotes dehydration and cross‐linking reactions, as deduced from the release of water at 230°C and ammonia above 280°C . The consequence is the formation of an insulating protecting layer, which increases the thermal stability at higher temperatures.…”

“…However, mostly non‐functionalized mesoporous silica materials were investigated in the literature. For example, PP/IFR system could reach V‐0 rating with SBA‐15 mesostructured silica content ranging from 0.5 to 3 wt%, while without SBA‐15, it had no rating at UL‐94 test . Meanwhile, the LOI value increased from 25 to 32% when the loading of SBA‐15 was 1 wt%.…”

Synergistic effect of cocondensed nanosilica in intumescent flame‐retardant polypropylene

“…As a lot of works have pointed out, the ordering of graphitized char layer is an important index to measure the quality of char layer . In the formation of an ordered charred layer, the polymer experiences the process of crosslinking, aromatization, formation of aromatic fused ring, and then graphitization .…”

Synergistic effect of phosphorus‐containing nanosponges on intumescent flame‐retardant polypropylene

“…This was because P–NS acted as a catalyst in the PP/IFR composite for char formation. When P–NS was more than 2.0 wt %, the esterification speed of the system did not match the foaming speed well; this destroyed the char swelling behavior of the composite and resulted in an unsatisfactory flame retardancy 18, 31. Therefore, on the basis of the results of the LOI and UL‐94 tests, an appropriate P–NS content of 2.0 wt % was optimum for the flame retardancy.…”