The search for bio-additives for enhancing the thermal and optical performance of epoxy resins has been increasing constantly. Lignin represents an interesting alternative for such purposes. Therefore, the aim of this work was promote the valorization of acetosolv coconut shell lignin (ACSL) and phosphorylated acetosolv coconut shell lignin (P-ACSL) as bio-additives in epoxy resins, evaluating their effects on the thermal and UV-blocking properties of the thermosetting materials. The phosphorylation of ACSL was carried out at 60 °C during 5, 10, and 20 min under microwave irradiation. ACSL and P-ACSL were characterized by TGA, DSC, GPC, and 1H and 31P NMR analyses. ACSL and P-ACSL were added to diglycidyl ether of bisphenol A (DGEBA) and isophoronediamine (IPDA) at 0, 0.5, 1.0, 2.5, 5.0, and 10 wt%, being cured at room temperature during 24 h. The neat and additivated epoxy resins were characterized by TGA, DSC, and UV-Vis analyses. It was observed a notorious enhancement of the thermal (≈ 9 °C for ACSL and P-ACSL) and thermo-oxidative (≈ 8.5 and 15 °C for ACSL and P-ACSL, respectively) stabilities of the thermosetting materials using both lignins, as well as for their glass transition temperatures (Tg), which presented a slight increase of 2.1 and 3.5 °C for ACSL and P-ACSL, respectively. Furthermore, ACSL and P-ACSL exhibited UV stabilizer properties through the complete absorption of UV light in the UV-A and UV-B regions. It can be concluded that P-ACSL could represent an alternative bio-additive that can be easily produced through a clean and fast methodology, capable of improving the thermal, optical, and chemical resistance properties of epoxy resins.

Microwave-assisted phosphorylation of organosolv lignin: new bio-additives for improvement of epoxy resins performance

The influence of hybrid flame retardant and impact modifier on recycled blends formulated from keyboard waste plastics: A study on its flame retardant, mechanical, thermal, and chemical properties

The structural, thermal, morphological, and mechanical properties of ecocomposites based on a High-Impact Polystyrene (HIPS) reinforced with açaí (Euterpe oleracea) fibers were evaluated. They were made using 5 wt% açaí fibers treated using 5% NaOH (FT5) and 7% NaOH (FT7). According to a SEM analysis, the alkaline treatment allowed us to remove of the low-molecular weight compounds. The FT5 ecocomposite had a higher elongation, (2.9 ± 0.5)%, and impact of resistance, (98 ± 2) J/m, probably due to the presence of mechanical anchoring, which improved its mechanical properties. The FT7 ecocomposite had a slightly higher thermal stability, with a total mass loss of 87.78%. 

https://link.springer.com/content/pdf/10.1007/s11029-023-10087-w.pdf

Ecocomposites Based on High-Impact Polystyrene (HIPS) and Amazon Açaí (Euterpe oleracea) Fibers: Influence of NaOH Treatment on Its Structural, Thermal, and Mechanical Properties

Thermal and thermo-oxidative decomposition and decomposition kinetics of flame retardant high impact polystyrene (HIPS) with triphenyl phosphate (TPP) and novolac type epoxy resin (NE) were characterized using thermo-gravimetric experiment. And the flammability was determined by limited oxygen indices (LOI). The LOI results show that TPP and NE had a good synthetic effect on the flame retardancy of HIPS. Compared with pure HIPS, the LOI values of HIPS/NE and HIPS/TPP only increased by about 5%, and the LOI value of HIPS/TPP/NE reached 42.3%, nearly 23% above that of HIPS. All materials showed one main decomposition step, as radical HIPS scission predominated during anaerobic decomposition. TPP increased the activity energy effectively while NE affected the thermal-oxidative degradation more with the help of the char formation. With both TPP and NE, the materials could have a comparable good result of both thermal and thermal-oxidative degradation, which could contribute to their effect on the flame retardancy.

Demin Jia

Papers

Thermal and Thermo-oxidative Degradation of Flame Retardant High Impact Polystyrene with Triphenyl Phosphate and Novolac Epoxy Resin