Dan Huang

As electronics become smaller and more power-dense, glass-fiber-reinforced polyamide 66 (PA66/GF) must combine halogen-free flame retardancy with electrical safety, including a glow-wire ignition temperature (GWIT) ≥ 775 °C and a comparative tracking index (CTI) ≥ 600 V. Conventional low-molecular-weight flame retardants often require loadings above 15 parts by mass, impairing mechanical and electrical properties. Here, a phosphorus-containing polyamide oligomer (DOPO–MA–oligomerPA6) was synthesized via a DOPO–MAH intermediate from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and maleic anhydride (MAH), followed by polymerization with ε-caprolactam, then melt-blended with aluminum diethylphosphinate (ADP) and melamine polyphosphate (MPP) in PA66/GF. Its oligo-PA6 backbone provides good compatibility with PA66, while its low molecular weight (Mn = 10,984 g mol⁻¹; PDI = 2.569) favors dispersion. The phosphorus groups enhance the efficiency of the ADP/MPP system. With 4 parts oligomer and a total flame-retardant loading of 14 parts by mass per 100 parts PA66/GF, the composite achieved UL-94 V-0 rating, a limiting oxygen index (LOI) of 36.1%, a GWIT of 800 °C, and a CTI of 600 V. Its heat deflection temperature, tensile strength, notched impact strength, and flexural modulus were 178.8 °C, 95.0 MPa, 8.7 kJ m⁻², and 8984 MPa, respectively. Compared with the conventional 20-part system, total additive loading decreased by 30%, with simultaneous improvements in flame retardancy, electrical safety, and mechanical properties. This offers a scalable route to high-performance PA66/GF composites.

Lignin is a promising bio-based filler for poly(butylene adipate-co-terephthalate) (PBAT), yet its true contribution to biodegradation remains unclear—most studies rely on weight loss alone, neglecting CO₂ mineralization and lignin’s antibacterial activity. Here, lignin/PBAT composites with 1 wt% (LP-1) and 3 wt% (LP-2) lignin are assessed under composting conditions using both weight loss and mineralization rate. Lignin exhibits a dual role: it promotes hydrolytic weight loss (18.3% and 28.6% for LP-1 and LP-2 at 40 days), but significantly inhibits ultimate mineralization (one-year mineralization: 65.71% for pure PBAT vs. 48.74% and 29.53% for LP-1 and LP-2). A negative initial mineralization rate suggests transient antibacterial activity from released phenolic compounds. Lignin increases crystallization temperature (48.4 → 92.6 °C) and T_g (−28.5 → 49.1 °C), with 1% loading largely preserving mechanical properties. These findings demonstrate that weight loss alone is insufficient to assess degradation; mineralization must be included. Appropriate lignin loading enables balanced performance and degradation controllability, offering new insights into lifecycle assessment of green composites.

While biodegradable plastics alleviate plastic pollution, their degradation-derived biodegradable microplastics (BMPs) pose new ecological risks, necessitating efficient quantification methods. This study explores a label-free approach by leveraging the intrinsic fluorescence of common biodegradable polyesters (PLA, PHB, PBS, PBAT, PCL). We find that biodegradable microplastics exhibit two types of characteristic fluorescence emission: one originating from molecular functional groups and the other originating from the chromophore formed by the aggregation of conjugated groups. Using PBAT as a model, we confirm that fluorescence intensity depends on the BMPs’ size and shape. Under 380 nm excitation, concentration-dependent signals are observed at 436 nm (indirectly from PBAT-enhanced water Raman scattering) and 465 nm (directly from PBAT intrinsic fluorescence), leading to successful linear models between BMPs’ mass concentration and fluorescence intensity over 100–500 mg/L, with correlation coefficients (R²) of 0.877 and 0.963, respectively. Compared with the fluorescence labeling method, the intrinsic fluorescence approach achieves comparable R² while exhibiting lower signal intensity (~10³). Nevertheless, its operational simplicity offers a distinct advantage for the rapid quantification of pre-isolated and purified microplastics.

A reactive synergist (BAAEP) was designed for PP, paired with IFR(APP/CFA) for two-phase flame retardancy. It catalyzed charring, scavenged radicals, and synergized with IFR's intumescent effect for efficient flame retardancy and smoke suppression.

In order to shorten the degradation incubation period of existing seawater‐degradable materials and achieve “disappearance” in seawater as soon as possible, based on the successful introduction of hydrolyzed sites GA into the PBS main chain to obtain the PBSG copolymer matrix, water‐soluble PVA is introduced to finally obtain a series of PBSG/PVA blends, aiming to promote the hydrolysis process of polyester matrix by the dual action of water‐soluble PVA and easily hydrolyzed site GA. Compared with pure polyester, PBSG/PVA blends exhibt rapid loss of mechanical properties, weight loss and molecular weight drop in seawater. Among them, PBSG50/PVA0588 = 50/50 with the fastest degradation rate completely loses its mechanical properties within 1 week, and its molecular weight decreases by about 97% after 417 days. In the first 51 days of degradation, the swelling and dissolution of PVA can effectively accelerate the decrease of the molecular weight of polyester matrix, and the M_n decreases by about 50%–80%, which is much higher than that of pure polyester (about 40%). After 417 days in the late stage of degradation, compared with PBS/PVA blends, the easy hydrolysis of GA promots the obvious degradation of the matrix, and the weight loss of matrix can reach 20%.