Study of the Compatibilization Effect of Different Reactive Agents in PHB/Natural Fiber-Based Composites

Fiber–matrix interfacial adhesion is one of the key factors governing the final properties of natural fiber-based polymer composites. In this work, four extrusion reactive agents were tested as potential compatibilizers in polyhydroxylbutyrate (PHB)/cellulose composites: dicumyl peroxide (DCP), hexamethylene diisocyanate (HMDI), resorcinol diglycidyl ether (RDGE), and triglycidyl isocyanurate (TGIC). The influence of the fibers and the different reactive agents on the mechanical properties, physical aging, and crystallization behavior were assessed. To evaluate the compatibilization effectiveness of each reactive agent, highly purified commercial cellulose fibers (TC90) were used as reference filler. Then, the influence of fiber purity on the compatibilization effect of the reactive agent HMDI was evaluated using untreated (U_RH) and chemically purified (T_RH) rice husk fibers, comparing the results with the ones using TC90 fibers. The results show that reactive agents interact with the polymer matrix at different levels, but all compositions showed a drastic embrittlement due to the aging of PHB. No clear compatibilization effect was found using DCP, RDGE, or TGIC reactive agents. On the other hand, the fiber–polymer interfacial adhesion was enhanced with HMDI. The purity of the fiber played an important role in the effectiveness of HMDI as a compatibilizer, since composites with highly purified fibers showed the greatest improvements in tensile strength and the most favorable morphology. None of the reactive agents negatively affected the compostability of PHB. Finally, thermoformed trays with good mold reproducibility were successfully obtained for PHB/T_RH/HMDI composition.

Determination of Triglycidyl Isocyanurate in Workplace Air

Triglycidyl isocyanurate (TGIC) is a white solid in powder or granular form. TGIC does not occur naturally in the environment. It is intentionally manufactured and used as a crosslinking agent or hardener to produce polyester powder coatings. TGIC may cause genetic defects. This article presents the method of TGIC determination in workplace air using high-performance liquid chromatography (HPLC) with a diode-array detector (DAD). The method is based on the collection of TGIC present in the air on a polypropylene filter, extraction with acetonitrile, and chromatographic analysis of the solution obtained in this way. The determination was carried out in the reverse-phase system (mobile phase: acetonitrile: water) using an Ultra C18 column. The measurement range is 2 to 40 µg/m3 for a 720 liters air sample. Limit of detection (LOD) is 23 ng/m3 and limit of quantification (LOQ): 70 ng/m3. The method can be used for assessing occupational exposure to TGIC and associated risk to workers’ health.

Synthesis and Characterization of a Novel Polyhydroxy Triazine Charring Agent and Properties of its Flame Retarded Polyproylene

In this study, a novel polyhydroxy triazine charring agent (PT-CA) was synthesized through the solid-state reaction of triglycidyl isocyanurate (TGIC) and pentaerythritol. Meanwhile, the molecular structure of the chemical compound was determined by FTIR, elemental analysis and thermalgravimetric analysis (TG).Then it is combined with microencapsulated ammonium polyphosphate (MAPP) and melamine phosphate (MP) to impart flame retardance and dripping resistance for polypropylene (PP).The fire performance of treated PP was investigated by limiting oxygen index (LOI) and vertical burning test (UL-94).It has been found that the treated PP with the optimal flame retardant formulation of MAPP:MA:PTCA=18:6:6 (weight ratio, formulation 10) gives an LOI of 31.5 and UL-94 V-0 rating.