Cellulose acetate (CA), an organic ester, is a biobased polymer which exhibits good mechanical properties (e.g., high Young’s modulus and tensile strength). In recent decades, there has been significant work done to verify the thermal and thermomechanical behaviors of raw and plasticized cellulose acetate. In this study, the thermomechanical properties of plasticized cellulose acetate—especially its ββ-relaxation and activation energy—were investigated. The general thermal behavior was analyzed and compared with theoretical models. The study’s findings could be of special interest, due to the known ββ-relaxation dependency of some polymers regarding mechanical properties—which could also be the case for cellulose acetate. However, this would require further investigation. The concentration of the plasticizers—glycerol triacetate (GTA) and triethyl citrate (TEC)—used in CA ranged from 15 to 40 wt%. DMTA measurements at varying frequencies were performed, and the activation energies of each relaxation were assessed. Increasing plasticizer content first led to a shift in ββ-relaxation temperature to highervalues, then reached a maximum before declining again at higher concentrations. Furthermore, the activation energy of the ββ-relaxation constantly rose with increases in plasticizer content. The trend in the ββ-relaxation temperature of the plasticized CA could be interpreted as a change in the predominant phase of the overlapping ββ-relaxation of the CA itself and the αα′-relaxation of the plasticizer—which appears in the same temperature range. The plasticizer used (GTA) demonstrated a higher plasticization efficiency than TEC. The efficiencies of both plasticizers declined with increasing plasticizer content. Additionally, both plasticizers hit the saturation point (in CA) at the lowest studied concentration (15 wt%).

The insect repellent ethyl butylacetylaminopropionate (IR3535) was used as a functional additive for poly (l-lactic acid) (PLLA) to modify its structure and mechanical properties and achieve insect repellency. PLLA/IR3535 mixtures at various compositions were prepared via melt extrusion. In the analyzed composition range of 0 to 23 m% IR3535, PLLA and IR3535 were miscible at the length scale represented by the glass transition temperature. Addition of IR3535 resulted in a significant decrease in the glass transition temperature of PLLA, as well as in the elastic modulus, indicating its efficiency as a plasticizer. All mixtures were amorphous after extrusion, though PLLA/IR3535 extrudates with an IR3535 content between 18 and 23 m% crystallized during long-term storage at ambient temperature, due to their low glass transition temperature. Quantification of the release of IR3535 into the environment by thermogravimetric analysis at different temperatures between 50 and 100 °C allowed the estimation of the evaporation rate at lower temperatures, suggesting an extremely low release rate with a time constant of the order of magnitude of 1–2 years at body temperature.

Bio-sourced and biodegradable poly(butylene succinate) (PBS) strands containing up to 40 m% mosquito-repellent N,N-diethyl-3-methylbenzamide (DEET) were obtained by extrusion, for an initial evaluation of the DEET evaporation characteristics and the possible application of such strands as biodegradable slow-release repellent-delivery devices. For DEET concentrations up to 20 m%, DEET is entrapped in the semicrystalline spherulitic superstructure of PBS. In contrast, at higher DEET concentrations, the liquid repellent, at least partially, is not fully incorporated in the PBS spherulites rather than segregates to form an own macrophase. Quantification of the release of DEET to the environment by thermogravimetric analysis at different temperatures between 60 and 100 °C allowed estimation of the evaporation rate at lower service temperatures, suggesting an extremely low release rate with a time constant of the order of magnitude of 1−2 years at 25 °C, independent of the initial concentration.

Cellulose acetate (CA) is a bio-based polymeric material suitable to replace foamed polystyrene (PS) boards in applications for building insulation. Foam boards can be produced by extrusion foaming with physical blowing agents. In addition, the high heat deflection temperature and good mechanical properties (e.g., tensile and compression strength) of CA make it suitable for the injection molding of technical parts. In general, flame retardancy of foamed products is often required in building or electronic applications. This article presents the effects of various flame retardant (FR) additives, process settings, and the calibration of the foam board on flammability, foam morphology, and mechanical properties of extruded CA boards. Different formulations of FR additives and foaming agents were investigated regarding density and morphology of the foamed boards. Furthermore, investigations on foam behavior for foam injection molding with physical blowing agents were conducted. The foamed parts were characterized with regard to their flammability.

Two types of externally plasticized cellulose acetate (CA) were chemically modified using 4,4'-methylene diphenyl diisocyanate (MDI) as crosslinking agent. Crosslinking was performed in the molten state by means of melt mixing in an internal mixer. The viscoelastic properties of the non-crosslinked, externally plasticized CA show typical temperature dependence, similar to conventional thermoplastics. A strong increase in storage modulus is observed with increasing crosslink density indicating that the crosslinked compounds exhibit predominately elastic response. The complex viscosity also increases considerably with increasing crosslink density and does not reach the typical Newtonian plateau at low radial frequencies any more. The viscoelastic properties correlate well with the data recorded online during reactive melt processing in the internal mixer. In comparison to the non-crosslinked CA, the crosslinked compounds show higher glass transition temperature, higher VICAT softening temperatures, improved thermal stability and lower plasticizer evaporation at evaluated temperatures.