Effect of long-term and short-term dynamic mechanical evaluation of networks based on urethane and soybean oil

Thermal and Viscoelastic Responses of Selected Lignocellulosic Wastes: Similarities and Differences

Woody lignocellulosic biomasses comprise the non-edible parts of fruit trees. In recent years, the exploitation of this biomass has been widening in order to mitigate environmental issues. At the same time, this waste could be transformed into a value-added product (active carbon by pyrolysis, isolation of nanocellulose, oils or proteins). For either valorization path, a complete thermo-mechanical characterization is required. A detailed thermo-mechanical study (TGA, DSC, DMA) was performed on two types of lignocellulosic wastes, with and without kernels: on one side, the walnut shells (WS) and the pistachio shells (PsS) and, in the second category, the apricot seeds (AS), the date seeds (DS), and the plum seeds (PS). The results of the sample-controlled thermal analyses (HiRes TGA) evidenced a better resolution of the degradation steps of WS. Kinetic studies conducted also by conventional TGA (Flynn-Wall-Ozawa) and modulated TGA (MTGA) allowed us to make comparative reasonings concerning the degradation of the investigated biomasses. The DMA results revealed the effect of water traces and oil kernels on relaxation and supported the atypical DSC endotherm emphasized in the freezing temperature domain.

Relaxation behavior of flax-reinforced ethylene–propylene–diene rubber

The molecular dynamics of flax-reinforced ethylene–propylene–diene monomer (EPDM) composites, with increasing quantities of flax (EPDM0–EPDM20), was investigated by dynamic mechanical analysis. Multifrequency experiments were also performed in order to distinguish between the relaxation and the kinetic events. Also the time–temperature superposition was applied to the multifrequency results for obtaining the master curves. They were used to anticipate the behavior of the composites in time and to calculate the activation energies using the Williams–Landel–Ferry equation.