Properties of poly(butylene adipate-co-terephthalate) and sunflower head residue biocomposites

All-natural environmentally degradable poly (butylene terephthalate-co-caprolactone): A theoretical and experimental study of its degradation properties and mechanisms

The design and production of materials with excellent mechanical properties and biodegradability face significant challenges. Poly (butylene terephthalate-co-caprolactone) copolyesters (PBTCL) is obtained by modifying the engineering plastic polybutylene terephthalate (PBT) with a simple one-pot process using readily biodegradable ε-caprolactone (ε-CL). The material has mechanical properties comparable to those of commercial biodegradable copolyester PBAT. Besides, this copolyester exhibited remarkable degradability in natural environments such as soil and ocean, for example, PBTCL1.91 lost >40 % of its weight after 6 months of immersion in the Bohai Sea. The effect and diversity of specific microorganisms acting on degradation in the ocean were analyzed by 16 s rDNA gene sequencing. Theoretical calculations such as Fukui function and DFT, and experimental studies on water-soluble intermediates and residual matrixes produced after degradation, confirmed that the insertion CL units not only act as active sites themselves susceptible to hydrolysis reactions, but also promote the reactivity of ester bonds between aromatic segments. This work provides insight for the development of novel materials with high performance and environmental degradability.

Study on composting and seawater degradation properties of diethylene glycol-modified poly(butylene succinate) copolyesters

The marine pollution caused by traditional plastics is becoming increasingly serious, and the fundamental way to solve this problem is to look for plastic substitutes that can degrade in the marine environment. Herein, a series of high-molecular-weight poly(butylene succinate-co-diethylene glycol succinate) (PBDS) was obtained by the introduction of low-cost diethylene glycol (DEG) into the main chain of poly(butylene succinate) (PBS), which aimed to obtain the materials that can be degraded both in compost and seawater. The research showed that the increase in the DEG content reduced the crystallinity of the copolyester, which led to the decrease in mechanical strength and thermal properties of the copolyester to a certain extent. Meanwhile, the increase in hydrophilicity and the decrease in crystallinity improved the degradation rate of the material. Compared with PBS, PBDS exhibited not only a faster composting degradation rate but also a faster degradation rate in seawater.

A Study of the Mechanical Properties in Composite Materials with a Dammar Based Hybrid Matrix and Reinforcement from Crushed Shells of Sunflower Seeds

The production of composite materials through the reuse of waste or by-products from the agri-food industry will be a challenge for environmental protection. This study focuses in that direction. In the first stage, composites were made with the hybrid resin matrix (with three major volume proportions of natural Dammar resin and epoxy resin) and the reinforcing from shredded shells of sunflower seeds. Based on the tensile and compressive stresses, the stress–strain and strain–strain diagrams were obtained. The surface area of the rupture was investigated with stereo-microscopic analysis, and the absorption/loss of water was studied with a high precision balance. The vibration behavior was investigated experimentally, determining the damping coefficient and its own frequency. In the second stage, the study of these materials was extended. Sandwich composites were made with the same type of hybrid matrix as in the first stage. The core was made of shredded shells of sunflower seeds and the outer faces of linen fabric. These composites were applied to the bend (in three points), being obtained the force-deformation diagrams. The determined mechanical properties allow the complete or partial realization of these composites of some furniture components or of some equipment used in the field of constructions.