Bio-Based Polyurethane Networks Derived from Liquefied Sawdust

The utilization of forestry waste resources in the production of polyurethane resins is a promising green alternative to the use of unsustainable resources. Liquefaction of wood-based biomass gives polyols with properties depending on the reagents used. In this article, the liquefaction of forestry wastes, including sawdust, in solvents such as glycerol and polyethylene glycol was investigated. The liquefaction process was carried out at temperatures of 120, 150, and 170 °C. The resulting bio-polyols were analyzed for process efficiency, hydroxyl number, water content, viscosity, and structural features using the Fourier transform infrared spectroscopy (FTIR). The optimum liquefaction temperature was 150 °C and the time of 6 h. Comprehensive analysis of polyol properties shows high biomass conversion and hydroxyl number in the range of 238–815 mg KOH/g. This may indicate that bio-polyols may be used as a potential substitute for petrochemical polyols. During polyurethane synthesis, materials with more than 80 wt% of bio-polyol were obtained. The materials were obtained by a one-step method by hot-pressing for 15 min at 100 °C and a pressure of 5 MPa with an NCO:OH ratio of 1:1 and 1.2:1. Dynamical-mechanical analysis (DMA) showed a high modulus of elasticity in the range of 62–839 MPa which depends on the reaction conditions.The authors would like to thank the National Science Centre of Poland (No. 2018/02/X/ST5/02784) for financial support

Morphology, Thermo-Mechanical Properties and Biodegradibility of PCL/PLA Blends Reactively Compatibilized by Different Organic Peroxides

Reactive blending is a promising approach for the sustainable development of bio-based polymer blends and composites, which currently is gaining more and more attention. In this paper, biodegradable blends based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were prepared via reactive blending performed in an internal mixer. The PCL and PLA content varied in a ratio of 70/30 and 55/45. Reactive modification of PCL/PLA via liquid organic peroxides (OP) including 0.5 wt.% of tert-butyl cumyl peroxide (BU), 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane (HX), and tert-butyl peroxybenzoate (PB) is reported. The materials were characterized by rotational rheometer, atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), tensile tests and biodegradability tests. It was found that the application of peroxides improves the miscibility between PCL and PLA resulted in enhanced mechanical properties and more uniform morphology. Moreover, it was observed that the biodegradation rate of PCL/PLA blends reactively compatibilized was lower comparing to unmodified samples and strongly dependent on the blend ratio and peroxide structure. The presented results confirmed that reactive blending supported by organic peroxide is a promising approach for tailoring novel biodegradable polymeric systems with controllable biodegradation rates.This research work was funded by the National Science Centre (NCN Poland) grant number PRELUDIUM 15 project 2018/29/N/ST8/02042

Natural Rubber Latex - Origin, Specification and Application

The chapter contains information about the origin of natural rubber latex (NRL) (Hevea brasiliensis) and the processing of field latex, considering quality changes occurring during the preparation of raw materials for distribution. The main types of concentrated natural rubber latex are described. A specification of natural rubber latex (NRL) in terms of key parameters tested by manufacturers and customers is presented. Test methods for verifying if the material meets the requirements of ISO 2004 and internal specifications are described based on standards and commonly used techniques. The next subject touched in the chapter is prevulcanization as the processing of concentrated latex with a change of its properties. One of the main industrial applications of NRL as prevulcanized latex (PV) is the production of dipped goods like gloves or balloons. Currently, some trends and challenges relate to sustainability issues are presented (carbon footprint, FSC)

Natural Rubber Latex Wastes from Balloon Production as Valuable Source of Raw Material: Processing, Physico-Mechanical Properties, and Structure

This study explores the potential for recycling natural rubber (NR) latex waste from balloon production through the devulcanization and revulcanization processes. The mechanical devulcanization of colored latex balloon waste was conducted, followed by revulcanization using a sulfur-based system. The reclaimed rubber’s properties, including crosslink density, tensile strength, and abrasion resistance, were compared with those of virgin NR. The results demonstrate that the reclaimed rubber maintains a crosslink density close to that of virgin NR. Hardness and abrasion resistance were comparable, indicating successful material recovery. Structural analyses, including FTIR and SEM microscopy, revealed that the devulcanization process effectively allowed for successful revulcanization. This study concludes that NR latex waste can be effectively recycled and reused in rubber composite formulations, offering a sustainable approach to waste management in the rubber industry and contributing to developing eco-friendly materials. In the context of this research, integrating advanced chemical and physical methods, such as solubility parameter calculations and enhanced devulcanization techniques, could further optimize the devulcanization process. These methods quantitatively enhance the efficiency of material recovery, offering a path to more sustainable recycling practices. The findings suggest that combining such advanced methodologies could significantly improve recycled NR latex’s overall performance and applicability in industrial applications