Kinetic Analysis of the Curing Process of Biobased Epoxy Resin from Epoxidized Linseed Oil by Dynamic Differential Scanning Calorimetry

Combined Thermomechanical Effect of Graphene Oxide and Montmorillonite on Biobased Epoxy Network Formation for Coatings

Epoxy nanocomposites derived from linseed oil, reinforced with graphene oxide (GO) and montmorillonite (MMT) nanostructures, were synthesized. The nanohybrids were developed by enriching the structure of MMT and GO with primary amines through a common and simplified method, which implies physical interactions promoted by ultrasonic processing energy. The influence of the new nanoreinforcing agents along with neat ones on the overall properties of the biobased epoxy materials for coating applications was assessed. Interface formation through surface compatibility was contained by the lower values of activation energy calculated from differential scanning calorimetry (DSC) curves, along with a consistent 70% increase in the cross-linking density when amine-modified MMT was used. Thermomechanical characteristics of the biobased epoxy nanocomposites were explained through the interaction of the functional groups over the curing process of epoxidized linseed oil (ELO), giving a 15 °C higher Tg value increase. Furthermore, the low surface energy values suggested an intrinsic antibacterial activity, as proved by a significant decrease of CFU against Staphylococcus aureus bacterial strains on the 0.25% reinforced coatings.

Experimental Study of Curing Temperature Effect on Mechanical Performance of Carbon Fiber Composites with Application to Filament Winding Pressure Vessel Design

During the forming process of carbon fiber composite pressure vessels, the parameters of the curing and forming processes become one of the critical factors affecting the production cost and forming quality. The curing temperature of 4251 A4/B2 epoxy resin is measured in this research, and the effect of curing temperature on the mechanical properties of composite materials for winding is studied, which is finally verified in the test of pressure vessels. First, the actual curing temperature of the epoxy resin is tested and analyzed using differential scanning calorimetry (DSC). Second, under two different curing regimes, the tensile and flexural properties are tested by making pure epoxy resin matrix test pieces, Naval Ordnance Laboratory (NOL) rings, and carbon fiber composite unidirectional plates that affect the overall performance of composite pressure vessels. At the same time, the test results provide reliable process parameters for numerical simulation and manufacturing of pressure vessels. Finally, the filament-wound 35 MPa type III pressure vessel is cured and carried out using a hydraulic burst test. The results show the resin matrix has good fluidity and excellent interface bonding with carbon fiber when the curing temperature is 112 °C. Compared with the results in curing temperature of 100 °C, the tensile strength of the NOL ring reaches 2260.8 MPa, up by 22%. In the 90° direction, the tensile and flexural strengths of the unidirectional plates increase by 68.86% and 37.42%, respectively. In the 0° direction, the tensile and flexural strengths of the unidirectional plates increase by 5.82% and 1.16%, respectively. The pressure vessel bursting form is reasonable and meets the CGH2R standard. The bursting pressure of the vessel is up to 104.4 MPa, which verifies the rationality of the curing regime used in the curing process of the pressure vessel. Based on the results of this paper, the curing temperature affects the fluidity of the epoxy resin, which in turn affects the interfacial bonding properties of the composite, and the forming quality of the wound components and the pressure vessel, ultimately. When using 4251A4/B2 epoxy resin for wet winding pressure vessels, the choice of a 112 °C curing temperature will help improve the vessel's overall performance. This work could provide reliable experience and insight into the curing process analysis of pressure vessel manufacturing.

Recent Advances in Development of Waste-Based Polymer Materials: A Review

Limited petroleum sources, suitable law regulations, and higher awareness within society has caused sustainable development of manufacturing and recycling of polymer blends and composites to be gaining increasing attention. This work aims to report recent advances in the manufacturing of environmentally friendly and low-cost polymer materials based on post-production and post-consumer wastes. Sustainable development of three groups of materials: wood polymer composites, polyurethane foams, and rubber recycling products were comprehensively described. Special attention was focused on examples of industrially applicable technologies developed in Poland over the last five years. Moreover, current trends and limitations in the future “green” development of waste-based polymer materials were also discussed.