Microcapsulated Of Microcrystalline Cellulose Modified Epoxy Composites And It’s Moisture And Thermal Kinetics

Owing to high modulus, corrosion resistance, thermal stability and low shrinkage upon cure, epoxy resin is a kind of high performance thermosetting polymers, which have been widely used in adhesives, coatings, composites, electric systems, and marine and aerospace applications. However, there is a default with these advantages that is big brittleness for cured epoxy resins. Currently, the main resolutions is added some filler into the epoxy matrices. In the quest for sustainable development around the world, using cellulose microfibrils from nature plant materials as renewable alternatives to conventional reinforcement materials such as glass fibers and carbon fibers is generating particular interest. It was found that these cellulose particles could impart higher stiffness to the polymer, the cellulose from biomass is more effective in composite reinforcement thanks to it’s large aspect ratio and their ability to form interconnected network structures through hydrogen bonding. However, achieving good dispersion in the epoxy matrices is one of the biggest challenges because of the high density of hydroxyl groups on the surface of cellulose, it remains a difficult task to disperse cellulose in matrices. Now many strategies were applied to overcome this problem, especially surface chemical modification. Lots of research literatures reported that this method maybe will produce some damage for cellulose, or have some potential security, or the harmful to the composites moisture absorption et al. The present work addresses this issue by developing two physical methods, sonication and microencapsulated, to improve the surface compatibility between cellulose and epoxy. The following analysis was finished with the help of TG, DSC, FT-IR, and a homemade moisture absorption instrument.In this research, a novel, simple and notoxic of physical method was applied to enmicrocapsulated microcrystalline cellulose(MCC) for switch the hydropholic properties into hydrophobic propeties, and also improve the interface compatibility between MCC and epoxy resin to modify the dispersion in the epoxy matrix. The kinetics of thermal degradation and curing of modified MCC/epoxy resin composites were analysised as well as the long term water absorption behavior in distilled water and sea water. As comparison, the effect of sonication on the properties of MCC/epoxy resin composites was studied, included thermal, curing and long term water absorption.Surfactants and paraffin wax were used to coat microcrystalline cellulose to prevent cellulose agglomeration during dispersion. The coated particles exhibited similar lengths but the area of coverage varied from little to complete coverage of the cellulose particles depending on the amount of surfactant and paraffin wax. The results demonstrated the possibility of coating microcrystalline cellulose with a desired amount of surfactants and paraffin wax.It was demonstrated that the compatibility between cellulose and epoxy resin could be maintained due to partial encapsulation resulting in an improvement in epoxy composite mechanical and physical properties. The decomposition temperature of epoxy was preserved up to a 5% EMC loading. An increase in wax encapsulated cellulose loading did increase water absorption but overall this absorption was still low(< 1%) for all composites. The 1:3 ratio of wax:MCC demonstrated the greatest dimensional stability across a loading range of 1 to 3%. FT-IR results indicated that all the epoxide groups in epoxy composites reacted completely. The thermal decompose behavior of EMC/epoxy resins composites were investigated by TGA curves with the help of two models, Coats-Redfern method and Flynn-Wall-Ozawa(FWO). The results revealed that the weight loss of the samples began at about 320°C, and the degradation almost finished below 600°C. Moreover, the initial degradation temperatures increased when the heating rates increased, and all the samples presented the similar patterns. The addition of EMC showed less influence on the thermostability of epoxy resin composites at low or high temperature. The activation energys(Eα) also are closely among different EMC loadings and have the quitely similar tendency. The kinetics results indicated that the composites sharply charing after 60% conversion.The curing kinetic behavior of EMC/epoxy resin composites showed that the samples by different EMC loading have the closely tendency, with the increasing of EMC loading in the EMC-epoxy resin mixture, the activation energys has a slightly decrease, but it can be ignored. The water absorption of the composites was found to follow a so-called Fickian behaviour. The effects of the immersion treatment on the flexural were also investigated. The composites were treared by sonication showed that energy activation during curing was a slightly bigger than EMC/epoxy resin composites but siginifacantly lower than pure epoxy resin. The similar change was showed on the thermal degradation. Water absorption of MCC/epoxy resin composites is bigger than pure epoxy resin and EMC/epoxy resin composites due to the big hydropholic properties of MCC particles.