This work investigates the possibility of isolating cellulose nanofibers from pulps of tall goldenrod plant, which are invasive plants in Korea, by a convenient method, without strong acids or high-pressure homogenization, using electron beam irradiation (EBI). The obtained cellulose nanofibers were characterized by scanning electron microscopy (SEM), ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and in terms of their mechanical properties. SEM showed that the initially isolated 10-μm-diameter cellulose fibers became more finely separated with increasing EBI dose, and that cellulose fibers treated with 300 kGy of EBI were separated into long cellulose nanofibers of around 160 nm in diameter. In addition, the paper samples prepared from more finely separated fibers generated by using higher doses of EBI had enhanced UV–vis transmittance. Via the XRD analysis, we observed that cellulose I in the EBI-treated cellulose fibers were gradually converted into a different type of cellulose similar to cellulose type II, as the EBI dose increased. Meanwhile, the TGA demonstrated that the finely separated cellulose fibers observed after administering the high EBI dose had lowered thermal stability due to the reduction of cellulose I but higher char yield. In addition, tensile strengths of paper samples increased with decreasing the diameters of their constituent fibers that result from the different EBI doses used in the preparation of the paper pulp.

Carbon foam was prepared from carboxymethyl cellulose (CMC) and Ag, Al and carbon nanotubes (CNTs), and graphene was added to the foam individually, to investigate the enhancement effects on the thermal conductivity. In addition, we used the vacuum method to impregnate erythritol of the phase change material (PCM) into the carbon foam samples to maximize the latent heat and minimize the latent heat loss during thermal cycling. Carbon foams containing Ag (CF-Ag), Al (CF-Al), CNT (CF-CNT) and graphene (CF-G) showed higher thermal conductivity than the carbon foam without any nano thermal conducting materials (CF). From the variations in temperature with time, erythritol added to CF, CF-Ag, CF-Al, CF-CNT, and CF-G was observed to decrease the time required to reach the phase change temperature when compared with pure erythritol. Among them, erythritol added to CF-G had the fastest phase change temperature, and this was related to the fact that this material had the highest thermal conductivity of the carbon foams used in this study. According to differential scanning calorimetry (DSC) analyses, the materials in which erythritol was added (CF, CF-Ag, CF-Al, CF-CNT, and CF-G) showed lower latent heat values than pure erythritol, as a result of their supplementation with carbon foam. However, the latent heat loss of these supplemented materials was less than that of pure erythritol during thermal cycling tests because of capillary and surface tension forces.