ABSTRACT
High temperature is required in carbon fiber synthesis in the carbonization step. However, direct high-temperature heating without the presence of additive materials would affect the yield and structure of carbon fibers produced. Thus, this study aims to synthesize carbon fibers from poly-vinyl alcohol (PVA), as the precursor and reducing agent, using silver nanoparticles (SNP) from silver nitrate (AgNO3) as additives. The pre-treatment of PVA was performed in three steps, i.e., mixing PVA/AgNO3, electrospinning, and iodination. The interaction of PVA and AgNO3 was assessed by FTIR, and SEM was used to characterize the electro-spun fibers prior and after iodination; Raman spectrophotometer was carried out to confirm the yield of carbon fibers. There was reduction in oxygen groups (3000-3800 cm-1) and emergence of -C=O (1100 cm-1) and -C=C- (1627 cm-1) functional groups, indicating formation of carbon layers. Based on the DT/GA results, the silver nanoparticles reduce the need of high temperature with optimum carbonization at 350 °C and lead to the formation of more regular graphene layers. Graphene layers with a size distribution of 0.438 nm and well-organized structures were successfully formed, and the Raman shifting showed higher intensities of G and G' bands in the presence of Ag. Based on DT/GA results, the yield of carbon fibers with iodinated PVA fibers and SNP as additive had higher rates around 800 µg/min, reaching 33% at 500 °C. Thus, it is demonstrated that iodinated PVA/AgNO3 samples can significantly improve carbon fiber yield at low temperatures.
ABSTRACT
High-density polyethylene (HDPE) is among the flexible polymers on account of its appropriate processability and adequate mechanical properties. Grafting reactive monomers such as glycidyl methacrylate (GMA) and maleic anhydride (MAH) onto polyethylene was one of the ultimate choices to improve the physicochemical properties of HDPE. MAH is an appropriate option for grafting onto HDPE owing to its low reactivity and it relatively undergoes a direct grafting onto the polymer. The grafting of MAH on HDPE copolymerization has been conducted using monomer microencapsulation method in this study. The monomer microencapsulation samples were extracted stratified using acetone and xylen. Samples were then analyzed using titration, melt flow rate, FTIR, DSC, TGA and C-NMR. The results showed the degree of paste monomer on HDPE with a microencapsulation method was greater when compared to the usual method. We were successfully improving the grafting degree of MAH onto HDPE by using a simple blending method. The pre-microencapsulated HDPE provided an increasing in grafting degree of 1.88% (HDPE-g-MAH) over the conventional one which shows the value of 1.39% (HDPE-g-MAH).
