In the present case, the functionalization of sodium salt of partially carboxymethylated tamarind kernel powder (Na-PCMTKP, DS= 0.15), an industrially important natural polymer, is carried out through photo-graft copolymerization of methyl methacrylate (MMA) and ethyl methacrylate (EMA) onto it using ceric ammonium nitrate (CAN) as a photo-initiator. The effects of the concentrations of photo-initiator (CAN), nitric acid, methacrylate monomers (MMA and EMA) and the amount of Na-PCMTKP as well as reaction time and temperature on photo-graft copolymerization are being investigated to achieve the maximum graft yields (%G = 232.2 and %GE = 91.0 in the case of MMA and %G = 206.2 and %GE = 90.0 in the case of EMA). A suitable mechanism to explain the photo-graft copolymerization is being proposed. The kinetics aspect of the photo-graft copolymerization is also studied and the values of the overall activation energy for the photo-graft copolymerization in the case of MMA and EMA are found to be 8.10 and 10.49 kJ mol −1 , respectively. Besides kinetics study, the chemical structure and thermal properties of the graft copolymers of Na-PCMTKP containing PMMA and PEMA is studied by FTIR, TGA, and SEM techniques and the results ascertains the evidence of the successful photo-graft copolymerization of both the methacrylate monomers onto Na-PCMTKP. The synthesized novel graft copolymers may find their potential applications to be used as metal adsorbents as well as novel excipients for direct compression matrix tablets.

Ultraviolet (UV) radiation-induced graft copolymerization of acrylonitrile (AN) onto sodium salt of partially carboxymethylated tamarind kernel powder (Na-PCMTKP, DS = 0.15) has been carried out using ceric ammonium nitrate (CAN) as a photo-initiator. The optimal UV-radiation-induced grafting conditions have been established with Na-PCMTKP = 0.5 g (dry basis), [HNO 3 ] = 0.2 mol L −1 , [AN] = 0.295 mol L −1 , [CAN] = 6.0 × 10 −3 mol L −1 , time = 6 h, temperature = 30°C, volume of water = 144.58 mL, and total volume = 150 mL. The maximum percentage of grafting (%G) and percentage grafting efficiency (%GE) achieved under these established optimum reaction conditions are 361.16% and 89.33%, respectively. The various reaction conditions have been varied with a view to study their influence on the grafting yields (%G and %GE). A plausible mechanism to explain initiation, propagation, and termination of UV-radiation-initiated graft copolymerization has also been suggested. The influence of the efficiency of the photo-initiator on the grafting yields has been investigated. Fourier transform infrared, thermogravimetric analysis, differential scanning calorimeter (DSC), and scanning electron microscopy techniques have been successfully used to provide the evidence of grafting of polyacrylonitrile onto Na-PCMTKP. The kinetics of thermal decomposition of the graft copolymer, Na-PCMTKP-g-PAN, has also been investigated with the help of the DSC curves obtained at different heating rates. The Ozawa and the Kissinger methods have been utilized for the evaluation of the kinetic parameters for the thermal decomposition of the graft copolymer sample. The synthesized graft copolymer after saponification may be used as a superabsorbent hydrogel for potential applications.