Sintesis kopolimer cangkok selulosa dan monomer asam akrilat menggunakan trimethallyl isocianurate (TMAIC) sebagai pengikat silang dengan metode pra-iradiasi untuk adsorpsi ion logam timbal (Pb) = Synthesis of graft copolymer of cellulose and acrylic acid monomer using trimethallyl isocianurate (TMAIC) as crosslinker by mean of pre-iradiation method for adsorption lead (Pb) metal ion