Efek ukuran, bentuk dan konsentrasi partikel precipitated calcium carbonate (PCC) yang ditambahkan pada sifat mekanik komposit karet alam

The objectives of this research was to study the effect of particle size, shape and concentration of PCC on mechanical properties of natural rubber composites, i.e. tensile strength (Ts) and elongation at break (Eb) at original and aging conditions. Two kinds of PCC were used, PCCL (local, size 12 μm, uncoated) and PCCD (commercial, size 0.03-0.06 μm, stearate coated). PCCL was pre-treated by applying stearic acid. PCCLA was characterized with FTIR, TG/DTA thermal analysis, and morphological test using SEM. The loading of PCC were 2.5; 5.0; 7.5; 10.0 and 12.5 phr respectively. Natural rubber composites were compounded using laboratory scale two roll mill. The incorporation of PCCLA or PCCD into rubber matrix increased Ts and Eb. Both Ts and Eb initially increased continued up to the maximum point then decreased. The maximum point of Ts and Eb of PCCLA were given on 10 phr, while of PCCD were on 10 phr and 5 phr resepectively. PCCLA with its cubical particle shape gave higher Ts and Eb than those PCCD with its needle-like shape, eventhough the particle size was larger. Aging increased tensile and elongation, because of excessive crosslinking. The characeristic of the interfacial adhesion between rubber matrix and PCC particle was estimated by Ts value, and proved that the Ts of PCCLA higher than those of PCCD.