PENGARUH VARIASI KOMPOSISI POLYLACTIC ACID DAN FILLER KULIT SINGKONG TERHADAP KEKUATAN TARIK DAN LAJU BIODEGRADASI BIOPLASTIK

THE EFFECT OF VARIATION IN POLYLACTIC ACID AND CASSAVA PEEL FILLER COMPOSITION ON THE TENSILE STRENGTH AND BIODEGRADATION RATE OF BIOPLASTICS

Peningkatan penggunaan plastik konvensional berbasis minyak bumi menimbulkan permasalahan lingkungan karena sifatnya yang sulit terurai. Bioplastik berbasis polylactic acid dan bahan pengisi alami dari limbah pertanian menjadi salah satu solusi yang menjanjikan. Penelitian ini bertujuan untuk menganalisis pengaruh variasi komposisi PLA dan filler pati kulit singkong terhadap sifat mekanik dan laju biodegradasi bioplastik. Bioplastik dibuat dengan metode pneumatic injection molding menggunakan variasi komposisi pati kulit singkong/PLA sebesar 0/100, 10/90, 20/80, dan 30/70 wt%. Pengujian sifat mekanik dilakukan menggunakan uji tarik sesuai standar ASTM D638 Tipe I, sedangkan uji biodegradasi dilakukan dengan metode soil burial test selama empat minggu.

Hasil penelitian menunjukkan bahwa penambahan pati kulit singkong berpengaruh signifikan terhadap sifat mekanik bioplastik. Kekuatan tarik rata-rata meningkat dari 28,59 MPa pada PLA murni menjadi 37,28 MPa 10 wt%, 40,26 MPa 20 wt%, dan mencapai nilai tertinggi sebesar 68,50 MPa pada komposisi 30 wt% pati kulit singkong. Peningkatan ini menunjukkan bahwa filler pati kulit singkong mampu berperan sebagai penguat dalam matriks PLA. Sementara itu, hasil uji biodegradasi menunjukkan bahwa semakin tinggi kandungan pati kulit singkong, semakin besar persentase kehilangan massa. Bioplastik dengan komposisi 30 wt% pati menunjukkan laju biodegradasi tertinggi selama empat minggu pengujian dibandingkan PLA murni yang mengalami degradasi paling rendah.

Kata kunci: Bioplastik, Pati Kulit Singkong, Polylactic Acid PLA, Variasi Komposisi.

The increased use of conventional petroleum-based plastics has led to environmental problems due to their non-biodegradable nature. Polylactic acid PLA based bioplastics combined with natural fillers from agricultural waste represent a promising solution. This study aims to analyze the effect of variations in PLA and cassava peel starch filler compositions on the mechanical properties and biodegradation rate of bioplastics. The bioplastics were produced using pneumatic injection molding with variations in cassava peel starch/PLA composition of 0/100, 10/90, 20/80, and 30/70 wt%. Mechanical properties were tested using a tensile test according to ASTM D638 Type I standards, while biodegradation was assessed through a soil burial test over four weeks.

The research results indicate that the addition of cassava peel starch significantly affects the mechanical properties of bioplastics. The average tensile strength increased from 28.59 MPa in pure PLA to 37.28 MPa 10 wt%, 40.26 MPa 20 wt%, and reached the highest value of 68.50 MPa at a composition of 30 wt% cassava peel starch. This increase demonstrates that cassava peel starch filler can function as a reinforcement in the PLA matrix. Meanwhile, the biodegradation test results show that the higher the cassava peel starch content, the greater the percentage of mass loss. Bioplastics with a 30 wt% starch composition exhibited the highest biodegradation rate over four weeks of testing compared to pure PLA, which experienced the lowest degradation.

Keywords: Bioplastics, Cassava Peel Starch, Polylactic Acid PLA, Composition Variations.