Pengaruh Kosentari Natrium Hidroksida Terhadap Ketangguhan Komposit Polyester Berpenguat Serat Serabut Kelapa: Effect of Sodium Hydroxide Cosentration on The Toughness of Polyester Composites Reinforced With Coconut Fiber. JTIRE 2026, 1 (1), 34-38.