Glass fiber reinforced unsaturated polyesters were prepared by hand lay-up technique. Effect of clay conditions and loading, as well as mixing time on tensile modulus, flammability, and wear resistance were evaluated. In general, the results showed that there might be two possible structures, dispersed and agglomerated, in the composite samples. The modulus results showed that the effect of clay drying, as well as higher filler loading increase the property. In contrast, the mixing time resulted in negative effect on modulus. The improvement on modulus and flammability might be influenced by clay dispersion due to shear and viscosity change, while the decrease on modulus and wear resistance might be caused by agglomerated structures due to lubrication effect of moisture content, and less crosslink point caused by styrene evaporation.

AbstrakPencampuran polimer (polymer blending) merupakan salah satu metode yang telah dikembangkan untuk merekayasa material polimer. Dalam penelitian ini telah dilakukan pembuatan komposit mikrofibril PET-HDPE dengan menggunakan alat ekstruder tipe co-rotating twin screw. Proses pembuatan komposit dalam alat ekstruder dengan parameter temperatur 170°C; 240°C; 265°C dan 280°C pada kecepatan putaran 40 rpm. Kondisi temperatur penarikan (drawing) pembuatan komposit diatur pada variasi temperatur 75°C; 80°C dan 85°C serta kecepatan rasio penarikan 2;3;4 dan 5 kali lebih cepat dari kecepatan awal. Hasil pembuatan komposit mikrofibril PET-HDPE dilakukan analisis sifat mikro dengan alat SEM (Scanning Electron Microscope) dan sifat mekanik dengan alat UTM (Universal Testing Machine) dan impact charpy. Pada penelitian ini didapatkan nilai kuat tarik tertinggi 24,60 MPa pada kondisi temperatur 85°C dengan kecepatan rasio penarikan 2 kali. Kekuatan impak tertinggi komposit PET/HDPE adalah 131.49 MPa pada kondisi temperatur penarikan 85 o C dan rasio kecepatan penarikan 4 kali. Sedang hasil analisa mikro menggunakan SEM terhadap komposit mikrofibril PET-HDPE belum dihasilkan fiber PET yang diharapkan pada komposit. Hal ini kemungkinan disebabkan proses penarikan yang tidak stabil dan temperatur penarikan yang belum tercapai. Kata-kata kunci: Komposit mikrofibril, ekxtruder twin screw, pencampuran polimer PET-HDPE AbstractPolymer blending is one of the methods that have developed to create new polymer materials with different physical properties. This paper aims to investigate of tensile strength, impact strength of microfibril PET-HDPE composites and to obtain PET fiber. Composites were prepared in co-rotating twin screw kneader extruder type ZK 25 E x 36 L/D. The tensile strength, impact Charpy strength from microfibril PET-HDPE and microstructure PET fiber was characterized using Shimadzu AG-X plus 50kN Universal Testing Machine, Resil Impactor CEAST and JEOL JSM 6510 LA Scanning Electron Microscope. Composites were varied at temperature 170 o C, 240 o C, 265 o C and 280 o C and mixing speed was controlled at 40 rpm. Drawing temperature was set at 75 o C, 80 o C, 85 o C, ratio drawing speed at 2; 3; 4 and 5-time initial drawing speed. The results showed that maximum tensile strength is 24.60 MPa on condition 85 o C with ratio drawing speed 2-time initial drawing speed. The maximum impact Charpy strength is 131.49 MPa on condition 80 o C with ratio drawing speed 4-time initial drawing speed. The result of microstructure was not obtained PET fiber. In this case, caused by drawing speed was not stable drawing temperature was not reached.