Fiber factor strongly influences the flexural properties of fiber-reinforced composites. Theoretically, strong fiber-matrix bonds combined with long fibers can produce high composite strength, while short fibers influence the ductility of the composite. Both conditions are obtained by aligning the fiber with the loading direction. In this study, an experimental study was conducted on the effect of fiber factors on the flexural strength and modulus of carbon fiber reinforced polypropylene. The fiber factors included in this study were: cryogenic fiber surface treatment, fiber length, and fiber orientation; each factor was divided into three levels. The relationship between the fiber factors and the responses was analyzed using the Response Surface Method (RSM) and Analysis of Variance (ANOVA). The results indicate that there is a good correlation between the predicted response values of the model and the results of the confirmation test. The fiber orientation has the most significant effect on the flexural strength of the composite. All fiber factors significantly affected flexural modulus, with fiber orientation as the most significant factor.

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Carbon fibre-reinforced polypropylene composite filaments were fabricated via the extrusion–pultrusion method. One of the important factors influencing composites’ filament processability and structural properties is the impregnation quality, which can be represented by interfacial adhesion between the matrix and fibre. To improve the interfacial shear strength (IFSS) of the filament, four processing variables—melt temperature, pulling speed, number of pins in the impregnation die and fibre treatment—have been optimised using the Box–Behnken response surface methodology (RSM). Analysis of variance (ANOVA) was conducted to evaluate the linearity of the response surface models. Three levels were set for each independent variable. The melt temperature was varied at levels 190, 210 and 230 °C, while the pulling speed was set at three levels, namely, 40, 47 and 50 cm/min. The number of spreader pins was varied at 1, 2 and 3 pins, and there were three variations of the fibre treatment, namely, vinyltrimethoxysilane (VTMS), γ-aminopropyltriethoxy silane (APTS) and liquid nitrogen. Twenty-seven experimental runs were conducted, and a significant regression for the coefficient between the variables was obtained. The filament IFSS was measured by a customised pull-out test, and its surface morphology was characterised using a scanning electron microscope. ANOVA showed that fibre treatment significantly affected the IFSS due to their surface roughness, followed by pulling speed and melt temperature in quadratic order. Liquid nitrogen is recommended for carbon fibre treatment because of the high surface roughness, thereby providing a better matrix–fibre bonding effect. The results demonstrated that a melt temperature of 190 °C, pulling speed of 40 cm/min, three spreader pins and treatment of the fibre with liquid nitrogen afforded the optimum impregnation quality. It is important to keep a reasonable low processing temperature to obtain the geometrical stability of the product.

Optimasi parameter proses 3D printing dengan bahan PETG terhadap respon kekuatan lentur menggunakan metode Taguchi telah dilakukan. Penelitian ini menggunakan desain eksperimen orthogonal arrays L9 (3 3 ) dengan tiga parameter proses yang digunakan yaitu nozzle temperature, extrusion width, dan feed rate serta dengan tiga variasi level pada setiap parameter (240 °C, 245 °C, 250 °C, 0.3 mm, 0.35 mm, 0.4mm, 50%, 75%, 100%). Spesimen dipersiapkan sesuai dengan Standar ISO 178:2010 menggunakan mesin 3D printer Prusa-i3, kemudian diukur dimensi, massa, waktu produksi dan kekuatan lenturnya. Respon kekuatan lentur dianalisis menggunakan metode Taguchi melalui SN Ratio dan ANOVA untuk mendapatkan parameter optimalnya. Hasil penelitian menunjukkan bahwa parameter proses paling berpengaruh terhadap respon kekuatan lentur berturutturut adalah nozzle temperature, extrusion width dan feed rate dengan kombinasi parameter optimal yaitu nozzle temperature (250 °C), extrusion width (0.35 mm), dan feed rate (75%). Eksperimen konfirmasi menunjukkan bahwa kombinasi parameter optimal tersebut mendapatkan kekuatan lentur tertinggi dengan sebaran data yang kecil (52,98 ±0,65 MPa). Selain itu, semua produk yang dihasilkan memiliki dimensi sesuai dengan standar yang digunakan.

Reinforcement of both fibrous and particulate materials can improve composite properties for various applications, such as biomedical applications. The alkali-treated kenaf fibers and (SiO2, bentonite, and CaCO3) microparticles 400 mesh in size reinforce the epoxy matrix for hybrid composites. The bending and impact properties of hybrid composites, as well as their water absorption, are compared. The hybrid composites were prepared in a compression mold using a hand lay-up technique at 100°C for 20 – 50 minutes consisting of 28 vol.% of short kenaf fibers ~5 mm in length, 2 vol.% of each type of microparticle, and 70 vol.% the epoxy resin. The flexural and impact properties of kenaf/silica/epoxy composite indicated the highest flexural strength (58.37±3.9 MPa), flexural modulus (4.68 ± 0.17 MPa), and impact strength (7.49 kJ/m2). The addition of the microparticles reduced water absorption in the composites. The water absorption of kenaf/silica/epoxy composite appeared to be stable for immersion time near 216 hours. Other microparticle-filled composites did not show this pattern. The incorporation of silica microparticles to the kenaf/epoxy composite potentially enhanced the mechanical properties of the composite, with the expectation of using it to be developed for biomedical composite material.

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Peningkatan jumlah sampah plastik di Indonesia disebabkan oleh meningkatnya penggunaan produk plastik. Menurut data, pada tahun 2018 sampah plastik akan diperkirakan 24.500 ton per hari. Daur ulang sampah plastik adalah salah satu cara untuk mengurangi jumlah sampah plastik di Indonesia. Pembuatan filamen 3D Printing berbahan plastik bekas daur ulang tidak hanya untuk mengurangi limbah sampah plastik, tetapi juga untuk memenuhi kebutuhan filamen untuk mesin 3D Printing tipe FDM (Fused Deposition Modeling). Dalam proses pembuatan produk, keakuratan dimensi menjadi faktor penting dalam mempengaruhi kualitas dan bentuk produk. Pada penelitian terkait keakuratan dimensi dilakukan dengan menggunakan metode Taguchi, dengan pengoptimalan parameter terukur seperti temperature printing, layer height and print speed. Penggunaan Signal to Noise Ratio (SNR) dengan tipe Smaller is Better untuk analisa hasil eksperimen yang memiliki tingkat perbedaan yang sedikit, dan untuk mengetahui parameter terukur yang berpengaruh dalam proses 3D Printing. Berdasarkan hasil analisa didapatkan parameter optimum untuk mencetak produk dengan dimensi 20x20x20 mm, berbahan dasar material plastik daur ulang PP adalah untuk parameter printing temperature adalah 260 o C, layer height 0,16 mm dan print speed 20 mm/s.