Mechanical, Morphological, Thermal, And Durability Properties Of Resin Transfer Moulded Kenaf Fibre Reinforced Unsaturated Polyester Composites

• Main Author: Ariawan, Dody
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: T Technology; TA401-492 Materials of engineering and construction. Mechanics of materials
• Online Access: http://eprints.usm.my/44297/1/Mechanical%2C%20Morphological%2C%20Thermal%2C%20And%20Durability%20Properties%20Of%20Resin%20Transfer%20Moulded%20Kenaf%20Fibre%20Reinforced%20Unsaturated%20Polyester%20Composites.pdf; http://eprints.usm.my/44297/
• Institution: Universiti Sains Malaysia

Dalam kajian ini, sifat-sifat komposit polyester tak tepu diperkuat dengan lembaran gentian kenaf (KF) tak teranyam yang dihasilkan dengan cara pengacuan pemindahan damar (RTM) telah dikaji. Lembaran gentian kenaf tak teranyam telah dirawat dengan alkali dan haba untuk jangkamasa yang berbeza sebelum proses pengacuan. Rawatan alkali telah menyebabkan penyingkiran sebahagian kandungan hemi-selulosa dan lignin dan telah dibuktikan melalui ujian spektroskopi infra-merah jelmaan Fourier (FTIR), analisis pembelauan sinar-X (XRD), mikroskop elektron imbasan (SEM) dan spektroskopi fotoelektron sinar-X (XPS). Sementara itu, rawatan haba hanya menyingkirkan bendasing dan kandungan sari. Penyingkiran bahan-bahan ini secara langsung meningkatkan sifat pelekatan dan kekuatan gentian seterusnya menambah baik kekuatan ricih antara laminar (ILSS), tegangan dan kekuatan lenturan komposit. Namun begitu rawatan alkali menghasilkan komposit yang mempunyai sifat-sifat mekanikal yang lebih baik daripada rawatan haba. Gentian kenaf yang paling optimum untuk rawatan alkali adalah yang direndam dalam larutan 6% NaOH selama 3 jam, manakala untuk rawatan haba pula adalah gentian kenaf yang dirawat pada suhu 140 ⁰C selama 10 jam. Hasil ujian eksperimen ke atas komposit diperkuat gentian kenaf tak terawat dan terawat didapati selari dengan hasil ujian pemodelan mikro-mekanik. Hasil ujian DMA menunjukkan bahawa rawatan gentian kenaf menghasilkan peningkatan bererti terhadap modulus storan (E’) komposit dan suhu peralihan kaca (Tg) bagi sampel komposit. Suhu peralihan kaca komposit berada di dalam julat 81oC – 85 ⁰C. Dalam kajian penuaan higro-terma, penyerapan air oleh sampel komposit pada suhu bilik adalah mengikut kelakuan Fickian, manakala pada suhu 60oC dan 90 ⁰C, penyerapan air sampel komposit mengikut kelakuan pseudo-Fickian. Komposit gentian kenaf yang telah melalui rawatan alkali menunjukkan penyerapan air paling sedikit dan kekuatan lenturan paling tinggi berbanding komposit gentian kenaf yang dilakukan perawatan haba. Penyerapan air dalam sampel komposit memacu proses penguraian, terutamanya pada suhu tinggi menyebabkan sifat-sifat mekanikal merosot dan tidak dapat dikembalikan walaupun sampel tersebut dikeringkan. Komposit poliester diperkuat gentian kenaf tak teranyam telah didedahkan terhadap cuaca persekitaran semulajadi selama 12 bulan. Di pendedahan terhadap cuaca semula jadi didapati mengurangkan kelenturan dan keliatan patah komposit disebabkan oleh kerosakan pada struktur komposit, pembentukan lompang/retakan mikro pada permukaan sampel, perubahan warna dan komposisi kimia komposit. Secara relatifnya, komposit diperkuat gentian kenaf terawat secara alkali menunjukan ketahanan yang lebih baik dari segi sifat-sifat mekanikal berbanding komposit diperkuat gentian kenaf yang terawatt haba. _______________________________________________________________________________________________________ In the present study, the properties of nonwoven kenaf fibre (KF) mat /unsaturated polyester composites manufactured by resin transfer moulding (RTM) were investigated. Nonwoven KF mats were prepared by the alkali treatment and heat treatment for different time of treatment. The alkali treatment resulted in the partial removal of hemicellulose and lignin as evident from the results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). Meanwhile, the heat treatment only removed impurities and extractives. These resulted in the increase of the adhesion properties and the fibre strength as well as the interlaminar shear strength (ILSS), tensile and flexural strength of composites, nevertheless alkali treated KF composites showed better mechanical properties than the heat treated KF composites. The optimum properties of alkali treated KF were obtained when KF was soaked in 6% NaOH solution for 3 hours. As for heat treated KF, the optimum properties were observed when KF was heat treated at 140oC for 10 hours. The experimental results of both untreated and treated KF mat composites were in line results with the results of micromechanic models. DMA results showed that both KF treatment resulted in a significant enhancement in the storage modulus (E’) and the glass transition temperature (Tg) of the composites samples. The Tg values of the composites were in the range of 81oC-85oC. In hygrothermal ageing investigation, the water uptake trend of composite samples at room temperature was found to follow the Fickian behaviour, whilst hygrothermal at 60oC and 90oC exhibited pseudo-Fickian behaviour. Alkali treated KF composites showed the lowest water uptake and superior flexural properties than heat treated KF composites. Moisture absorption promoted the degradation of composite samples, particularly at elevated temperatures and the mechanical properties could not be restored by subsequent drying. Nonwoven KF mat reinforced unsaturated polyester resin composites were exposed to a natural weathering environment for 12 months. This natural weathering was found to reduce flexural and fracture toughness due to the damage in composite structures, formation of void/micro cracks on the sample surface, discolouration and chemical composition alteration. Alkali treated KF composites relatively showed better durability with the respect to the retention of the mechanical properties than heat treated KF composites.