Muhammad Remanul Islam

Polyurethane types, synthesis and applications – a review

Polyurethanes (PUs) are a class of versatile materials with great potential for use in different applications, especially based on their structure–property relationships. Their specific mechanical, physical, biological, and chemical properties are attracting significant research attention to tailoring PUs for use in different applications. Enhancement of the properties and performance of PU-based materials may be achieved through changes to the production process or the raw materials used in their fabrication or via the use of advanced characterization techniques. Clearly, modification of the raw materials and production process through proper methods can produce PUs that are suitable for varied specific applications. The present study aims to shed light on the chemistry, types, and synthesis of different kinds of PUs. Some of the important research studies relating to PUs, including their synthesis method, characterization techniques, and research findings, are comprehensively discussed. Herein, recent advances in new types of PUs and their synthesis for various applications are also presented. Furthermore, information is provided on the environmental friendliness of the PUs, with a specific emphasis on their recyclability and recoverability.

Preparation and characterization of natural silk fiber-reinforced polypropylene and synthetic E-glass fiber-reinforced polypropylene composites: a comparative study

Bombyx mori silk fiber-reinforced polypropylene (PP) matrix and E-glass fiber-reinforced PP matrix composites were fabricated using compression molding. The prepared silk/PP composite tensile strength (TS), bending strength (BS), and impact strength (IS) were 55.1 MPa, 56.3 MPa, and 17 kJ/m2, respectively. E-glass fiber-reinforced PP matrix composites were fabricated in the same way and TS, BS, and IS values of these composites were 128.7 MPa, 141.6 MPa, and 19 kJ/m2, respectively. Environmental degradation of the composites showed that silk/PP composites degrade faster. Other degradation studies like thermal aging and soil degradation tests also gave similar result.

Characterization of Oil Palm Empty Fruit Bunch and Glass Fibre Reinforced Recycled Polypropylene Hybrid Composites

The effects of hybridization of glass fibre on oil palm empty fruit bunch (EFB) and recycled polypropylene-based composites are described in this paper. The compounding process involved extrusion followed by injection moulding technique to prepare the samples for characterizations. Fibre loading were considered as 40 % of the total weight of the blends and EFB:glass fibre ratio was maintained as 30:70, 50:50, 70:30 and 90:10. Two types of coupling agents of maleic anhydride-grafted polypropylene such as polybond-3200 and fusabond P-613 of different molecular weight and maleic anhydride level were used to improve the interfacial adhesion between the fibres and the matrix. Composites were characterized by density, melt flow index, tensile, Izod impact and flexural testing. Morphological images of the fractured surfaces of the composites were examined by field-emission scanning electron microscopy. Samples were also characterized by thermal tests such as thermogravimetric analysis and differential scanning calorimetry to evaluate the thermal and crystalline properties, respectively. Optimization of hybridization of the fibres and effect of coupling agents were evaluated in terms of various properties of the samples. The composite prepared with EFB:glass fibre ratio of 70:30 showed better reinforcing properties than that of others.

Characterization of alkali-treated kenaf fibre-reinforced recycled polypropylene composites

In this study, composites were produced using alkali-treated kenaf fibre and recycled polypropylene to improve the interfacial bonding between them. Maleic anhydride grafted polypropylene was used at a ratio of 1:10 to the fibre as a coupling agent. Blends are mixed together by means of a twin screw extruder and test specimens for mechanical testing were prepared through injection moulding machine. Fibre density, tensile property, elemental analysis, structural and morphological changes due to treatment was observed and their effects on the properties of the formulated composites were analyzed. Characterization of the composites was done by the tensile, flexural, impact and melt flow index tests. Thermogravimetric analysis and differential scanning calorimetry analysis were carried out to evaluate the thermal properties of the composites. Experiment showed that best tensile strength (TS) was found at 40% loading of fibre and alkali treatment of fibre enhanced the TS by 57%. Activation energies were calculated through Broido’s equation. It was also found that recycled polypropylene degrades at one stage, while composites degrade at two stages. Incorporating fibres decrease the activation energies of the composites but both coupling agent and treatment of fibres in that case enhance activation energies by 11 kJ mol−1 and 29 kJ mol−1, respectively, in the second stage. Field emission scanning electron microscope of the fractured surface showed that treatment of fibre improves the interfacial bonding between fibres and matrix. Density and water uptake of the composites were also studied in this study.

Preparation and Characterization of Poly(lactic acid)-Based Composites Reinforced with Poly Dimethyl Siloxane/Ultrasound-Treated Oil Palm Empty Fruit Bunch

Oil palm empty fruit bunch fiber and polylactic acid were used to produce composites by melting cast method. Fiber loading was considered up to 40 wt%. Oil palm empty fruit bunch fibers were treated using ultrasound and polydimethylsiloxane to improve the interfacial adhesion. The structure and surface properties of the fibers were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and contact angle measurement. Moreover, Fourier transform infrared spectroscopy, tensile, flexural, X-ray diffraction, contact angle, differential scanning calorimetry, and thermogravimetric analysis were used to investigate composites’ properties. The analysis revealed that polydimethylsiloxane treatment composites show reduced wettability with increased crystallinity. GRAPHICAL ABSTRACT

Characterization Of Ultrasound-Treated Oil Palm Empty Fruit Bunch-Glass Fiber-Recycled Polypropylene Hybrid Composites

Abstract Glass fiber (GF) and ultrasound-treated oil palm empty fruit bunch (EFB) were used to prepare recycled polypropylene (RPP)-based hybrid composites through the extrusion and injection molding technique. The ultrasound technique was used to remove the lignin and other surface impurities from the EFB fiber by varying the treatment conditions (treatment time and temperature). A fixed concentration (10%) of NaOH solution was used as the treatment medium. Fiber loading was considered as 40%, while EFB and GF ratio was maintained as 70:30. Two types of coupling agents of maleic anhydride grafted PP (MAPP), Polybond and Fusabond, were used, each of an amount 2.5% (of the total fiber content), to improve the interfacial adhesion between fibers and matrix. Composites were characterized through density, melt flow index (MFI), tensile, flexural and Izod impact testing. In addition, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were also performed to evaluate the thermal and morphological properties, respectively. X-ray diffraction (XRD) analysis was performed to evaluate the crystalline structure of the samples. Finally, water uptake (WU) measurement was performed for 180 days of soaking period. Result analyses revealed improved mechanical, thermal and crystalline properties, with reduced WU as the outcome of treatment and coupling agent effects.

Effects of coupling agent on oil palm clinker and flour-filled polypropylene composites

This study gives the comparative analysis of polypropylene (PP)/oil palm flour (OPF) and PP/oil palm clinker (OPC) composites using maleated polypropylene (MAPP) as a coupling agent. Ground flour and crashed OPC were compounded separately into polypropylene with and without MAPP using a twin-screw compounder. The incorporated OPF and OPC in the composites were up to 40 wt%. The compounded samples were prepared into test specimens by injection molder. The composites were characterized by tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, and melt flow index. The surface morphology of composites was evaluated by scanning electron microscope. Incorporation of coupling agent showed better result than that of without coupling agent. Various properties of composites incorporated with OPC represented considerably close to the composites with OPF.

The effects of wettability, shear strength, and Weibull characteristics of fiber-reinforced poly(lactic acid) composites

Abstract The wettability, interfacial shear strength (IFSS), and Weibull characteristics of oil palm empty fruit bunch (EFB) fibers were studied to evaluate the mechanical properties of EFB- and poly(lactic acid) (PLA)-based composites. The fiber surface was modified through ultrasound and poly(dimethyl siloxane) treatment. The effects of treatment on the morphology, wettability, and structure of fibers were examined by scanning electron microscopy, contact angle, and Fourier transform infrared spectroscopy analysis, respectively. In addition, the Weibull characteristic was used to find the variability in strength of the fibers with respect to surface treatment. Furthermore, the IFSS of EFB fiber-PLA sandwich was investigated through single-fiber pull-out test, using a less strenuous technique. The mechanical properties (tensile strength, tensile modulus, flexural strength, and flexural modulus) of the composites were determined through mechanical testing. A comparison was drawn among the properties of PLA, raw EFB fiber-based composites, and treated EFB fiber-based composites. Additionally, the inter- and intra-relationship of fiber treatment, wettability, and IFSS with the mechanical properties of the PLA/EFB composites were also accounted.

Dispersion characteristics of hydroxyl and carboxyl-functionalized multi-walled carbon nanotubes in polyester nanocomposites

Abstract Multi-walled carbon nanotube (MWCNT) reinforced polyester-based composites were prepared by mixed blending in a solvent. Orthophthalic unsaturated polyester was blended individually with different types of non-functionalized and functionalized MWCNTs. Two types of functional groups: hydroxyl (-OH) and carboxyl (-COOH) were introduced with MWCNTs for the nanocomposites. The mechanical properties of the composites, like tensile, three-point bending and impact energy were evaluated. Fourier transform infrared spectroscopy was used for the functional group analysis. The dispersion characteristics of the samples were observed by transmission electron microscopy and field-emission electron microscopy. In addition, the thermal decomposition and melting behavior of the samples was assessed by differential scanning calorimetry and thermogravimetric analysis. The properties were varied due to the variation of the functional groups. The result analysis showed that the entangled agglomerations of hydroxyl-functionalized MWCNTs were destroyed to relatively smaller clusters. The hydroxyl-functionalized MWCNTs were more effective for homogeneous dispersion and contributed for better mechanical properties of the composites, compared to non-functionalized and carboxyl group-functionalized MWCNTs.

Effect of Curing on Hydrolytic Degradation of Montmorillonite Nanoclays Filled Biobased Polyesters

Palm oil based polyester (POPE) reinforced with montmorillonite nano clays (MNCs) were investigated for curing kinetics and hydrolytic degradation analysis. Alcoholises and esterification process were followed to produce POPE. The prepared resins were cured thermally by using methyl ethyl ketone peroxide (MEKP), styrene and cobalt-naphthenate at 120°C. The curing kinetics was analysed by differential scanning calorimetry (DSC). The rate of reaction, activation energy and degree of conversion were measured by this analysis. The activation energy and reaction order were found to be decreased due to increase of heating rate of the curing process. Alkali solution was used for the hydrolytic degradation for different samples prepared at different curing conditions such as low period-high temperature (LPHT) and high period-low temperature (HPLT). The properties were affected due to the variation of curing process as confirmed by degradation behaviours in terms of tensile strength, melting point and surface morphology. The degradation of the composites were influential and faster at LPHT condition compared to HPLT condition.