Fiber-reinforced Unsaturated Polyester Composites Research Articles

Interfacial microstructure and properties of carbon fiber-reinforced unsaturated polyester composites modified with carbon nanotubes

To improve the interfacial properties in carbon fiber (CF)-reinforced unsaturated polyester (UP) composites, we directly introduced functionalized carbon nanotubes dispersed in the fiber sizing onto the fiber surface. For comparing the influence of polymer type on sizing effect, two different polymers (UP MR13006 and water-soluble epoxy (EP)) were used to prepare sizing agent. Morphology and surface energy of CFs were examined by scanning electron microscopy and dynamic contact angle analysis test. Tensile strength was investigated in accordance with ASTM standards. Mechanical properties of the composites were investigated by interlaminar shear strength (ILSS) and impact toughness. Test results indicate that TS, ILSS, and impact toughness were enhanced simultaneously. For UP matrix, the sizing agent containing UP has better reinforcing and toughening effect than the sizing agent containing water-soluble EP.

Thermal behavior of E-glass fiber-reinforced unsaturated polyester composites

The aim of this work is to study the behavior of E-glass fiber unsaturated polyester composites, subjected to moderate and high temperatures. The obtained results show that the chemical, physical and mechanical properties of the resin and the composite change with the rise of the temperature. A thermogravimetric analysis (TGA) revealed that the thermal degradation of the composite occurs in two steps: the first between 130 and 200°C and the second between 250 and 440°C.The characterization of the resin and the composite, after heating, revealed that at moderate temperatures (lower than 100°C) an improvement of the properties of materials is observed. For high temperatures but lower than the temperature of decomposition (Td), the mechanical strength of the resin does seem to be very affected, even improved for certain cases. For these temperatures, the composite presents some fractures of the fiber–matrix interfaces, which causes losses in strength and ductility.When the temperature reaches the temperature of decomposition (Td), a fall of the mechanical properties was recorded for both resin and composite.

Tensile and Impact Properties of Different Morphological Parts of Sugar Palm Fibre-Reinforced Unsaturated Polyester Composites

The present study investigated the tensile and impact behaviour of unsaturated polyester composites reinforced by fibre from different parts of the sugar palm tree. Sugar palm fibre i.e. sugar palm frond (SPF), sugar palm bunch (SPB), black sugar palm fibre ( ijuk) and sugar palm trunk (SPT) which have high content of cellulose, low density, abundance and low cost, have the potential for polymer reinforcement. All composites were fabricated and labelled as SPF/PE, SPB/PE, ijuk/PE and SPT/PE. It was found that SPF/PE had the highest tensile strength which was 15.179 MPa (±2.425) followed by SPB/PE, ijuk/PE and SPT/PE with 12.809 MPa (±1.580), 11.473 MPa (±0.536) and 9.817 MPa (±1.890) respectively. For the impact strength analysis, SPF/PE showed the highest value (8.091 kJ m-2). Generally, SPF/PE had better tensile and impact properties than the other composites, due its high cellulose content.

Evaluation of Water Absorption Damage in Hemp Fibre Reinforced Unsaturated Polyester Composites by the Nanoindentation Testing

The effect of water absorption damage on the nanohardness and elastic modulus properties of the hemp fibre reinforced unsaturated polyester composites (HFRUPC) have been investigated using the nanoindentation testing. HFRUPC specimens containing 0, 28, 37 and 45 fibre wt.%, corresponding to neat UP, UP/3 layer hemp, UP/4 layer hemp and UP/5 layer hemp, respectively, were prepared and subjected to water immersion tests in a de-ionised water bath at 25 C and 100 C for different time durations. Elastic modulus and nanohardness properties of water immersed specimens subjected to both aging conditions are evaluated and compared alongside dry composite specimens. The elastic modulus and nanohardness properties of HFRUPC specimens were found to increase with the increase in fibre wt.% and decrease with increase in percentage moisture uptake. Nanoindentation is an effective technique to measure elastic modulus and hardness on a nanometer range. Its attractiveness lies largely from the fact that nanomechanical properties can be determined directly from indentation load and displacement measurements. SEM study was also applied to relate the decrease in properties as a result of water uptake in hemp composites.

Effects of Surface Treatments on Mechanical Properties and Water Resistance of Kenaf Fiber-Reinforced Unsaturated Polyester Composites

Effects of surface treatments on the strength and water resistance of kenaf fiber-reinforced unsaturated polyester (UPE) composites were investigated. A new coupling agent that consists of 1,6-diisocyanato-hexane (DIH) and 2-hydroxylethyl acrylate (HEA) was investigated for surface treatments of kenaf fibers. The surface treatments were found to significantly enhance the tensile strength, modulus of rupture, modulus of elasticity, and water resistance of the resulting kenaf–UPE composites. Fourier transform infrared spectroscopy (FTIR) confirmed that DIH-HEA was covalently bonded onto kenaf fibers. Scanning electron microscopy (SEM) images of the composites revealed that chemical treatment of kenaf fibers with a combination of DIH and HEA improved the interfacial adhesion between kenaf fibers and UPE resin in the DIH–HEA-treated kenaf–UPE composites. The mechanisms by which the chemical treatment of kenaf fiber surfaces improved strength and water resistance of the resulting kenaf–UPE composites were discussed.

Variations of mechanical properties of jute/polyester composite aged in various media

Woven roving jute fiber-reinforced unsaturated polyester composites were subjected to water absorption tests in order to study the effects of water ageing on the mechanical properties. Composite specimens were immersed in distilled water and salt water up to 2736 h. The water absorption of specimens reached to an equilibrium level after an immersion time of 300 h. It was observed that tensile, flexural, and interlaminar shear strengths (ILSSs) of jute/polyester composites decreased depending on the immersion time. The ILSS values of the composites were reduced by more than 53% for both the distilled water and the salt water after an immersion time of 2736 h.

Effect of low-profile additives on thermo-mechanical properties of glass fiber-reinforced unsaturated polyester composites

Low profile additives (LPA) are thermoplastics particles incorporated into unsaturated polyester (UP) resin in order to improve the surface finish of fiber glass/UP composites by shrinkage compensation. They are widely used in automotive applications where high-quality surface finish is required. In this article, the effect of low-profile additives on the thermo-mechanical properties of resin transfer molded fiber glass/UP panels is investigated. A combination of poly vinyl-acetate and poly methyl-methacrylate additives was tested with three concentrations (0%, 10%, and 40%). The flexural and shear properties were measured by three-point bending and short-beam tests. Thermo-mechanical and dynamic mechanical analyses were performed to measure the coefficient of thermal expansion and the glass transition temperature. The mechanical properties as well as the coefficient of thermal expansion were reduced upon addition of low-profile additives, whereas the glass transition temperature was improved with the content of low profile additives due to a better compatibility of the LPA/UP system.

Comparative Study of Physical Properties Based on Different Parts of Sugar Palm Fibre Reinforced Unsaturated Polyester Composites

This research was conducted to evaluate the potential of sugar palm residue as a raw material to produce the new green composites. The physical properties of sugar palm fibre reinforced unsaturated polyester composites from different part which are sugar palm frond (SPF/PE), sugar palm bunch (SPB/PE), sugar palm trunk (SPT/PE) and black sugar palm fibre (ijuk/PE) were studied. Samples were submerged in distilled water for 24 hours. The water absorption and thickness swelling were investigated in order to determine the dimensional stability of the composites. It is found that SPF/PE showed the higher value of water absorption and thickness swelling which are 1.57%, and 1.56% followed by SPB/PE (1.35%, 1.11%), ijuk/PE (0.65%, 0.76%) and SPT/PE (0.39%, 0.50%). Generally, this investigation is valuable for researchers in order to evaluate the potential and some possible application of sugar palm residues as a new natural composites product.

Impacts of Molding Pressure on Performances of Kraft Fiber Reinforced Unsaturated Polyester Composites

Novel Kraft fiber reinforced unsaturated polyester (UPE) composites were prepared at various molding pressures in order to investigate the effects of molding pressure on resin content, the mechanical properties and creep resistance. The results indicated that the novel composites had much higher mechanical properties and better creep resistances than traditional wood plastic composites because of the applications of strong Kraft fibers as reinforcement and thermosetting UPE as matrix. Molding pressure had various effects on the many properties of composites. With molding pressure increased from 6MPa to 25MPa, the mechanical properties and creep resistances increased gradually until about 20MPa and then decreased, which were attributed to the different interface adhesions between UPE resin and Kraft fibers at various molding pressures as evidenced by DMA analysis. Benefited from the use of low-viscosity UPE resin, the resin content of Kraft fiber reinforced UPE composites could reduce to 28.3% while strength and creep resistance were still much better than that of the thermoplastic wood-plastic composite (WPC) with 40% polymer matrix.

Effect of Chemical Surface Modifications on the Properties of Woven Banana-Reinforced Unsaturated Polyester Composites

Chemical surface modifications involving 1% sodium hydroxide (NaOH) and 1% acrylic acid (AA) treatments are applied to woven banana fabric and it is used as reinforcement in an unsaturated polyester matrix. Vacuum bagging technique was used to prepare the woven banana fiber-reinforced unsaturated polyester composites with four different volume percentages of fibers (5, 10, 15, and 20%). The effects of fiber-loading and fiber surface treatments on the flexural, impact and water absorption properties of the composites were investigated. The acrylic acid treatment results in improved mechanical and water absorption properties of the composites compared to the alkali treatment and untreated fiber composites. The treatment effects on the banana fibers have been characterized by means of infrared spectroscopy (FTIR) and microscopy analysis (SEM). The moisture absorption test showed that acrylic acid-treated woven banana fabric composites exhibit less water absorption than both alkali-treated and untreated woven banana fabric composites.