Reinforced Unsaturated Polyester Composites Research Articles

Manihot esculenta tuber microcrystalline cellulose and woven bamboo fiber-reinforced unsaturated polyester composites: mechanical, hydrophobic and wear behavior

In this research Manihot esculenta (cassava) tuber stem microcrystalline cellulose (MCC) and woven bamboo fiber (WBF) reinforced unsaturated polyester (UP) composites are prepared and tested. The main aim of this study was to synthesis the microcrystalline cellulose from Manihot esculenta tuber stem and investigate the mechanical, wear and hydrophobic properties of UP resin composite made using MCC and WBF. The laminated composites were prepared by the hand layup method and characterized according to ASTM standards. According to the results, the composite containing 40 vol% of WBF increased the tensile strength and modulus, flexural strength and modulus, interlaminar shear strength, Izod impact as well as hardness by 39%, 10%, 42%, 27%, 1%, 91%, and 1%, respectively as compare to pure polyester resin composites. In comparison to all composites, the composite with 4 vol% of MCC exhibits the lowest sp. wear rate of 0.011 mm3/Nm. The water absorption contact angle indicated that all composite designations had a wider contact angle of more than 70°, which indicates a stronger hydrophobicity of composites. The SEM fractography reveals improved bonding and toughness for 4 vol% of MCC and WBF reinforced UP composites. Such mechanically stronger, wear resistance, as well as high hydrophobic composites, could be used in aerospace, automobile, defence and industrial sector.

Prediction and analysis of properties of ramie fiber staple yarn reinforced unsaturated polyester composite based on fiber packing density

The limitation of plant fiber length can be overcome by using staple spinning to achieve continuity on short fibers. Ramie fiber staple yarn reinforced unsaturated polyester composites (RSYCs) were fabricated with ramie fiber and unsaturated polyester matrix. The unique fiber packing density of staple yarn must be tackled first to reflect the structure of RSYCs. The relationship between fiber packing density of staple yarn and fiber volume fraction of composite was evaluated to investigate the effect of fiber packing density on properties and predict the tensile strength of RSYCs using the rule of mixture. A scanning electron microscope illustrated fiber packing density of staple yarn. When the twist factor was 380 with the optimal yarn count of 80 tex, the fiber packing density was 19.9% higher than that at 260. Compared with the minimum tensile strength of RSYCs at 120 tex, the maximum of RSYCs at 380 was 399.2 MPa, improved by 238.6%. Measured by dynamic mechanical analysis, the viscoelastic rigidity and damping property of RSYCs was the best at 380, with the storage modulus of 31.9 GPa at 40 °C and the tan delta of 0.1226 at 80.59 °C. Compared with the neat resin and ramie fiber, the onset temperature of weight loss of RSYCs tested by thermogravimetric was reduced. The increasing fiber packing density significantly reduced the resin permeability of RSYCs, according to the contact angle and ultrasonic nondestructive testing results. There is no doubt that the obtained fiber packing density possessed great potential for promoting the development of RSYCs.

Effect of Graphene Nanoplatelets on Water Absorption Properties of Coconut Shell Reinforced Unsaturated Polyester Composites

Coconut shell (CS) reinforced unsaturated polyester (UPE) composites have been prepared by using hand lay-up and compression molding techniques. To improve fiber-matrix adhesion, the CS was chemically treated by two chemical treatments, which are alkali (NaOH) and alkali-silane with concentration NaOH (6%) and silane (2%). To enhance the performance of CS-UPE composites, graphene nano platelets (GNP) was also added as nanofiller. The water absorption tests were conducted to characterize the physical properties of the composites. The result shows that water absorption increases with the increasing GNP. The more adding of GNP fillers’ weight percentages, the higher the water absorption will be getting.

Application of Micromechanical Modelling for the Evaluation of Elastic Moduli of Hybrid Woven Jute-Ramie Reinforced Unsaturated Polyester Composites.

Woven laminated composite has gained researchers’ and industry’s interest over time due to its impressive mechanical performance compared to unidirectional composites. Nevertheless, the mechanical properties of the woven laminated composite are hard to predict. There are many micromechanical models based on unidirectional composite but limited to the woven laminated composite. The current research work was conducted to evaluate elastic moduli of hybrid jute–ramie woven reinforced unsaturated polyester composites using micromechanical effectiveness unidirectional models, such as ROM, IROM, Halpin–Tsai, and Hirsch, which are based on stiffness. The hybrid jute–ramie laminated composite was fabricated with different layering sizes, and the stacking sequence was completed via hand lay-up with the compression machine. Tensile modulus values for hybrid composites are between those for single jute and single ramie. Obtained p-values less than 0.05 prove the relationship between layering size and tensile modulus. This study showed that several micromechanical models, such as Halpin–Tsai’s predicted value of homogenized mechanical properties, were in good agreement with the experimental result. In the case of the hybrid composite, the micromechanical model deviates from the experimental result. Several modifications are required to improve the current existing model. A correlation function was calculated based on the differences between the elastic modulus values determined experimentally and those derived from each micromechanical model calculation.

Kenaf fibers reinforced unsaturated polyester composites: A review

Recently development of high-performance polymer composites made from natural resources in the various sectors is increasing tremendously due to the environmental issues and health hazard possessed by the synthetic fibers during disposal and manufacturing. Among the many different types of natural resources, kenaf fibers have been extensively investigated as an alternative reinforcement for polymer composites over the past few years due to their low cost, good mechanical properties, high specific strength, nonabrasive, eco-friendly, and biodegradability characteristics. Kenaf is regarded as an industrial crop in Malaysia and grown commercially in other parts of the world for different applications. It is certainly one of the important plants cultivated for natural fibers globally which has great potential to use as automotive and construction materials. In many research studies, kenaf fibers have been used as reinforcement in unsaturated polyester (UPE) which perfectly improved the features of the polyester resin. The tensile properties of kenaf fiber reinforced UPE are mainly influenced by the interfacial adhesion between the fibers and the polyester resin. Several chemical modifications are employed to improve the interfacial bonding between kenaf fibers and polyester, resulting in the enhancement of mechanical properties of the composites. Therefore, this paper explores and highlights of the previous studies around kenaf fiber reinforced UPE composites, in terms of processing methods, mechanical, water absorption, and morphological properties to provide a perfect source of literature for doing further research in this topic.

Effect of water and mechanical retting process on mechanical and physical properties of kenaf bast fiber reinforced unsaturated polyester composites

The properties of polymer composite filled or reinforced with kenaf fiber have been extensively studied in recent decades as an alternative for replacing synthetic fiber in composite structures. Although many studies have been conducted on natural fiber filled or reinforced composite, lack of researches have been done on the processing factors that contributed to the overall fiber strength. Thus, this study aims to determine the efficiency of retting process which significantly influences the characteristics and performance of the final composite products. In this study, the kenaf bast fibers composites were prepared using hand lay-up method at different fiber loadings (weight%) of 10, 15, 20, 25, 30 and 35 through two retting methods namely water and mechanical retting process. Unsaturated polyester (UPE) resin and methyl ethyl ketone peroxide (MEKP) were used as binder and catalyst, respectively. This current research aims to examine the effects of different retting processes and fiber loadings on tensile strength, water absorption and morphology which consists of tensile fracture and fiber surface, using Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The tensile strength of water retted kenaf bast fibers reinforced UPE composites exhibited higher value than mechanical retted kenaf bast fibers reinforced UPE composites. In terms of water absorption, it was found that mechanical retted kenaf bast fiber reinforced UPE composites absorb more moisture than water retted kenaf bast fibers reinforced UPE composites. From the results, it can be concluded that the water retting process yielded higher mechanical and water absorption properties compared to mechanical retting process at all different fiber loadings (weight%). This current study contributes to the current field of knowledge by providing a clear reference for future development of high-performance polymer composites based on kenaf bast fibers as reinforcements, specifically in structural applications such as floor decking, door and window frames.

Mechanical Properties of Coconut Shell Reinforced Unsaturated Polyester Composites with the Presence of Titanium Dioxide as Additional Filler

Unsaturated polyester (UPE) composites filled with coconut shell (CS) powder was prepared by compression molding technique. To improve the mechanical and physical properties of CS-UPE composites, titanium dioxide (TiO2) filler was added. CS also undergo two types of chemical treatment which were alkaline (NaOH) and silane treatment. Fourier transform infrared (FTIR) was used to investigate the changes of fibers chemical constituents after the two chemical treatments have been done. CS-TiO2-UPE composites was characterized with physical testing (density, water absorption and thickness swelling), mechanical properties (tensile and flexural test) and scanning electron microscopy (SEM). Overall, the result shows that, the presence of CS and TiO2 filler in UPE composites demonstrated the highest density. For water absorption and thickness swelling study, it was observed that the treated CS-UPE composites showed lower water absorption properties in comparison to those of untreated CS-UPE composites. The presence of TiO2 filler showed an increased in those water absorption properties but still low compared to CS filled UPE. Both chemical treatment of CS caused a significant increase in the tensile and flexural properties. The presence of TiO2 filler demonstrated a significant improvement in modulus properties but at the expense of strength properties. SEM investigation has shown that the surface modification of CS has better fiber-matrix interaction. Thus, chemical treatments on the CS improve fiber/matrix adhesion of UPE composites.

Effect of Fibre Length and Sea Water Treatment on Mechanical Properties of Sugar Palm Fibre Reinforced Unsaturated Polyester Composites

This study presented the effect of different fibre length and seawater treatment on mechanical properties of the fabricated composites. The composite was reinforced with fixed 30wt.% of fibre loading. Sugar palm was treated using sea water for 30 days and have been cut into three different lengths by 5cm, 10cm and 15cm. The mechanical properties of the untreated and treated fibre with different fibre length composites were characterised includes tensile test and flexural test. Treated sugar palm fibre composites with 15cm fibre length exhibited higher tensile strength at 18.33 MPa. However, it shows the lowest value for the tensile modulus at 4251.96MPa. The flexural strength shows an increasing trend as the fibre length increased up to 15cm and the maximum flexural strength was exhibited by treated sugar palm fibre with 5 cm at 80.80MPa.Effect of Fibre Length and Sea Water Treatment on Mechanical Properties of Sugar Palm Fibre Reinforced Unsaturated Polyester Composites

Study of Dimensional Changes on Alkali Treated Zallaca Fibre Reinforced Unsaturated Polyester Composites under Different Aqueous Environments

In this research, alkali treated zallaca fibre reinforced with high density polyethylene (HDPE) composites are subjected to water immersion tests in order to study the dimensional changes and flexural properties of composites. Composites were frabricated using compression molding method with zallaca fiber content of 30% vt. Composite specimens were immersed under three different solution included distilled water, sea water and acidic solutions for 2 months at room temperature. The highest dimensional changes was recorded for composite immersed in seawater followed by acidic solution and distilled water. The dimensional changes of Zallaca fibre reinforced HDPE in different solution were found to follow a Fickian behaviour. Alkali treated fiber composites after immersion has lower results both in dimensional changes and its slope than untreated fiber composites in different aquaeous environment. The severe degradations are observed by using Scanning Electron Microscopy (SEM) that showed microcracks growth, and degradation of interfacial region between fiber and matrix. Flexural properties of composites decrease after immersion stage in different values.

Mechanical Properties of Chicken Feather Reinforced Unsaturated Polyester Composites

In this paper, chicken feather fibers (CFFs) from poultry industries were used as reinforced materials incorporated with unsaturated polyester (UP) to create composites. It is prepared by varied the percentage weight fraction of CFFs by 2wt%, 4wt%, 6wt%, 8wt%, and 10wt%. Alkaline treated potassium hydroxide (KOH) was used to alter the structure of the CFFs. From the results it showed that the tensile strength of the CFFs/UP composites was reduced. The flexural modulus has optimum results of 35.3MPa, improved by 11.86% from pure UP (31.1MPa). For flexural modulus at 2wt% and 4wt% the untreated CFFs/UP performed better performance. However, started at 6wt% onwards, chemically treated fibers surpass untreated fiber. Even though CFFs has unique characteristics properties such as hollow honeycomb structure and low density, the poor adhesion due to its smooth surface roughness and uneven distribution of fiber during mixing contributed to the low strength and flexural values. Thus, treatment caused changes in the structure of the CFFs to increase the surface roughness of the fibers, which improve adhesion.

The Effect of Alkaline Treatment on the Mechanical Properties of Treated Sugar Palm Yarn Fibre Reinforced Unsaturated Polyester Composites Reinforced with Different Fibre loadings of Sugar Palm Fibre

The aim of this paper was to describe the effects of treated sugar palm yarn fibre loading on the mechanical properties of reinforced unsaturated polyester composites. Composites with varying fibre loads (10, 20, 30, 40 and 50 wt. %) were prepared using a hand-layup process. The composites were tested for tensile, flexural and impact strength according to ASTM D3930, ASTM D790 and ASTM D256 standards, respectively. The results showed that an increase in fibre loading of up to 30 wt. % increased tensile strength (31.27 MPa), tensile modulus (4.83 GPa), flexural strength (58.14 MPa) and modulus (4.48 GPa). Maximum loading can be attained at 40 wt. % of fibre loading for impact strength (38 kJ/ m2). The effectiveness of stress transfer mechanism through the fibre-matrix interaction, coupled with the optimization of fibre loading in resisting fracture and failure, boosts the overall mechanical performance of sugar palm composite.

Mechanical and Water Absorption Properties of Hybrid Kenaf/Glass Fibre Mat Reinforced Unsaturated Polyester Composites

Hybrid kenaf/glass fibre mat reinforced unsaturated polyester (UPE) composites have been prepared by using simple hand lay up moulding technique. The composites with various formulations were characterized by flexural test while water absorption behaviour were investigated with immersion in distilled water at room temperature. The result shows that the hybrid composites with kenaf fibre mat at the innermost layers (glass fibre mat at the outer layers) has given the highest flexural strength and modulus. On the other hand, water absorption study shows that, the hybrid composites with glass fibre mat at the innermost layers (kenaf fibre mat at the outer layers) showed the highest water uptake and thickness swelling. Further investigations on morphological properties were also done to correlate the mechanical properties of the hybrid kenaf/glass fibre mat reinforced UPE composites.

The Effect of Cellulose Surface Treatment on the Fracture Toughness of Microfibrillated Cellulose Reinforced Unsaturated Polyester Composites

The Effect of Cellulose Surface Treatment on the Fracture Toughness of Microfibrillated Cellulose Reinforced Unsaturated Polyester Composites

Tensile Property Analysis and Prediction Model Building for Coir Rope Reinforced Unsaturated Polyester Composite

Because of the light weight and environmental advantages of natural fibers, an increasing amount of natural fibers have been used to replace synthetic fibers in reinforced unsaturated polyester (UPE). Because of the impact property advantage of coir fibers, coir toughened UPE composites can achieve excellent impacting toughness, but at the cost of a lower tensile performance. In order to get the better comprehensive performance, the tensile strength must be maintained in a higher level, so coir ropes as an appropriate reinforced form were added to UPE matrix. The different weight-percent contents for the coir rope addition were set to achieve coir rope reinforced UPE composites with different coir contents. The tensile test results showed increasing tensile strength with the increased content of coir ropes. To reasonably and accurately predict the composite performance, taking the original performance prediction model based on a continuous reinforced fiber composite (using the Classical Mixed Law as a reference) and assuming each coir rope was ideally continuous fiber, the destructive principle of coir rope reinforced UPE composite under the action of tensile load was analyzed and the tensile failure mechanics model was improved. According to the experimental proof, the new model can be proven to have higher precision accuracy, which can provide new train of thought for the building of the theoretical models for natural fiber reinforced composites, thus guiding the actual production application.

Tensile Properties of Pineapple Leaf Fibre Reinforced Unsaturated Polyester Composites

In recent years natural fibres such as sisal, jute, kenaf, pineapple leaf and banana fibres appear to be the outstanding materials which come as the viable and abundant substitute for the expensive and non-renewable synthethic fibre. This paper investigate the effect of fibre length and fibre content on the tensile properties of pineapple leaf fibre (PALF) reinforced unsaturated polyester (UP) composites. PALF as reinforcement agent will be employed with UP to form composite material specimens. The various of fiber length (<0.5, 0.5–1, and 1-2 mm) and fibre content (0, 5, 10 and 15 % by volume) in UP composite have been studied. The fabrication of PALF/UP composites used hand lay-up process, and the specimens for tensile test prepared follow the ASTM D3039. The result obtained from this study show that the 1-2 mm fibre length has higher tensile strength (42 MPa) and tensile modulus (1344 MPa) values compared to fibre length of <0.5 mm (30 MPa and 981 MPa) and 0.5-1 mm (35.40 MPa and 1020 MPa) respectively. Meanwhile, for the effect of various fibre content in study has shown that the increase of fibre content has decreased in tensile strength dan tensile modulus of composites. The increase of fibre content due to poor interfacial bonding and poor wetting of the fibre by unsaturated polyster. The treatment of natural fibre are suggested in order to improve the interfacial adhesion between natural fibre and the unsaturated polyester.

Mechanical and Wear Properties of Sisal Fiber Cellulose Microcrystal Reinforced Unsaturated Polyester Composites

ABSTRACTIn this paper, sisal fiber cellulose microcrystal (SFCM) was prepared by the sulfate pulping method, and sisal fiber cellulose microcrystal/unsaturated polyester (SFCM/UP) in situ resin was polymerized. Furthermore, the SFCM/UP composite was prepared by rolling and molding techniques. Effects of SFCM content on mechanical and wear properties of the UP composites were studied. Structure and properties of the in situ SFCM/UP resin and its composites were characterized by using Fourier transform infrared, polarized optical microscopy, thermogravimetric analysis, scanning electron microscopy, and other methods. The results showed that the addition of SFCM by in situ polymerization significantly improves the thermal stability of UP: The decomposition temperature (Td5) of SFCM/UP in situ resin, at thermal weight loss of 5%, is increased by 16°C compared to that of the pure UP resin. On a condition that the SFCM content was 2%, the impact strength, flexural strength, and flexural modulus of SFCM/UP composites are higher than those of UP composites by 41.08%, 52.52%, and 32.31%, respectively. Moreover, the addition of SFCM significantly enhances the wear properties of unsaturated polyester composite at 200°C; the volume wear rate of SFCM/UP composite is lower than that of UP composites by 64%, indicating SFCM could significantly strengthen and toughen UP composites.

Enhanced mechanical properties and water resistance of bamboo fiber–unsaturated polyester composites coupled by isocyanatoethyl methacrylate

Bamboo fibers were mechanically extracted from raw green bamboos by crushing, rolling, and combing techniques with 1,4-butanediol as a solvent. The morphology of the bamboo fibers thus obtained was analyzed. The bamboo fibers were treated with isocyanatoethyl methacrylate (IEM) in the presence of dibutyltin dilaurate as a catalyst, to improve the interfacial adhesion between the fibers and unsaturated polyester (UPE) resins. The bamboo fibers reinforced UPE composites were prepared by hand lay-up compression molding. FTIR, XPS, and NMR analyses indicated that the IEM was covalently bonded onto the bamboo fibers via carbamate linkages. The IEM treatments significantly increased the tensile strength, flexural strength, flexural modulus, and water resistance of the resulting composites and yet decreased the impact strength of the composites. The SEM images of the tensile-fractured surfaces of the IEM-treated bamboo fibers–UPE composites revealed that the fiber treatments markedly improved the interfacial adhesion between the bamboo fibers and UPE resins.

Tensile Properties of Kenaf Yarn Fibre Reinforced Unsaturated Polyester Composites at Different Fibre Orientations

This paper reported the study of tensile properties of kenaf yarn fibre reinforced unsaturated polyester (UP) composites at different fibre orientations, i.e. 0o, ±45o and 90o. It is concluded that composites with 0o orientation show higher strength and stiffness than composites with ±45o and 90o angle fibre orientation. The highest value of stress is 29 MPa for 0o loading direction followed by ±45o loading direction (28 MPa) and 90o loading direction has the lowest stress value of 6 MPa. Tensile modulus results revealed the highest value of 10.61 GPa for 0o loading direction and the tensile modulus for 45o orientation of loading direction is 5 GPa, followed by the modulus for 90o of fibre loading direction of 1.2 GPa; which is the lowest.

Tensile Strength of Untreated Napier Grass Fibre Reinforced Unsaturated Polyester Composites

This paper describes the experimental investigation of the tensile strength of untreated Napier grass fibre reinforced polyester composites. Napier grass fibres were extracted trough conventional water retting process and used as reinforcing materials in the polyester composite laminates. Tensile tests were then conducted for the composite specimens from the laminates at 25% fibre loading using the electronic extensometer setup to obtain the tensile properties. The results show significant differences in tensile strength between random short fibres laminates and random long fibre laminates with the long fibres yield almost 45 % higher in the strength. The laminates also show higher maximum strength compared to other commonly available natural fibre composites with over 70 % increase in the maximum strength compared to the short kenaf fibre reinforced composites.

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.