INTRODUCTION
The urgency
Throughout history, humans have utilized natural materials to create tools and weapons for hunting, evolving through significant periods such as the Stone Age, Iron Age, and Bronze Age The introduction of synthetic plastic in the 20th century has dramatically transformed modern society, marking a pivotal shift in material use and innovation.
Plastic is an integral part of our daily lives, found in everything from our pillows and toothbrushes to keyboards and food packaging Our constant interaction with plastic makes it nearly impossible to avoid it throughout the day.
The convenience of plastic has led to significant harm to both our health and the environment, as it contributes to widespread pollution across land and sea Unfortunately, by the time we recognized the dangers of plastic, it was already too late to fully mitigate its impact.
In response to the increasing demand for sustainable alternatives to plastic, researchers are exploring various eco-friendly materials, yet a complete replacement for plastic remains elusive To address this challenge, with the approval of the Faculty of Mechanical Engineering and the Faculty for High Quality Training, we are undertaking a capstone project titled "Study on the Effect of Component Content on Mechanical Properties of Coconut Coir Fiber Powder-Plastic Composite Material." This study aims to investigate the potential of coconut coir fiber as a viable composite material to enhance mechanical properties while reducing plastic dependency.
Scientific and practical significance
Environmental pollution, particularly from plastic waste, is a growing concern Our project aims to address this issue by successfully minimizing plastic usage in products while maintaining their quality and characteristics.
When researching this topic, we realized that this topic is efficient, and the possibility of development on other plastics further studied if the project is successful.
Objectives
• Fabricate and testing of tensile specimens
• Create a premise for research on other thermoplastics
Object and scope
• Calculation of proportions, statistics of the number of specimens
Methodology
• Based on the need to find environmentally friendly materials
• Based on the ability to combine fillers and additives to increase the mechanical properties of plastic
• Conduct research and collect related documents such as books, videos, and journals
• Research documents, and process experimental data
• Pour specimens on different mold materials
• Find the appropriate mold material
• Learn the solidification process of pure plastic when combined with coconut coir fiber powder based on 2 types of temperatures
• Analysis and evaluation of strength results, concluding whether this coir material is better than pure plastic
• Chapter 4: Conclusion and future work
THEORETICAL BASIS
Coconut coir fiber powder
Coconut coir fiber powder is derived from the dried coconut fruit The following the structure of the coconut and the process of separating the coir powder from the fruit:
Figure 2.1 Dried coconut and cross-section [2]
The process of separating coir powder from the coconut fruit
Figure 2.3 Outer shell and inner shell [4] Figure 2.4 Coconut shell [5]
Figure 2.5 Coconut coir fiber powder [6]
Seventy percent of coir powder is derived from the inner shell of the coconut, which includes both coir fiber and powder Additionally, the coconut shell contains a substantial amount of coir fiber powder, particularly from the upper section after it is separated from the outer shell.
Coconut coir fiber powder is an eco-friendly raw material known for its neutral pH of 5.5–6.5, excellent moisture retention, and long shelf life in soil Rich in natural organic materials and beneficial microbes, it is ideal for planting trees and enhancing soil quality to nourish plants.
Also, because coconut coir is a plentiful source of raw materials from nature, it is quite inexpensive
Coconut coir fiber powder, known for its exceptional gyroscopic properties, is an ideal material for livestock and poultry bedding When mixed with coconut fiber, it effectively insulates barns, helping to maintain warmth while minimizing odors and reducing environmental pollution This combination also plays a crucial role in preventing diseases among livestock and poultry, making it a valuable addition to the agricultural industry.
+ Coir is frequently used in the agriculture sector to mulch and chill crops in hot weather
Combining organic matter with coconut coir fiber powder significantly enhances soil moisture retention and improves soil texture, making it softer and more conducive to plant growth.
For optimal seedling growth in small tree stages, sow seeds using a blend of organic matter and coconut coir fiber powder, which promotes healthy and rapid development.
- In the handicraft industry: coir is the most crucial raw material for weaving attractive, eco-friendly handicrafts in a variety of shapes, such as floor mats, foot mats, and bags
2.1.4 How to recognize coconut coir fiber powder in the market: [1]
Coconut coir fiber powder is initially light yellow due to its photosensitive color, but after treatment, it transforms into a reddish-brown hue and retains high moisture levels To identify untreated coconut coir fiber powder, some regions employ a soaking method; however, the presence of a red color alone may not guarantee it is untreated, as some untreated powders can also appear brown This variability underscores the importance of standard processing methods for accurate differentiation.
– Qualitative: Untreated coconut coir fiber powders have poor water-holding capacity Treated coconut coir fiber powders have good water-holding capacity
To assess the quality of materials, it's essential to measure EC conductivity and pH levels Untreated types should maintain a moisture content between 45-55%, an electrical conductivity (EC) value exceeding 2.5, and a pH range of 5.5 to 6.5 In contrast, treated types should exhibit higher moisture levels of 70-80%, an EC value of 0.5 or lower, and a pH between 6 and 7.
2.1.5 A process of treating coconut fiber powder [8]
2.1.5.a Why is it necessary to treat coconut coir fiber powder?
Coconut coir fiber powder contains two key chemicals that significantly affect plant growth: Lignin, a robust material soluble only in alkaline conditions, and Tannin, an astringent compound that can dissolve in water, commonly found in tea and coir products.
- Tannin and lignin have a negative influence on plant root metabolism, rendering plants weak As a result, before using coir, Tannin and Lignin must be removed
– Soak raw coconut coir fiber in a container of water for 2-3 days; the amount of water depends on the amount of coir required
After three days, drain the water that has been absorbed by the coconut coir fiber in the barrel; during this period, the water will darken, and the coir fiber will take on a reddish hue.
– To remove tannin, repeat three times
– Prepare a bucket of clean water and pour lime into the water; the amount of lime depends on the amount of coconut coir fiber needed
– Soak the coconut coir fiber that has been separated from the tannin, and stir the coconut coir fiber with the tree
– Soak for 5-7 days to allow the lignin to completely dissolve in water
To effectively remove lignin and lime powder from coir, rinse it thoroughly with clean water For optimal results, soak the coir in clean water for one day, then continue to drain the water daily for the next 3 to 5 days to ensure complete removal of lignin.
- After processing and removing all harmful substances, coconut fiber is squeezed out and dried for use
Introduce plastics
- PE plastic's full name is Polyethylene
Polyethylene (PE) is a popular semi-crystalline plastic widely utilized in the plastics industry due to its excellent chemical resistance, fatigue resistance, and wear resistance It effectively withstands exposure to organic solvents, detergents, grease, and electrolytes, making it a versatile material for various applications.
- Polyethylene is easily distinguished from other plastics because it floats in water
Figure 2.6 Structural formula of Polyethylene [9]
2.2.1.3 Classify Polyethylene: [I] There are 3 types of PE:
LDPE exhibits excellent corrosion resistance and low moisture permeability, making it ideal for applications demanding high durability against corrosion However, it has limitations in hardness, high-temperature resistance, and structural strength.
Polyethylene (PE) is the most commonly used grade due to its excellent impact resistance, lightweight nature, low heat absorption, and high tensile strength High-Density Polyethylene (HDPE) is particularly notable for being non-toxic and non-staining, making it suitable for food processing applications, as it meets FDA and USDA certification standards.
2.2.1.3c.UHMW PE (Ultra High Molecular Weight Polyethylene)
UHMW PE is a lightweight material, weighing only 1/8 of steel, yet it boasts high tensile strength and is easy to machine Its excellent wear resistance makes it ideal for components in machines that experience frequent wear Additionally, UHMW PE is self-lubricating, shatterproof, and resistant to corrosion, making it a versatile choice for various applications.
- UHMW PE, like HDPE, is suitable for use in food and pharmaceuticals due to its ability to withstand high temperatures of up to 1800 °F (820 °C)
Typical LDPE HDPE MHMW PE
(*) - ASTM: ASTM International, is an international standards organization that develops and publishes technical standards for a wide range of materials, products, systems, and services [10]
- UL: Organization of cooperation between laboratories [11]
- Food containers (For HDPE and UHMW PE)
- PP commonly known as Polypropylene
Polypropylene is a versatile thermoplastic polymer widely used across various industries It is produced through chain growth polymerization of polypropylene monomers and falls under the polyvinyl group, characterized by its partially non-polar crystalline structure This white material boasts excellent chemical resistance and mechanical strength, making it an ideal choice for numerous applications.
- Polypropylene has structural formula is (C3H6)n
Figure 2.10 The molecular structure of Polypropylene [15]
Figure 2.12 The basic structural sequence of polypropylene [15]
- Polypropylene can exist in three basic structural chains after polymerization of the polypropylene monomer chain, depending on the position of the methyl groups: + Atactic Polypropylene (aPP): irregular methyl groups
+ Isotactic Polypropylene (iPP): methyl groups arranged on one side of the carbon chain
+ Syndiotactic Polypropylene (SPP): methyl groups arranged alternately
It is the most widely used type It contains polypropylene monomer in a semi- crystalline solid form Major applications include packaging, textiles, healthcare, pipelines, automotive, and electrical applications
Divided into random co-polymers and block co-polymers by protein and ethane polymerization:
Polypropylene Random Copolymer containing up to 6% ethene.These polymers are flexible and optically clear, so they are used for products that require transparency and a good look
Polypropylene Block Copolymer, containing 5 to 15% ethene by mass, offers superior hardness and reduced brittleness compared to Random Co-polymers, making it an ideal choice for high-strength applications.
Test by ASTM or U.L Typical Homopolymer Copolymer
D256 IZOD impact (ft-ln/in) 1.9 7.5
- Polypropylene is widely used in life due to its good chemical resistance and weld ability
- Some common applications of polypropylene:
Polypropylene is an ideal material for product packaging, excelling in blow molding and sheet forming applications for food, medical, and laboratory uses due to its high strength and cost-effectiveness It is also suitable for packaging household chemicals and beauty products.
+ Consumer Goods: Polypropylene is used in a number of household products, including home appliances, furniture, appliances, luggage, toys, and a few other items
Automotive parts manufacturing extensively utilizes materials known for their low cost, excellent mechanical properties, and ease of moldability Key applications include carrying cases, fender liners, automotive interior trim, and dashboards, all of which benefit from superior chemical and weather resistance.
Polypropylene fibers are utilized in the production of raffia films and durable belts, making them ideal for marine applications due to their moisture resistance and high durability.
Polypropylene (PP) is widely utilized in the medical field due to its exceptional chemical and bacterial resistance, making it ideal for applications such as medical vials, diagnostic equipment, intravenous bottles, specimen containers, drug storage, and single-use syringes.
PP sheets are ideal for industrial applications such as acid and chemical tanks and pipelines due to their high tensile strength, excellent temperature resistance, and corrosion resistance.
- PVC commonly known as Polyvinyl Chloride
Polyvinyl Chloride (PVC or Vinyl) is a cost-effective and adaptable thermoplastic polymer widely utilized in the construction sector, as well as in the production of doors, pipes for clean water and wastewater, wire and cable insulation, and medical devices.
PVC is a lightweight and durable white material available in powder or granule form Its low cost and easy machinability make it an ideal alternative to traditional materials like wood, metal, concrete, and rubber in various manufacturing applications.
- Polypropylene has the structural formula (C2H3Cl)n
Figure 2.14 Structure of Polyvinyl Chloride [17]
Figure 2.15 Structure of Polyvinyl Chloride [18]
- There are two types of polyvinyl chloride: flexible and rigid.But there are more types like CPVC, PVC-O, and PVC-M:
2.2.3.3a Flexible PVC (density is 1.1-1.35 g/cm3):
Also known as PVC-P, it is formed by adding compatible plasticizers to PVC to reduce its crystallinity
Called UPVC, PVC-U, or uPVC, it is a cost-effective hard plastic that is resistant to impacts in environments such as water, chemicals, corrosive environments, or extreme weather
+ Chlorinated Polyvinyl Chloride or Perchlorovinyl (CPVC): prepared by chlorinating PVC resin, providing high strength, chemical stability, and fire resistance
+ Molecular-oriented PVC or PVC-O: a layered structure formed by reorganizing the amorphous structure of PVC-U.PVC-O has enhanced physical properties such as stiffness, fatigue resistance, and lightness
+ Modified PVC, or PVC-M: is an alloy of PVC formed when adding modifiers to make PVC-M have enhanced toughness and impact properties
Table 2.3 Typical of Polyvinyl chloride
Test by ASTM or UL Typical PVC CPVC
Table 2.4 Application of Polyvinyl chloride
- ABS is commonly known as Acrylonitrile Butadiene Styrene
- Acrylonitrile Butadiene Styrene is an amorphous polymer and an impact-resistant thermoplastic In nature, it is opaque ABS is made from a combination of 3 monomers: Acrylonitrile, Butadiene and Styrene:
+ Acrylonitrile: a substance derived from propylene and ammonia that improves the chemical and thermal stability of ABS plastic
+ Butadiene: is formed from ethylene production and steam cracking, enhancing the strength and impact resistance of ABS plastic
Application Rigid PVC Flexible PVC
Construct Door frames, pipes, gates, roofs Waterproof membrane, cable insulation, greenhouse
Housewifely Hanging bar, carrying case, video tape Curtains, fabric, plumbing
Pack Water bottle, sachet, blister, transparent package Adhesive film
Transportation Car seat back Leather fabric cover, insulated wire
Medical - Oxygen tank, bag and transfusion tube
Belongings Safety tools Rubber boots, life jackets, waterproof gear for fishermen
Electricity Insulated tubes, switches, plug covers, battery terminals
Insulated wires, cables, sockets, plugs Other Signs, credit cards, … Conveyors, toys, sporting goods
+ Styrene: a byproduct of the modification of ethylbenzene that contributes to the increased hardness and workability of ABS plastic
Figure 2.16 Plastic composition of Acrylonitrile Butadiene Styrene [20]
- Acrylonitrile Butadiene Styrene has the structural formula is (C8H8-C4H6- C3H3N)n
Figure 2.17 Structure of Acrylonitrile Butadiene Styrene [21]
Table 2.5 Typical of Acrylonitrile Butadiene Styrene
ABS plastic is the ideal engineering material for automotive parts manufacturing, thanks to its lightweight nature and favorable mechanical properties Its outstanding impact resistance effectively absorbs and redistributes energy during collisions, making it a safe choice for various applications Common products made from ABS include steering wheel covers, door handles, and seat belts, highlighting its versatility and reliability in the automotive industry.
TYPICAL OF ACRYLONITRILE BUTADIENE STYRENE
- Electricity and electronics applications: commonly used for electrical and electrical appliances in the home that are not exposed to sunlight, such as refrigerator covers and computer keyboards
- Household appliances: used to make many appliances such as vacuum cleaners, shavers, irons, food processors, and many more
- PS plastic full name is Polystyrene
Polystyrene (PS) is a synthetic thermoplastic polymer derived from the monomer styrene, known for its hardness and brittleness It offers excellent electrical insulation and is resistant to gamma radiation, making it a popular choice in the plastic injection industry However, PS has limited resistance to chemicals and UV rays Its transparent properties contribute to its widespread use in toys and household items.
Has lower impact strength and brittleness than HIPS, as well as lower dimensional stability
As its name suggests, HIPS resin has high impact strength and good dimensional stability Used in applications where low temperatures are required due to the ease of thermal profiling
- Low cost, easy to process
- Packing food and kitchen utensils
- Beautiful gloss and easy to paint, paste and print
- Has a natural white color and has a matte finish However, it can still be dyed and glued easily
Figure 2.22 Yogurt lid and box [28] Figure 2.23 Toilet seat [29]
- Has glass-like clarity, so it is popular in transparent food packaging
- Popular in toys, plastic household appliances
Figure 2.25 Refrigerator tray [31] Figure 2.26 Disc box [32]
- PLA commonly known as Polylactic Acid
Introduction to mechanical properties [vi]
According to ISO 527 standard [VI]
- Because of using the direct molding method of plastic sheets, so the size standards are as follows:
+ Test specimen thickness: according to ISO 527-3 (Page 117 [VI]) need to be thicker than 1mm
According to ISO 527-2, there are two types of specimen sizes: type 1A and type 1B Type 1A is designated for direct casting specimens, while type 1B is intended for machined specimens For our study, we utilized the specimen size based on type 1A.
Figure 2.31 Tensile test specimen type 1A
Table 2.9 Dimensions of specimen type 1A
- According to ISO 527-1: at least 5 pieces for tensile
- Reference: electro mechanical gauges and servo hydraulic testers
- According to ISO 527-1 (Page 116 [VI]) we follow these speeds of test:
According to ISO 604 standard [VI]
- The shape of the test piece can be quite different from cross-section and thinness ratio
For accurate compression testing, specimens must have flat and parallel faces, with a parallelism tolerance of 0.025 mm to the long axis It is essential to prepare these specimens using a lathe or milling machine prior to testing.
- Warping is also an important issue that needs attention Short and square specimens will be less to warping than long and thin
According to (page 129 [VI]) we have the following specimen sizes:
Figure 2.32 Specimen of compress Module and compress Strength
- According to ISO 527-1: at least 5 pieces for compress
Reference: INSTRON's "6800 series" or "3400 series"
- The speed is selected from 1, 2, 5, 10 or 20 mm/min, it depend on the nature of the material and the measurement to be taken
For module testing, the optimal speed should be approximately 5% of the specimen length, while for ductile materials, it should be around 50% of the specimen length Therefore, the ideal testing speed for both module testing and tensile testing of ductile materials is 5mm/min.
- According to ISO 178 standard (page 147 [VI])
The thickness tolerance of the test piece does not exceed by more than 2%
The width tolerance on the of the test piece does not exceed by more than 3% The test specimen must have a rectangular cross-sectional shape without rounded edges
If the specimens are deemed unusable, we can implement certain limitations, including a length-to-thickness ratio of 20 (l/h = 20 ± 1) Additionally, the width of the test piece will be specified in the accompanying table.
Table 2.11 Table of values for width b, in thickness h
- According to ISO 178: at least 5 pieces for flexural
- Reference: INSTRON's "6800 series" or "3400 series"
+ The test machine must be able to maintain the test speed as in table 3.4
+ Specimen testing speed is as follows:
Values for width b, in thickness h
Width b ± 0.5 1 (mm) Molding and extrusion compound, thermoplastic and thermosetting sheet
Textiles and plastics reinforced with long fibers
1 For materials with very coarse fillers, the minimum width should be between 20 and 50mm
Table 2.12 Table of recommended values for specimen test rate
+ The requirements for brackets and ledges are arranged as figure *
Figure 2.33 ISO 178 standard test specimen layout
+ The radius R1 of the floating edge and the radius R2 of the supports follow as:
Recommended value for test speed
1 Lowest speed used for specimens with thicknesses from 1mm to 3.5mm
* R2 = 5 mm ± 0.1 mm for specimen thickness > 3 mm
+ The length range L is adjustable
+ In addition, a micrometer and caliper are required to measure
- According to BS EN ISO 179-1 standard [VI] and ASTM D6110 (page 158 [VI])
- There are two basic types of impact testing for plastics:
The test can be conducted with either notched or un-notched specimens, but we will focus on notched specimens due to their prevalence There are three standardized types of notches utilized in this testing process.
+ Preferred type has a notch radius of 0.25 mm (type A)
+ Non-sharp notch type with root radius of 1 mm (type B)
+ Sharp type with root radius of 0.1 mm (type C)
Figure 2.34 Three types of notches in impact test specimens
- According to ISO 527-1: at least 5 pieces for impact
Reference: Cometech's QC-505M2F flexural strength tester series
- The ISO standard stipulates two pendulum lengths, resulting in different velocities at the point of impact
- The type that is frequently used in impact velocity tests is specified with five pendulums having energies of 0.5J, 1J, 2J, 4J and 5J and an impact velocity of 2.9 m/s
- For larger machines, the impact velocity is 3.8 m/s and the pendulums have energies of 7.5J, 15J, 25J, and 50J.
Review
Recycled high-density polyethylene (r-HDPE) composite materials reinforced with Nypa fruticans flower stalk (NFFS) fibers were produced using hot-pressing methods The process began with chemically treating the extracted NFFS fibers, which were then pressed into a random fiber mat HDPE plastic was washed, chopped, and hot-pressed into thin sheets, with the final composite formed by alternating layers of plastic and fiber Structural and compositional analyses of NFFS fibers were conducted using SEM and TGA The study examined the impact of varying NFFS fiber volume ratios on the shrinkage, tensile strength, flexural strength, and impact strength of the composites NFFS fibers, containing 34% cellulose, exhibit a unique arrangement of microfibers and lack large central holes, enhancing their mechanical properties Optimal mechanical performance was achieved at a fiber volume ratio of 60%, resulting in a tensile strength of 45 MPa, flexural strength of 46 MPa, and impact strength of 19 KJ/m².
37 expected, these results are approximately two times higher than those of the composite materials made from coir fibers under the same conditions
The article discusses a method for producing flat sheets, known as MAT plates, from coir fibers, utilizing both adhesive and non-adhesive substrates with composite materials The primary raw materials used are polypropylene and coir fibers, processed using a hot pressure machine that includes a hydraulic press and heating press molds The study analyzes the mechanical properties of the MAT plates, focusing on tensile strength, bending behavior, and impact resistance The findings indicate that the fabrication process is effective, demonstrating that coir MAT plates can be used as a substrate to enhance thermoplastic composites.
The article explores the properties of composite materials made from biodegradable plastic and coir fiber, focusing on research, fabrication, and testing processes Utilizing a pressing method, composites with coir fiber proportions ranging from 10% to 50% are created, and their mechanical properties—including tensile strength, flexural strength, compressive strength, water absorption, and biodegradability—are evaluated in simulated environments Notably, composites containing 10% to 30% coir fiber exhibit superior mechanical properties compared to those with higher fiber content, particularly highlighting that the 30% coir fiber composite strikes an optimal balance between mechanical performance and biodegradability.
Alkali and silane treatments were applied to coir fiber (CF) and coconut shell powder (CSP) surfaces to enhance the reinforcement of vinyl ester (VE) composites Mono-composites of VE incorporating treated CFs and CSP, along with hybrid composites featuring as-received aramid fibers (AFs), were created using hand layup and compression molding techniques The study demonstrated that the surface-treated reinforcements significantly improved the mechanical properties of the composites.
The study reveals significant differences in hardness and tensile properties between VE mono-composites and hybrid reinforcements, with the latter showing no improvement except for Young’s modulus in composites with AFs Notably, surface-treated CFs and CSP-reinforced VE composites exhibited enhanced hardness and tensile properties SEM imaging indicated reduced fiber pull-out in VE reinforced with alkali-treated CFs due to improved adhesion with the VE matrix Although the flexural properties of all composites decreased, the research confirms that modifying reinforcements with alkali and silane can enhance the mechanical properties of hybrid VE composites These findings are supported by structural and morphological analyses based on the fractography of VE composites, highlighting alkali treatment as an effective method for mechanical property enhancement.
This research [45] aimed at the production of reinforced polymer composites from coconut fibers and plastics Coir fiber (CF) sheets with dimensions of 200 x
Natural fibers measuring 200 x 12 mm (3 mm) were combined with a thermosetting plastic or elastomer, specifically unsaturated polyester (UPE) or silicone rubber (SIR), as a binder in the matrix The vacuum infiltration method was employed to ensure the liquid polymer permeated the cellulose structure of the natural fibers, effectively dispersing within the composite matrix The study assessed how various production variables influenced the thermal, acoustic, and flexural properties of the composites Characterization tests indicated that incorporating UPE and SIR significantly enhanced the thermal conductivity of the composites, with UPE also improving the modulus of rupture Additionally, the CF/SIR composites exhibited remarkable ductility, and analysis of their sound absorption capabilities revealed a notable noise reduction coefficient (NRC) for the CF/400 wt composites.
% SIR composite was the highest Moreover, the CF/SIR composites showed higher sound absorption efficiency () values at high frequencies than the CF/UPE
This study demonstrates that coconut husk waste can be effectively utilized to create reinforced polymer composites that exhibit favorable thermal conductivity and sound absorption properties Notably, the addition of polymers at a low concentration (200 wt%) did not impact the noise reduction coefficient (NRC) of the neat carbon fibers (CFs).
The study in Project [46] investigates the mechanical and wear behavior of inorganic particle-filled polymers, specifically focusing on epoxy matrices with varying ratios of solid glass microspheres (SGM) ranging from 0 to 30 wt% Through a mechanical stirring process, the composites were fabricated, and their bending strength, compression strength, and compression modulus were assessed based on the SGM weight percentage Additionally, the wear resistance of these composites was tested against an EN-32 steel disk using a pin-on-disk test rig, measuring mass loss across different SGM ratios The findings revealed that incorporating an appropriate percentage of SGM significantly enhanced the mechanical and wear properties of the composites, while also leading to an increase in density as the SGM content rose.
The research aims to experimentally determine key mechanical characteristics of RTM hemp plain weave fabrics and epoxy laminates, with a focus on the RTM process improvement, preliminary tensile and fracture toughness tests, and impact performance The study critically discusses the equipment and test methods used, emphasizing the significant influence of the process on the mechanical performance of natural long fiber-reinforced composites Additionally, it analyzes low-velocity impact behavior, which is crucial for future aeronautical applications, ensuring that composite structures maintain adequate residual compression properties (CAI: Compression After Impact) following barely visible impact damage (BVID).
[48] The world is now concentrating on alternate material sources that are environment-friendly and recyclable in nature Because of the growing natural
Bio composites made from natural fibers and polymeric resin represent a significant advancement in engineering, particularly in the growing use of composite materials These composites consist of two main components: the matrix and the fiber The accessibility of cost-effective fibers has encouraged global inventors to explore their potential in structural applications Fiber-reinforced polymer composites offer numerous benefits, including lower production costs, ease of manufacturing, and improved strength compared to pure polymers, making them a preferred choice in various construction applications The demand for advanced materials is particularly high in the aerospace, automotive, and aircraft industries Recently, natural fibers have gained attention for their advantages over traditional reinforcement materials, leading to increased interest in biofiber composites This study specifically examines the production of banana fiber/epoxy resin composites at volume fractions of 30%, 40%, and 50%, along with different fiber orientations (0°, 45°, and 90°).
The increasing use of composite materials, known for their superior mechanical properties, is influenced by various factors, particularly the reinforcement content in the form of fibers and particle powder However, previous studies have overlooked the impact of hardener weight fraction on the mechanical properties of resin composite materials Given that the hardener plays a crucial role in determining these properties, this study aims to explore the optimal composition of reinforcing content and hardener fraction to achieve desired mechanical characteristics.
This study investigates the effect of varying weight fractions of coconut fiber powder on the mechanical properties of EPR-174 epoxy resin matrix composites Three levels of fiber powder content (6%, 8%, and 10%) and three levels of hardener fraction (0.4, 0.5, and 0.6) were tested Results indicated that pure resin exhibited the lowest impact strength of 1.37 kJ/m², while the composite with 6% fiber powder content achieved the highest impact strength of 4.92 kJ/m² The optimal hardener fraction for impact strength was found to be 0.5, yielding 4.55 kJ/m² Additionally, an 8% fiber powder content resulted in the highest shear strength of 1.00 MPa, with a hardener fraction of 0.6 providing the maximum shear strength of 2.03 MPa.
Kinds of ratios between Epoxy and Hardener
Based on research [49]: SINERGI Vol 25, No 3, October 2021: 361-370
We divided into 5 types of ratio between Epoxy and Hardener:
Figure 2.35 Procedure for testing harden when combining epoxy and Hardener ratios
Table 2.13 Procedure for testing harden when combining epoxy and Hardener ratios
Temperature conditions
In the specimen manufacturing process, temperature plays a crucial role as it significantly influences the hardness time of the samples This study investigates two temperature conditions: one at 60°C and the other at a standard room temperature of 25-30°C The tensile strength of the specimens was tested under both conditions, allowing for a comparative analysis of their mechanical properties.
Figure 2.36 The process of case 1
Table 2.14 The process of case 1
Previous findings indicate that the remaining ratios of epoxy resin and hardener can effectively harden when mixed Consequently, we incorporated coconut coir fiber powder into the formulation to enhance its properties.
With: - 3E: is the ratio of Epoxy resin
- cP: is the ratio of coir flour, we replace it with 6%, 8%, and 10%, respectively
This study examines the effects of varying the coefficient of 3E by substituting b values of 1, 1.5, and 2, alongside c values of 6%, 8%, and 10% The primary focus is to evaluate whether these mixtures can successfully harden when coconut coir fiber is added.
Figure 2.37 The process of case 2
Table 2.15 The process of case 2
The number of layer Epoxy Hardener CCFP
Informed by the experiment detailed in the scientific article [49], we proposed hypothesis 2, utilizing a testing temperature of 60°C while maintaining the same component ratios as in hypothesis 1 The increased temperature resulted in a quicker hardening time, prompting the introduction of layered samples to ensure an even distribution of coconut fiber components This variation in the number of layers may influence the mechanical properties, potentially yielding the most reliable results.
Component ratio
According to ISO 527-1: at least 5 pieces
Table 2.16 Number of specimens required for case 1 (25-30˚C)
Table 2.17 Number of specimens required for case 2 (temperature 60˚C)
Thus, the total of test specimens to be obtained in both cases is 210 specimens
2.7.2 Volume required for one pour
Volume of one specimen: 10 ml
Volume of one set of molds (x5 specimens): 50 ml
2.7.2a Specimens without coconut coir fiber powder
Ratio of Epoxy Resin + Hardener: 3:1 ̴ 75% : 25%
2.7.2b Specimens with coconut coir fiber powder
Ratio of Epoxy Resin + Hardener: 3:1 ̴ 75% : 25%
Ratio of coconut coir fiber powder: 10%
→ From the above calculation method, we get the following statistical table:
Table 2.18 Necessary volume for mold pouring
Mold for testing specimens
The tensile sample must adhere to the ISO 527-2 standard for size and the ISO 527-3 standard for thickness, with Type 1A samples being chosen Consequently, it is essential to design and process the tensile sample mold to fulfill the necessary conditions for sample creation.
Inox 201 is part of the austenitic family of stainless steels, which includes around 200 types It is characterized by its higher manganese and nitrogen content, along with a significantly reduced nickel content This unique composition gives Inox 201 distinct advantages over other stainless steel types, although it also presents certain drawbacks.
Table 2.19 Chemical composition of Inox 201
- The outstanding Feature of stainless steel 201 (Stainless steel 201) is high strength, heat resistance, and corrosion resistance
- As a well-formed material, it is possible to use cutting or welding processing methods on this material
Stainless steel 201, with its high manganese content and lower nickel ratio compared to 304 and 316 stainless steel, is more prone to rusting However, it offers superior oxidation resistance and durability when compared to materials like steel or aluminum.
- The melting point of stainless steel 201 is in the range of 1400-1450˚C
Introduce the wire EDM method
The wire EDM (Electrical Discharge Machining) method was selected for processing due to its effectiveness in utilizing an electrode to discharge electric sparks for metal shaping This approach is particularly advantageous for the author's group, as it aligns perfectly with their design requirements and effectively accommodates size variations in the components.
- Disadvantages: High cost, time-consuming processing
Fe Cr Mn Ni N Si C
Figure 2.38 AccuteX Wire Cutting Machine
Use Mastercam software to operate the machine
Material composition
Ultra Clear Crystal ABEPOXY Resin is produced in Vietnam with minimal shrinkage
Figure 2.39 Epoxy Resin Figure 2.40 Hardener
Coconut coir fiber powder has been processed with a moisture content of 1-3%
Figure 2.41 Coconut coir fiber powder
Introduce the INSTRON 3367 machine
The INSTRON 3367 is a displacement-controlled load frame featuring a screw mechanism for raising and lowering the slider Its load frame is uniquely designed in an H shape, which contributes to its stability and functionality The following is an overview of the machine's components.
(A) Slide frame: The part of the load frame that moves up and down during tensile testing or moves down during compression testing
A load cell is a measuring transducer designed to handle loads up to a maximum of 30 kN Additionally, the sample clamp serves to securely hold the sample during testing and is available in various shapes and sizes to accommodate different testing requirements.
(D) Upper and lower limit switches: The limit switches for the maximum height that the crosshead is allowed to move during testing
The manual up/down switch allows users to control the movement of the crosshead, enabling it to move up and down according to their preferences However, it is important to note that this switch functions only when the accompanying software is active on the computer; using it without the software may lead to machine locking issues.
EXPERIMENTAL TENSILE TEST
The result of hardeness
After experiment on pouring and evaluating the hardness between Epoxy resin and Hardener, we found that:
- 2/5 ratios: 0.4 and 0.5 Hardener combined with Epoxy resin according to article
[49] could NOT HARDEN In contrast, with a ratio of 0.6 Hardener is able to harden
- Reason: The Epoxy component in the article [49] and the Epoxy in Vietnam are different When combined with the same amount of Hardener, they will produce different results.
Mold for testing specimens
Using metal materials to make test molds Specifically, stainless steel 201
Using an electrode to discharge an electric spark to process metal
Figure 3.4 Using electrode to cut metal Figure 3.5 Finished mold
Specimen Making Process
Step 1: Preparing the mold release agent
- At this step, we used machine oil as the mold release agent
Step 2: Apply a sufficient amount of mold release agent onto the surface in contact with the base plate
Step 3: Apply it onto the edge surface
Step 4: Fix the mold onto the base plate
In this step, we used hot glue to fix the mold and the base plate together
Proceed to withdraw the Epoxy, Hardener, and coconut fiber according to the calculated volume
Step 6: The amount of coconut fiber after taking will be poured into a container
Step 7: Next, the amount of Epoxy resin is poured in until the calculated ratio is reached
Step 8: Finally, the calculated amount of Hardener is poured into the mixture
Step 9: Stir the mixture in a specific direction Stir until all the air bubbles disappear
Step 10: Pouring the mixture after stirring into the mold
Step 11: Perform the hardeness process in 2 cases
According to case 1 (in room temperature): Put the mold into a fixed position and watch the curing process and remove the specimen.
According to case 2 (in 60˚C): The mold is moved into a Dryer Then, waiting for the specimen to harden, take the mold from the dryer and remove the specimen
- All cases of sample ratios, both with and without fiber, are completely solidified
- In all cases, the proportions of fibrous and non-fibrous specimens were completely hardened
- Therefore, the time required to solidify the sample at 60°C is much less than in case 1
The number of layers in a project significantly affects the overall time required for completion, as each layer must show signs of solidification before the next one can be poured.
* Note on specimens naming convention::
- The numbers are signed to distinguish the ratios from each other abc
+ a is the ratio of Epoxy Resin
+ b is the ratio of Hardener
+ c is the ratio of coconut coir fiber powder
Figure 3.6 Ratio 3:1 and coconut coir fiber powder
Figure 3.7 Ratio 3:1.5 and coconut coir fiber powder
Figure 3.8 Ratio 3:2 and coconut coir fiber powder
Figure 3.9 3:1:1 ratio and number of layers
Figure 3.10 3:1:0.8 ratio and number of layers
Figure 3.11 3:1:0.6 ratio and number of layers
Figure 3.12 3:1.5:1 ratio and number of layers
Figure 3.13 3:1.5:0.8 ratio and number of layers
Figure 3.14 3:1.5:0.6 ratio and number of layers
Figure 3.15 3:2:1 ratio and number of layers
Figure 3.16 3:2:0.8 ratio and number of layers
Figure 3.17 3:2:0.6 ratio and number of layers
Tensile Strength
Tensile testing machine INSTRON series 3367
3.4.3.1 Density of coconut coir fiber powder in the specimen
Figure 3.18 SEM micrographs of a specimen
Comment: The density of coconut fiber particles in the sample is relatively evenly distributed Along with that are defects such as air bubbles and voids caused by breakage
- A: Empty spaces where coconut fiber particles are located
- B: The area has been stretched and torn
3.4.3.2 The tensile strength of the specimen at 60˚C
The ratio of 310 is used as a standard for comparison with samples containing coconut coir fiber powder:
The force value of 3:1:0 = 92,2 (kgf)
Figure 3.19 Force value chart of specimen in ratio 3E:1H (60˚C)
+ Specimen with 10% coconut coir fiber powder:
Table 3.2 3:1 force value with 10% coconut coir fiber powder
→ Comment: the results show that with 10% coconut coir fiber powder, combined with 3E:1H, then:
Layer most durable: 3 layers (152.4 kgf > 92.2 kgf)
Layer least durable: 2 layers (56.7 kgf < 92.2 kgf)
+ Specimen with 8% coconut coir fiber powder:
Table 3.3 3:1 force value with 8% coconut coir fiber powder
→ Comment: From the results show that with 8% coconut coir fiber powder, combined with 3E:1H, then:
Layer most durable: 2 layers (131.1 kgf > 92.2 kgf)
Specimen without coconut coir fiber powder is least durable
+ Specimen with 6% coconut coir fiber powder:
Table 3.4 3:1 force value with 6% coconut coir fiber powder
→ Comment: the results show that with 6% coconut coir fiber powder, combined with 3E:1H, then:
Layer most durable: 2 layers (158.7 kgf > 92.2 kgf)
Specimen without coconut coir fiber powder is least durable
The ratio of 31.50 is used as a standard for comparison with samples containing coconut coir fiber powder:
The force value of 3:1.5:0 = 42,5 (kgf)
Figure 3.20 Force value chart of specimen in ratio 3E:1.5H (60˚C)
+ Specimen with 10% coconut coir fiber powder:
Table 3.6 3:1.5 force value with 10% coconut coir fiber powder
→ Comment: the results show that with 10% coconut coir fiber powder, combined with 3E:1.5H, then:
Layer most durable: 1 layer (50.9 kgf > 42.5 kgf)
Layer least durable: 2 layers (37.4 kgf < 42.5 kgf)
+ Specimen with 8% coconut coir fiber powder:
Table 3.7 3:1.5 force value with 8% coconut coir fiber powder
→ Comment: From the results show that with 8% coconut coir fiber powder, combined with 3E:1.5H, then:
Layer most durable: 2 layers (59.4 kgf > 42.5 kgf)
Layer least durable: 1 layer (27.5 kgf < 42.5 kgf)
+ Specimen with 6% coconut coir fiber powder:
Table 3.8 3:1.5 force value parameter with 6% coconut coir fiber powder 31.50 = 42.5 (kgf) Strength (kgf) Compare
→ Comment: the results show that with 6% coconut coir fiber powder, combined with 3E:1.5H, then:
Layer most durable: 2 layers (81.4 kgf > 42.5 kgf)
Specimen without coconut coir fiber powder is least durable
The ratio of 320 is used as a standard for comparison with samples containing coconut fiber:
The force value of 3:2:0 = 4.4 (kgf)
Figure 3.21 Force value chart of specimen in ratio 3E:2H (60˚C)
+ Specimen with 10% coconut coir fiber powder:
Table 3.10 3:2 force value with 10% coconut coir fiber powder
→ Comment: the results show that with 10% coconut coir fiber powder, combined with 3E:2H, then:
Layer most durable: 3 layers (7.7 kgf > 4.4 kgf)
Layer least durable: 2 layers (4.1 kgf < 4.4 kgf)
+ Specimen with 8% coconut coir fiber powder:
Table 3.11 3:2 force value with 8% coconut coir fiber powder
→ Comment: the results show that with 8% coconut coir fiber powder, combined with 3E:2H, then:
Layer most durable: 3 layers (16.2 kgf > 4.4 kgf)
Specimen without coconut coir fiber powder is least durable
+ Specimen with 6% coconut coir fiber powder:
Table 3.12 3:2 force value parameter with 6% coconut coir fiber powder
→ Comment: the results show that with 6% coconut coir fiber powder, combined with 3E:2H, then:
Layer most durable: 3 layers (9.9 kgf > 4.4 kgf)
Layer least durable: 2 layers (2.8 kgf < 4.4 kgf)
In our study, the optimal tensile strength was achieved with a mixture of 6% coconut fiber powder, epoxy, and hardener, surpassing the performance of specimens with 8% and 10% fiber ratios.
- About the number of layers:
+ For the ratio 3E:1H and 3E:1.5H, the number of layers is 2 with higher strength than 3E:2H with the same number of layers
+ The 3E:2H ratio is the opposite Due to the nature of the sample being more flexible than the two ratios mentioned above Therefore, it yields the same result of
3 layers with the highest strength
• With the ratio of 3E:1H and 3E:1.5H combined with 6% coconut fiber - 2 layers give the best tensile strength
• On the contrary, with the ratio of 3E:2H, all ratios of 2 layers are the least durable
3.4.3.3 The tensile strength of the specimen at 25-30˚C
The ratio of 310 was used as a standard to compare with samples containing coconut fiber powder:
The force value of 3:1:0 = 214 (kgf)
Figure 3.22 Force value chart of specimen in ratio 3E:1H (25-30˚C)
Table 3.14 3:1 force value with 10%,8% and 6% coconut coir fiber powder
→ Comment: the results show that with ratio coconut coir fiber powder, combined with 3E:1H, then:
Specimen without coconut coir fiber powder is most durable (214 kgf)
Ratio 311 is least durable (89.5 kgf < 214kgf)
The ratio of 31.50 was used as a standard to compare with samples containing coconut fiber powder:
The force value of 3:1.5:0 = 72.1 (kgf)
Figure 3.23 Force value chart of specimen in ratio 3E:1.5H (25-30˚C)
Table 3.16 3:1.5 force value with 10%, 8% and 6% coconut coir fiber powder
→ Comment: the results show that with ratio coconut coir fiber powder, combined with 3E:1.5H, then:
The specimen with 10% fiber content has the highest tensile strength (72.4 kgf), which is only 0.3 kgf higher than that of the specimen without fiber
Ratio 31.50.8 least durable (51.2 kgf < 72.1 kgf)
The ratio of 31.50 was used as a standard to compare with samples containing coconut fiber powder:
The force value of 3:2:0 = 4.7 (kgf)
Figure 3.24 Force value chart of specimen in ratio 3E:2H (25-30˚C)
Table 3.18 3:2 force value with 10%,8% and 6% coconut coir fiber powder
→ Comment: the results show that with ratio coconut coir fiber powder, combined with 3E:2H, then:
Specimen without coconut coir fiber powder is most durable (4.7 kgf)
Ratio 311 is least durable (3.6 kgf < 4.7kgf)
At room temperature, the results of the specimen's strength are relatively different from using a temperature of 60°C Specifically:
+ The specimen without fiber at a temperature of 25-30°C has the highest strength compared to specimens with coconut fiber
+ The 3E:1.5H ratio specimens at a temperature of 25-30°C are more durable than the specimens at a temperature of 60°C with the same number of layers
+ The 3E:2H ratio specimens at a temperature of 25-30°C are less durable than the specimens at a temperature of 60°C with the same number of layers
Thus: The coconut coir fiber powder composition is not optimal when added at this temperature
Compare tensile strength of specimen at ratios with 2 temperature conditions: Table 3.19 Compare force value between 1-layer specimen ratio at 60˚C and 25-
CONCLUSION AND FUTURE WORK
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[II] LAMINATED PLASTICS – Technical data sheet polyepropylene
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[IV] LAMINATED PLASTICS – Technical data sheet acrylonitrile butadiene styrene
[V] LAMINATED PLASTICS – Technical data sheet high impact polystyrene [VI] Handbook of Polymer Testing
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