Fiber Reinforced Polymer Composites: Mechanical Properties and Applications

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Composites and Nanocomposites".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 30163

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Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
Interests: natural fibre composites; material selection; biobased packaging
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School of Mechanical and Manufacturing Engineering, Supmeca-Paris, 3 rue Fernand Hainaut, 93400 Saint Ouen, France
Interests: advanced manufacturing processes (sinter forging, thixoforming); damage mechanisms of materials (metallic, intermetallic, rubber and epoxy-based composites); design of new composites and damage characterization; design and manufacturing of recycled constituent composites
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Centre for Advanced Composite Materials (CACM), Faculty of Engineering, Universiti Teknologi Malaysia (UTM), Johor Bahru 81310, Johor, Malaysia
Interests: composites materials; structures; composites structure durability; recycling composites; biomimetics design; composites testing; natural fibre composites; hybrid composites; composites bonding; polymer mortar composites
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Department of Rubber Technology and Polymer Science, Faculty of Science and Technology, Prince of Songkla University, Pattani Campus, Muang, Thailand
Interests: rubber recycling; rubber nanocomposites; rubber products

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Department of Materials, School of Engineering and Technology, National Textile University, Faisalabad, Pakistan
Interests: composites joining, natural fibers, biopolymers, green composites

Special Issue Information

Dear Colleagues,

Composites have been discovered to be the most promising material available in the twenty-first century. Composites reinforced with synthetic or natural fibers are becoming extremely prevalent as the market grows in demand for lightweight materials with high strength for specific applications. Not only does fiber-reinforced polymer composite have a high strength-to-weight ratio, but it also has excellent properties such as high durability, stiffness, damping property, flexural strength, and resistance to corrosion, wear, impact, and fire. Various properties of composites materials have led to applications in construction, aerospace, automobile, biomedical, marine, and many other industries. Because the performance of composite materials is primarily determined by their constituent elements and manufacturing techniques, the functional properties of various fibers available worldwide, their classifications, and the manufacturing techniques used to fabricate the composite materials must be investigated.

Dr. Rushdan Ahmad Ilyas 
Prof. Dr. Salit Mohd Sapuan
Prof. Dr. Emin Bayraktar
Dr. Shukur Abu Hassan
Dr. Nabil Hayeemasae
Dr. Khubab Shaker
Guest Editors

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Keywords

  • fiber
  • natural fiber
  • polymer
  • polymer composites
  • biocomposites
  • mechanical properties
  • green material
  • sustainability material

Published Papers (14 papers)

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Editorial

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6 pages, 1511 KiB  
Editorial
Fibre-Reinforced Polymer Composites: Mechanical Properties and Applications
by R. A. Ilyas, S. M. Sapuan, Emin Bayraktar, Shukur Abu Hassan, Nabil Hayeemasae, M. S. N. Atikah and Khubab Shaker
Polymers 2022, 14(18), 3732; https://doi.org/10.3390/polym14183732 - 7 Sep 2022
Cited by 3 | Viewed by 3368
Abstract
"Fibre-Reinforced Polymer Composites: Mechanical Properties and Applications" is a newly open Special Issue of Polymers, which aims to publish original and review papers on new scientific and applied research and make boundless contributions to the finding and understanding of the reinforcing effects [...] Read more.
"Fibre-Reinforced Polymer Composites: Mechanical Properties and Applications" is a newly open Special Issue of Polymers, which aims to publish original and review papers on new scientific and applied research and make boundless contributions to the finding and understanding of the reinforcing effects of various synthetic and natural fibres on the performance of biopolymer composites [...] Full article

Research

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11 pages, 1211 KiB  
Article
Evaluation of the Shear Bond Strength of Immediate and Delayed Restorations of Various Calcium Silicate-Based Materials with Fiber-Reinforced Composite Resin Materials
by Merve Candan, Fatıma Kübra Altinay Karaca and Fatih Öznurhan
Polymers 2023, 15(19), 3971; https://doi.org/10.3390/polym15193971 - 2 Oct 2023
Cited by 1 | Viewed by 1062
Abstract
Due to significant tissue loss in teeth requiring pulp treatments, hermetic restoration of the remaining dental tissues is one of the most crucial factors in determining the treatment’s success. The adhesion of composite resins to calcium silicate cements (CSCs) is considered challenging. Consequently, [...] Read more.
Due to significant tissue loss in teeth requiring pulp treatments, hermetic restoration of the remaining dental tissues is one of the most crucial factors in determining the treatment’s success. The adhesion of composite resins to calcium silicate cements (CSCs) is considered challenging. Consequently, it is crucial to identify the optimal method for obtaining optimal adhesion. The aim of the present study is to evaluate the shear bond strength (SBS) values of immediate and delayed restorations with fiber-reinforced composites on powder–liquid, premixed, and resin-containing flowable CSCs. In the present study, the SBS values obtained after immediate (14 min) and delayed (7 days) restorations of three different CSCs (NeoMTA2, NeoPutty, and TheraCal PT) with three different resin composite materials (EverX FlowTM, EverX PosteriorTM, and Filtek Z550) were compared. The fracture types were evaluated using a stereomicroscope and SEM. TheraCal PT had the highest SBS values for both immediate and delayed restorations, and the comparison with other materials showed a statistically significant difference (p = 0.001). In contrast, there was no statistically significant difference between the SBS values of NeoMTA and NeoPutty (p > 0.05). In both immediate and delayed restorations, there was no statistically significant difference between nanohybrid and fiber-reinforced composites (p > 0.05). The simple use and strong bonding ability of TheraCal PT with composite resins may provide support for the idea that it is suitable for pulpal interventions. Nevertheless, due to the in vitro nature of this study, additional in vitro and clinical studies are required to investigate the material’s physical, mechanical, and biological properties for use in clinical applications. Full article
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15 pages, 3365 KiB  
Article
An Experimental Study on Drilling Behavior of Silane-Treated Cotton/Bamboo Woven Hybrid Fiber Reinforced Epoxy Polymer Composites
by Karthik Aruchamy, Sathish Kumar Palaniappan, Rajeshkumar Lakshminarasimhan, Bhuvaneshwaran Mylsamy, Satish Kumar Dharmalingam, Nimel Sworna Ross and Sampath Pavayee Subramani
Polymers 2023, 15(14), 3075; https://doi.org/10.3390/polym15143075 - 18 Jul 2023
Cited by 10 | Viewed by 1327
Abstract
Machining is considered to be an important post-manufacturing process. Evaluation of machinability of natural-fiber-reinforced composites is important owing to its wide application spectrum. Current experiments focus on the drilling parameters of cotton/bamboo woven fabric reinforced epoxy composites laminates using a solid twist drill. [...] Read more.
Machining is considered to be an important post-manufacturing process. Evaluation of machinability of natural-fiber-reinforced composites is important owing to its wide application spectrum. Current experiments focus on the drilling parameters of cotton/bamboo woven fabric reinforced epoxy composites laminates using a solid twist drill. Composites were manufactured with 45 wt.% cotton/bamboo woven fabric in epoxy resin using a compression molding method. Drilling experiments were carried out in pillar-type drilling machine and the drilling characteristics, such as thrust force, were analyzed using four process parameters like spindle speed, feed rate, drill diameter, and silane-treated fabric. Drilling experiments were carried out using the Box–Behnken Experimental Design, and the recommended drilling characteristics were analyzed using quadratic models based on response surface methodology. It was observed from the results that the thrust force is low with small drill-bit diameter, higher cutting speed, and lower feed rate, according to the response surface analysis. Surface morphology of the drilled hole suggested that a better quality of hole can be obtained at lower feed rates. Full article
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14 pages, 1970 KiB  
Article
Effect of Cymbopogan citratus Fibre on Physical and Impact Properties of Thermoplastic Cassava Starch/Palm Wax Composites
by Zatil Hafila Kamaruddin, Ridhwan Jumaidin, Zatil Hazrati Kamaruddin, Muhammad Rizal Muhammad Asyraf, Muhammad Rizal Razman and Tabrej Khan
Polymers 2023, 15(10), 2364; https://doi.org/10.3390/polym15102364 - 18 May 2023
Cited by 5 | Viewed by 1507
Abstract
Cymbopogan citratus fibre (CCF) is an agricultural waste plant derived from a natural cellulosic source of fibre that can be used in various bio-material applications. This paper beneficially prepared thermoplastic cassava starch/palm wax blends incorporated with Cymbopogan citratus fibre (TCPS/PW/CCF) bio-composites at different [...] Read more.
Cymbopogan citratus fibre (CCF) is an agricultural waste plant derived from a natural cellulosic source of fibre that can be used in various bio-material applications. This paper beneficially prepared thermoplastic cassava starch/palm wax blends incorporated with Cymbopogan citratus fibre (TCPS/PW/CCF) bio-composites at different CCF concentrations of 0, 10, 20, 30, 40, 50 and 60 wt%. In contrast, palm wax loading remained constant at 5 wt% concentration using the hot moulding compression method. TCPS/PW/CCF bio-composites were characterised in the present paper via their physical and impact properties. The addition of CCF significantly improved impact strength by 50.65% until 50 wt% CCF loading. Furthermore, it was observed that the inclusion of CCF resulted in a little decrement in biocomposite solubility compared to neat TPCS/PW biocomposite from 28.68% to 16.76%. Water absorption showed higher water resistance in the composites incorporating 60 wt.% fibre loading. The TPCS/PW/CCF biocomposites with different fibre contents had 11.04–5.65% moisture content, which was lower than the control biocomposite. The thickness of all samples decreased gradually with increasing fibre content. Overall, these findings provide evidence that CCF waste can be utilised as a high-quality filler in biocomposites due to its diverse characteristics, including improving the properties of biocomposites and strengthening their structural integrity. Full article
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17 pages, 36943 KiB  
Article
Fiber Orientation and Strain Rate-Dependent Tensile and Compressive Behavior of Injection Molded Polyamide-6 Reinforced with 20% Short Carbon Fiber
by Joonhee Lee, Hyungyil Lee and Naksoo Kim
Polymers 2023, 15(3), 738; https://doi.org/10.3390/polym15030738 - 31 Jan 2023
Cited by 4 | Viewed by 2135
Abstract
As the interest in short-fiber reinforced polymer (SFRP) composites manufactured by injection molding increases, predicting the failure of SFRP structures becomes important. This study aims to systemize the prediction of failure of SFRP through mechanical property evaluation considering the anisotropy and strain rate [...] Read more.
As the interest in short-fiber reinforced polymer (SFRP) composites manufactured by injection molding increases, predicting the failure of SFRP structures becomes important. This study aims to systemize the prediction of failure of SFRP through mechanical property evaluation considering the anisotropy and strain rate dependency. To characterize the mechanical properties of polyamide-6 reinforced with carbon fiber of a weight fraction of 20% (PA6-20CF), tensile and compressive experiments were conducted with different load-applying directions and strain rates. Additionally, the results were discussed in detail by SEM image analysis of the fracture faces of the specimen. FE simulations based on the experimental condition were constructed, and the numerical model coefficients were derived through comparison with experimental results. The coefficients obtained were verified by bending tests of the specimens manufactured from composite cross members fabricated by injection molding. Predicting under static and high strain rate conditions, small errors of about 9.6% and 9.3% were shown, respectively. As a result, it proves that explained procedures allow for better failure prediction and for contribution to the systematization of structural design. Full article
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12 pages, 2501 KiB  
Article
High-Efficiency Carbon Fiber Recovery Method and Characterization of Carbon FIBER-Reinforced Epoxy/4,4′-Diaminodiphenyl Sulfone Composites
by Yong-Min Lee, Kwan-Woo Kim and Byung-Joo Kim
Polymers 2022, 14(23), 5304; https://doi.org/10.3390/polym14235304 - 4 Dec 2022
Cited by 2 | Viewed by 2352
Abstract
Globally, the demand for carbon fiber-reinforced thermosetting plastics for various applications is increasing. As a result, the amount of waste from CFRPs is increasing every year, and the EU Council recommends recycling and reuse of CFRPs. Epoxy resin (EP) is used as a [...] Read more.
Globally, the demand for carbon fiber-reinforced thermosetting plastics for various applications is increasing. As a result, the amount of waste from CFRPs is increasing every year, and the EU Council recommends recycling and reuse of CFRPs. Epoxy resin (EP) is used as a matrix for CFRPs, and amine hardeners are mainly used. However, no research has been conducted on recycling EP/4,4’-diaminodiphenyl sulfone (DDS)-based CFRP. In this study, the effect of steam and air pyrolysis conditions on the mechanical properties of re-cycled carbon fiber (r-CF) recovered from carbon fiber-reinforced thermosetting (epoxy/4,4′-diaminodiphenyl sulfone) plastics (CFRPs) was investigated. Steam pyrolysis enhanced resin degradation relative to N2. The tensile strength of the recovered r-CF was reduced by up to 35.12% due to oxidation by steam or air. However, the interfacial shear strength (IFSS) tended to increase by 9.18%, which is considered to be due to the increase in functional groups containing oxygen atoms and the roughness of the surface due to oxidation. The recycling of CFRP in both a steam and an air atmosphere caused a decrease in the tensile strength of r-CF. However, they were effective methods to recover r-CF that had a clean surface and increased IFSS. Full article
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22 pages, 16444 KiB  
Article
Ballistic Limit of UHMWPE Composite Armor under Impact of Ogive-Nose Projectile
by Li Ding, Xiaohui Gu, Peihui Shen and Xiangsheng Kong
Polymers 2022, 14(22), 4866; https://doi.org/10.3390/polym14224866 - 11 Nov 2022
Cited by 2 | Viewed by 3941
Abstract
The ballistic response of armor has been widely used to evaluate its feasibility and advantages as a protective structure. To obtain the ballistic performance and ballistic limitations of composite armor, a type of ultra–high molecular weight polyethylene (UHMWPE) composite armor is designed, which [...] Read more.
The ballistic response of armor has been widely used to evaluate its feasibility and advantages as a protective structure. To obtain the ballistic performance and ballistic limitations of composite armor, a type of ultra–high molecular weight polyethylene (UHMWPE) composite armor is designed, which is composed of UHMWPE laminates and steel face sheets of Q235. The total thickness of the armor is 53 mm, with an in–plane dimension of 300 mm × 300 mm. Then, an experimental study of the ballistic impact response of composite armor subject to a typical ogive–nose projectile was carried out. In the velocity range of 501.1 to 1026.1 m/s, the 14.5 mm caliber armor–piercing projectile could penetrate through the composite armor. At the velocity of 433.3 m/s, the A–P projectile was embedded in the armor, leaving a bulge mark on the back sheet. Therefore, 467.2 m/s is taken as the ballistic limit of the armor under the impact of the ogive–nose projectile. In addition, a corresponding numerical simulation model is also established to predict the ballistic limit of the projectile. The numerical predictions are consistent with the experimental results. The ballistic limit obtained from the numerical simulation results is 500 m/s, which is acceptable with a relative error of 7.02%. The failure mechanism of the composite armor is also obtained. Petaling is the main dominant failure mode for both face sheets, while delamination and shear failure dominate the penetration process of UHMWPE laminates. Finally, the perforation mechanism of composite armor under the impact of an A–P projectile is analyzed with theoretical models to predict the residual velocity, the work performed during the perforation, and the resisting stress of σs in the cavity–expansion model. The experimental and numerical simulation results can provide necessary data in the analysis of the composite structure’s dynamic response under the impact of sharp head penetrators. The research results present the ballistic performance, failure mechanism, and ballistic limit of the composite armor under the impact of a typical ogive–nose projectile, which can be significant in the design of composite armor in the areas of ship shield, fortifications protection, and bulletproof structures against threats from sharp head penetrators. Full article
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16 pages, 1812 KiB  
Article
Thermal Effects on Mechanical Strength of Additive Manufactured CFRP Composites at Stable and Cyclic Temperature
by Isyna Izzal Muna, Magdalena Mieloszyk, Ruta Rimasauskiene, Nabeel Maqsood and Marius Rimasauskas
Polymers 2022, 14(21), 4680; https://doi.org/10.3390/polym14214680 - 2 Nov 2022
Cited by 7 | Viewed by 1834
Abstract
Additive manufacturing (AM) techniques can be applied to produce carbon-fiber-reinforced polymer (CFRP) elements. Such elements can be exposed to different environmental factors, e.g., temperature, moisture, and UV radiation, related to their operational conditions. From a variety of environmental factors, the temperature is one [...] Read more.
Additive manufacturing (AM) techniques can be applied to produce carbon-fiber-reinforced polymer (CFRP) elements. Such elements can be exposed to different environmental factors, e.g., temperature, moisture, and UV radiation, related to their operational conditions. From a variety of environmental factors, the temperature is one of the most typical. Temperature strongly influences matrix material joining together CFRP components, resulting in material strength reduction. Therefore, it is important to understand processes in the composite material caused by temperature. This experimental work investigated the thermal effects on the performances of AM CFRP composites. Specimens with unidirectional (UD) alignments of the fiber reinforcement were printed using the fused deposition modeling (FDM) technique. The printed specimens were subjected to two different thermal conditions: stable continuous at 65 °C and cyclic temperature between 50 and 70 °C. Tensile testing was performed to study the mechanical strength and Young’s modulus of AM UD-CFRPs. In order to investigate the morphological structure on the surface of AM specimens, an optical microscope, scanning electron microscope (SEM), and digital microscope were utilized. Untreated (intact) samples attained the highest average tensile strength value of 226.14 MPa and Young’s modulus of 28.65 GPa. The ultimate tensile strength of the sample group subjected to stable heat treatment decreased to 217.99 MPa, while the thermal cycling group reduced to 204.41 MPa. The Young’s modulus of the sample group subjected to stable thermal exposure was decreased to 25.39 GPa, while for the thermal cycling group, it was reduced to 20.75 GPa. The visual investigations revealed that the intact or untreated specimen group exhibited lateral damage in top failure mode (LAT), the thermally stable group underwent edge delamination in the middle (DGM) as the nominated failure mode, and the explosive breakage at gauge in the middle (XGM) failure mode occurred in the sample from the thermal cycling group. Based on morphological observations at the microscale, the delamination, fiber pull-out, and matrix cracking were the dominant damages in the 3D-printed tensile-tested specimens. The molecular chains of the polymer changed their structure into an amorphous one, and only local motions of stretching occurred when the specimens were exposed to stable heating (prolonged). In the case of thermal cycling, the strain gradients were accumulated in the matrix material, and the local stresses increased as a result of the reheating and re-cooling exposure of the polymeric composites; the molecular motion of the long-range polymer structure was reactivated several times. Micro-cracking occurred as a result of internal stresses, which led to material failure and a reduction of the mechanical properties. Full article
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16 pages, 5570 KiB  
Article
Evaluation of Physico-Mechanical Properties on Oil Extracted Ground Coffee Waste Reinforced Polyethylene Composite
by Hoo Tien Nicholas Kuan, Ming Yee Tan, Mohamad Zaki Hassan and Mohamed Yusoff Mohd Zuhri
Polymers 2022, 14(21), 4678; https://doi.org/10.3390/polym14214678 - 2 Nov 2022
Cited by 7 | Viewed by 2489
Abstract
The current work discusses ground coffee waste (GCW) reinforced high-density polyethylene (HDPE) composite. GCW underwent two types of treatment (oil extraction, and oil extraction followed by mercerization). The composites were prepared using stacking HDPE film and GCW, followed by hot compression molding with [...] Read more.
The current work discusses ground coffee waste (GCW) reinforced high-density polyethylene (HDPE) composite. GCW underwent two types of treatment (oil extraction, and oil extraction followed by mercerization). The composites were prepared using stacking HDPE film and GCW, followed by hot compression molding with different GCW particle loadings (5%, 10%, 15% and 20%). Particle loadings of 5% and 10% of the treated GCW composites exhibited the optimum level for this particular type of composite, whereby their mechanical and thermal properties were improved compared to untreated GCW composite (UGC). SEM fracture analysis showed better adhesion between HDPE and treated GCW. The FTIR conducted proved the removal of unwanted impurities and reduction in water absorption after the treatment. Specific tensile modulus improved for OGC at 5 vol% particle loading. The highest impact energy absorbed was obtained by OGC with a 16% increment. This lightweight and environmentally friendly composite has potential in high-end packaging, internal automotive parts, lightweight furniture, and other composite engineering applications. Full article
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19 pages, 19031 KiB  
Article
Investigation of the Contact Interface between Natural Fibre Metal Laminates under Tension Using Finite Element Analysis (FEA)
by Chun Han Song, Khaled Giasin, Abu Saifullah and Antigoni Barouni
Polymers 2022, 14(21), 4650; https://doi.org/10.3390/polym14214650 - 1 Nov 2022
Cited by 1 | Viewed by 1508
Abstract
Fibre Metal Laminates (FMLs) consist of layers of metals combined with layers of fibre-reinforced composites bonded together to create a laminate. The behaviour of a Fibre Metal Laminate (FML) with natural fibre composites has been investigated in this study with a specific focus [...] Read more.
Fibre Metal Laminates (FMLs) consist of layers of metals combined with layers of fibre-reinforced composites bonded together to create a laminate. The behaviour of a Fibre Metal Laminate (FML) with natural fibre composites has been investigated in this study with a specific focus on the performance of the laminate under uniaxial tension. The integration of aluminium layers with natural fibre flax/pp layers at different fibre orientations has been numerically modelled and analysed, by investigating the contact interface between natural fibre metal laminates (NFML) using finite elements (FE) implemented in ABAQUS/Explicit. The finite element model was developed by the isotropic-hardening behaviour of metal layers, the built-in Hashin damage model and cohesive surface-based behaviour for the interface. The results of the simulation included stress–strain response, failure sequences, delamination effect and ultimate tensile strength. It was found that those results are significantly affected by the layup sequence, giving a significant advantage to the unidirectional laminate, when the uniaxial loading is taken into consideration. This advantage is measured as a 41.9% reduction of the ultimate tensile strength when the flax fibres are oriented at [0/90] configuration between the aluminium layers and a 30% reduction when the fibres are oriented at [±45] angles. Full article
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14 pages, 1551 KiB  
Article
Chemical and Enzymatic Fiber Modification to Enhance the Mechanical Properties of CMC Composite Films
by Xiaobao Li, Zhengjie Tang, Zhenbing Sun, John Simonsen, Zhinan Luo, Xiaoping Li and Jeffery J. Morrell
Polymers 2022, 14(19), 4127; https://doi.org/10.3390/polym14194127 - 2 Oct 2022
Cited by 8 | Viewed by 2325
Abstract
Carboxymethyl cellulose (CMC) is a cellulose derivative that can be obtained from wood, bamboo, rattan, straw, and other cellulosic materials. CMC can be used to produce biofilms for many purposes, but the properties of these resulting films make them unsuitable for some applications. [...] Read more.
Carboxymethyl cellulose (CMC) is a cellulose derivative that can be obtained from wood, bamboo, rattan, straw, and other cellulosic materials. CMC can be used to produce biofilms for many purposes, but the properties of these resulting films make them unsuitable for some applications. The effects of three kinds of plant fiber addition on CMC film properties was investigated using CMC derived from eucalyptus bark cellulose. Tensile strength (TS) and elongation at break (EB) of CMC/sodium alginate/glycerol composite films were 26.2 MPa and 7.35%, respectively. Tensile strength of CMC composite films substantially increased, reaching an optimum at 0.50 g of fiber. The enhancement due to industrial hemp hurd fiber on CMC composite films was more obvious. Pretreatment with hydrogen peroxide (H2O2) and glacial acetic acid (CH3COOH) produced films with a TS of 35.9 MPa and an EB of 1.61%. TS values with pectinase pretreated fiber films was 41.3 MPa and EB was 1.76%. TS of films pretreated with pectinase and hemicellulase was 45.2 MPa and EB was 4.18%. Chemical and enzymatic treatment both improved fiber crystallinity, but film tensile strength was improved to a greater extent by enzymatic treatment. Surface roughness and pyrolysis residue of the film increased after fiber addition, but Fourier transform infrared spectroscopy (FTIR), opacity, and water vapor transmission coefficients were largely unchanged. Adding fiber improved tensile strength of CMC/sodium alginate/glycerol composite films and broadened the application range of CMC composite films without adversely affecting film performance. Full article
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20 pages, 11077 KiB  
Article
Effects of Polypropylene Fibers on the Frost Resistance of Natural Sand Concrete and Machine-Made Sand Concrete
by Yan Tan, Junyu Long, Wei Xiong, Xingxiang Chen and Ben Zhao
Polymers 2022, 14(19), 4054; https://doi.org/10.3390/polym14194054 - 27 Sep 2022
Cited by 7 | Viewed by 1554
Abstract
In order to study the effect of polypropylene fibers on the frost resistance of natural sand and machine-made sand concrete, polypropylene fibers (PPF) of different volumes and lengths were mixed into natural sand and machine-made sand concrete, respectively. The freeze–thaw cycle test was [...] Read more.
In order to study the effect of polypropylene fibers on the frost resistance of natural sand and machine-made sand concrete, polypropylene fibers (PPF) of different volumes and lengths were mixed into natural sand and machine-made sand concrete, respectively. The freeze–thaw cycle test was carried out on polypropylene-fiber-impregnated natural sand concrete (PFNSC) and polypropylene-fiber-impregnated manufactured sand concrete (PFMSC), respectively, and the apparent structural changes before and after freezing and thawing were observed. Its strength damage was analyzed. A freeze–thaw damage model and a response surface model (RSM) were established used to analyze the antifreeze performance of PFMSC, and the effects of the fiber content, fiber length, and freeze–thaw times on the antifreeze performance of PFMSC were studied. The results show that with the increase in the number of freeze–thaw cycles, the apparent structures of the PFMSC gradually deteriorated, the strength decreased, and the degree of freeze–thaw damage increased. According to the strength damage model, the optimum volume of PPF for the PFNSC specimens is 1.2%, and the optimum volume of PPF for the PFMSC specimens is 1.0%. According to the prediction of RSM, PFNSC can maintain good antifreeze performance within 105 freeze–thaw cycles, and when the PPF length is 11.8 mm, the antifreeze performance of PFNSC reaches the maximum, its maximum compressive strength value is 33.8 MPa, and the split tensile strength value is 3.1 MPa; PFMSC can maintain a good antifreeze performance within 96 freeze–thaw cycles. When the length of PPF is 9.1 mm, the antifreeze performance of PFMSC reaches the maximum, its maximum compressive strength value is 45.8 MPa, and its split tensile strength value is 3.2 MPa. The predicted values are in good agreement with the measured values, and the model has high reliability. Full article
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17 pages, 7871 KiB  
Article
Reinforced Structure Effect on Thermo-Oxidative Stability of Polymer-Matrix Composites: 2-D Plain Woven Composites and 2.5-D Angle-Interlock Woven Composites
by Xingzhong Gao, Tiancong Han, Bolin Tang, Jie Yi and Miao Cao
Polymers 2022, 14(17), 3454; https://doi.org/10.3390/polym14173454 - 24 Aug 2022
Cited by 3 | Viewed by 1386
Abstract
The thermo-oxidative stability of carbon fiber polymer matrix composites with different integral reinforced structures was investigated experimentally and numerically. Specimens of 2-D plain woven composites and 2.5-D angle-interlock woven composites were isothermally aged at 180 °C in hot air for various durations up [...] Read more.
The thermo-oxidative stability of carbon fiber polymer matrix composites with different integral reinforced structures was investigated experimentally and numerically. Specimens of 2-D plain woven composites and 2.5-D angle-interlock woven composites were isothermally aged at 180 °C in hot air for various durations up to 32 days. The thermal oxidative ageing led to the degradation of the matrix and the fiber/matrix interface. The degradation mechanisms of the matrix were examined by ATR-FTIR and thermal analysis. The interface cracks caused by thermal oxidative ageing were sensitive to the reinforced structure. The thermo-oxidative stability of the two composites was numerically compared in terms of matrix shrinking and crack evolution and then experimentally validated by interlaminar shear tests. Full article
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19 pages, 7476 KiB  
Article
Prediction of Long-Term Tensile Properties of Glass Fiber Reinforced Composites under Acid-Base and Salt Environments
by Jihua Zhu, Yangjian Deng, Piyu Chen, Gang Wang, Hongguang Min and Wujun Fang
Polymers 2022, 14(15), 3031; https://doi.org/10.3390/polym14153031 - 26 Jul 2022
Cited by 11 | Viewed by 2146
Abstract
This study investigates the effects of deionized water, seawater, and solutions with various concentrations (5% and 10% by mass) of HCl and NaOH on the physical and mechanical properties of glass fiber reinforced polymers (GFRPs) through aging tests at 20 °C, 50 °C, [...] Read more.
This study investigates the effects of deionized water, seawater, and solutions with various concentrations (5% and 10% by mass) of HCl and NaOH on the physical and mechanical properties of glass fiber reinforced polymers (GFRPs) through aging tests at 20 °C, 50 °C, and 80 °C. The tensile properties of GFRP were assessed by tensile testing at room temperature, and the strain during the tensile process was observed using digital image correlation. Additionally, the degradation mechanism was analyzed using scanning electron microscopy, and long-term tensile properties were predicted based on the Arrhenius model. The results indicated that the tensile strength of the GFRP decreased by 22%, 71%, and 87% after 56 d of exposure to 5% NaOH solutions at 20 °C, 50 °C, and 80 °C, respectively. The alkaline solutions had a more severe effect on the GFRP than deionized water, seawater, and acidic solutions. The experimental values and Arrhenius model predictions were found to be in good agreement with each other. Full article
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