Increment In Tensile Strength Research Articles

Surface engineering of carbon fiber using microwave micro arcing (MwMA) for enhanced performance of resulting PEEK composites

In this work microwave micro arcing (MwMA) has been utilized to engineer the surfaces of carbon fibers (CF) to enhance the interfacial bonding of resulting PEEK based composites. The CF were subjected to MwMA at different power levels ranging from 360 W to 900 W for 60 s to engineer their surfaces. The influence of MwMA on CF at various power levels was analyzed using SEM, contact angle measurement, AFM scans, and XPS study. Subsequently, MwMAed CF reinforced PEEK composite laminates were developed using compression molding. The MwMA on CF increased the surface wetting energy by 38% at 540 W microwave power level. XPS analysis suggested that MwMA at 540 W introduced oxygen containing functional group (C-O and C = O), which are likely responsible for increasing the adhesion between CF and PEEK polymer. The current study suggests that MwMA CF at 540 W showed an increment in tensile strength, flexural strength, interlaminar shear strength, and impact strength nearly by 22%, 61%, 28%, and 98% respectively. The MwMA method is novel method to improve the surface properties of carbon fibers and shows the potential use in structural applications.

Carbon nanotubes perpendicularly grown on graphene oxide nanosheets derived from metal-organic frameworks: Synergistic reinforcement of poly(l-lactic acid) scaffold

The construction of the nanohybrid composed of two carbonaceous nanomaterials is a promising strategy to inhibit their aggregation, and effectively exert the advantages of their excellent mechanical properties as reinforcement for polymers. Here, carbon nanotubes (CNTs) were in situ perpendicularly growing on the surface of graphene oxide (GO) through metal-organic frameworks (MOF)-derived strategy by chemical vapor deposition (CVD), aiming to facilitate their dispersion on poly(l-lactic acid) (PLLA) bone scaffold fabricated by selective laser sintering (SLS). Specifically, GO provided nucleation sites for the growth of MOF, and worked as the templates when CNTs grew, in which MOF provided catalysts and carbon sources simultaneously. The precursor was heated to 550 °C and kept for 2 h, then heated to 900 °C and kept for 2 h before cooling. The obtained nanohybrid (GO@CNT) exhibited a superior dispersion state than the pure GO in the scaffold at the same loading, especially when the loading was 0.75 wt%. Adding 0.75 wt% GO@CNT endowed the scaffold with a remarkable increment in tensile strength and compressive strength of 13.36 MPa and 24.72 MPa with enhancement of 55.35% and 18.85%, respectively, compared to the scaffold containing 0.75 wt% GO. A crack extension model combined with experiment results was proposed to better understand reinforcement mechanisms. Additionally, the scaffold containing GO@CNT exhibited benign cytocompatibility with a cell-spreading area of 86.31% and cell density of 564 cells/mm2 after culturing for 5 d according to the results of cell adhesion and immunofluorescence tests, making it a promising candidate for bone defect repair.

Fabrication of biopolyethylene-based biocomposites with coffee ground waste: Effect of polyethylene-graft-maleic anhydride

The production of plastic products from non-renewable raw materials, such as petroleum, damages the environment. Consequently, biocomposites have aroused interest from industry and researchers due to their ecologically correct characteristics, mainly because they come from renewable sources. Therefore, this study aimed to produce biopolyethylene/coffee ground waste (BioPE/CGW) biocomposites and analyze the impact of CGW and polyethylene-graft-maleic anhydride (PE-g-MA) on BioPE. The biocomposites were prepared in a co-rotational twin-screw extruder equipped with a side feeder to feed the CGW. The materials were subsequently injection molded to produce the impact, tensile, and HDT samples. The temperature profiles used during extrusion and injection were between 170 and 180°C. The BioPE and biocomposites were investigated for the vibrational (Infrared Spectroscopy - FTIR), thermal (differential scanning calorimetry), mechanical (tensile, impact, and hardness), thermomechanical (heat deflection temperature (HDT) and Vicat softening temperature (VST)), and morphological (scanning electron microscopy (SEM)) properties. The compatibilizer improved the interface between phases, promoting mechanical and thermomechanical improvements in the biocomposites. PE-g-MA promoted increments in tensile strength and elastic modulus of up to 38% and 25% in the BioPE/CGW30 and an increase of 44% in the elastic modulus compared to BioPE. The thermomechanical investigations showed that HDT increased by 8.8 and 3.3°C and VST increased by 2.5 and 6.6°C compared to BioPE and the BioPE/CGW30, respectively. Biocomposites from renewable and biodegradable sources align with a sustainable development concept.

Synergistic effect of graphene nanoplatelets and titanium dioxide nanopowder-reinforced aluminium nanohybrid composites on mechanical properties

Due to their effectiveness, lightweight materials have gained international attention in recent decades, with industrial sectors being the primary users of them. Metal matrix composites with nanohybrid reinforcement are a unique composite system combination that enhances the material’s mechanical qualities. In the present article, the mechanical properties of graphene nanoplatelets (GNP) and titanium dioxide (TiO2)-reinforced aluminium 7075 alloy are discussed with varying weight percentages of reinforcements prepared by the stir casting technique. 1 wt.% GNP with and 3 wt.% TiO2-reinforced composites show optimum properties within the range of reinforcement studied, with a 71.9% increment in tensile strength and an 86.6% improvement in microhardness observed; however, elongation is decreased by 31.7% in contrast to the base alloy. Maximum toughness is found to be in 0.5 wt.% GNP with 1 wt.% TiO2-reinforced nanohybrid composites. XRD results show phase analysis. SEM analysis of the fractured surface reveals a mixture of ductile and brittle fractures.

Experimental study of Yushania alpina bamboo fiber

The characteristics of bamboo fiber depend on the source species. This study investigated the properties of Yushania alpina bamboo fibers extracted using mechanical, chemical, and combined methods. Samples from each extraction method were tested for tensile strength. Scanning electron microscopy was used to examine the morphology of the fibers. Fourier transform infrared was used to trace functional group changes. The absorption capacity of the fibers was also examined. The thermal properties of the fibers were investigated using thermogravimetric analysis. The chemical compositions of the fibers were studied using a gravimetric method. In contrast to mechanically and combinedly extracted bamboo fibers, chemically extracted fiber had up to 90.84% and 67.06% increments in tensile strength, respectively. Scanning electron microscopy revealed the removal of attachments on the surfaces of the fibers extracted chemically. The diameter of the fibers extracted chemically was reduced. Fourier transform infrared showed no change in functional groups among the extracted fibers. However, lignin content was reduced in chemically extracted fibers. The absorption capacity of the fibers was encouraging for use in composites. Thermal analysis showed improved thermal properties with the chemical method. Chemical analysis revealed reduced lignin and hemicellulose compositions in chemically extracted fibers. This study suggests bamboo fibers can be used in the construction industry for sustainability.

Synthesis of poly(maleic anhydride-co-vinyl chloride) crosslinked microspheres and its superior enhancement in mechanical strength and antibacterial activity for poly(vinyl alcohol) composite films

Poly(vinyl alcohol) (PVA) is an attractive raw material and widely applicated in multiple fields owing to its unique features. However, the poor mechanical strength and without intrinsic antimicrobial activity severely restrained its further use. Herein, we proposed a novel strategy to fabricate PVA-based composites film with excellent mechanical properties and superior antibacterial activity by employing functional polymeric microspheres as a hydrogen bonding cross-linker and bactericide loading platform. Firstly, we synthesized poly(maleic anhydride-co-vinyl chloride) cross-linked microspheres (PDVM) via self-stabilized precipitation polymerization and subsequently the PDVM microspheres were reacted with gaseous ammonia to endow the microsphere surface with abundant carboxyl and amidogen group. As a result, uniform PDVM microspheres with diameters ranging from 175 to 685 nm and controlled gel content (25.3–91.8%) were prepared successfully and aminolyzed PDVM microsphere (NPDVM) were obtained. By incorporating 5 wt% NPDVM in PVA matrix, the composite film has a significant increment in tensile strength (63.9 MPa) and elongation at break (107 %) in comparison to neat PVA (51.8 MPa, 80%) mainly attributed to the formation of multiple hydrogen bonding network. Furthermore, by immobilizing Zn2+ on the surface of NPDVM/PVA film via complexation, the composite film exhibited outstanding antibacterial efficiency against E. coli and S. aureus.

Synergistic effect of different high-performance fibers on the microstructural evolution and mechanical performance of novel hybrid metal matrix composites produced via friction stir processing for automotive applications

The present study aims to produce novel hybrid metal matrix composite (HMMC’s) material using a mixture of reinforcement (basalt, E-glass, and carbon fibers) in long, chopped, and flakes form via Friction Stir Processing (FSP) techniques. Subsequently, the effect of hybrid reinforcement on microstructural evolutions, mechanical performance, and the fracture mechanism of HMMC’s was investigated. The results demonstrated that hybrid reinforcement synergistically enhanced the tensile, flexural, and impact performance of FSPed HMMC’s compared to monolithic composites (non-hybrid) and received base metal (BM). The long fiber-reinforced hybrid aluminum metal matrix composites (HL) show a ~156% increment in tensile strength and ~196% increment in impact strength, while flakes-reinforced hybrid aluminum metal matrix composites (HF) show a ~101% increment in flexural strength compared to the BM. The field emission scanning electron microscopy (FESEM) analysis demonstrated a homogeneous dispersion of reinforcement and an excellent interfacial bonding of fibers with the aluminum matrix in the fabricated composites. The validation of element distribution and composition within the composites was confirmed using FESEM elemental mapping and energy-dispersive X-ray spectroscopy (EDS) spectrum.

Abnormal annealing-induced strengthening in Ni39.3Al15.7Fe45 eutectic medium entropy alloy

Cold-working combined with annealing is frequently used to enhance strength of traditional alloy materials. However, this thermal-mechanical processing is not adapted to the preparation for some near net shape parts. In this paper, a dual-phase Ni39.3Al15.7Fe45 eutectic medium entropy alloy (EMEA) was prepared by vacuum arc melting and abnormal annealing-induced strengthening is demonstrated and analyzed via XRD, SEM, EDS, TEM and room temperature tensile testing. It is found that the Ni39.3Al15.7Fe45 EMEA is composed of FCC solid solution phase and BCC phase. After annealing, ordered L12 phase precipitated from FCC solid solution, which induces a significant increment of tensile strength and a weak decrease of tensile plasticity. The tensile strength and elongation are 991 MPa and 24.1 % at as-cast state, the tensile strength and elongation are 1279 MPa and 22.4 % after annealing at 700 °C for 1 h.

Effect of Coconut Fiber Loading on the Morphological, Thermal, and Mechanical Properties of Coconut Fiber Reinforced Thermoplastic Starch/Beeswax Composites

The increasing concern about global warming and the accumulation of non-biodegradable plastic has caused serious environmental issues. Hence, the need to create a more environmentally friendly material such as thermoplastic starch (TPS) has grown. However, the poor properties of TPS, such as high moisture sensitivity and low mechanical properties, have limited the potential application of this biopolymer. This study aims to modify TPS’s thermal and mechanical properties by incorporating coconut fiber. The composites were prepared by incorporating various coconut fiber loading (0, 10, 20, 30, 40, and 50 wt.%) into the TPS matrix. The mixture was fabricated using a hot press at 145°C for 1 hour. The sample is then characterized using thermogravimetric analysis and tensile and flexural tests. The results show that the composite with 50 wt.% coconut fiber had higher thermal stability than samples with lower fiber content. A significant increment in tensile strength and modulus of up to 20.7 MPa and 2890 MPa were recorded for samples with 50 wt.% fiber content—the sample with 50 wt.% fiber also demonstrated the highest flexural strength and modulus of up to 30.3 MPa and 3266.3 MPa, respectively. These changes are consistent with the FTIR and SEM findings, which show good compatibility of TPCS and coconut fiber with a homogeneous structure. Overall, coconut fiber shows good potential as reinforcement for biodegradable-based polymer composites.

Microstructure and high-temperature mechanical properties of Cu-W composite prepared by hot isostatic pressing

In current work, Cu-20wt%W (Cu-20W) composite of near theoretical density (99.69 %) and high electrical conductivity (86.78 %IACS) was fabricated by spray drying technique and hot isostatic pressing (HIP), aiming to enhance the mechanical properties of Cu-W composite while maintaining high conductivity. The impacts of W nanoparticles on the microstructure and properties of Cu-20W samples were evaluated. Adding W nanoparticles can remarkably refine the grain of Cu and strengthen the Cu-W composite through a pinning effect. Room temperature tensile strength and compressive yield strength of Cu-20W composite were 380 MPa and 304.49 MPa, which are 117.14 % and 616.95 % higher than that of pure Cu (175 MPa and 42.47 MPa), respectively. Tungsten nanoparticles can promote the high-temperature reliability of Cu-W samples. Tensile strength of pure Cu and Cu-20W sample gradually decreased with increasing test temperature, but the percentage increment of tensile strength increased. The tungsten particles pinned at grain boundaries during hot deformation inhibit recrystallization grain growth and hinder dislocation movement, thereby contributing to the high-temperature properties of Cu-20W composite. The peak stress of Cu-20W sample is 146.60 % higher than pure Cu, even at close to the melting point of Cu (940 °C). The strength of Cu-20W composite is heightened by combining fine-grain strengthening and dispersion strengthening due to the introduced W nanoparticles.

Effect of polyurethane matrix and steel fiber in combination with glass fiber or basalt fiber on the properties of hybrid composite laminates

Abstract Polyurethane is a versatile polymer with a high degree of toughness and ductility used in a wide variety of applications. In this study, two-part thermoset polyurethane was used as a matrix material to prepare hybrid and non-hybrid composites. Hybrid laminates were prepared by combining either glass fiber or basalt fibers with steel fibers. The mechanical properties of prepared composite specimens were characterized and scanning electron microscope (SEM) observation was performed around the fracture region of the tested specimens. The results revealed a significant increment in tensile strength, and flexural strength in BS1-PU (8 layers of basalt-1 layer of steel) hybrid laminate by 357.74 % and 64.59 %, respectively, compared to steel fibers reinforced polyurethane composites. Furthermore, GS4-PU hybrid composite (5 layers of glass-4 layers of steel) achieved an improvement in tensile strain by 12.07 %, flexural strain by 25.32 %, and absorbed energy by 18.21 %, compared to glass fibers reinforced polyurethane composite. Moreover, the SEM observations revealed that the replacement of some basalt and glass layers with steel layers leads to a positive hybridization effect of the overall produced hybrid composites.

Lignocellulose Nanofibers Enhanced Mechanical and UV-Blocking Properties of Polyvinyl Alcohol Films

Lignin-containing cellulose nanofibers (LCNFs) from bamboo were prepared by choline chloride–lactic acid solvent treatment at 110–130∘C in combination with ultrasonication. Effects of LCNFs dosages on UV-blocking property, mechanical property, thermal stability and water vapor barrier property of LCNFs/PVA composite film were determined by UV spectrophotometer, universal mechanical testing machine, thermogravimetric analysis and weightlessness method, respectively. The results indicated that PVA film composited 10% LCNFs obtained from 120∘C showed best properties. As compared to pure PVA film, the UV-blocking property of composite film increased from 30% to 53%. LCNFs addition enhanced mechanical properties, resulting increment of tensile strength from 42[Formula: see text]MPa to 81[Formula: see text]MPa and elongation at break from 3% to 9%, respectively. LCNFs also introduced 2.4 times increment of water vapor barrier property of PVA film. The LCNFs/PVA composite films not only have excellent thermal stability and mechanical properties but also have UV-resistance and water vapor barrier properties. It provides a new idea for replacing some petroleum-based packaging materials and also shows the great potential of LCNFs materials.

Effect of surfactants on the properties of rubber composites prepared from pyrolytic carbon black/natural latex via wet blending method

Pyrolytic carbon black (CBp) is the main by-product of waste tire pyrolysis. CBp has high ash content and poor surface activity which leads to the composites reinforced with CBp has lower performance than composites reinforced with commercial carbon black, making it difficult to meet the requirements of tire. In order to realize the application of CBp in tires, the effect of surfactants on the properties of rubber composites prepared by wet mixing of CBp/natural latex was investigated. In the experimental process, sodium stearate (C17H35COONa), sodium dodecylbenzene sulfonate (C18H29NaO3S), and sodium p-styrenesulfonate (C8H7NaO3S) were used to improve the surface activity and uniform dispersion of the CBp in the natural rubber matrix. The experimental results showed that the dispersity of C18H29NaO3S and C8H7NaO3S modified CBp in rubber matrix has [X] and [Y] values of 7.5 and 7.9, and 9.3 and 9.5, respectively, and the dispersion of these rubber composites is significantly better than that of C17H35COONa. The rubber composites prepared by C18H29NaO3S and C8H7NaO3S surfactants has the better physical and mechanical properties. The rubber composite prepared by C18H29NaO3S has the highest tensile strength of 25.63 MPa, which increment in tensile strength is 15.6% compare to the rubber composite prepared by C17H35COONa. Meanwhile the dynamic mechanical properties of rubber composites prepared by modifying CBp with C18H29NaO3S and C8H7NaO3S are better than CBp with C17H35COONa. The C8H7NaO3S modified CBp/rubber composite has the lowest loss factor (tanδ) value at 60°C, and the C18H29NaO3S modified CBp/rubber composite has the highest tanδ value at 0°C.

Microstructure and mechanical properties of GMAW cladded AA 6063 using friction stir processing as a post-processing technique

ABSTRACT Aluminum alloy being a significant material for many industries, and due to its favourable properties like low density and the high strength-to-weight ratio, is used for cladding. But because of low wear resistance, non-uniform grain structure, and other certain insufficiencies, Friction stir processing (FSP) was applied over the cladded part to overcome these deficits and drawbacks and improve the mechanical characteristics of the produced component further. In this work, mechanical and microstructural characteristics were investigated and analysed by varying rotational speed and number of passes at the time FSP. After FSP finer grains were found, and other solidification defects were eliminated from the final components. Processed part shows the increment in tensile strength, the hardness of the component increases while erosive wear decreases with the number of passes. Maximum hardness and minimum erosion wear rate for all three passes were attained at 598 RPM. Tensile strength and percentage elongation have been found to be highest at three passes at 938 RPM. Microstructure also reflects the finer grains at the highest RPM at the third pass. Also, modern quality management tools and process improvement technique like ANOVA was utilised to formulate the mathematical model and to study the relationship between the input and output of the process.

Influence of cellulosic particle fillers on mechanical properties of hemp fibre-reinforced composites

ABSTRACT Plant-based hemp natural fibre-reinforced composites are sustainable in the view of the environment. However, these composites have not attracted many applications due to their less mechanical properties compared to the synthetic fibre-reinforced composites. The present work reports the hemp fibre-reinforced composite loaded with cellulose-based filler to improve their mechanical properties. At equal proportions of cellulose filler such as pistachio shell powder, teak wood powder, groundnut shell powder reinforced with the hemp fibre-reinforced epoxy composite, the improvement in the tensile strength, flexural strength, % of elongation and % of deformation is reported. The hemp fibre/epoxy composite loaded with 5 wt% of pistachio shell powder shows a 9.28% increment in tensile strength, 50.96 % increment in flexural strength compared to hemp fibre/epoxy composite. The hemp/epoxy composite loaded with 5 wt% teak wood powder particles shows enhancement in tensile, flexural by 31.56 %, 35.97%, respectively. The hemp/epoxy composite loaded with 5 wt% groundnut shell powder particles shows enhancement in tensile, flexural by 42.99 %, 83.99%, respectively.

Assessing the role of polypropylene fibres on tensile strength of alccofine and silicafume blended high strength concrete

In the present study, the M40 grade of concrete is designed with binder materials comprising of 70% cement and 30% Supplementary Cementitious Materials (SCM). Of the 30% SCM, flyash C (FA) accounts for 20% whereas the remaining 10% is either Silicafume (SF) or Alccofine (AL), respectively. In addition to binder materials, the polypropylene fibres with weight proportions ranging from 0 to 0.5% of binder materials is added. For unreinforced specimens, the split tension strength at 28 and 90 days curing period is 3.80 and 4.36 MPa, respectively for AL blended concrete whereas it is 3.93 and 4.16 MPa for SF blended concrete. For incrementing proportion of polypropylene fibres, the split tensile strength and strain energy of both SF and AL blended concrete increases with increasing curing period. For AL blended concrete, the increment in tensile strength at 90 days curing period ranges from 6 to 20% while the strain energy increase is upto 120%. The study confirms that the inclusion of polypropylene fibres is more effective towards improving tensile strength and energy absorption capacity of AL blended concrete than SF blended concrete. In addition to tensile strength and strain energy, optical microscopy images have been used to evaluate the effect of polypropylene fibres on porosity and calcium hydroxide (CH) content.

Preliminary study on utilization of steel mill scale in concrete

Modern society is witnessing rapid advancement in science and technology, which increases the natural resource demand. Due to these advancements, an extra burden comes on such resources. Due to this, an alternative approach requires to fulfill these demands. In the same context, concrete is one of the world's most widely used building materials. So, in present study aims to provide a sustainable alternative to one of the principal constituents of concrete, i.e., sand. Natural river sand is typically used as a fine aggregate in concrete. The water table is lowered due to the extraction of natural river sand from the river bed, posing another environmental concern. Thus, it is essential to find a substitute for river sand. The present study attempts to find an alternative in the form of the Steel Mill Scale (SMS), which is obtained as a byproduct of the Steel industry. For the study, the fine aggregate was replaced partially by the SMS in various weight-based proportions such as 5%, 10%, 15%, 20%, and 25%. Super-plasticizers were added in varying amounts to keep the Constant workability. Due to its higher water absorption rate, SMS was used in surface-saturated dry condition. All concrete properties, including compressive strength, split tensile strength, flexural strength, density, abrasion resistance, water absorption, and porosity, were tested using M30-grade concrete. Strength tests were conducted at the age of 7, 28, and 56 days, while all the other tests were done at 28 days only. In addition to all of these, XRF was performed on SMS to know the different oxides present in the material. Due to iron availability in SMS, compressive strength results were desirable up to 15% replacement, and in split tensile strength increment was clearly visible up to 15% replacement. Based on the all results, 15% replacement gives an encouraging result.

Synergetic Effect of α-ZrP Nanosheets and Nitrogen-Based Flame Retardants on Thermoplastic Polyurethane

A supramolecular self-assembly method was used to prepare melamine cyanurate/α-ZrP nanosheets (MCA@α-ZrP) as a novel hybrid flame retardant for thermoplastic polyurethane (TPU). Microstructure characterization showed a uniform dispersion with strong interfacial strength of the MCA@α-ZrP hybrid within the TPU matrix, leading to simultaneous enhancements in both mechanical and fire-safety properties. The TPU/MCA@α-ZrP nanocomposite exhibited 43.1 and 47.0% increments in tensile strength and fracture energy, respectively. Thanks to the platelike structure of α-ZrP coupled with the dilution effect of MCA (releasing nonflammable gases), the hybrid MCA@α-ZrP reduced the peak heat release rate of TPU by 49.7% in comparison with 15.8 and 35.4% for TPU/MCA and TPU/ α-ZrP composites, respectively. The fire performance index of TPU is significantly promoted by 90% upon adding the MCA@α-ZrP hybrid. Additionally, LOI and UL-94 tests showed high flame-retarding characteristics for the MCA@α-ZrP hybrid. For example, LOI increased from 20.0% for neat TPU to 25.5% for the MCA@α-ZrP hybrid system, and it was rated V-1 from the UL-94 test. Furthermore, the smoke production and pyrolysis products were significantly suppressed by adding the MCA@α-ZrP hybrid into TPU. Interfacial hydrogen bonding, the dilution effect of MCA, forming a "labyrinth" layer, and catalytic action of α-ZrP nanosheets synergistically improved both the mechanical performance and flame retardancy of TPU nanocomposites. This work provides a new example of integrating traditional flame retardants with functional nanosheets to develop polymeric nanocomposites with high mechanical and fire-safety properties.

Edible pullulan enhanced water-soluble keratin with improved sizing performance for sustainable textile industry

Feather keratin from waste feather has become an attractive target to replace petroleum-based Poly (vinyl alcohol) sizes due to its easy film-forming ability, excellent adhesive property, biodegradability and low cost. However, poor water-solubility and brittleness of pure keratin films have become the bottlenecks and restricted the application of keratin as sizing agents. Therefore, water-soluble keratin was extracted by the reduction-preservation method and enhanced by saccharides in aqueous system to obtain all-green keratin-based slurry. The results showed that the keratin-based slurry exhibited improved sizing performance in the order of sucrose ≤ glucose ≤ pullulan by the moderate Maillard reaction. Among them, the fabricated pullulan-keratin sizes films had 27.86 %, 2684.08 % and 2911.31 % increment in tensile strength, elongation and work of facture compared with pure keratin sizes films. Besides, the addition of pullulan and subsequently moderate Maillard reaction improved the thermo-tenacity of keratin-based sizes, which was expected to tackle with the brittleness of pure keratin size films. In addition, novel pullulan-keratin sizes had good sizing performance and high desizing efficiency to cotton, cotton/polyester and polyester yarns and fabrics. Successful utilization of pullulan-keratin sizes will bring opportunities for high value utilization of waste feather and promote the green and low-carbon development of textile industry.

Coupling effect of fiber reinforcement and MICP stabilization on the tensile behavior of calcareous sand

Coupling method of fiber reinforcement and microbial induced carbonate precipitation (MICP) stabilization was adopted to improve the tensile behaviors of calcareous sand. Three types of fibers, including polypropylene fiber (PF), carbon fiber (CF), and basalt fiber (BF), were used to prepare fiber-reinforced MICP-stabilized calcareous sand samples with various fiber contents and lengths. Direct tensile tests were conducted on a specially designed 8-shaped sample to evaluate the tensile behaviors of the samples. Experimental results revealed that the coupled use of fiber reinforcement and MICP stabilization technique could significantly improve the calcareous sand tensile behaviors. By adding the fibers of PF, CF, and BF, the maximum tensile strength of the sample was increased by 234.0%, 111.8%, and 100.7%, and the corresponding maximum residual strength reached 26.8 kPa, 30.63 kPa, and 50.7 kPa, and their maximum failure displacement was increased by 121.2%, 95.4%, and 100%, respectively compared to the MICP stabilized sample. The coupling mechanism was attributed to the fiber inclusion promoting the calcium carbonate precipitation and forming more effective and extra-effective bonding. The interfacial shear resistance between fibers, calcium carbonate, and calcareous sand and the bridging performance of the crossing fibers facilitated the coupling effect. For all three types of fibers, the higher the fiber content, the greater the tensile strength, residual strength, and failure displacement. The tensile behaviors varied due to the difference in surface properties and mechanical properties of the fiber. PF had the best reinforcement performance on tensile behavior. For the sample with PF (0.1% fiber content), the optimal fiber length was 6 and 9 mm. Moreover, a theoretical relationship between the tensile strength increment and fiber content or fiber length was established. The results of this study are of some significance for the stability and safety of coastal engineering.