Hybrid Biocomposites Research Articles

Thermoplastic starch hybrid biocomposite films with improved strength and flexibility produced through crosslinking via carboxylic acid

Thermoplastic starch (TPS) suffers from its intrinsic low mechanical strength and high brittleness due to its strong hydrogen bonding and low chain mobility. The conventional way to crosslink the TPS film can improve the strength and stiffness of the films, but usually reduces the flexibility of the film, and increases its brittleness. In this study, the incorporation of the hybrid nanofiller [1 wt% nanocellulose (C) and 4 wt% nano bentonite (B)] into the TPS proved to improve greatly the films’ strength and flexibility. The hybrid nanofillers with ratio 4B:1C was incorporated into the crosslinked thermoplastic corn starch (CR-TPCS) film to increase the its flexibility and toughness and produced a high mechanical strength fully biodegradable film. Two different aqueous carboxylic acids: citric acid (CA) and tartaric acid (TA) with different pH values (2,4,6) as the green crosslinker were employed. Substantial increase of tensile strength (3.98 to 9.17 MPa), Young’s modulus (9.10 to 46.30 MPa) and elongation at break (55.2 to 135.7%) was observed for the CA- 4B1C/pH2 films compared to the CR-TPCS films. The melting temperature (Tm) of the CA-4B1C/pH2 improved compared to the TPCS/4B1C (un-crosslinked) film due to its crosslinking effect. Meanwhile, the CA-4B1C films exhibited the highest degree of substitution and di-esterification with the lowest swelling and water solubility properties due to the formation of a special “bridge” structure between the CA, nanocellulose and plasticizer. The “bridge” structure developed between the TPCS chains serves as the toughener to motivate higher chain stress relaxation and load endurance. The crosslinked “bridge structure” also proved to effectively reduce the retrogradation phenomenal in the TPCS films. This combination method of hybridization and crosslinking is an efficient, low cost, and environmentally friendly technique to overcome the low flexibility and brittleness problem of the TPS based packaging film.

Novel hybrid biocomposites for tendon grafts: The addition of silk to polydioxanone and poly(lactide-co-caprolactone) enhances material properties, in vitro and in vivo biocompatibility.

Biopolymers play a critical role as scaffolds used in tendon and ligament (TL) regeneration. Although advanced biopolymer materials have been proposed with optimised mechanical properties, biocompatibility, degradation, and processability, it is still challenging to find the right balance between these properties. Here, we aim to develop novel hybrid biocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL) and silk to produce high-performance grafts suitable for TL tissue repair. Biocomposites containing 1-15% of silk were studied through a range of characterisation techniques. We then explored biocompatibility through in vitro and in vivo studies using a mouse model. We found that adding up to 5% silk increases the tensile properties, degradation rate and miscibility between PDO and LCL phases without agglomeration of silk inside the composites. Furthermore, addition of silk increases surface roughness and hydrophilicity. In vitro experiments show that the silk improved attachment of tendon-derived stem cells and proliferation over 72h, while in vivo studies indicate that the silk can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. Finally, we selected a promising biocomposite and created a prototype TL graft based on extruded fibres. We found that the tensile properties of both individual fibres and braided grafts could be suitable for anterior cruciate ligament (ACL) repair applications.

Development of hybrid composite with natural fillers for mechanical property and machinability study

The urge to build a more environmentally friendly future has motivated researchers to examine composites outside of synthetic fiber and continue to consider natural fibre polymer composite. This present research, the hybrid bio composite was developed by bio fillers and natural fibres. The preliminary investigation was done to examine the possibility of using natural fillers (palm and coconut shell) in natural fibre (hemp and basalt) reinforced polymer (NFRP) composite for manufacturing application. In that way initially mechanical (tensile and flexural) properties testing were done on four different combinations of NFRP by using palm and coconut shell particles, to their influence on mechanical properties (tensile stress 278 MPa and flexural stress 330 MPa). It was found that 5% wt. palm + coco shell fillers combination hybrid composite presented good results in mechanical properties. Then 5% wt. palm + coco fillers was added in the matrix phase of NFRP composite was developed and study the machinability properties by using Abrasive Water Jet Machining (AWJM). NFRP machining in the relationships of material removal rate (MRR), kerf angle and surface roughness has been experimentally examined for various process parameters (nozzle pressure, distance stand and transverse speed). The research values for quality properties (MRR, Kt and Ra) were analysis-based on the trimming factors by developing the Taguchi method. The influence of optimized input process parameters on quality features were examined by utilizing experiential models. From this study, it is noticeable that, filler material in natural fiber composites reduces the kerf angle and the low and very high traverse speed leads the wide disparity in kerf inclination. For obtaining the good surface roughness and material removal rate medium traverse speed and medium stand of distance is the significant parameter respectively and moreover impact of jet pressure on surface finish is 3 times lower than the impact supplied to the surface finish by traverse speed

Design and Development of Power Transmission System for Tractor Operated Hybrid Bio-Composite Mulch Sheet Laying Machine

Tractor 3 point hitch drawn hybrid bio-composite bio degradable mulch laying machine was designed and developed based on the formulation of the hybrid bio-composite mulch sheets with a intension of the integrate the field operations at easy pace and conserve the time and labour. The prototype was fabricated and tested in the fields in order to perform the operations such as hybrid bio-composite mulch sheet laying, Mulch sheet pressing and guiding and soil covering on the edges of the mulch sheets in one forward movement of the machine. The machine was fabricated with design of many components but the power transmission system was plays a major role in this machine as the entire forward movement of machine and performance of the mulch sheet laying unit was depends on the power transmission system only. Various components of power transmission system was designed such as shafts, chain, bearings and sprockets etc. The shaft design was done considering the two conditions of fields while in operation like considering twisting and bending moments of the shaft as well as sudden applied shocks and fluctuated loads. Considering the two conditions, the main shaft, counter shaft and rear wheel shafts diameters were designed based on this two conditions and obtained results were 30 mm, 40 mm and 25 mm respectively The chain and sprocket will be used for the transmitting the power from one shaft to other one. The length of the chain was calculated 162.56 cm and the HP transmitted by the selected chain and HP of chain drive system were calculated as 2.05 hp and 0.339 hp respectively. Based on the results, the calculated horse power was less than the horse power of selected chain that means required horse power was 0.339 hp but we have got 2.05 hp, hence the design was safe and machine will be operate without any hassles.

Synergic effect of basalt/wood fiber reinforced polylactic acid hybrid biocomposites against fungal decay

In addition to the traditional fibre-reinforced composites, the investigation of novel composites with significant potential for engineering applications attracts increasing attention. In this study, the decay resistance of basalt and/or wood fibre-reinforced polylactic acid (PLA) biocomposites was evaluated with a soil block test by using white rot fungi, Trametes versicolor (Trv) and Irpex lacteus (Irl), and brown rot fungi, Poria placenta (Pop) and Gloeophyllum trabeum (Glt), and a soft rot fungus, Chaetomium globosum (Chg) after 8 weeks of water submersion. Water absorption rate during the water submission and weight losses after the decay test were determined. Furthermore, decay in biocomposites was characterized by SEM and ATR-FTIR. Results showed that the water absorption increased between 52.4–67.5% for wood fibre composites when compared to basalt fibre-reinforced biocomposites. PLA showed good decay resistance against all fungi attacks. However, as the ratio of basalt and wood fibre in the hybrid biocomposites increased, the fungi resistance decreased. The lowest weight loss, 4.9% was found in the biocomposites containing the highest percentage of basalt fibre. On the other hand, the highest weight loss, 54.2% was observed in the composites containing the highest percentage of wood fibre. The results clearly showed that the hybridization of basalt and wood fibres improves the decay resistance of the biocomposites compared to only wood fibre-reinforced composites. However, as the percentage of wood increased in the composites, the decay resistance decreased. SEM and FTIR analysis confirmed the degradation and revealed the degradation mechanism.

Thermal and electrical behaviors of activated carbon-filled PLA/PP hybrid biocomposites

Activated carbon-based composites are prominent thanks to their unique surface properties, high thermal and mechanical stability, and good electrical performance. They are also used to produce special-purpose hybrid composites in strategic sectors such as defense, military, microelectronic, and medical industries. Hence, this study was expected to enlighten the thermal and electrical effect of activated carbon (AC) on polylactic acid (PLA)/polypropylene (PP) hybrid biocomposites and determine the possible advantages of using compatibilizers in hybrid biocomposites between natural fiber and polymer matrix. AC was produced by combining chemical (pre-activation) and thermal activation (pyrolysis) techniques. The AC-filled hybrid PLA/PP biocomposites were manufactured by extrusion process followed by hot-press molding. Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, thermal conductivity analysis, and electrical resistivity were conducted to measure the thermal behaviors of the biocomposites. The results showed that the crystallization temperatures (Tc) of the hybrid biocomposites increased by about 5 °C with the addition of AC to the biocomposite blend. The thermal insulation properties of hybrid biocomposites were up to 40% higher performance compare to virgin polymers due to the porous nature of AC and natural fiber. The hybrid composites conduct electricity slightly by adding AC to the PLA/PP polymer matrix. Thanks to adding a compatibilizer to the composite, a filling effect on porosity was observed and electrical conductivity improved by up to 66% in some samples.

Silica Aerogel-Polycaprolactone Scaffolds for Bone Tissue Engineering.

Silica aerogel is a material composed of SiO2 that has exceptional physical properties when utilized for tissue engineering applications. Poly-ε-caprolactone (PCL) is a biodegradable polyester that has been widely used for biomedical applications, namely as sutures, drug carriers, and implantable scaffolds. Herein, a hybrid composite of silica aerogel, prepared with two different silica precursors, tetraethoxysilane (TEOS) or methyltrimethoxysilane (MTMS), and PCL was synthesized to fulfil bone regeneration requirements. The developed porous hybrid biocomposite scaffolds were extensively characterized, regarding their physical, morphological, and mechanical features. The results showed that their properties were relevant, leading to composites with different properties. The water absorption capacity and mass loss were evaluated as well as the influence of the different hybrid scaffolds on osteoblasts' viability and morphology. Both hybrid scaffolds showed a hydrophobic character (with water contact angles higher than 90°), low swelling (maximum of 14%), and low mass loss (1-7%). hOB cells exposed to the different silica aerogel-PCL scaffolds remained highly viable, even for long periods of incubation (7 days). Considering the obtained results, the produced hybrid scaffolds may be good candidates for future application in bone tissue engineering.

Thermal and dynamic performance of kenaf/washingtonia fibre-based hybrid composites

The application of hybrid natural fibres incorporated with bio phenolic composites is significant due to their sustainability and low-cost rates. In this paper, two natural fibres composites were prepared using a hand lay-up technique. The thermal stability, dynamic-mechanical, and thermo-mechanical characterisations of kenaf fibre (KF)/Washingtonia Leaf Stalk Fibres (AW)/epoxy biocomposite were investigated in this paper. Thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA), respectively, were used to examine the thermal stability and the coefficient of thermal expansion (CTE) and the dynamic mechanical properties of composites, respectively. The Thermogravimetric (TG) analyses showed that the addition of KF and AW enhanced the thermal stability of the epoxy composites. 7AW/3KENAF showed the most significant improvement in thermal stability (Tonset; 284.52 °C and Tmax; 368.25. Furthermore, the hybrid biocomposite exhibited the highest storage modulus (2668.9 MPa) among all other pure and hybrid biocomposites. On the other hand, the TMA findings illustrated that the 50% AW sample exhibited the highest value of CTE (242 μm/m °C) at the maximum temperature (175 °C) among all samples. Briefly, it is obvious that the combination of WA with KENAF enhanced the potential in improving thermal, dimensional and dynamic mechanical characterisations of epoxy composites and can be utilised in building applications that dictate elevated dimensional stability. It was proven that the hybrid biocomposites prepared in this work supported by hybrid natural fibres as strengthened bio fillers might benefit the performance of epoxy composites, which could broaden the application range of industrial and engineering applications and provide novel ways for its effective uses.

Static, Dynamic Mechanical and Thermal Characteristics of Luffa, Morinda tinctoria, and Myrobalan Reinforced Epoxy Hybrid Biocomposites

Static, Dynamic Mechanical and Thermal Characteristics of Luffa, Morinda tinctoria, and Myrobalan Reinforced Epoxy Hybrid Biocomposites

Enhanced adsorptive removal of hazardous methyl violet 2B and methyl orange dyes by Algerian diatomite-loaded polysaccharide-based hydrogel beads

The present paper is devoted to the synthesis of hybrid biocomposites through immobilization of Algerian treated diatomite (TD) within the semi-interpenetrating network of carboxymethyl cellulose/dextran sulfate (CMC/DS). The physicochemical properties of the cross-linked beads were investigated by SEM, XRD, FTIR and TGA. Biocomposite beads were explored as adsorbents for the removal of cationic methyl violet 2B-(MV2B) and anionic methyl orange-(MO) dyes. The swelling ability in different media were studied. The outcomes revealed that the TD was successfully immobilized in CMC/DS matrix through hydrogen bonding which improved the structural stability of biocomposites. TD depicted to improve the adsorption capacity of hydrogels. Indeed, the beads prepared at low TD levels (5 and 10 % (w/w)) showed higher adsorption capacities (925.92 and 892.86 mgg−1) compared to the matrix (877.19 mg g−1). MV2B adsorption modeling showed the process well fitted the pseudo-second order kinetics and Langmuir models. Furthermore, the role of TD was better considered during the MO adsorption study. Pristine hydrogel were not able to effectively remove it (10 %), while for biocomposites the efficiency reached 62–98 %. The suggested mechanism for MO adsorption involved ion exchange, pore-filling and π-electron specific interactions. Lastly, reusability study confirm that C/D-TD biocomposites are promising materials for anionic/cationic dyes adsorption.

New hybrid bio-composite based on epoxidized linseed oil and wood particles hosting ethyl palmitate for energy storage in buildings

In this study, the incorporation of ethyl palmitate (EP) as a bio-based phase change material (BPCM) in wood particles, the preparation and properties of the novel biocomposite for building applications were investigated. The wood particle-based composites hosting BPCM were produced by cold compression moulding. The EP impregnation step was optimized in terms of uptake and its ratio by post-addition of non-impregnated fibers. The optimized wood particles/EP ratio were combined with 37.5% epoxidized linseed oil (ELO) as a binder to produce a composite with energy storage function containing more than 99% bio-ingredients. The optimum BPCM content in the composite was 25%. The produced biocomposites were characterized by T-hystory, DSC, TGA, and a moisture buffer test. The results revealed excellent moisture buffer values (2.07 g/m2 RH%) according to the Nordtest protocol, significant thermal mass, ability to store excessive energy in terms of latent heat and maintain the temperature constant for longer time, good thermal stability and improved specific heat capacity when compared to a reference composite without BPCM. The effect of incorporating BPCM into biocomposite for regulating temperature fluctuations was confirmed by comparing test prototype cubes, with and without BPCM, subjected to temperature fluctuation between 0 and 40 °C.

Effect of reinforcement of Alkaline-treated sugar palm/bamboo/kenaf and fibreglass/ Kevlar with polyester hybrid biocomposites: mechanical, morphological, and water absorption properties

In this age of globalisation, decreasing synthetic resources have exhilarated global communities to apply natural fibres as substitute materials for green technology development. The growth of products from lignocellulose fibre-reinforced composites has been a wide topic among material scientists and engineers due to their abundance, sustainability in nature, biodegradability, and availability at low cost. A series of natural/synthetic hybrid fibre-reinforced composites are prepared by reinforcing polyester resin as the matrix. Natural fibres such as sugar palm/kenaf/bamboo with fibreglass/Kevlar hybrid composite materials were used in this research to determine the mechanical and water absorption properties. The difference between the weight content of natural fibres which were 0 (control sample), 15, 45, and 60 wt% influenced their strength of mechanical properties. The Charpy impact and tensile test were performed following the ASTM D6110-10 and ASTM D3039, respectively. A water absorption test in accordance with ASTM D570-98 was also performed on three different natural fibre-reinforced hybrid composite materials to determine which composite had the best water resistance property. The results showed that hybrid fibre-reinforced composite for 45 wt% kenaf fibre possessed better tensile properties and 60 wt % sugar palm fibre performed better during the Charpy impact strength test compared to other natural/synthetic hybrid fibre-reinforced composites. It was concluded that sugar palm fibres demonstrated the best water resistance in this study.

Mechanical characterization of hybrid biocomposites reinforced with nonwoven hemp and unidirectional flax fibers

AbstractFiber‐reinforced polymers are widely used in many applications where high specific strength and high specific stiffness are required. Biocomposites have replaced synthetic‐based fiber‐reinforced polymers as a preferred option due to their environmental friendliness, ease of supply, and affordability. Comparable strength synthetic‐fiber‐reinforced polymers and biocomposites both have lower specific weights. This study aims to characterize hybrid biocomposites produced from unidirectional prepregs made of flax/polypropylene fibers and nonwoven mats made of hemp/polypropylene fibers. Research has also been conducted on how the number of layers and the stacking sequence affect the mechanical performance of hybrid biocomposites. Three different designs of biocomposite plates have been produced using compression molding. They were then subjected to tensile, compressive, shear, bending, Charpy impact, and drop‐weight impact tests. According to the test results, it is found that each design has its own characteristics, and the characterized static and dynamic behaviors are very different from each other. Therefore, each biocomposite mentioned here may be a good candidate for engineering design based on the given engineering design criteria.

Nanosilica incorporated coarse wool-epoxy hybrid biocomposites with improved physico-mechanical properties

In the reported work, the wool fabric was coated with epoxy resin by hand layup method to fabricate the wool-epoxy composites. Hydrophobic nanosilica was used as a filler to improve their mechanical characteristics. The physico-mechanical properties of the composites were analyzed using various analytical techniques. The surface morphology was examined with the aid of Scanning Electron Microscope. The biodegradability of the developed composites was determined by soil burial test. The presence of nanosilica in the composite was confirmed by Fourier Transform Infrared Spectroscopy (FTIR). According to the findings, up to 0.5% nanosilica content significantly increases the tensile and impact strength of the wool-epoxy composites. The contact angle measurement showed a slight enhancement in the hydrophobic properties of the composites due to the dispersion of hydrophobic nanosilica particles. The presence of nanosilica slightly reduced the water diffusivity in wool-epoxy-nanosilica composites when compared to wool-epoxy composites. The SEM images detected nanosilica inside the composites. After soil burial test, all the composites showed a weight reduction below 1.0%.

Development of light weight sustainable pineapple/kevlar hybridized fiber and peanut husk cellulose toughened vinyl ester biocomposite for unmanned aerial vehicle applications

AbstractThe aim of this study is to develop a light weight hybrid biocomposite using pineapple and Kevlar fiber with peanut husk cellulose in vinyl ester resin for applications in unmanned aerial vehicles. This study focuses on how the silane treatment on fiber and cellulose particle influences the mechanical, fatigue and low velocity impact properties of this hybrid biocomposites. Using hand lay‐up technique, the biocomposite was prepared with cellulose loading ranging from 1 to 5 vol%. The results revealed that the 5 vol% of cellulose added composite had an improved tensile, impact, flexural, hardness and ILSS of 161 MPa, 224 MPa, 6.8 J, 84 shore‐D and 21.4 MPa. Moreover, the biocomposite with the inclusion of 3 vol% cellulose had an improved fatigue life count of 42 697, 29 821, 22 381 and 18 164 at 25%, 50%, 75% and 90% of UTS. Similarly, the 3 vol% cellulose reinforced composite showed an improved low velocity impact toughness of 12.36 J. The obtained results clearly indicated that these mechanically strengthened and highly toughened biocomposites could be used as working material for number of applications, especially in making of UAVs for the aerospace industry, automotive components for the transportation sector and structural material in domestic infrastructure.

Performance analysis of hybrid bio-composites developed through different processing routes for automobile application

The performance of polymer composites strongly depends upon the constituents and the processing method of composite fabrication. The present study investigates the effect of fabrication processes (hand lay-up process, compression molding and resin transfer molding (RTM)) on the physical and mechanical properties of the developed bio-composites having different combinations of uni-directional sisal and uni-directional ramie fiber mat reinforcement in unsaturated polyester matrix. Scanning electron micrographs (SEM) were used to study the failure behavior of composite constituents under various loading conditions. Results indicate that composites fabricated by RTM process showed 5%–15% voids (percentage density change) while hand lay-up showed 30%–45% voids (percentage density change). Longitudinal and transverse flexural modulus of composites fabricated by RTM and compression molding are 2–3 times higher than composites developed by hand lay-up process. The study concludes that processing of composites through different routes and varying the reinforcement have significant effect on mechanical properties of the developed bio-composites.

Synergistic association of wood /hemp fibers reinforcements on mechanical, physical and thermal properties of polypropylene-based hybrid composites

Natural fiber-reinforced composites with thermoplastic matrices are gaining prominence in society as their applications are found in varied industries, e.g., automotive and aerospace. A recent trend shows the use of hemp fibers as reinforcements for the manufacture of bio-based composites, which are thermally and dimensionally stable, and durable. In this work, polypropylene (PP) was reinforced with 5, 10, 20, 30, and 40 wt% hemp fibers, having undergone an alkaline treatment, were processed, and investigated. Results showed that the composites made of hemp fibers with PP have exhibited good mechanical properties. A value of 2.12 GPa for young's modulus is achieved from a biocomposites containing 30 wt% of hemp fibers which is significantly higher than the 0.85 GPa of PP matrix. The full potential of hemp fibers as reinforcement for the PP matrix is demonstrated by this maximum, which represents a rise of 149% for the young's modulus and 40% for the tensile strength. Flexural modulus increased of 46%, 165%, and 232% compared to virgin PP at 10, 30, and 40 wt% fiber content. Such stiffness increases were followed by flexural strength increases of 52%, 78%, and 92% relative to virgin PP in the presence of 20, 30, and 40 wt% hemp fibers, respectively. A study was also conducted to evaluate the effects of various parameters on the thermo-mechanical properties of the final composites, which were hybrids made of PP reinforced with both hemp fibers and wood flour. These hybrid bio-composites prepared with 20 and 40 wt% hemp fibers and wood flour and variable ratios of the two reinforcements showed a positive hybridization effect. Nevertheless, the modulus of the hybrid biocomposites reinforced by both fibers, hemp/Wood floor (20/20), is 166% greater than the modulus of unreinforced PP and 34% greater than the Hemp/PP composite with 40% fiber content. Finally, a comparative study shows that the newly formulated hybrid composite has the potential to replace various existing natural fiber-reinforced composites. This study's approach is, although we know, unique.

Collagen/Nigella sativa/chitosan inscribed electrospun hybrid bio-nanocomposites for skin tissue engineering

The sophisticated new tissue regeneration focused on nanocomposite with different morphologies achieved through advanced manufacturing technology with the inclusion of bio-inscribed materials has piqued the research community’s interest. This research aims at developing hybrid bio-nanocomposites with collagen (Col), Nigella sativa (Ns) oil and chitosan (Cs) by a bi-layered green electrospinning on polyvinyl chloride (PVA) layer in a different ratio for tissue regeneration. Fiber morphologies through scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), moisture management, tensile test, antibacterial activity, cell cytotoxicity and wound healing through rabbit model of the fabricated hybrid bio-nanocomposites were investigated. It is worth noting that water-soluble Col (above 60% solution) does not form Taylor cones during electrospinning because unable to overcome the surface tension of the solution (viscosity) to form fibers. The results show that water soluble Col (50% solution) to Cs (25% solution) and Ns (25% solution) has good fiber formation with mean diameter 384 ± 27 nm and degree of porosity is 79%. The fast-absorbing and slow-drying hybrid bio-nanocomposites maintain a moist environment for wounds and allowing gaseous exchange for cell migration and proliferation by the synergistic effects of bio-polymers. All of the biopolymers in bio-nanocomposite improve the H-bonds, which accounts for enough tensile strength to withstand cell pulling force. The antibacterial ZOI concentrations against S. aureus and E. coli were 10 and 8 mm, respectively, which appeared to be sufficient to inhibit bacterial action with 100% cell viability (cytotoxicity). The synergistic effects of Ns and Cs improve tissue regeneration, while native Col improves antibacterial activity, and the rabbit model achieves approximately 84% wound closure in only 10 days, which is 1.5 times faster than the control model. So, the fabricated hybrid bio-composites may be useful for skin tissue engineering.

Use of tyrosinase-inorganic salt hybrid nanoflowers and tyrosinase-MOF hybrid composites for elimination of phenolic pollutants from industrial wastewaters

Removal of phenolic pollutants from industrial wastewaters is always an important practical problem. Use of enzymes for dephenolization provides a green solution. In this work, enzymatic methods were developed by employing mushroom tyrosinase immobilized as enzyme-Cu3(PO4)2 hybrid nanoflowers and enzyme-metal organic framework (i.e., ZIF-8 and HKUST-1) hybrid composites, which were shown to be superior to processes mediated by tyrosinase immobilized on other supports in both dephenolization efficiency and reusability. Comparatively, tyrosinase@Cu3(PO4)2 and tyrosinase@HKUST-1 were better than tyrosinase@ZIF-8 in both specific activity and dephenolization efficiency. Typical phenolic pollutants, including 3 monophenols (phenol, p-cresol, p-chlorophenol) and 3 bisphenols (BPA, BPB, BPF), can be completely eliminated within 0.5–4 h. The dephenolization order was discussed based on the enzyme's substrate specificity. The operability and reusability of these hybrid biocomposites were highly improved by entrapping into alginate gels or by incorporating with modified magnetic Fe3O4 nanoparticles. Particularly, the magnetic biocatalyst was prepared via a facile one-pot/one-step de novo synthetic strategy, optimized by using response surface methodology (RSM). The as-prepared magnetic tyrosinase@mHKUST-1 retained a high dephenolization efficiency of 81% after 10 cycles and was effective for continuous dephenolization for at least 24 h. These hybrid biocomposites were also successfully applied to treatment of real industrial wastewater from a coke plant.

Improving the Biological Properties of UHMWPE Biocomposite for Orthopedic Applications.

Bone plates are essential for bone fracture healing because they modify the biomechanical microenvironment at the fracture site to provide the necessary mechanical fixation for fracture fragments. The objective of this study was to determine cell availability, antibacterial activity, and wettability through a contact angle test. However, biocomposites that involve UHMWPE reinforced with n-HA and n-TiO2 particles at different fractions (0, 1.5, 2.5, 3.5, and 4.5%) and 5% from carbon and Kevlar fibers were fabricated by hot pressing technique. In vitro studies revealed good cell viability on the surface of the hybrid biocomposite even after 72 hr. The UHMEPE nanocomposite reinforced with carbon showed better cell attachment for fibroblasts than other UHMWPE nanocomposite materials reinforced with Kevlar fiber. The results of the contact angle measurements indicated that the incorporation of nanoparticles and the fiber reinforcement increased the wettability due to the hydrophilic character of nanobiocomposite, and also (UHMWPE-4.5% wt. TiO2-CF) biocomposite was the best wettability (∼48% as compared to neat UHMWPE). Antibacterial experiments involving Gram-positive bacteria, Staphylococcus aureus, confirm excellent bactericidal property for (UHMWPE-4.5% wt. TiO2-CF) biocomposite. Thermal analysis of the produced nanocomposites revealed that they had higher melting and crystallinity temperatures than pure UHMWPE.