Forming and mechanical properties of boron Nitride-Reinforced aluminum composites fabricated via an accumulative roll bonding process

In this study, physical, mechanical, thermal, fire and biological properties of thermoplastic composites filled with fire retardant and tea mill waste fiber were investigated. The composites produced with the extrusion method were accomplished by using tea mill waste fiber as lignocellulosic materials and high-density polyethylene and polypropylene as thermoplastic polymer. Aluminum trihydrate and zinc borate were incorporated with different contents into polymer matrix for improving fire properties of the composites, and their effects on technological properties of the composites were evaluated. Aluminum trihydrate had a positive effect on the tensile modulus of the composites whilst zinc borate had adverse effect on that of the composites. The strength properties of the composites slightly decreased with usage of fire retardant. In the light of obtained results, it was specified that use of fire retardants improved physical, biological, thermal and fire properties of tea mill waste fiber-filled thermoplastic composites.

Biobased plasticizer and cellulose nanocrystals improve mechanical properties of polylactic acid composites

The above paper presents the assumptions and results of the research whose aim was to determine the influence of 2024, 6061 and 7075 aluminum alloys on the final properties of GLARE-type composites. GLARE 3 2/1 type composites, made of two layers of the epoxy prepreg, reinforced with unidirectional glass fibers, arranged in the direction of 0°/90°, and two sheets of aluminum with a thickness of 0.4 mm, were investigated. Composites of various stacking configurations of alloy layers, made of one type of aluminum alloy (so-called ‘homogeneous composites’), and two different alloys (mixed composites), were analyzed. The properties of the composites were evaluated with the use of the mixing rule and compared with the test results. The influence of the used aluminum alloys on mechanical properties of GLARE-type composites has been determined. GLARE-type composite made of 7075 alloy sheets had the most favorable mechanical properties in comparison to properties of composites with 2024 and 6061 sheets. It has been shown how the properties of GLARE-type composites depend on the type of the aluminum alloy. It has been also proved that the properties of GLARE-type composites can be evaluated with the use of the mixing rule.

To fabricate homogeneous bamboo fiber reinforced thermoplastic composites, polypropylene (PP) fiber and 3-aminpropyltriethoxysilane (APTES) modified bamboo fibers were first formed into mats by non-woven air paving technology, and then the composites were created by hot-pressing the mats. The modification of BFs was characterized by XPS and FTIR analyses, and the results confirmed that APTES had been grafted onto the surfaces of BFs. The effects of concentrations of APTES on the mechanical, physical, morphological, and thermal properties of the bamboo-polypropylene composites were examined by tests of bending strength, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and water absorption. The analysis of physical and mechanical properties revealed improved mechanical properties and water resistance (3 wt% of APTES). SEM images were used to assess the influence of modification treatment on the properties of the composites. The results confirmed that the modification of APTES improved the interfacial adhesion between BFs and PP matrix. DSC results indicated the melting point of composites decreased with an increase in concentration of APTES up to 3 wt%, while the melting point of composites increased when the concentration of APTES was higher than 3 wt%.

Polymer hybrid composites and hybrid polymer composites are distinct but interconnected composite classes, each with unique compositions and design philosophies. The mechanical properties of these composites are vital in advanced materials due to their impacts on performance, durability, and suitability for various applications. The addition of ionic liquids into these composites is a promising innovation in advanced materials. In this short review, various polymer matrices (e.g., thermosets, thermoplastics, and biopolymers), fillers (e.g., inorganic, carbon, organic, and metal), and ionic liquids (e.g., imidazolium- and phosphonium-based) used to fabricate polymer hybrid composites and hybrid polymer composites with added ionic liquids are identified. Furthermore, the addition of ionic liquids into these composites through different methods (e.g., magnetic stirring, mechanical stirring, solid grinding, etc.) is discussed. The influence of ionic liquid addition on the mechanical properties, specifically the tensile properties of these composites, is also shortly reviewed. The changes in the tensile properties, such as the tensile strength, tensile modulus, and elongation at break, of these composites are explained as well. The information presented in this review enhances the understanding of the methods applied to add ionic liquids into polymer hybrid composites and hybrid polymer composites, along with their tensile properties. In short, some ionic liquids have the capacity to enhance the tensile properties of hybrid polymer composites, and several ionic liquids can reduce the tensile properties of polymer hybrid composites.

The aim of this work was to improve the mechanical and water barrier properties of composite films prepared from starch and clays, plasticized with glycerol at different concentrations. The effects of hydrophilic Closite Na+ and Nanomer PGV were compared with that exerted by organically modified more hydrophobic Nanofil 2 and NanoBent ZR‐1. The antimicrobial activity of composites containing hydrophobic clays was also investigated. The hydrophilic Nanomer PGV at concentrations of 5–10% increased the tensile strength (TS) of unplasticized composites, but starch‐Closite Na+ composites were too brittle to measure their mechanical properties. The hydrophobic clays did not improve the mechanical properties of the unplasticized composites. In the presence of glycerol at concentrations of 20–30%, TS of composites containing hydrophilic clays and even hydrophobic NanoBent ZR‐1 increased in comparison to plasticized films without clay. None of the clays improved the water barrier properties of the unplasticized composites, while in the plasticized composites all the clays decreased the water vapor permeability to an extent dependent on the kind and concentration of clay and glycerol concentration. Starch‐NanoBentZR‐1 composite showed very high activity against gram‐positive Staphylococcus aureus and Listeria innocua. Starch‐Nanofil 2 composites were characterized by smaller activity. Neither composite showed any antimicrobial activity, or their activity against gram‐negative bacteria was low.

In the present work, high density polyethylene based composites filled with glass spheres, talc and calcite particles were prepared. Fillers contents in the HDPE were 5, 10, 15, and 20 wt%. The mechanical, morphological and tribological properties of the polymer composites were investigated. Substantial improvements in the some mechanical properties were obtained by the addition of filler. For example, the results showed that the elasticity modulus of composites improved with increasing the filler content. The addition of fillers to the HDPE changed significantly the friction coefficient and wear rate of the composites. HDPE filled with a high level content of fillers showed higher wear rate than pure HDPE under dry sliding. The structure and properties of the composites are characterized using a scanning electron microscopy (SEM).

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

Wollastonite has a huge potential to be utilized as a functional filler in the thermoplastic composites, providing an enhancement to the mechanical strength, as well as thermal stability and flame retardancy, thus replacing the other conventional fillers such as glass fibre and talc. Due to the reinforcing ability and good thermal stability of wollastonite, the wollastonite-filled polymer composites have attracted the attention of academicians and industrialists. Many studies are reported on the effect of wollastonite incorporation into the polymers, in the aspect of mechanical, thermal, and flammability properties, meanwhile exploring the potential of wollastonite usage in the desired applications. This review article will be focusing on the thermal and flammability properties of wollastonite-filled thermoplastic composites. The popular thermoplastics used as the matrix are polypropylene, polylactic acid, and poly(ethylene terephthalate). Studies on flammability properties of wollastonite-filled thermoplastic composites are relatively less compared to thermal properties. Generally, the properties of the composites are influenced by the wollastonite dispersion, loading, size and shape of wollastonite, and its interfacial adhesion with the polymer matrix. Most of the previous studies focused on thermoplastic filled natural micro-sized wollastonite composites. Thus, the effect of nano-sized synthetic wollastonite as a functional filler in polymers is worth investigating. Further research on hybrid wollastonite/nanofillers is also interesting to develop high-performance materials to meet the requirements of society and industries.

Commingled polypropylene (PP)/banana granules were fabricated from slivers by mixing PP fibers and banana fibers by textile equipment. By twisting the sliver, the reinforcing fibers were compacted and bonded with the molten matrix material. PP/banana composites were prepared from commingled PP/banana granules by injection moulding method with special reference to the effect of maleic anhydride modified polypropylene (MAH-PP) concentration. The mechanical properties of the composites were found to depend on the concentration of MAH-PP. The tensile and flexural properties of the composites increased with the addition of MAH-PP up to 2 wt%. After 2 wt% addition of MAH-PP, these properties tend to be stabilized. On the other hand the unmodified composites showed the maximum impact strength. Fourier transform infrared spectroscopic (FTIR) analysis of the MAH-PP modified composites showed evidence of a chemical bridge between the hydroxyl group of the banana fiber and maleic anhydride of the MAH-PP through an esterification reaction. The feature peak of the esterification occurred in the range ∼ 1743 cm−1. In order to confirm the esterfication reaction further, FTIR spectra of the banana microfibrils and MAH-PP modified PP/banana microfibril composites were taken and compared. The tensile fracture surfaces of the unmodified and MAH-PP modified PP/banana composites were studied by scanning electron microscopy (SEM). An improvement in adhesion between the fiber and the matrix was observed in the case of MAH-PP modified composites. Two different processing methods, both injection and compression mouldings were performed to prepare the PP/banana composites. Tensile properties of the composites prepared by these two methods were compared. The enhancement of tensile properties for injection-moulded composites compared to the compression-moulded composites is owing to the occurrence of orientation, better mixing and interaction between the fiber and the matrix during injection moulding. Finally, experimental results of the tensile properties of the injection-moulded composites have been compared with theoretical predictions.

Sintering temperature might have varied effects on the properties of composites in general. Through this paper, an attempt has been made to investigate the effect of sintering temperature on the properties of Aluminium composites fabricated by powder metallurgy process. Alumina and Silicon Carbide were different types of reinforcements in this work. Green compacts of Aluminium composites were made at a compressing load of 1 tonne and 2 tonne separately. These compacts were sintered at 2 different sintering temperatures of 400°C and 450°C in oxygen free environment using muffle furnace for 1 hour, followed by annealing process which took 12 hours. Sintered compacts were than subjected to micro-structural examination and mechanical properties evaluation. Higher hardness has been attained for the composites containing 2.5% Silicon Carbide. Optical microstructure images show the uniform distribution of particles into aluminium matrix.

Objective: The objective of this study was to explore the effect of Chlorhexidine-loaded Halloysite nanotubes (HNT/CHX) fillers (diverse mass fractions from 1 to 10 wt.%) on physicochemical, morphological and biological properties of newly developed experimental dental resin composite, in order to compare with the properties of composites composed of conventional glass fillers. Methods: The dental resin composites were prepared by incorporating various proportions of HNT/CHX. Six different groups of specimens: control group and five groups composed of varied mass fractions of HNT/CHX (e.g., 1.0, 2.5, 5.0, 7.5 and 10 wt.%) as fillers in each group were fabricated. Mechanical properties of the composites were monitored, using UTM. The degree of conversion of dental resin composites and their depth of cure were also evaluated. Antimicrobial properties of dental composites were studied in vitro by applying agar diffusion test on strain Streptococcus mutans and cytotoxicity were studied using NIH-3T3 cell line. Results: The incorporation of varied mass fractions (1.0 to 5.0 wt.%) of HNT/CHX in dental resins composites enhanced mechanical properties considerably with significant antibacterial activity. The slight decrease in curing depth and degree of conversion values of composites indicates its durability. No cytotoxicity was noticed on NIH-3T3 cell lines. Significance: Consistent distribution of HNT/CHX as a filler into dental composites could substantially improve not only mechanical properties but also biological properties of dental composites.

Multi-constituent particulate composites consist of individual particles of more than one material dispersed throughout and held together by a polymer binder. The mechanical and physical properties of the composite depend on the mechanical and physical properties of the individual components, particularly the binder; their loading density; the shape and size of the particles; the interfacial adhesion; residual stresses; and matrix porosity. Multi-constituent composites with cast-cure epoxy binder have been presented recently. In this study, the microstructure is varied by injection molding PMMA-based composites. The dynamic mechanical properties of PMMA-based and epoxy-based composites are measured using a split Hopkinson pressure bar. The mechanical properties of these composites are compared.

Shortening the curing time is critical to improve the processing efficiency of composites. In this paper, unidirectional carbon fibre-reinforced rapid curing epoxy composite laminates were fabricated by vacuum-assisted resin injection moulding (VARIM). Different rapid curing processes (namely P80, P85, and P90) were employed, which preheating temperatures were 80, 85 and 90 °C, respectively. Different preheating temperatures of mould and fibre preform were conducted, to demonstrate the effects on the properties and processing time of the composites. In addition, a slow curing process (N80) was investigated to verify the effect of rapid curing on the mechanical properties of the composites. The relationships among preheating temperature, curing cycle and properties of the composites were analyzed. The results showed that the preheating temperature had obvious effects on the total cycle time and properties of the composites. The cycle time of the P80 process was 947 s, whereas that of the P90 process was 702 s. However, nonuniformity of the mechanical properties along the resin flow direction was more obvious for the P90 process, and more voids formed in the resin outlet region. Composites fabricated by the P80 process showed comparable mechanical properties and processing quality to those from the N80 process. It is suggested that a rapid curing process with proper preheating temperature is acceptable to improve the processing efficiency.

Fiber-reinforced composites represent 75% of the application of these materials in several industrial segments. It has the purpose of improving technical characteristics and reducing environmental impact through the use of sustainable raw materials such as natural fibers and other fibers from industrial waste. In this sense, the objective of this work was to study and compare the mechanical properties of polyester composites (PL) reinforced with natural sisal fiber and residues of polyethylene terephthalate (PET) synthetic fibers. Initially, we evaluated the moisture and morphology of the fibers. The composites with PL matrix were obtained and the fiber concentration varied by 1%, 3%, and 5% by weight. In the composites, the mechanical properties under flexion and impact resistance were evaluated. We concluded that the level of reinforcement with sisal fibers did not significantly affect the mechanical properties. However, the PET fiber provided significant improvements in the properties of the composite. Thus, the composites reinforced with PET fiber residue have advantages in the development of new material with sustainable characteristics.