This study presents an in vitro analysis of the bactericidal and cytotoxic properties of hybrid films containing nickel oxide (NiO) and nickel ferrite (NiFesub.2Osub.4) nanoparticles embedded in ...polypropylene (PP). The solvent casting method was used to synthesize films of PP, PP@NiO, and PP@NiFesub.2Osub.4, which were characterized by different spectroscopic and microscopic techniques. The X-ray diffraction (XRD) patterns confirmed that the small crystallite sizes of NiO and NiFesub.2Osub.4 NPs were maintained even after they were incorporated into the PP matrix. From the Raman scattering spectroscopy data, it was evident that there was a significant interaction between the NPs and the PP matrix. Additionally, the Scanning Electron Microscopy (SEM) analysis revealed a homogeneous dispersion of NiO and NiFesub.2Osub.4 NPs throughout the PP matrix. The incorporation of the NPs was observed to alter the surface roughness of the films; this behavior was studied by atomic force microscopy (AFM). The antibacterial properties of all films were evaluated against Pseudomonas aeruginosa (ATCCsup.®: 43636™) and Staphylococcus aureus (ATCCsup.®: 23235™), two opportunistic and nosocomial pathogens. The PP@NiO and PP@ NiFesub.2Osub.4 films showed over 90% bacterial growth inhibition for both strains. Additionally, the effects of the films on human skin cells, such as epidermal keratinocytes and dermal fibroblasts, were evaluated for cytotoxicity. The PP, PP@NiO, and PP@NiFesub.2Osub.4 films were nontoxic to human keratinocytes. Furthermore, compared to the PP film, improved biocompatibility of the PP@NiFesub.2Osub.4 film with human fibroblasts was observed. The methodology utilized in this study allows for the production of hybrid films that can inhibit the growth of Gram-positive bacteria, such as S. aureus, and Gram-negative bacteria, such as P. aeruginosa. These films have potential as coating materials to prevent bacterial proliferation on surfaces.
Supercritical COsub.2 (scCOsub.2) extrusion foamed high-melt-strength (HMS) polypropylene (PP) often suffers from low cell density, large cell sizes, and poor cell structure uniformity due to the ...poor nucleation rates of COsub.2 in the PP. To remedy this, various inorganic fillers have been used as heterogeneous nucleation agents. Although their efficient nucleation effects have been demonstrated, the preparation of these fillers causes some adverse effects on the environment/human health or involves relatively expensive processes or non-eco-friendly chemicals. In this work, biomass-based lignin is studied as a sustainable, lightweight, and cost-effective nucleating agent. It is found that scCOsub.2 could assist in situ dispersion of lignin in the PP in the foaming process, leading to significantly increased cell density, smaller cells, and improved cell uniformity. The Expansion Ratio is also simultaneously improved due to reduced diffusive gas loss. The PP/lignin foams with low lignin loadings exhibit higher compression moduli and plateau strengths than the PP foams with the same densities owing to the improved cell uniformity and probably also the reinforcing effect of the small lignin particles in cell walls. Moreover, the energy absorption capability of the PP/lignin foam with 1 wt% lignin could match the PP foam with similar compression plateau strengths; even the density of the former is 28% lower than the latter. Therefore, this work provides a promising approach to a cleaner and more sustainable production of HMS PP foams.
It is difficult to enhance the char yields of polypropylene (PP) due to the preferential complete combustion. Successful formation of abundant char layer structure of PP upon flammability was ...obtained due to the synergistic effect of NiO, Alsub.2Osub.3 and activated carbon (AC). From characterization of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), it was revealed that the microstructure of residual char contained large amount of carbon nanotubes. Compared to the modification of AC, NiO and Alsub.2Osub.3 alone, the combination of AC, NiO and Alsub.2Osub.3 dramatically promotes the charring ability of PP. In the case of AC and NiO, NiO plays a role of dehydrogenation, resulting in the degradation product, while AC mainly acts as carbonization promoter. The addition of Alsub.2Osub.3 results in higher dispersion and smaller particle size of NiO, leading to greater exposure of active sites of NiO and higher dehydrogenation and carbonization activity. Compared to the neat PP, the decomposition temperature of the PP modified by combined AC, NiO and Alsub.2Osub.3 was increased by 90 ℃. The yield of residual char of AC-5Ni-Al-PP reached as high as 44.6%. From the cone calorimeter test, the heat release rate per unit area (HRR) and total heat release per unit area (THR) of PP composite follows the order AC-5Ni-Al-PP < AC-10Ni-Al-PP < AC-Ni-PP < AC-15Ni-Al-PP < AC-1Ni-Al-PP. Compared to the neat PP, the peak of HRR declined by 73.8%, 72.7%, 71.3%, 67.6% and 62.5%, respectively.
The crystallization behavior, melting characteristics, and semicrystalline morphologies of wollastonite-filled recycled polypropylene (R-PP) composites without and with beta-nucleating agent were ...investigated in this study. The crystallization temperature (T.sub.c) of 20 mass% wollastonite-filled R-PP composite is 0.4 °C higher than that of R-PP, suggesting that the adding of wollastonite has little nucleation effect on crystallization of R-PP. However, 0.3 mass% TMB-5 significantly increases the T.sub.c of R-PP and induces a large number of beta-crystals in wollastonite-filled R-PP composites. For calcium pimelate-supported wollastonite (beta-W) filled R-PP composites, the T.sub.c and the relative beta-phase content of R-PP increase with increasing addition amount of beta-W (from 1 to 20 mass%). As a result, wollastonite-filled R-PP composites with beta-phase content higher than 85% can be obtained by adding 0.3 mass% TMB-5 or 20 mass% beta-W, which provides an effective method for realizing high value-added and low-cost recycling of R-PP.
The mechanical characteristics of hybrid polypropylene composites may be enhanced by adjusting the fibre loading and ratio, according to this study. The hot press technique was utilised to generate a ...variety of composites with four different amounts of fibre loading. In addition, the fibre ratio in composites with a 20-weight-percent fibre loading was changed. The composites were characterised using Fourier transform infrared analysis as well as tensile, flexural, and hardness tests. In the composites that have been created, Fourier transform infrared examination showed that hemicelluloses, lignins, and moisture were present, all of which have the potential to reduce tensile strength. Fibre loading resulted in a decrease in tensile strength but an increase in Young’s modulus. With increasing fibre loading, flexural modulus and hardness rose, whereas flexural strength declined. The best mechanical qualities were found in a composite made primarily of arecanut and glass fibres, with a weight ratio of 1 : 3.
Sargassum is a type of marine algae that has caused environmental problems in Mexico because it arrives in high quantities along the Mexican coast, especially in the Mexican Caribbean. This situation ...has become an environmental and economic problem, impacting tourism and other activities. As a result, it is reasonable to try to find an application for these algae. Recently, some applications in civil construction, cosmetics, and the food industry, among others, have been reported. The present work evaluates the thermal and structural properties of new polypropylene (PP)–Sargassum-based composites. Also, the effect of adding calcium stearate (CS) to increase the interaction between PP and Sargassum particles was investigated. PP–Sargassum particle composites were prepared by a melt mixing process, and the properties of these composites were evaluated using thermal techniques such as dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and infrared spectroscopy (FTIR). The DMA results showed that composites with low concentrations of Sargassum particles perform better than those with higher concentrations. When CS was added to composites, there was a significant improvement in storage modulus compared with composites without CS. This was attributed to the good adhesion of the particles to the matrix because the mobility of macromolecules increased in the presence of CS. The thermal stability of PP–Sargassum particle composites decreases when the amount of particles increases, and the addition of CS does not positively affect the thermal behavior of composites. The findings open the possibility of using Sargassum particles in new applications of these algae as a polymer additive to generate sustainable materials.
The thermal stability of nucleation effect of three highly effective beta-nucleating agents, namely an aryl diamide-based nucleating agent (TMB-5), a rare earth complex (WBG-II), and calcium pimelate ...(Ca-Pi) in isotactic polypropylene (iPP) was investigated by DSC multi-scanning cycles. All three nucleating agents induced iPP to form high contents of beta-crystals. After several thermal cycles, the relative content of beta-phase crystals (K.sub.DSC) in the nucleated iPP was decreased and the crystallization peak temperature ( Formula omitted) was also decreased. The K.sub.DSC and Formula omitted of iPP nucleated with TMB-5, WBG-II, and Ca-Pi were decreased by 0.0477, 0.1257, 0.0603, and 0.97, 2.71, 1.18 °C, respectively. It indicated that the nucleation effect became worse. The nucleation effect of TMB-5 decreased less while that of WBG-II and Ca-Pi was significantly reduced. Thus, the orders of thermal stability for nucleation effect of these three nucleating agents were TMB-5 > Ca-Pi > WBG-II.
A number of production methods have been developed for high-performance fibers; however, most processes use toxic solvents or generate a lot of unwanted by-products. Our research resulted in the ...development of a new family of high-performance polypropylene (PP) fibers by utilizing a simple, ecologically friendly bath (ECOB). Various commodity polymers can be used with ECOB melt spinning system at high throughputs and performance benefits. Our treated as-spun PP fibers had a highly oriented, but not crystalline precursor morphology with f.sub.a up to 0.6 generating superior mechanical properties. After drawing at draw ratios of 1.49 at 120°C, highly oriented crystalline and amorphous phases were achieved for the drawn fibers with f.sub.c and f.sub.a values of 0.95 and 0.87, respectively. This fine structure for ECOB-treated fibers resulted in tenacity close to 12 g/d, initial modulus higher than 150 g/d, and ultimate elongation at break of 20 %. The polymer melting point of the new fibrillar PP fibers increased by 9°C.
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