Advances in Polymer Technology最新文献

Polymeric and plastic materials currently have numerous positive impacts due to their unique properties that make them important for various engineering applications. However, sustainability is a vital factor that should be considered, because of environmental issues. Eggshells (ES) are an important way to reduce the impact of nondegradable materials when applied to reinforce different types of polymer matrices, whether natural or synthetic polymers. Therefore, this study is an attempt to explore the potential application of waste eggshell fillers for the first time as a natural reinforcement in polyamide 12 (PA) composites. PA was loaded with three different ratios (3, 5, and 10 wt. %) of eggshell powder. Morphological studies of the PA powder, ES powder, and their composites were carried out by scanning electron microscopy (SEM). Furthermore, differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were performed to study the thermal and chemical properties of the raw materials and the produced composites. The results indicate ES fillers’ potential usage as a reinforcement material to develop the thermal and chemical properties of the PA polymer matrix composites, thereby reducing costs and minimizing the environmental pollution caused by waste eggshells and petroleum-based polymers.

Polymeric materials were evaluated with regard to their spinnability and respective fibre diameters. A modified single fibre spinning device was firstly used to derive a novel generalised model, utilising process parameters (die diameter, throughput, and stretching relevant take-up pressures) and material properties (zero shear viscosity) to predict the diameter of polymeric fibres on the basis of four different polymers. Further evaluation of the resulting power law dependence was conducted on filaments produced via conventional melt spinning and meltblown processes. Fibres produced on the pilot machines showed close agreement with the model equation with only the need to adjust an easily calculable device dependent factor. The outcome of the presented work is a user-friendly model of high practical relevance, which can be used to predict the diameter of amorphous and semicrystalline polymeric fibres, independent of material and machine used with sufficient accuracy for fast estimations.

In this study, both polyvinyl chloride (PVC) and polyacrylonitrile (PAN) were dissolved in dimethyl formaldehyde (DMF) with 8 wt. % concentrations at 25 : 75, 50 : 50, and 75 : 25 of PVC: PAN blending. For the investigation of the homogeneity and compatibility of mixture polymer solutions, it is examined by rheological properties such as viscosity, shear stress, shear rate, and calculation of the flow behavior index, while the investigation of the stability and high density of nanofibers without beads used field-emission scanning electron microscopy (FE-SEM), Fourier transform near-infrared spectroscopy (FT-NIR), X-ray diffraction (XRD), and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The results show that blending of PAN with PVC leads to improving of the electro spun ability of PVC with more stability, and the mean nanofiber diameter was 90.873 ± 40.82 nm at 25 : 75 PVC: PAN. Moreover, mechanical properties are ultimate tensile strength and modulus of elasticity decreasing with decreasing the blending ration from pure PVC to 75 : 25 PVC: PAN nanofibers by 71% and 83%, respectively, while the elongation at break increases by 79%, and decomposition temperatures decreased from 451.96 to 345.38°C when changing the PVC content from pure PVC to 25 : 75 PVC: PAN. On the other hand, changing of the nanofiber behavior from hydrophobicity to hydrophilic increased the PAN content in PVC: PAN blends. Furthermore, the low interaction between the chains of polymers and the crystallinity (%) and crystalline size (nm) of blend nanofibers slightly decreased compared to the pure polymers. According to all tests, the 25: 75 PVC: PAN was the best blending ratio, which gave a more stable nanofiber produced at low concentrations and more compatible between the PVC and PAN.

Recovery of fat-and-oil production wastes will reduce the technogenic impact on the environment, as well as involve them in a new production cycle as a secondary material resource. As part of solving this problem, the possibilities of using fat-and-oil production wastes in the production of a tyre reclaim and a modified tyre reclaim are considered. In the course of the studies, the fat-and-oil industry wastes’ sorption characteristics are determined, and in relation to oils in static and dynamic conditions, the spent reagent reclamation ways are determined. The authors obtained a tyre reclaim and a modified tyre reclaim using the fat-and-oil industry wastes (soap stock, diatomite, bleaching clay, and fatty acids isolated from soap stock). In this work, the authors studied the possibility of using the fat-and-oil industry wastes in the formulations of a tyre reclaim and a modified tyre reclaim. Extended physical and mechanical tests of experimental rubbers led to the conclusion that it is most expedient to use the fat-and-oil industry wastes in the formulation of rubber compounds for production of sleeper pads for railroad tracks, since when using a tyre reclaim and a modified tyre reclaim, the indicators of rubber properties practically do not change and comply with control standards.

Packaging plastics are called ‘single-use plastics’ because of short lifetime. Among which, the three plastics of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) take more than 70%. Due to incompatibility, few research has been done on the alloy of the three plastics. The aim of this study is to investigate the possibility of single-use plastic alloy (SUPA) of ternary PE, PP, and PET as the 3D printing material. Tensile and bending tests are carried out to investigate the mechanical properties, photographs of scanning electron microscope (SEM) are taken for morphology analysis, and differential scanning calorimetry (DSC) are used to study the crystallization behavior of the alloys. The results show that there is an optimal ratio for all the components to obtain the best mechanical performances, i.e., the ratio of PP/PE = 40/60 with 20 wt% PET, 2 wt% maleic anhydride grafted polypropylene (PP-g-MAH) and 2 wt% organic modified montmorillonite (OMMT). This SUPA has a tensile strength of 14.48 MPa, a tensile modulus of 586.42 MPa, a flexural strength of 15.85 MPa, and a flexural modulus of 544.67 MPa. Due to the function of compatibilizer and nanoclay (NC) will be affected by redundancy, the potential primary fibrosis while collecting the feeding filaments and the secondary fibrosis at the nozzle of 3D printing might be responsible for the variation of the mechanical performances.

Vinyl acetate (VAc) was polymerized to about 90% conversion in 9 h at 40°C from the colloidal microstructure of the VAc/fumed silica/cetyltrimethylammonium bromide (CTAB) system. The glass transition (T_g) of poly(vinyl acetate) (PVAc) polymerized in these emulsion gels with silica was higher (T_g = 41^°C) than those of PVAc made from bulk polymerization at 60°C (T_g = 31^°C) and the weight average molar mass (M_w) was also larger (M_w about 300 kg/mol) than those from bulk polymerization (M_w = 125 kg/mol). Increased M_w, T_g, and lowered processing temperature for these composites could facilitate new applications for PVAc.

Research shows that the composite material is used as an adsorbent to remove pollutants from wastewater. This work is aimed at producing a novel composite film comprising chitosan, polyvinyl alcohol, and cornstarch incorporating nanocellulose (CPCN). The composite film was prepared by a blending method wherein nanocellulose was extracted using a chemical method from banana bract. The prepared CPCN was characterized using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) with EDX to understand their molecular interaction and surface morphology, respectively. The effect of parameters including pH, adsorbent dosage, initial dye concentration, and contact time on the adsorption of methylene blue (MB) dye was studied. The maximum adsorption was found to be up to 63.13 mg/g MB with a pH of 10, adsorbent dosage of 2 g, an initial concentration of 150 ppm, and contact time of 120 min at room temperature (25°C) indicating a moderate adsorption capacity of the CPCN. Comparing the Langmuir and Freundlich adsorption isotherm models, the former fitted well with MB dye adsorption data, implying that the models can be applied to uptake MB dye by CPCN. In the kinetic adsorption experiment, the adsorbed dye almost reached equilibrium at about 120 min for the CPCN and followed the pseudo-second-order kinetic model. Therefore, the CPCN can be used as a potential adsorbent in wastewater treatment.

Polymeric foams have characteristics that make them attractive for different applications. However, some foaming methods rely on chemicals that are not environmentally friendly. One of the possibilities to tackle the environmental issue is to utilize supercritical carbon dioxide ScCO₂ since it is a “green” solvent, thus facilitating a sustainable method of producing foams. ScCO₂ is nontoxic, chemically inert, and soluble in molten plastic. It can act as a plasticizer, decreasing the viscosity of polymers according to temperature and pressure. Most foam processes can benefit from ScCO₂ since the methods rely on nucleation, growth, and expansion mechanisms. Process considerations such as pretreatment, temperature, pressure, pressure drop, and diffusion time are relevant parameters for foaming. Other variables such as additives, fillers, and chain extenders also play a role in the foaming process. This review highlights the morphology, performance, and features of the foam produced with ScCO₂, considering relevant aspects of replacing or introducing a novel foam. Recent findings related to foaming assisted by ScCO₂ and how processing parameters influence the foam product are addressed. In addition, we discuss possible applications where foams have significant benefits. This review shows the recent progress and possibilities of ScCO₂ in processing polymer foams.

Graft modifications of PVDF fluoropolymers have been identified as the efficient route to improve the properties and expand the applications. Taking advantage of C-F and C-Cl bonds in the repeat units, atom transfer radical polymerizations (ATRP) were widely used for graft modification. Recently, photoinduced ATRP has shown good spatial and temporal control over the polymerization process in contrast to thermal activation mode. This minireview highlights the progress in PVDF-based fluoropolymer modifications by using photoinduced Cu(II)-mediated ATRP and organocatalyzed ATRP. The challenges and opportunities are proposed with the aim at advancing the development of synthesis and applications of fluoropolymer.

In order to reveal the dielectric properties of the nonaqueous reactive polyurethane grouting material, combined with the electron microscope test analysis, it can be seen that the nonaqueous reactive polyurethane material is a porous two-phase body composed of a polyurethane matrix and closed cells. At the microscopic scale, the porous two-phase physical model is established, and the dielectric model of the material is constructed on this basis. In order to verify the dielectric model, 40 groups of nonaqueous reactive polyurethane specimens with different densities were designed and prepared in this paper. The dielectric permittivity was measured by a vector network analyzer (VNA) with an open coaxial probe within the frequency range of 1050 MHz~5010 MHz for the first time, and the dielectric properties and influencing factors were revealed according to the test data. The result shows that the dielectric permittivity of nonaqueous reactive polyurethane materials increases with the increase of density, and decreases slightly with the increase of frequency. Compared with the three models of the Rule of Mixture, Clausius-Mossotti Model and Lichtenecker Model, the calculation accuracy of the Maxwell-Garnett Model is higher, and the calculation results are more consistent with the experimental results of nonaqueous reactive polyurethane grouting materials. The experimental results can be applied to the nondestructive testing of polyurethane grouting materials and provide reference and basis for the quality evaluation of polymer structures.