Polymer Science, Series B最新文献

Hydrophobic modification of hydroxyethyl cellulose is carried out in ionic liquids homogeneously, with bromododecane as the etherification agent. FTIR, XRD, XPS, and DSC analysis are used to characterize the obtained products. The effect of reaction temperature, time and the content of bromododecane on the viscosity of the aqueous solution of the modified product are discussed in detail. It is found that when hydroxyethyl cellulose is modified with the optimal conditions (at 80°C for 6 h), the crystalline structure changes to amorphous completely, the degree of substituent is 0.27, the glass transition point increases from 102.1 to 128.6°C. The thickening property, viscosity temperature resistance and salt tolerance before and after grafting long alkyl chain into the molecular chains are compared. It concludes that by hydrophobically modifying hydroxyethyl cellulose with long alkyl chains, all the above properties can be significantly improved, which may extremely expand the applications of hydroxyethyl cellulose.

Materials with different morphologies may possess different electrical conductivities which contribute to different photodegradation efficiencies. Hence, it is crucial to control the morphology of the photocatalysts. Therefore, the effect of PANI morphology on the electrical conductivity is investigated in this research. PANI with different morphologies have been fabricated via template-free method in the presence of various dopants and utilized as photocatalyst. The different morphologies of PANI are expected to yield different photocatalytic ability towards pollutants such as dyes in wastewater due to their differences in surface area and charge carriers (conductivity). The chemical structures and oxidation states of the prepared photocatalysts were confirmed by FTIR and UV–Vis spectra. The electrical conductivity of photocatalysts were measured using four probe point method on PANI pellet while the morphological studies were investigated using FESEM. From the results, nanotube-PANI exhibited the highest electrical conductivity (1.22 × 10^–2 S/cm), followed by nanosphere-PANI (1.16 × 10^–2 S/cm), nanofiber-PANI (4.59 × 10^–3), star-PANI (5.84 × 10^–4 S/cm) and leaf-PANI (5.57 × 10^–3 S/cm). PANI with nanotube structure is more conductive as the nanostructure has a longer conjugated polymer chain than the other micro/nanostructures and hence it can facilitate electron transport and subsequently enhances electrical conductivity of PANI.

Effect of four reaction factors including reaction time, concentration of NaOH, propylene oxide, and composition (methanol : water, v/v) of reaction medium was determined on hydroxypropyl content (%) and viscosity of hydroxypropyl guar gum using orthogonal design of experiment. Among all synthesized hydroxypropyl guar gum derivatives highest viscosity, and hydroxypropyl content was determined 5708.0 cPs and 0.487% respectively. Taguchi L9 (3⁴) design of experiment suggested 3 h and 0.1 mol as optimized reaction duration and concentration of etherifying reagent for higher hydroxypropyl content as well as viscosity. Optimized amount of NaOH was determined 0.03 and 0.02 mol for hydroxypropyl content and viscosity respectively. While the optimized composition of reaction medium (methanol : water, v/v) was determined 7 : 1 and 9 : 1 for hydroxypropyl content and viscosity respectively. Reaction time, and concentration of propylene oxide were determined as most impacting factor for hydroxypropyl content and viscosity of hydroxypropyl content respectively. Optimized products determined to exhibit 0.83% and 5902 cPs of hydroxypropyl content and viscosity respectively.

Composites with a two-layer coating consisting of ultra-high molecular weight polyethylene and a lower molecular weight high-density polyethylene are synthesized by the sequential two-step polymerization of ethylene on the surface of catalyst-activated Al₂O₃ particles to modify the properties of composite materials with the ultra-high molecular weight polyethylene matrix. The pressed specimens of the composites with the two-layer coating are characterized by the uniform distribution of components. The effect of composition of polymer coating of Al₂O₃ particles on the thermophysical and rheological properties of composite reactor powders and the deformation–strength properties of pressed specimens is studied. In nascent composite particles with the two-layer coating, the morphology of outer polymer layers is different and depends on the polymer type. The creation of two-layer coatings with the outer layer of a lower molecular weight polyethylene on filler particles renders it possible to realize the melt flowability of the composites at certain component ratios, while preserving deformation–strength characteristics at a high level. The proposed polymerization technique shows promise for development of ultra-high molecular weight polyethylene composite powders with the desired morphology and rheological characteristics suitable for selective laser sintering 3D printing. All synthesized composite powders based on Al₂O₃ spherical particles with one- and two-layer polymer coatings have shape close to spherical, repeating the shape of filler particles. In terms of rheological characteristics, they meet the requirements of selective laser sintering 3D printing and have free flowability, and the material of parts printed by this technology does not suffer from warping and shrinkage.

A series of poly[dimethyl(methylbenzyl)siloxanes] with different content of the methylbenzylsiloxane fragments have been synthesized. Structure of the polymers has been confirmed by means of ¹Н and ²⁹Si NMR spectroscopy. Thermal properties of the polymers have been investigated by means of differential scanning calorimetry and thermogravimetric analysis. It has been found that the copolymer crystallization is suppressed at the content of the methylbenzylsiloxane fragments on the copolymer of 3 mol % and higher, while the glass transition temperature is only insignificantly shifted towards the positive range. The copolymers have exhibited high temperature resistance and can be used over a wide temperature range.

Herein, firstly, sodium montmorillonite (Na⁺-MMT) was modified with Ganoderma lucidum (GL), and then the anti-corrosion properties of new nanoparticles (GL-MMT) were evaluated. For this purpose, GL-MMT was added to epoxy (EP), and their nanocomposite was prepared. GL-MMT was evaluated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Polarization and salt spray tests showed that GL‑MMT improved corrosion resistance. The hydrophobic nature of GL-MMT caused the hydrophobic properties to be observed in nanocomposites so that the EP/3% GL-MMT showed a contact angle of 73°. Also, the results of thermogravimetric (TGA) analysis, adhesion strength, and tensile test showed that GL‑MMT improves the properties of the coating. This enhanced in properties is due to the uniform distribution of GL-MMT in the matrix and also the polymer chains are easily able to penetrate into the MMT galleries. Moreover, the antimicrobial results showed that the coatings containing GL-MMT are inhibitory and killing against Staphylococcus epidermidis and Streptococcus pyogenes.

In this contribution, we reported the investigation of EPDM rubber reinforced by talcum grafted polybutadiene (MSi-Talc). First, poly (3-methacryloxypropyltrimethoxysilane)-b-polybutadiene-b-poly(3-methacryloxypropyltrimethoxysilane) (PMSi-b-PB-b-PMSi) triblock copolymer was synthesized by esterification reaction and RAFT polymerization of 3-methacryloxypropyltrimethoxysilane. Second, talcum powder (Talc) was spraying with PMSi-b-PB-b-PMSi solution and drying to obtain modified talc (MSi-Talc). MSi-Talc and Talc were incorporated into EPDM simultaneously. It was found that Talc in the EPDM/MSi-Talc vulcanizates was much better distributed and dispersed than in the EPDM/Talc composites. Compared to Talc dispersion and Talc-rubber interaction of the EPDM/Talc composites, the mechanical properties (tensile strength, elongation at break, and tear strength) of the EPDM/MSi-Talc composites were significantly improved, and the compression set of the EPDM/MSi-Talc composites was greatly decreased and much lower than that of the EPDM/Talc composites.

The non-biodegradable plastic waste accounts for the major portion of landfill solid waste leading a threat to both fossil fuels and the environment. As biodegradable nature bioplastics are a good replacement for conventional plastics. The global market for biopolymers and bioplastics is expanding rapidly as they make a significant contribution in reduction of environmental pollution. Bioplastics are completely decomposed into natural compounds by fungi, algae, and bacteria in a very short time under aerobic and anaerobic conditions. Bioplastics are categorized into three types namely, biodegradable, and biobased bioplastics (e.g., PLA, PHA, PGLA), nonbiodegradable and biobased bioplastics (e.g. Bio PE, Bio PET), and biodegradable and petroleum-based bioplastics (e.g. PCL, PBS, PBSA). Fungal degradation of bioplastics depends upon several physical, microbiological, and characteristic features of the polymer. The fungal strain-mediated biodegradation of bioplastics leads to the release of natural inorganic and inorganic compounds that do not negatively impact microbial diversity, nutrient cycle, and nitrogen content in the soil. This review highlights the impact of bioplastics on environmental sustainability and role of fungal biodegradation of bioplastics. The information provided in this review will help in development of more efficient strains of fungal as well as in research and development of bioplastic.

In this work, a good degree of epoxidation on poly(styrene)-b-poly(isoprene)-b-poly(styrene) (SIS) block copolymers containing different styrene content (15, 24, and 43%) has been achieved to get epoxidized SIS (eSIS). Thus, obtained eSIS has been blended with epoxy in different compositions. The role of styrene content on eSIS in generating the nanostructure on epoxy matrix has been carefully studied. The morphological findings have also been confirmed by dynamic mechanical analysis. Compared to other blend systems, a composition of 10 wt % eSIS having 24% styrene content is able to form a highly ordered nanostructure in the epoxy network with highest value of glass transition temperature (T_g). As the ratio of PS block in SIS increased, the plasticization effect due to the penetration of ePI block in the blends becomes less, which reflect in their T_g and thermal expansion coefficient (CTE). 10 wt % of eSIS having 43% styrene content largely reduces the CTE of epoxy matrix.

In this study, we aim to synthesize a novel hyperbranched unsaturated polyester resin nanocomposite based on graphene oxide using dicyclopentadiene maleate and poly methyl methacrylate-co-butyl acrylate. The incorporation of graphene oxide in the unsaturated polyester resin enhances the mechanical properties of the nanocomposite. Free radical copolymerization between double bonds of soya fatty acid, which is used to terminate the polyester and methyl methacrylate and butyl acrylate along with the reaction of dicyclopentadiene maleate with graphene oxide results in a three-dimensional cross-linked structure, allowing the unsaturated polyester resin to dry faster which makes it suitable for metal coating, especially car coating. The synthesized graphene oxide unsaturated polyester resin was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The results showed that the modified graphene oxide unsaturated polyester resin exhibited improved thermal stability and mechanical properties compared to the unmodified resin. This study provides a promising approach for developing high-performance nanocomposite materials using modified graphene oxide unsaturated polyester resin.