Polymer International最新文献

A novel smart catalyst was developed with amino-modified thermo-responsive poly(N-isopropyl acrylamide) (PNIPAM) grafts on silica-coated magnetic nanoparticles using the conventional free radical polymerization process. By this methodology, the polymer was successfully grafted mainly onto silica-modified iron oxide nanoparticles (Fe₃O₄@Si). The PNIPAM-grafted Fe₃O₄@Si was then subjected to ethylenediamine treatment to produce the amino-functionalized support (Fe₃O₄@Si@PNIPAM-NH₂), which was subsequently modified with carboxyl functional groups by using EDTA (ethylenediaminetetraacetic acid) to create Fe₃O₄@Si@PNIPAM-NH₂-EDTA. Au nanoparticles were then decorated on this support through its two amines and four carboxylates. Different methods were used to study this novel catalyst, including inductively coupled plasma, Fourier transport infrared spectroscopy, TGA, dynamic light scattering, SEM, energy-dispersive X-ray analysis, vibrating sample magnetometry, XRD and elemental CHN analysis. The reduction of several aryl-nitro derivatives demonstrated a significant catalytic activity for the as-synthesized gold catalyst (Fe₃O₄@Si@PNIPAM-NH₂-EDTA-Au). The Au catalyst can be successfully removed from the reaction components using a magnetic field and used again in eight successive reduction reactions without significant gold leaching and loss of catalytic activity. © 2024 Society of Industrial Chemistry.

Phenol–formaldehyde (phenolic) thermosets are known for excellent heat and chemical resistance, high flame retardance, and good mechanical performance. However, phenolics are also known for their high brittleness, and tendency to form voids, due to a condensation reaction forming water during curing. These voids can decrease the mechanical performance of the resultant phenolic composite and introduce undesirable performance characteristics. This work aims to develop a technique that uses high-pressure infiltration to obtain dense phenolic matrix composites, with commercially available resin and fiber reinforcement. The high-pressure system developed in this work is compared to a conventional low-pressure resin infusion technique, and the porosity after each infusion is analyzed. A model of the low- and high-pressure systems was developed, and the predicted time of infiltration was compared to the experimental results. The high-pressure system had 97% less open porosity after infusion than the low-pressure technique, suggesting that it can produce a higher-quality and better-performing phenolic composite than conventional techniques. Also, the mechanical test performed indicates improved performance for the high-pressure injection with a 30.73% increase in ultimate tensile strength in comparison to low pressure, indicating better mechanical performance. © 2024 Society of Industrial Chemistry.

Carbon fiber reinforced polyether ether ketone (CF/PEEK) composites are widely used as tribo-materials in the aerospace and automotive industry. To amplify the industrial utilization of extrusion-based additive manufacturing fused deposition modeling in fabricating CF/PEEK tribo-composites, the composites' microstructure–property relationship was studied with respect to carbon fiber content varying between 5 wt% and 30 wt%. This revealed that the incorporation of carbon fibers helped enhance the mechanical strength of PEEK greatly with an optimal content of 5 wt%, at which the composite material exhibited the highest crystallinity as well as the best mechanical performance. Tribological tests indicated that CF/PEEK composites were more suitable for high speed and heavy load conditions especially for 20 wt% CF/PEEK, which was associated with the establishment of high quality transfer films covered on counter steel surfaces. The present work provides a simple and low cost way of fabricating high performance PEEK composites used as tribo-materials. © 2024 Society of Industrial Chemistry.

The use of functional polymeric composites with superior thermal properties, capable of replacing conventional polymers, has increased in recent years, particularly in the electrical-electronics sector where thermal management is crucial. Carbon fiber (CF) polymer–matrix structural composites have relatively high in-plane thermal conductivity but low through-plane conductivity. In order to further enhance the through-plane and in-plane conductivity of CF-reinforced polybutylene terephthalate (PBT) composite, a hybrid loading approach was employed, incorporating synthetic graphite (SG), boron nitride (hBN), aluminium nitride (AlN) and graphene (G) in composite formulations. It was found that the in-plane conductivity of PBT-20CF-20SG-3G and the through-plane conductivity of PBT-20CF-20SG-3AlN are 69% and 25% higher, respectively, than those of PBT-40CF. However, the mechanical properties of hybrid composites exhibit lower values compared to those of CF-reinforced PBT composites. The tensile strength value of PBT-40CF is about 33% and 57% higher than those of PBT-20CF-20SG-3G and PBT-20CF-20SG-3AlN. Moreover, the flexural strength of PBT-40CF is about 48% and 38% higher than those of PBT-20CF-20SG-3G and PBT-20CF-20SG-3AlN, respectively. The density value of PBT-40CF is lower than that of the composites of PBT-20CF-20SG. From TGA it was observed that the thermal stability of PBT-40CF is comparable to that of the composites PBT-20CF-20SG. From the conducted study, it can be proposed that the hybrid combination of SG, hBN, AlN and G can be utilized to achieve higher thermal conductivity values, instead of relying solely on CF in the composites. © 2024 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

Blends of polycarbonate (PC) and poly(1,4-cyclohexylene dimethylene terephthalate glycol) (PCTG) were synthesized using a twin-screw extruder. Four distinct PC/PCTG blends were produced with PCTG constituting 10%, 20%, 30%, and 40% of the total weight. Comprehensive evaluations were performed to investigate their thermal properties, solvent resistance, light transmittance, mechanical characteristics, and melt flow index. Differential scanning calorimetry and thermogravimetric analysis demonstrated a single glass transition temperature in the PC/PCTG blends, indicating high compatibility. The incorporation of PCTG was observed to affect the blends' thermal stability. The data revealed a progressive increase in solvent resistance, light transmittance, and melt flow index with increasing PCTG content. The light transmittance of the blend reached 87.5%, and the melt flow index was recorded at 124.2 g (10 min)⁻¹. Mechanical tests showed that the tensile and bending strengths were relatively stable with the addition of PCTG, but there was a noticeable reduction in notched impact strength as the proportion of PCTG increased. © 2024 Society of Industrial Chemistry.

Chlorinated plastics are part of the everyday lives of consumers and producers alike. They can be found in buildings, automobiles, fashion, packaging and many other places. This prevalence makes them a considerable part of the plastic waste crisis. Interest in ‘upcycling’ (as opposed to recycling) has grown recently to augment the possibilities of managing plastic waste. The advances made in plastic upcycling have focused on polyethylene, polypropylene, poly(ethylene terephthalate) and polystyrene while chlorinated plastics, chiefly poly(vinyl chloride), have received much less attention. The release of chlorine-containing molecules during treatment of chlorinated plastic greatly complicates cross-method upcycling, or even the treatment of plastic mixes containing chlorinated plastics. This review presents a case for extracting value from chlorinated plastics by highlighting appealing upcycling products made owing to, or despite, the CCl bond via depolymerization, carbonization and modification. © 2024 Society of Industrial Chemistry.

Herein, we develop an approach to achieve performance-advantaged polydicyclopentadiene (PDCPD) via sequential ring-opening metathesis polymerization (ROMP) and radical reactions. We mix dicyclopentadiene (DCPD), Grubbs' catalyst and radical initiator in one pot, and then polymerize first at low temperature by ROMP and initiate radical reactions at elevated temperature. As a result of our strategy, the crosslink density of PDCPD increases, leading to outstanding performance. For instance, the glass transition temperature T_g of ROMP-prepared PDCPD is ca 155–175 °C, whereas the T_g of PDCPD prepared by this strategy can be increased to 191 °C and can be further enhanced to 216 °C after polymerization at 250 °C. We believe this can help researchers design and synthesize high performance ROMP-derived polymers and apply PDCPD in harsh conditions. © 2024 Society of Industrial Chemistry.

Poly(ether ether ketone) (PEEK) is an important high-performance engineering polymer that is used extensively in numerous engineering applications that require chemical, solvent and thermal resistance. These attributes make PEEK attractive for the preparation of porous materials and membranes. Chemical modifications of preformed porous PEEK materials can expand the utilization of PEEK in a range of applications. It is desirable to carry out chemical functionalization without affecting the preformed porous structure or the degree of polymer crystallinity responsible for the sought-after properties. We report here on the heterogeneous functionalization of preformed mesoporous PEEK materials with hydroxyl groups using sodium borohydride as a reducing agent in a poly(ethylene glycol)/tetrahydrofuran solvent mixture. The pore structure of functionalized materials was characterized, and the degree of modification with functional groups was measured as a function of reaction protocol. The methodology was applied to the preparation of porous PEEK materials in the form of beads and hollow fibers that differed in semicrystalline morphology and pore structure. The degree of surface modification by –OH groups in reduced PEEK (PEEK-OH) porous materials was determined quantitatively by measuring the carbocation adduct concentration formed upon the dissolution of PEEK-OH in sulfuric acid using UV–visible spectroscopy. Bis(4-(4-methoxyphenoxy)phenyl)methanone was used to optimize the reaction condition protocol. The degree of crystallinity and pore structure of the functionalized articles were largely preserved following modification. © 2024 Society of Industrial Chemistry.

Different carbon black (CB) contents in poly(butylene adipate-co-terephthalate) (PBAT)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) blends were prepared by melt blending using chain extender multifunctional styrene-acrylic- epoxy random oligomer (ADR), as a compatibilizer. PBAT and P34HB were immiscible, and ADR could react with PBAT and P34HB to improve interfacial adhesion force and molecular entanglement. CB fillers were uniformly and selectively located in the PBAT matrix and could act as a nucleating agent to promote the nucleation of PBAT crystallization. At a CB content of 5 wt%, a percolation network structure of CB was formed. The most interesting result in the work was the achievement of composites with improved rheological and mechanical properties under the synergistic effect of chain extender and CB fillers. The viscoelasticity of the system was markedly improved and a transition from liquid-like to solid-like behavior was observed. Young's modulus and yield strength of chain extender modified PBAT/P34HB/CB composite with 10 wt% CB increased by 502% and 69% compared to neat PBAT, and by 89% and 43% compared to PBAT/P34HB binary blend. The combination of improved melt viscoelasticity and mechanical properties will further broaden the practical application of biodegradable polymers. © 2024 Society of Industrial Chemistry.

Thermoplastic elastomers are rubber-like in their elasticity, plastic-like in their ease of processing and recyclable. Styrene–butadiene–styrene (SBS) block copolymer is the world's most consumed thermoplastic elastomer. However, because of the carbon–carbon double bonds in its molecular structure, SBS exhibits poor thermal oxidation stability, which significantly limits the service lifetime and reliability of SBS. Here, we dramatically improve the thermal oxidation stability of SBS by incorporating graphene (GE) into the layered structure of SBS, which is attributed to GE's capacity to function as a gas barrier and scavenge free radicals. Compared with pure SBS, the oxidation induction time of SBS/GE nanocomposites can be increased by up to 225 times. This thermoplastic elastomer has potential in applications related to medical supplies, sports equipment, home appliances and automated office equipment. © 2024 Society of Industrial Chemistry.