Search

The flame resistance of kraft paper was greatly modified by an eco-friendly, phosphorus-containing and reactive flame retardant, ammonium phosphite, which was grafted on kraft paper via pad-bake method. The results showed that the limiting oxygen index of treated kraft paper could increase from 19.1 to 48.2%. The results of vertical flammability tests imply that the char length of treated sample decreased from 210 to 45 mm. Thermogravimetry analysis showed that treated kraft paper had the lower initial decomposition temperature and more residues than control sample. Thermogravimetry analysis/infrared spectrometry indicated that the flammable volatile species of treated kraft paper reduced obviously compared with that of control sample. Fourier transform infrared spectroscopy suggested that ammonium phosphite was grafted on the cellulose molecules by P-O-C covalent bonds and the flame retardant is reactive in condensed phase. Scanning electron microscopy showed that the modification had little effect on the surface of kraft paper and the residual carbonized frame of treated kraft paper retained the fiber shape after combustion. EDX results showed that the flame retardant introduced a large amount of phosphorus and nitrogen into kraft paper. X-ray diffraction indicated that the modification did not significantly affect the crystal structure of kraft paper. And the strength of kraft papers slightly declined after the modification, but it still remained well. [ABSTRACT FROM AUTHOR]

The Journal of Materials Science awards the annual Robert W. Cahn Prize to recognize the best paper published in the journal each year. The winner of the 2023 Cahn Prize is a research paper titled "Molecular modelling of graphene nanoribbons on the effect of porosity and oxidation on the mechanical and thermal properties." The paper presents molecular simulation models of graphene nanoribbons and examines the impact of porosity and oxidation on their mechanical and thermal conductivity properties. The paper is well-written and provides valuable insights for researchers in this field. Two other papers were selected as runners-up for the prize. All the monthly finalists for the Cahn Prize can be downloaded for free on the journal's website. [Extracted from the article]

Starch is one of the most popular biodegradable polymers in nature, which is gaining increasing attention because of its abundant availability and low cost. However, starch film itself is very brittle and its barrier property is poor for many applications. Polyvinyl alcohol (PVA), a versatile polymer in paper industry, is used to improve the barrier property of starch film. In this study, painting paper with exceptional barrier properties against organic solvents is successfully prepared for art creation purpose by coating a thin layer of environmentally friendly starch/PVA film on its surface. The coated paper can resist the penetration of the ink from marker pens. Furthermore, the solvent resistance and mechanical flexibility of freestanding starch/PVA hybrid film were investigated in detail. It found that the excellent barrier properties of the coated painting paper against solvents are due to the superior solvent resistance and mechanical flexibility of starch/PVA hybrid film. Therefore, the biodegradable and cost-effective strategy in this study provides a promising approach to enhance the barrier property of painting paper against solvents, which can find potential applications in painting field. [ABSTRACT FROM AUTHOR]

The December 2023 cover paper of the Journal of Materials Science features a study by Xie and Luo from Chongqing Jiaotong University in China. The paper, included in the "Computation & Theory" Topical Collection, focuses on the use of carbon fiber-reinforced polymer (CFRP) for construction projects. The authors aim to provide insights into the transport behavior of liquids in epoxy-modified C–S–H pores in cement-based materials, combining MD simulations with experimental measurements. Xie is currently pursuing a master's degree in civil engineering, while Prof. Luo is an associate professor at Chongqing Jiaotong University and a researcher at Aarhus University in Denmark, with a focus on reducing the carbon and energy footprint of civil engineering materials and infrastructure. The paper is published open access and can be widely shared with readers using the provided link. [Extracted from the article]

We described a new concept, carbon paper-free membrane electrode assembly (MEA) fabricated from Nafion membrane and multi-walled carbon nanotubes-based electrocatalyst, in which platinum nanoparticles were deposited on carbon nanotubes after coating with pyridine-polybenzimidazole (PyPBI). Polymer-coated carbon nanotubes served as platinum nanoparticles support and current collector in carbon paper-free MEA. The fabricated carbon paper-free MEA was systematically studied by in situ cyclic voltammetry, SEM and fuel cell test. Pt utilization efficiency of carbon paper-free MEA improved with decreasing in Pt loading and reached 62% with 0.1 mg cm. Meanwhile, the mass power density reached 1.1 W mg, which was comparable to that of MEA with carbon paper. Fuel cell performance maintained 50% after 100000 startup-shutdown cycles, suggesting that carbon paper-free MEA was applicable in real fuel cell operation. To the best of our knowledge, this is the first study of carbon paper-free MEA in polymer electrolyte fuel cells. [ABSTRACT FROM AUTHOR]

Fiber length and fiber-to-fiber bonding effects on tensile strength and fracture toughness of kraft paper have experimentally been investigated. Laboratory sheets were made from kraft pulp, each with a distinct set of fiber lengths. Additionally, the fiber-fiber bond strength was improved by carboxymethyl (CMC) grafting. The tensile strength and work of fracture toughness results were compared to predictions from a shear-lag model which considers the fiber-fiber bond shear strength, the fiber tensile strength and fiber pull-out work. The tensile strength and fracture work for papers with weak fiber-fiber bonds increased with fiber length consistent with the shear-lag model. CMC-treated fibers provided strong fiber-fiber bonds. Papers made from such fibers displayed high strength and work of fracture independent of fiber length which indicates that the failure process is governed by fiber failures rather than bond failures. The fracture toughness, expressed as the critical value of the J-integral, increased strongly with fiber length for both untreated and CMC-treated papers. The results show that long fibers and CMC addition are extremely beneficial for improving the fracture toughness. [ABSTRACT FROM AUTHOR]

Influence of the ion irradiation at elevated temperatures on the novel preceramic paper-derived SiCf/SiC laminated composites fabricated by spark plasma sintering was investigated. The composites were subjected to high-dose simultaneous irradiation of silicon (Si) ions at 400 °C. Irradiation induces amorphization of the damaged area up to 30 dpa, and then recrystallization of amorphous regions with increasing dose occur. No evidence of cavities was found in SiCf/SiC composites irradiated by silicon ions up to 100 dpa. The irradiated composites pre-injected with 5000 appm He displays low swelling (~ 0.3%). The irradiation with Si ions may suppress the cavity nucleation and they growth in SiC layers. [ABSTRACT FROM AUTHOR]

The change of mechanical (folding endurance index, breaking stress, breaking length, breaking index, tear index ), optical (brightness), chemical (cold extract pH, alkali reserve) and physical (water absorbency by surface, smoothness) characteristics of 5 paper samples were measured during the accelerated aging at 105 ± 2°C, and the measured exponential dependencies were described and fitted by the formal first-order kinetics. The statistic parameters of such fitting calculations evidenced good agreement of the experimental and calculated data. The relative decrease of each paper property corresponding to 48 days of accelerated aging was evaluated in order to compare the durability of paper samples. The best aging resistance was obtained for paper MAESTRO® Classic (SCP Ružomberok, Slovak Republic) and this paper material may be recommended for archival applications. [ABSTRACT FROM AUTHOR]

The disappearance of bibliographic heritage is one of the biggest problems facing libraries. One of the most common methods used to restore paper, lining, is to apply a reinforcing layer to the document. This study focuses on lining papers with bacterial cellulose (BC) sheets from Gluconacetobacter sucrofermentans. For this purpose, several model papers have been selected. They have been characterized before and after the lining with this BC and a specific Japanese paper (JP) to compare both materials. Taking into account the differences between bacterial and vegetal cellulose is expected that the results may be similar to other BC and JP. The samples have been characterized before and after an aging process. There are no significant differences in some of the characteristics studied. Nevertheless, BC-lined papers present higher gloss values and b* coordinate. The wettability decreases with both BC and JP. However, in papers lined with BC, the wettability decreases more markedly and independently of the model paper used. This is related to the sealing of the surface structure by BC, which also leads to a reduction of air permeability. When the lined papers go through an aging process, there are no significant changes in any characteristic, except in b* and L* color coordinates. Additionally, the wettability rate decreases in all cases. This study indicates that papers lined with BC are stable over time. Finally, the use of BC as reinforcing material may offer advantages for specific conservation treatments, being more suitable for certain types of paper than JP. [ABSTRACT FROM AUTHOR]

Cellulose nanopaper consists of a dense fibrous self-binding network composed of cellulose nanofibres connected by physical entanglements, hydrogen bonding, etc. Compared with conventional printing paper, cellulose nanopaper has higher strength and modulus because of stronger fibres and inter-fibre bonding. The aim of this paper is to investigate the fracture properties of cellulose nanopaper using double edge notch tensile tests on samples with different notch lengths. It was found that strength is insensitive to notch length. A cohesive zone model was used to describe the fracture behaviour of notched cellulose nanopaper. Fracture energy was extracted from the cohesive zone model and divided into an energy component consumed by damage in the material and a component related to pull-out or bridging of nanofibres between crack surfaces which was not facilitated due to the limited fibre lengths for the case of nanopapers. For comparison, printing paper which has longer fibres than nanopaper was tested and modelled to demonstrate the importance of fibre length. Buckypaper, a fibrous network made of carbon nanotubes connected through van der Waals forces and physical entanglements, was also investigated to elaborate on the influence of inter-fibre connections. [ABSTRACT FROM AUTHOR]

Graphical abstract: [ABSTRACT FROM AUTHOR]

Graphical abstract: [ABSTRACT FROM AUTHOR]

Preservation of documentary heritage is one of the biggest challenges facing paper conservators today. The singular properties of bacterial cellulose (BC) lead us to propose to reinforce paper with BC sheets. In the first part of this study, the reinforcing capability of BC was tested on model papers of well-known fiber composition. The aim of the present study was to verify the suitability of rebuilding degraded old papers with BC. The degraded papers were characterized before and after the reinforcement. In addition, lined samples were characterized before and after an aging process in order to study the stability in time. The same methodology was used with Japanese paper (JP), a material commonly used by paper conservators, in order to compare both materials as reinforcement. Mechanical properties of paper lined with BC are as good as those obtained with JP. Papers lined with BC have more marked modifications on their optical properties than those restored with JP. Nevertheless, letters in books lined with BC are more legible. Moreover, only the papers restored with BC show high changes in porosity. The aging process leads to a slight decrement in burst index. Changes on tear index and optical properties with the aging process depend on the paper to be restored. This study suggests that BC improves deteriorated paper quality, without altering the information contained therein, and that this improvement is maintained over time. Hence, BC is a promising alternative material for the restoration of paper. [ABSTRACT FROM AUTHOR]

We demonstrate in this paper that commercially available printing paper can reach very high fracture toughness, comparable to that of steel, simply due to a special arrangement of the paper sheets with respect to the crack. Fracture mechanics experiments are conducted on single sheets of paper as well as on multilayer specimens in crack divider and crack arrester configuration. It is demonstrated that an arrangement in crack arrester configuration leads to an increase of the fracture toughness by a factor ten. An explanation of the effect is given and the transferability to other materials is discussed. [ABSTRACT FROM AUTHOR]

Flexible graphene-based paper is promising for wide applications due to its outstanding electrical and thermal conductivities. Graphene flakes with large size are usually known as the key factor for improved paper performance. However, we find that a combination of flakes with large and small sizes is more favorable for both electrical and thermal conductivities than pure large flakes. In this work, flexible paper with enhanced electrical and thermal properties was fabricated by mixing graphene flakes with various size distributions. Large-size graphene (LSG) flakes play the role of a backbone structure, whereas small-size graphene (SSG) flakes fill the voids in the paper without disturbing the high orientation. The physical properties of the as-prepared graphene papers with contents of SSG varying from 0 to 100% have been investigated. It is found that the electrical and thermal conductivities of the paper with 25 wt% SSG are both around 140% higher than that of pure LSG paper. Our results indicate that the lightweight and flexible graphene-based paper has great potential for lateral heat dissipation applications requiring heat movement in a particular direction. [ABSTRACT FROM AUTHOR]

This study presents a comparison of the mechanical and barrier properties of papers coated with microfibrillated cellulose (MFC) by two different coating processes: (i) bar coating and (ii) size press. Due to the high water content of MFC, water-treated papers were taken as references to highlight the effects of MFC on the properties of papers. Structural, mechanical and barrier properties of the ensued materials were performed respectively with SEM, tensile and stiffness testers, and air and oxygen permeability equipments. The properties of the water-treated papers were considerably damaged compared to those of the base paper that underlined the negative impact of both coating processes on the papers structure. With MFC, the air barrier and the bending stiffness were considerably improved (+90 and +50 % respectively), especially when the bar coating was used, i.e. with 7 g m of MFC. Size press was indeed not able to considerably improve papers properties as the MFC coat weight barely reached 4 g m resulting from ten successive MFC layers. [ABSTRACT FROM AUTHOR]

Carbon papers (CPs) have been fabricated using wet-laying carbon fibers (CFs) and polyacrylonitrile (PAN) fibers. Scanning electron microscopy revealed that the PAN fibers tightly interconnected the CF junctions with the pores between the fibers. The tensile strength of the carbon webs (CWs) increased as the fraction of PAN fibers used as the binder increased. The CW fabricated with 0.15 wt% PAN fibers had a tensile strength six times greater than that of the CW without PAN fibers. Moreover, by mixing the CFs with PAN fibers in water, the CFs separated from each other in the webs due to the interruption of hydrophobicity between the CFs. After mixing with PAN fibers, the CWs were carbonized at 1200 °C in the presence of a phenolic resin. The PAN fibers maintained their morphology due to their high carbon content after carbonization. The electrical resistivity of the CPs with high PAN fiber content was significantly lower than that of a CP without PAN fibers due to the interconnection of the CFs by the carbonized PAN fibers. [ABSTRACT FROM AUTHOR]

The hydrogel in this paper is designed to do just that, by using controlled release from a hydrogel to deliver the drug quickly and at a relatively high concentration to the interior of cancer cells. The paper describes the synthesis and in-vitro testing of a hydrogel composite that is designed to maximize toxicity to cancer cells by both efficiently delivering the cancer drug doxorubicin (DOX) and overheating the cells with magnetically induced hyperthermia. This makes it highly desirable to develop a delivery system that can encapsulate the drug, bring the drug directly to the cancer cells then release the drug into the cancer tumor or cells. [Extracted from the article]