Synthesis and Characterization of Fluorinated Polyurethane Containing Carborane in the Main Chain: Thermal, Mechanical and Chemical Resistance Properties

In this study, two fluorinated polyurethanes（FPU） containing carborane groups in the main chains were firstly designed and synthesized via the reaction of hexamethylene diisocyanate trimer（HDI trimer） with fluorinated polyesters（CFPETs） having hydroxyl-terminated carborane groups at room temperature. The structures of carborane fluorinated polyesters（CFPETs） and polyurethanes（CFPUs） were characterized by gel permeation chromatography（GPC）, Fourier transform infrared（FTIR） spectroscopy and nuclear magnetic resonance（NMR） measurements. The thermal stability, mechanical properties, Shore A hardness, solvent resistance and acid-alkali resistance of the carborane fluorinated polyurethane films were also studied. Thermogravimetric analysis（TGA） tests manifested that the introduction of carborane groups into the main chain of fluorinated polyurethane endowed the obtained fluorinated polyurethane with excellent thermal stability. The thermal decomposition temperature of carborane fluorinated polyurethane（CFPU） increased by 190 °C compared with that of the carborane-free fluorinated polyurethane（FPU）. Even at 800 °C, CFPU showed the char yield of 66.5%, which was higher than that of FPU（34.3%）. The carborane-containing fluorinated polyurethanes also showed excellent chemical resistance and prominent mechanical property even after the cured films being immersed into Jet aircraft oil or 37% HCl for 168 h or at high temperature（700 °C）. It is found that the structural characteristics of carborane group and the compacted structure of CFPU effectively improve the thermal stability, mechanical property, solvent resistance and acid-alkali resistance of the carborane-free fluorinated polyurethane. These excellent properties make CFPU as the useful raw materials to prepare the high temperature resistant coatings or adhesives for automotive engines, engine or fuel tank of aircraft and other equipment working in high-temperature or high concentrations of acid-alkali environments.

Resistance to chemical attack of bittern-resisting cement in high-bittern environment

A new kind of bittern-resisting cement （BRC） was introduced. This material is based on the ternary cementitious system of clinker containing C4A3 S phase, high-activity ground granulated blast-furnace slag （GGBFS） and fly ash （FA）. The hydration process and the hydrated products of BRC were studied by means of XRD, TG-DTA and SEM, and the resistance to chemical attack of BRC in high-bittern environment was also examined. The corrosion experiment in seven kinds of brines proved that BRC exhibits an excellent resistance to chemical attack of bittern. The corrosion resistance factors were calculated and all of them were greater than 0.96. It showed that BRC totally controls the cement-based material corrosion in brines from four aspects： （1） making full use of the dominant complementation effect of mineral materials; （2） diminishing the hydrated products easy to be attacked; （3） improving the microstructure of hardened cement mortar; （4） degrading the chemical attack of bittern.

Preparation and Properties of Spray Polyurea Elastomer for Aquaculture Foam Floating Balls

[Objectives] This study was conducted to develop a polyurea elastomer which can be sprayed on the surface of expanded polystyrene (EPS) floating balls, so as to improve the surface strength and service life of the floating balls. [Methods] The effects of the types and amounts of isocyanate, chain extenders and polyether polyols on the gelation rate, adhesion and wear resistance of polyurea elastomer were investigated, and it was finally determined the preparation process of polyurea elastomer using liquid isophorone diisocyanate (IPDI) and amino-terminated polyether (D2000) as the main raw materials, dimethylthiotoluene diamine (E300) as the chain extender and silica as the wear resistance modifier through two-step solution polymerization of prepolymerization and chain extension. [Results] The physical properties and chemical resistance tests of spray polyurea elastomer showed that it had good physical properties and acid and alkali resistance, and could meet the requirements of spraying and protection of EPS floating ball surface in marine environment. [Conclusions] Polyurea elastomer coating can improve the aging resistance, wear resistance and acid and alkali resistance of EPS floating balls, and prevent them from being fragile and floating randomly to form marine floating garbage which results in "white pollution".

Manufacture of Industrial Refractory Crucibles Based on Clays from Burkina Faso

In Burkina Faso, one of the three largest gold producers in West Africa, foundry activity is often paralyzed when basic equipment such as crucibles and cups are not available or should be imported. However, previous studies have shown the availability of kaolinite-rich clay resources that could be used for the local manufacture of silico-aluminous ceramic crucibles. This work allowed to manufacture industrial ceramic crucibles with local clays and then they were tested in foundry industry. The materials were manufactured from three (03) raw materials including two clays (SAB and ROU) and sand. The chemical and mineral analysis has shown that the raw materials are suitable for the formulation of refractory materials. The results of characterization of the materials formulated showed that the properties of use are appreciable. The porosity of the materials is relatively low (23 - 28 vol%) with a diametral compressive strength between 0.61 and 1.34 MPa. Crucibles sintered at 1250˚C with a stay of 2 hours have a mechanical strength capable of supporting the weight of the ores contained. These crucibles have a refractoriness under load (T0.5) above 1141˚C and resist chemical attacks. Tests were carried out in the industry at 1100˚C, and the results were satisfactory.

An Alkali Activated Binder for High Chemical Resistant Self-Leveling Mortar

This paper reports the development of an Alkali Activated Binder (AAB) with an emphasis on the performance and the durability of the AAB-matrix. For the development of the matrix, the reactive components granulated slag and coal fly ash were used, which were alkali activated with a mixture of sodium hydroxide (2 - 10 mol/l) and aqueous sodium silicate solution (SiO2/Na2O molar ratio: 2.1) at ambient temperature. A sodium hydroxide concentration of 5.5 mol/l revealed the best compromise between setting time and mechanical strengths of the AAB. With this sodium hydroxide concentration, the compressive and the 3-point bending tensile strength of the hardened AAB were 53.4 and 5.5 MPa respectively after 14 days. As a result of the investigation of the acid resistance, the AAB-matrix showed a very high acid resistance in comparison to ordinary Portland cement concrete. In addition, the AAB had a high frost resistance, which had been validated by the capillary suction, internal damage and freeze thaw test with a relative dynamic E-Modulus of 93% and a total amount of scaled material of 30 g/m2 after 28 freeze-thaw cycles (exposure class: XF3).

A New Method of Photopatterning with LB Films Based on a Chemically Amplified Mechanism

A new approach to introducing a photoacid generator（PAG） into Langmuir-Blodgett （LB） films to draw photopatterns as a lithographic process is described here. The chemically amplified positive-tone resist system used here consists of two components ： a copolymer, poly （ dodecrylacrylamide-co-4-t-butyloxylvinyl-phenylcarbonate ） [ P （ DDA-t- BVPC53 ） ] and a PAG, tri （2,3-dibromopropyl） isocyanurate （ TDBPIC ）. In the two-component system, the acid generated by the PAG catalyzes the deprotection reaction of P（ DDA-t-BVPC53）, to remove the tert-butoxycarbonyl group（t-BOC） in the exposed region during the postexposure baking process, thus rendering the exposed region soluble to alkaline aqueous solvents to form a positive tone. Photolithographic properties of the LB films have been evaluated. The patterns can be resolved with a resolution of 1 μm line width by UV irradiation, followed by development with an alkaline solution. The LB films can be used to generate etched gold relief images on a glass substrate via an aqueous iodide, like ammonium iodide, in alcohol/water as the etchant. The etch resistance of such LB films is sufficiently good, allowing patterning of a gold film suitable for photomask fabrication.

Effect of Additional Applied Thermal/Electric Field on the Float-glass Surface

The chemical resistances of float-glasses subjected to different electric field strength and temperature were investigated. It is indicated that the chemical resistance increases after the float-glasses are annealed with suitable temperature and electric field strength. It is also observed that the Na＋ content varies obviously under the conditions of 570℃, 1500 V/cm and 10 min, implying that the application of thermal/electric field improves the chemical resistance of float-glass online.

Performance Survey of PVC Insulation of LC/Gecamines Electrical Cables Subjected to Ageing and Its Life Span Evaluation

Considering the insulators ageing in a mixture of PVC and dye, set following operating conditions and time to ensure proper operation and perfect safety of industrial installations using insulated conductors. The results showed that the insulation carried out by the L.C main office was a good quality (on thermal aspect), because the resistance of the insulation is so high (i.e. 3940 Mega Ohms under normal conditions). The results showed a lifespan of 50 years at a temperature of 40°C (close to ambient temperature), plus minus 33 years at a temperature of 70°C;plus minus 22 years at a temperature of 100°C and 12 years at a temperature of 160°C. Furthermore, information on chemical attack, the results showed that PVC cables have poor resistance to sulfuric acid attack (having a pH of 1.5 and a density of 1.84 g/cm3). LC/Gecamines is able to produce locally a good quality of electrical cables.

From chemical mixtures to antibiotic resistance

In real environment, it is unlikely that contaminants exist singly; environmental contamination with chemical mixtures is a norm. However, the impacts of chemical mixtures on environmental quality and ecosystem health have been overlooked in the past.Among the complex interactions between different contaminants, their relationship with the rise of antibiotic resistance（AR） is an emerging environmental concern. In this paper,we review recent progresses on how chemicals or chemical mixtures promote AR. We propose that, through co-selection, agents causing stress to bacteria may induce AR. The mechanisms for chemical mixtures to promote AR are also discussed. We also propose that,mechanistic understanding of co-selection of chemical mixtures for AR should be a future research priority in environmental health research.

Transgenic Expression of a Functional Fragment of Harpin Protein Hpa1 in Wheat Represses English Grain Aphid Infestation

The harpin protein Hpa1 produced by the rice bacterial blight pathogen promotes plant growth and induces plant resistance to pathogens and insect pests. The region of 10-42 residues （Hpa110-42） in the Hpa1 sequence is critical as the isolated Hpa110-42 fragment is 1.3-7.5-fold more effective than the full length in inducing plant growth and resistance. Here we report that transgenic expression of Hpa110-42 in wheat induces resistance to English grain aphid, a dominant species of wheat aphids. Hpa110-42-induced resistance is effective to inhibit the aphid behavior in plant preference at the initial colonization stage and repress aphid performances in the reproduction, nymph growth, and instar development on transgenic plants. The resistance characters are correlated with enhanced expression of defense-regulatory genes （EIN2, PP2-A, and GSL10） and consistent with induced expression of defense response genes （Hel, PDF1.2, PR-1b, and PR-2b）. As a result, aphid infestations are alleviated in transgenic plants. The level of Hpa110-42-induced resistance in regard to repression of aphid infestations is equivalent to the effect of chemical control provided by an insecticide. These results suggested that the defensive role of Hpa110-42 can be integrated into breeding germplasm of the agriculturally signiifcant crop with a great potential of the agricultural application.

ZrO_2-Containing Refractories for Cement Rotary Kilns

ZrO2 -containing refractories have been increasingly used for cement rotary kilns. This paper discusses how the properties and performance of ZrO2-containing refractories are improved in terms of chemical attack resistance, thermal shock resistance , thermal conductivity and mechanical stress.

Chemically Amplified Resist Based on Dendritic Molecular Glass for Electron Beam Lithography

A novel dendritic molecular glass(MG)containing adamantane core(AD-15)was synthesized and characterized.It exhibits good solubility in common organic solvents and a stable amorphous state at room temperature,which contributes to forming films with different thicknesses by spin-coating.The thermal analysis of AD-15 indicates that no apparent glass transition temperature(Tg)is observed before the thermal decomposition temperature(Td=160℃).The good thermal resistance suggests that it can satisfy the lithographic process and is a candidate for photoresist materials.The patterning properties of AD-15 resist were evaluated by electron beam lithography(EBL).By optimizing the lithographic process parameters,AD-15 resist can achieve 40 nm half-pitch patterns with a line-edge roughness of 4.0 nm.The contrast and sensitivity of AD-15 resist were 1.9 and 67µC/cm^(2),respectively.Compared with the commercial PMMA(950k)electron beam resist,the sensitivity of AD-15 resist increases by 6 times.This study provides a new example of molecular glass resist with high resolution and sensitivity for EBL.

用于高风险环境安全监测和可调热管理的具有分层核壳结构的耐化学品纱线

Chemical resistant textiles are vital for safeguarding humans against chemical hazards in various settings.such as industrialproduction,chemicalaccidents,laboratory activities,and road transportation.However,the ideal integration of chemical resistance,thermal and moisture management,and wearer condition monitoring in conventional chemically protective textiles remains challenging.Herein,the design,manufacturing,and use of stretchable hierarchical core-shell yarns(HCSYs)for integrated chemical resistance,moisture regulation,and smart sensing textiles are demonstrated.These yarns con-tain helically elastic spandex,wrapped silver-plated nylon,and surface-structuredpolytetrafluo-roethylene(PTFE)yarns and are designed and manufactured based on a scalable fabrication process.In addition to their ideal chemical resistance performance,HCSYs can function as multifunctional stretch-able electronics for real-time human motion monitoring and as the basic element of intelligent textiles.Furthermore,a desirable dynamic thermoregulation function is achieved by exploiting the fabric structure with stretching modulation.Our HCSYs may provide prospective opportunities for the future development of smart protective textiles with high durability,flexibility,and scalability.

Safe growth of graphene from non-flammable gas mixtures via chemical vapor deposition

Chemical vapor deposition has emerged as the most promising technique for the growth of graphene.However, most reports of this technique use either flammable or explosive gases, which bring safety concerns and extra costs to manage risk factors. In this article, we demonstrate that continuous monolayer graphene can be synthesized via chemical vapor deposition technique on Cu foils using industrially safe gas mixtures. Important factors, including the appropriate ratio of hydrogen flow and carbon precursor,pressure, and growth time are considered to obtain graphene films. Optical measurements and electrical transport measurements indicate graphene films are with comparable quality to other reports. Such continuous large area graphene can be synthesized under non-flammable and non-explosive conditions, which opens a safe and economical method for mass production of graphene. It is thereby beneficial for integration of graphene into semiconductor electronics.

Insertion of Supramolecular Segments into Covalently Crosslinked Polyurethane Networks towards the Fabrication of Recyclable Elastomers

Thermoset plastics have become one of the most important chemical products in the world. The consequent problem is that although the thermosets possess excellent performance in mechanical strength, they cannot be reprocessed because of the internal permanent network structures. Optimizing the molecular design of thermosets is one of the most feasible ways to improve their recyclability. Here we present a facile and robust strategy to engineer the reprocessability of thermoset polyurethanes without compromising their mechanical toughness and chemical resistance via adding supramolecular additives during the polymer synthesis process. By using a multiple hydrogen bonding moiety as the model supramolecular additive, we demonstrate that the mechanical properties, recyclability, and chemical resistance of the crosslinked polyurethanes can be precisely controlled by adjusting the contents of the supramolecular additive. Systematic studies on the relations between molecular design and material properties are performed, and the optimized polyurethane network with a moderate amount of the supramolecular additive achieves the right balance between the robustness and recyclability. This work provides a cost-effective and practical way to chemically engineer thermoset plastics, aiming to enable the recycling of mechanically tough and chemically stable polymer materials.