电力封堵用缩合型硅橡胶泡沫防火材料的制备及性能

研究了不同黏度和用量的乙烯基硅油、具有不同形态的防火填料对脱氢缩合型硅橡胶泡沫材料泡孔结构及防火性能的影响,使用橡胶加工分析仪表征了硅橡胶发泡过程中的发泡速率和交联速率,同时考察了氢氧化铝、云母、硅灰石3种填料对硅橡胶泡沫材料防火性能的影响。结果表明,不加入乙烯基硅油时,硅橡胶泡沫材料的储能模量较低,泡孔以闭孔结构为主;乙烯基硅油的加入提高了硅橡胶泡沫材料的交联速率和储能模量,使之形成较多的开孔结构,同时对硅橡胶泡沫材料泡孔尺寸分布也有影响;加入片状云母容易造成泡孔的坍塌或破裂,但是经火焰烧蚀后泡孔结构和烧蚀面的完整性保持较好,所形成的完整的陶瓷化阻隔层可起到较好的防火作用,而加入氢氧化铝和硅灰石后硅橡胶泡沫材料烧蚀后开裂比较严重。     

Effect of cell structure on oil absorption of highly oil absorptive polyurethane foam for on-site use

This article reports the effect of cell structure on oil absorption of highly oil-absorptive polyurethane foam (ON-PUR), which is suitable for on-site foaming. We have developed ON-PUR as an oil absorbing polyurethane foam using a very reactive recipe. ON-PUR was synthesized by mixing polyol, water, additives, and polymeric diphenylmethane diisocyanate (P-MDI) using a high-pressure foaming machine. Density, airflow, oil absorption of this foam, and cell structure by microscopy were measured. From these results, it was found that the airflow of this foam increased by crushing, and the oil absorption of this foam increased sharply in a narrow airflow range (from 0.1 to 0.8 scfm). This increase is estimated to be due to the decrease of closed cell structures by crushing treatment. Furthermore, we constituted on-site foaming system in bench scale, which was expected to be applicable to on-site preparation of ON-PUR. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 179–186, 1997     

Organic/inorganic nanoobjects with controlled shapes from gelable triblock copolymers

A functional gelable triblock copolymer, poly(2-vinylpyridine)-block-poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene (P2VP-b-PTEPM-b-PS), was prepared by the combination of reversible addition-fragmentation chain transfer (RAFT) mediated radical polymerization and copper catalyzed click chemistry. Bulk microphase separation of P2VP₃₁₀-b-PTEPM₅₈-b-PS₃₂₂ under different conditions was studied in order to prepare organic/inorganic nanoobjects by a procedure of crosslinking PTEPM phases and dispersing in a solvent. The conditions included using different annealing solvents and adding stearic acids to form supramolecular complexes with P2VP blocks respectively. Then the packed cylinders with P2VP cores and PTEPM shells dispersed in the PS matrix, lamella with alternating PS, PTEPM and P2VP layers, and the inverse cylindrical morphology with PS cores and PTEPM shells dispersed in the matrix of P2VP/stearic acid complex were obtained respectively just from the same triblock copolymer sample. After crosslinking PTEPM microdomains by sol-gel process and dispersing in solvents, a series of organic/inorganic polymeric nanoobjects, including two types of nanofibers with inverse internal structure and one novel kind of nanoplates, were produced. Further modification of the fibers with P2VP cores has been studied.     

The preparation and properties of some urethane foams from castor oil and elaidinized castor oil

Summary The preparation and properties of two series of castor oil urethane foams, one from castor oil and the other from elaidinized castor oil, were investigated. The first series of foams was made from prepolymers containing 60% of castor oil prepared at increasing temperature levels to vary the degree of crosslinking in the final foams. These foams had lower tensile strengths than observed for a previously prepared foam of 60% castor oil and did not show significant differences in water resistance as crosslinking varied. They were increased nearly 100% in compressive strength with increased crosslinking and had very good shrinkage characteristics as values of only 1 to 2% were obtained. A second series of foams was prepared from 50, 60, 70, and 80% of elaidinized castor oil to compare with foams from a similar series from castor oil. This series of foams of 50 to 80% elaidinized castor oil contents was similar in density (1.7 to 6.7 lbs./cu. ft.), had improved shrinkage characteristics (11, 1, 3, and 4%, respectively), showed increased compressive and tensile strengths (up to 12.1 p.s.i. at 50% compression modulus and 34.7 p.s.i. ultimate tensile for the 60% foam formulation), and had better water-resistance properties (411 to 155%vs. 515 to 170% water absorption) than the analogous foams from castor oil. In general, humid aging only slightly affected the values obtained for the foams and was significant in only a few instances,e.g., decreased tensile in the elaidinized castor oil series. Thus increasing crosslinks in the foam apparently did not improve water resistance but did improve shrinkage characteristics in addition to some increased strength properties, as would be anticipated. Foams from elaidinized castor oil, while similar in density and foaming characteristics to analogous foams from castor oil, exhibited less shrinkage and improved water-resistance. Presented at the 50th Annual Meeting of the American Oil Chemists' Society, New Orleans, La., April 20–22, 1959. Ono of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Fabrication by photoinitiated polymerization and characterization of millimeter‐size poly(divinyl benzene) hollow foam shells

In this study, millimeter‐size compound droplets were prepared easily by a one‐step microfluidic method. We varied the diameter and wall thickness of the shells over a wide range by setting the flow rate. Poly(divinyl benzene) (PDVB) shells with a 3–4.8 mm diameter were fabricated through photopolymerization and supercritical drying. The gel point of photopolymerization was monitored by a rotational rheometer. Moreover, the influence of the oil‐soluble photoinitiator phenyl bis(2,4,6‐trimethyl benzoyl) phosphine oxide (BAPO) on the properties of the foam shell were investigated by transmission electron microscopy, scanning electron microscopy, and nitrogen sorption measurements. Significant differences in the mechanical properties and porous features were obtained for different BAPO concentrations. The surface areas of the foam shells decreased, and the densities of the foam shells increased with increasing BAPO concentration. In addition, the nonconcentricity and out‐of‐roundness values were mainly less than 7 and 3%, respectively, for most of the shells. The results indicate that the PDVB hollow foam shells are a promising inertial fusion energy target. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41625.     

Macrostructural design of highly porous SiOC ceramic foams by preceramic polymer viscosity tailoring

Highly porous SiOC ceramic foams with gradient or uniform macrostructures were obtained through polymer derived ceramic routes. Precuring of preceramic polymers and introduction of SiO₂ powders were used to tailor precursor viscosity and hence SiOC foam macrostructure. Effects of polymer viscosity on porosity, pore size, pore distribution were investigated by light microscopy and micro-computed tomography techniques. SiOC ceramic foams. Foams from one unmodified precursor, showed pore size gradient with small pores located at bottom and large pores at the top. To address this non-uniformity, the viscosity of the precursor was increased by pre-curing the preceramic polymer, which resulted in decrease of the average pore size and improvement in pore size uniformity. For a different system with a self-foaming preceramic polymer, because of the simultaneous release of foaming gases and rapid increase in viscosity during crosslinking, the foam had non-uniform macrostructure with large pores and thick struts at the bottom. By addition of SiO₂ fillers, the crosslinking reaction rate was reduced leading to homogeneous pore nucleation and uniform small pore size foams.     

Study of the formulations and process conditions in the crosslinking of polyethylene foams at atmospheric pressure

The aim of this work is the study of the foaming process of a commercial polyethylene in the presence of a crosslinking agent. Foams have been produced under nearly atmospheric pressure conditions, which commonly occur during polymer rotomolding. Different processingtemperatures and different combinations of blowing agent/kicker (azodicarbonamide/zinc oxide) and crosslinking agent (dicumyl peroxide) concentrations have been employed. Thus, the melt viscosity, crosslinking degree, and temperature of the gas evolution and its rate have been changed to a certain degree. The obtained results have revealed that all these factors are critical to obtaining uniform and low‐density foams. Under certain processing temperatures and with an appropriate formulation, foam densities have been reduced up to 70% with respect to nonfoamed polymer. The interactions among the different components of the formulation have also been observed, and the results have led to the conclusion that in this kind of process, when a low pressure is applied, the foam density can be controlled by an adequate synchronization of the melt‐crosslinking, foaming, and gas‐expansion processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Shrinkage in extruded moisture crosslinked silane‐grafted polyethylene wire insulation

Shrinkage studies were conducted on silane‐grafted moisture crosslinkable linear low‐density polyethylene (LLDPE) insulation stripped from extrusion‐coated copper conductors. The insulation, which possesses orientation imparted during melt processing, showed remarkable levels of shrinkage when heated above the melting point of the polymer, though the shrinkage can be greatly reduced by moisture crosslinking the insulation below the melting point of the LLDPE. Shrinkage along the direction of orientation was accompanied by swelling in the other dimensions. Differential scanning calorimetry (DSC) revealed several trends, including a decrease in both melting point and degree of crystallinity with increasing crosslinking. In the first heat after annealing, crosslinked samples exhibited a shoulder in the DSC endotherm several degrees below the normal melting point of the LLDPE. In agreement with prior studies in silane‐grafted HDPE, relaxation of orientation by annealing appeared to result in an increase in the enthalpy of melting. The degree of shrinkage was also found to be dependent on the insulation thickness, which is attributed to faster cooling in thinner insulation immediately following extrusion coating. The results highlight the extensive built in stresses that can be frozen into polymer layers in fabricated articles due to melt orientation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Stability improvement of CO2 foam for enhanced oil‐recovery applications using polyelectrolytes and polyelectrolyte complex nanoparticles

CO₂ foam for enhanced oil‐recovery applications has been traditionally used in order to address mobility‐control problems that occur during CO₂ flooding. However, the supercritical CO₂ foam generated by surfactant has a few shortcomings, such as loss of surfactant to the formation due to adsorption and lack of a stable front in the presence of crude oil. These problems arise because surfactants dynamically leave and enter the foam interface. We discuss the addition of polyelectrolytes and polyelectrolyte complex nanoparticles (PECNP) to the surfactant solution to stabilize the interface using electrostatic forces to generate stronger and longer‐lasting foams. An optimized ratio and pH of the polyelectrolytes was used to generate the nanoparticles. Thereafter we studied the interaction of the polyelectrolyte–surfactant CO₂ foam and the polyelectrolyte complex nanoparticle–surfactant CO₂ foam with crude oil in a high‐pressure, high‐temperature static view cell. The nanoparticle–surfactant CO₂ foam system was found to be more durable in the presence of crude oil. Understanding the rheology of the foam becomes crucial in determining the effect of shear on the viscosity of the foam. A high‐pressure, high‐temperature rheometer setup was used to shear the CO₂ foam for the three different systems, and the viscosity was measured with time. It was found that the viscosity of the CO₂ foams generated by these new systems of polyelectrolytes was slightly better than the surfactant‐generated CO₂ foams. Core‐flood experiments were conducted in the absence and presence of crude oil to understand the foam mobility and the oil recovered. The core‐flood experiments in the presence of crude oil show promising results for the CO₂ foams generated by nanoparticle–surfactant and polyelectrolyte–surfactant systems. This paper also reviews the extent of damage, if any, that could be caused by the injection of nanoparticles. It was observed that the PECNP–surfactant system produced 58.33% of the residual oil, while the surfactant system itself produced 47.6% of the residual oil in place. Most importantly, the PECNP system produced 9.1% of the oil left after the core was flooded with the surfactant foam system. This proves that the PECNP system was able to extract more oil from the core when the surfactant foam system was already injected. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44491.     

Fabrication of foamed polypropylene with excellent behaviors by adding a special foam stabilizer

Foamed polypropylene (PP) has attracted more and more attention in recent years due to its unique properties, such as heat resistance and high flexural modulus. In this work, foamed PP with excellent properties was successfully fabricated by adding a special foam stabilizer, which was prepared by a simple one-step strategy using fatty acid and amino silicone oil as reactants. The two-component stabilizer mixed uniformly with PP and reduced the surface tension during foaming. The foam stabilizer significantly reduced density and cell diameter of the foam. When the amount of foam stabilizer was 1.0 wt%, the density dropped to 0.958 g/cm³, about 2.8% lower vs foam generated without stabilizer. The tensile strength increased to 18.4 MPa from 16.1 MPa, and the elongation at break increased to 495% from 328%.     

Modification of poly(vinyl chloride). XXXIII. Novel poly(vinyl chloride) foam crosslinked with 6-dibutylamino-1,3,5-triazine-2,4-dithiol

The formulation for producing the PVC foam crosslinked with a novel crosslinking agent such as 6-dibutylamino-1,3,5-triazine-2,4-dithiol (DB) was studied to determine the processing conditions. DB was almost consumed by radical combination with a coexistent blowing agent such as azobisformamide to give a high-density foam with excessively low crosslinking density. Blowing agents such as p-toluenesulfonylhydrazide (TSH) and 4,4′-oxybis(benzenesulfonylhydrazide) (OBSH) gave a crosslinked foam of low density, while a combination of the two crosslinking agents had moderate crosslinking reaction rate. The formulation recommended in the present study consists of PVC Zeon 101EP or Zeon 121 for paste, 100 parts; DOP, 100 parts; DB, 3–5 parts; OBSH or TSH, 10 parts; MgO, 1–3 parts; and RP101 (mixture of Ba, Ca, and Zn stearate), 2 parts, which gave colorless and insoluble foam of apparent density 0.14 under hot pressing at 180°C. The molded foam could be released without extraction of heat from a hot mold for fusion and expansion.     

UV-polymerization of 2-ethylhexyl acrylate in interpenetrating polymer networks – some mechanical properties

Interpenetrating polymer networks were prepared by photopolymerizing 2-ethylhexyl acrylate in the presence of polyurethanes derived from castor oil. The films obtained which contained varying amounts of both polyacrylate and crosslinking agent, hexamethylene diacrylate, were investigated as to their mechanical properties. Received: 22 August 1997/Revised version: 2 November 1997/Accepted: 21 November 1997     

Structure and properties of closed‐cell foam prepared from irradiation crosslinked silicone rubber

Silicone rubber foam was prepared through crosslinking with electron beam irradiation and foaming by the decomposing of blowing agent azobisformamide (AC) in hot air. The crosslinking and foaming of silicone rubber was carried out separately, which was different from the conventional method of chemical crosslinking and foaming. After foaming, the silicone rubber foam was irradiated again to stabilize the foam structure and further improve its mechanical properties. The effects of irradiation dose before and after foaming, and the amount of blowing agents on the structure and properties of silicone rubber foam were studied. The experimental results show that with the increase of AC content, the average cell diameter of silicone rubber foam increases a little, the foam density decreases to a minimum value when AC content is 10 phr. With the increase of irradiation dose before foaming from 10 to 17.5 kGy, the cell nucleation density of silicone rubber foam increases, the average cell diameter decreases, and the foam density increases. With the increase of irradiation before foaming, the tensile strength, tensile modulus, and the elongation at break of the silicone rubber foam increase. Through irradiation crosslinking again after foaming, the foam density is decreased and the mechanical properties of silicone foam are further improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Glycols in polyurethane foam formulations with a starch–oil composite

A dry starch–oil composite was blended with each of three glycols; ethylene, polyethylene, and propylene, and then reacted with isocyanate to produce polyurethane foams. The liquid glycols permitted the dry composite to blend well with the other ingredients in the foam formulations. Infrared spectra confirmed the presence of urethane structures in the composite–glycol foams. Polyethylene glycol provided a slightly less dense foam than the other glycols in the composite–glycol products. Microscopy showed a greater number of larger cells in the composite–polyurethane glycol foams. Infrared spectra indicated essentially no qualitative differences in the composite–glycol foams with the three glycols. By prestaining starch with toluidene blue and oil with sudan red, the location of the starch and oil components of the milled composite were observed in the composite–propylene glycol foam. Intact flakes of the composite were observed in the foam. An apparent loss of mobility of oil in the composite–polyurethane foam, as evidenced by NMR analysis, is probably due to crosslinking by isocyanate diffusing into the flakes. Both the cell structure and uniformity of blending were improved by using these glycols rather than the polyester polyol described previously. J Appl Polym Sci 69: 957–964, 1998. Published 1998 John Wiley & Sons, Inc.     

Molecular dynamics simulation of the synergistic effect of a compound surfactant on the stability of CO2 oil-based foam

It is of great significance to study the stability of foams in the petroleum industry. Therefore, the stability mechanism of Span 20, the fluorinated surfactant FCO-80 and their mixture FS in a CO₂ oil-based foam system were studied by molecular simulation. The sandwich model of CO₂ oil-based foam was constructed to reveal the stability of the foam system from the microscopic perspective. The result shows that under the synergistic effect of Span 20 and FCO-80, the oil–CO₂ distance of the FS foam system and the coordination number of oil molecules are larger than those of Span 20 and FCO-80 foam system. In FS foam system, the diffusion coefficients of CO₂ molecules are small, and the surface tension is reduced, which can improve the stability of foam. The results can supplement previous experimental results on the stability of oil-based foam.     

Microcellular foaming of silicone rubber with supercritical carbon dioxide

In spite of great concern on the industrial application of microcellular silicone rubber foams, such as in electric and medical devices, only a few works can be found about the foaming of silicone rubber. In this study, microcellular silicone rubber foams with a cell size of 12 μm were successfully prepared with curing by heat and foaming by supercritical CO₂ as a green blowing agent. The microcellular silicone rubber foams exhibited a well-defined cell structure and a uniform cell size distribution. The crosslinking and foaming of silicone rubber was carried out separately. After foaming, the silicone rubber foam was cross-linked again to stabilize the foam structure and further improve its mechanical properties. Foaming process of cross-linked silicone rubber should be designed carefully based on the viscoelastic properties because of its elastic volume recovery in the atmosphere. The basic crosslinking condition for small cell size and high cell density was obtained after investigating the rheological behavior during crosslinking.     

Producing biodiesel from high free fatty acids waste cooking oil assisted by radio frequency heating

Efficient biodiesel conversion from waste cooking oil with high free fatty acids (FFAs) was achieved via a two-stage procedure (an acid-catalyzed esterification followed by an alkali-catalyzed transesterification) assisted by radio frequency (RF) heating. In the first stage, with only 8-min RF heating the acid number of the waste cooking oil was reduced from 68.2 to 1.64 mg KOH/g by reacting with 3.0% H₂SO₄ (w/w, based on oil) and 0.8:1 methanol (weight ratio to waste oil). Then, in the second stage, the esterification product (primarily consisting of triglycerides and fatty acid methyl esters) reacted with 0.91% NaOH (w/w, based on triglycerides) and 14.2:1 methanol (molar ratio to triglycerides) under RF heating for 5 min, and an overall conversion rate of 98.8 ± 0.1% was achieved. Response surface methodology was employed to evaluate the effects of RF heating time, H₂SO₄ dose and methanol/oil weight ratio on the acid-catalyzed esterification. A significant positive interaction between RF heating time and H₂SO₄ concentration on the esterification was observed.     

Removal of Emulsified Oil from Water by Coagulation and Foam Separation

Abstract

A new method of emulsified oil separation for oily wastewater incorporating simple operation and shortened treatment time is necessary for improved wastewater treatment in some manufacturing plants. In the present study, the removal of emulsified oil from water by coagulation and foam separation using poly aluminum chloride (PAC) and milk casein was examined. By adding casein before the foam separation process, the oil removal was dramatically improved. By using surfactant (LAS) as a frother, the dosage of casein was drastically reduced. Furthermore, for processing actual oily water, LAS was unnecessary because a sufficient amount of surfactants for foaming was included in the wastewater. For treatment of the actual oily wastewater collected from a steel manufacturing plant, the optimum condition for PAC and casein was 30 mg‐Al/L and 10 mg/L, respectively, and the oil concentration decreased from 170 mg/L to 2.2 mg/L. After examining several types of oily wastewater, 96–99% of oil removal efficiency was obtained by adjusting the dosages of PAC and casein. Coagulation and foam separation using casein has shown a high potential as an alternative method to dissolved air flotation (DAF) for processing emulsified oil water.     

Jet-cooked starch-oil composite in polyurethane foams

A new jet-cooked starch—oil composite has been blended with a polyester polyol and then reacted with isocyanate to give a polyurethane foam. Infrared spectroscopy and microscopy have been used to examine the resultant products. Infrared spectra have shown the products contain the urethane structures and light and electron microscopy have shown the differences in the cell wall structures and networks of the foams when compared to the control foams. Inclusion of the starch—oil composite in the formulation resulted in increased viscosity of the reaction mixture as well as a more irregular cellular structure and a rougher texture of the cured foam. Larger cells were more abundant and there was more evidence of tearing during expansion. The scanning electron photomicrographs show the open-cell structure of both the control and blended foams and their reticular network, which is more uniform in the control. This examination provides insight into the foaming process and provides information to make the necessary adjustments for acquiring the desired polymeric product. Incorporation of the starch—oil composite in polyurethane foams provides a new dimension of possibilities for enhancing their physical, functional, and environmental properties. © 1997 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

J Appl Polym Sci 64: 1355–1361, 1997     

高吸油性树脂的合成和应用

本文叙述了高吸油性树脂的合成和应用方面的最新发展，介绍了六种现有的合成方法，简要说明其结构特点以及吸油特性。六种合成方法包括：单烯—双烯化学交联，溶剂致孔的单烯—双烯化学交联，官能团化学交联，辐射化学交联，聚氨酯泡沫，复合材料。高吸油性树脂的结构特点是：高分子之间形成一种三维的交联网状结构，材料内部具有一定微孔结构。由于树脂分子内的亲油基链段和油分子的溶剂化作用，高吸油性树脂发生膨润。吸油过程由分子扩散控制和Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ方程控制两部分组成。适度交联，适当减小粒径可提高树脂的吸油速度。介绍了高吸油性树脂在三废处理、芳香剂、杀虫剂、诱鱼剂基材，纸张添加剂、渔网防污剂基材，合成树脂的改性添加剂等方面的应用