A study of the properties of hydrophobically associating water-soluble polymers used in drilling fluids

Hydrophobically associating water-soluble polymers (HPAP) have been synthesized from acrylamide(AM), acrylate (AA), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and hydrophobic monomer (AP) in aqueous solution by radical polymerization. New polymer drilling fluids are made up of HPAP, which is used as viscosifiers and encapsulation agents. Properties of this system are reported in this paper. Results indicate that this system has a high value of yield point to plastic viscosity (YP/PV≥0.7), high viscosity at a low-shear rate (LSRV≥30000mPa·s), excellent shear thinning behavior, good solid-carrying behavior, resistance to shear, good thermal stability (as high as 140℃) and salt resistance. The system has excellent behavior in high-density solution of NaCl and in calcium and magnesium rich saline solutions. Hence, HPAP also can be used in saltwater polymer drilling fluids.

Preparation of Ultrafine Water-soluble Polymers Nanofiber Mats via Electrospinning

A series of water-soluble polymers such as poly（ethylene oxide）（PEO）, polyacrylamide（PAM） and poly（vinyl pyrrilidone）（PVP） was successfully prepared via the electrospinning of their aqueous solutions without the use of a surfactant. The effects of solution properties on the electrospinning of PEO, PAM and PVP solutions were investigated. The viscosity of the solution, charge density carried by the jet, and the surface tension of the solution are the key factors that influence the morphology and diameter size of the fibers. The viscosity of the solution was measured on a modular compact rheometer. The morphology and the diameter size distribution of the fibers were observed under an environmental scanning electron microscope（ESEM）. The results show that the diameters of the nanofibers electro spun from the solutions of these water soluble polymers were uniform and less than 300 nm.

STUDY ON UV CURABLE POWDER COATINGS BASED ON HYPERBRANCHED POLYMERS

By introducing semicrystalline moieties into hyperbranched molecular smictures three kinds of prepolymers of potential use as UV powder coatings were prepared and characterized.

Selective laser sintering mechanism of polymer-coated molybdenum powder

A type of polymer-coated molybdenum powder used in selective laser sintering technology was prepared by coating polymer on molybdenum particles and frozen grinding techniques, with the maximum particle diameter of 71 μm. The laser sintering experiments of polymer-coated molybdenum powder were conducted by using the self-developed selective laser sintering machine (HLRP-350I). The method of microscopic analysis was used to investigate the dynamic laser sintering process of polymer-coated molybdenum powder. Based on the study, the laser sintering mechanisms of polymer-coated molybdenum powder were presented. It is found that the mechanism is viscous flow when the laser sintering temperature is between 100 ℃ and 160 ℃, which can be described by a two-sphere model; and the mechanism is melting /solidification when the temperature is above 160 ℃.

Numerical simulation of temperature field during selective laser sintering of polymer-coated molybdenum powder

The technology of length-alterable line-scanning laser sintering was introduced. Based on the research of laser heating property, powder thermal physics parameters and laser sintering process, a numerical model of the temperature field during length-alterable line-scanning and laser sintering of polymer-coated molybdenum powder was presented. Finite element method (FEM) was used to simulate the temperature field during laser sintering process. In order to verify the simulated results, a measuring system was developed to study the laser sintering temperature field. Infrared meter was introduced to measure the surface temperature of sintering powder; the temperature of its inside part was measured by thermocouple. The measured results were compared with the numerical simulation results; the conformity between them is good and the relative error is less than 5%.

Application of Water-Soluble Polymer in Dewatering of Fine Coal

The addition of water-soluble polymer to a fine coal slurry to enhance dewatering process is considered to be one of the most effective ways of solving the problems of dewatering of fine coal. A series of tests are conducted with a vacuum dewatering apparatus to study the effects of various factors such as the species of polymer, polymer dosage and its ways of addition, and the pH of fine coal slurry on filtrating and dewatering of fine coal.

Selective laser sintering of polymer-coated Al_2O_3/ZrO_2/TiC ceramic powder

A type of polymer-coated Al2O3/ZrO2/TiC ceramic powder was prepared. The laser sintering mechanism of polymer-coated Al2O3/ZrO2/TiC powder was investigated by studying the dynamic laser sintering process. It is found that the mechanism is viscous flow when the sintering temperature is between 80 ℃ and 120 ℃, and it is melting/solidification when the temperature is above 120 ℃. The process parameters of selective laser sintering were optimized by using ortho-design method. The results show that the optimal parameters include laser power of 14 W, scanning velocity of 1 400 mm/s, preheating temperature of 50 ℃ and powder depth of 0.15 mm. A two-step post-treatment process is adopted to improve the mechanical properties of laser sintered part, which includes polymer debinding and high temperature sintering. After vacuum sintering for 2 h at 1 650 ℃, the bending strength and fracture toughness of Al2O3/ZrO2/TiC ceramic part reach 358 MPa and 6.9 MPa·m1/2, respectively.

SCIENTIFIC PRINCIPLES FOR MODIFICATION OF WATER-SOLUBLE POLYMERS. FORMATION OF MACROMOLECULAR COMPLEXES

The study of nanosecond dynamics of macromolecules with the lumines-cent methods make it possible to investigate the formation and functioning of polymericcomplexes, polymeric conjugates and macromolecular metal complexes, which are widelyused for solving many practical tasks. The nanosecond dynamics of macromolecules are ahighly sensitive indicator of interpolymer complexes (IPC) formation. It enables us to solvethe problems of studying IPC formation and stability and to investigate the interpolymerreactions of exchange and substitution. The investigation of changes in the rotational mo-bility of globular protein molecules as a whole makes it possible to determine the complexcomposition and its stability, and to control the course of polymer-protein conjugate forma-tion reaction. The nanosecond dynamics of polymers interacting with surfacants' ions (S)are the sensitive indicator of the S-polymer complex formation. A method for determin-ing the equilibrium constants of the S-polymer complex formation was developed on thebasis of the study of polymer chains mobility. It is established that nanosecond dynamicsinfluences the course of chemical reactions in polymer chains. Moreover, the marked effectof the nanosecond dynamics is also revealed in the study of photophysical processes (theformation of excimers and energy migration of electron excitation) in polymers with pho-toactive groups. It was found that the efficiency of both processes increases with increasingthe mobility of side chains, the carriers of photoactive groups.

XPS Study on Water-Soluble Polymer Surfactant Film

By means of changing the detection angle, the molecular conformation of a new type of polymer surfactant, acrylamide-poly(oxyethykene alkyl ether)acrylate-anionic monomer random copolymer, was studied by x-ray photoelectron spectroscopy(XPS) in detail.

Advances in selective laser sintering of polymers

Polymers are widely used materials in aerospace,automotive,construction,medical devices and pharmaceuticals.Polymers are being promoted rapidly due to their ease of manufacturing and improved material properties.Research on polymer processing technology should be paid more attention to due to the increasing demand for polymer applications.Selective laser sintering(SLS)uses a laser to sinter powdered materials(typical polyamide),and it is one of the critical additive manufacturing(AM)techniques of polymer.It irradiates the laser beam on the defined areas by a computer-aided design three-dimensional(3D)model to bind the material together to create a designed 3D solid structure.SLS has many advantages,such as no support structures and excellent mechanical properties resembling injection moulded parts compared with other AM methods.However,the ability of SLS to process polymers is still affected by some defects,such as the porous structure and limited available types of SLS polymers.Therefore,this article reviews the current state-of-the-art SLS of polymers,including the fundamental principles in this technique,the SLS developments of typical polymers,and the essential process parameters in SLS.Furthermore,the applications of SLS are focused,and the conclusions and perspectives are discussed.

Polymer-based nanoparticulate solid dispersions prepared by a modified electrospraying process

A modified electrospraying process is exploited to enhance the dissolution profiles of a poorly water-soluble drug. With polyvinylpyrrolidone (PVP) as a hydrophilic polymer matrix and ketoprofen (KET) as a model drug, polymer-drug composites in the form of nanoparticles were prepared and characterized. The surface morphologies, the physical status of the drug, and the drug-polymer interactions were studied using FESEM, DSC, XRD, and ATR-FTIR. FESEM observations demonstrated that the nanoparticles gradually decreased in size from 640 ± 350, to 530 ± 320, 460 ± 200 and 320 ± 160 nm as the KET content increased from 0, to 9.1%, 16.7% and 33.3% w/w, respectively. Results from DSC and XRD suggested that KET was distributed in the PVP matrix in an amorphous manner at the molecular level. This is thought to be due to their compatibility, arising through hydrogen bonding as demonstrated by ATR- FTIR spectra. In vitro dissolution tests showed that the nanoparticles released the incorporated KET within 1 min, evidencing markedly improved dissolution over pure KET and a KET-PVP physical mixture. Electrospraying can hence offer a facile route to develop new polymer composites for biomedical applications, in particular for improving dissolution rate of poorly water-soluble drugs.

STUDY ON HIGH PERFORMANCE ANTI—WEAR ADDITIVES FROM WATER—SOLUBLE POLYMERIC LUBRICANT

A series of high performance lubricants of water-soluble polymers with telechelic or star structures has been studied. Their average molecular weights (M) over bar are 1800-6000. The chemical structures of the lubricants are characterized by their hydrophilic groups (-CH2CH2O-), -COOH, -OH, -CONH2 and antiwear active elements (S,P,Zn and Mo). The results of assessing for the anti-wear property indicate that this kind of water-soluble polymeric lubricants possesses excellent watersolubility, lubricity and anti-wear property. A preliminary study on the anti-wear mechanism of the polymers is performed by means of electron probe and scanning electron microscopy (SEM).

STUDIES ON THE POLYMERIZATION OF β-CYCLODEXTRIN WITH EPICHLOROHYDRIN

Different proportions of β-cydodextrin and epichlorohydrin were used to prepare a group of β-cyclodextrin polymers. The relationship between the reaction extent and the molar ratios of reactants was discussed according to the results of ~1H-NMR, ^(13) C-NMR spectra and elemental analysis. Especially, high resolution ~1H-NMR spectra were usd for studying the reaction active sites and the extent of reaction. The solubility of oil soluble drugs in water was largely improved in the presence of water-soluble β-cyclodextrin polymer.

Polymer Coatings for Protection of Wood and Wood-Based Materials

Three major types of protective coating of wood and wood-based materials have been considered. These three types include the coatings based on carboxyl-containing water-soluble polymers which are easily cross-linked by inorganic salts or OH-containing compounds, pH-sensitive coatings and polymer multi-layer structures. First of three mentioned approaches allows affecting permeability and enhancing the prevention the loss of water from the surface of wood to its surrounding. The advantage of the second approach is its ability to vary and purposely adjust the polymer composition and the number and distribution of -COOH groups in the chain which make the originally water-soluble polymers completely insoluble. The strong feature of the third approach which includes broad use of hydrogen-bonded films produced by layer-by-layer self-assembly is the possibility of manipulation of coatings stability after construction.

Mechanical Properties of Epoxy Composite Materials Produced with Different Ceramic Powders

In this study, production and mechanical properties of polymer composite materials obtained by using Al2O3, SiO2, MgO and TiO2 hard ceramic fillers were studied. Epoxy resin was used as the matrix material, and four different ceramic powders were mechanically mixed into the resin at 3% and 5% as reinforcement. The mechanical properties of the polymer composite materials were then characterized. For this purpose, flexural modulus and flexural strength of composite materials were determined by using three point bending test and impact toughness of the materials were determined by Charpy impact test. In addition, the hardness values of the samples were determined by Shore D hardness test.

改性干粉型聚合物水泥砂浆试验研究

本文研究两种不同的可再分散乳胶粉(醋酸乙烯-乙烯共聚物和醋酸乙烯/叔碳酸乙烯酯共聚物)对干粉型聚合物水泥砂浆力学性能、粘结强度、吸水率、干燥收缩的性能影响。结果表明,可再分散乳胶粉的掺量、类型对聚合物水泥砂浆的性能影响较大,力学性能较普通水泥砂浆有明显的提升和改善。可再分散乳胶粉的加入虽然降低了砂浆的抗压强度,但显著提高了抗折强度和折压比,改善了砂浆的柔韧性和抗裂能力;砂浆的干燥收缩、粘结强度和吸水率等性能均有较为明显的改善。

石粉替代率对聚合物机制砂粘结砂浆性能及微细观结构的影响

为研究凝灰岩石粉在聚合物粘结砂浆中应用的可行性,分析了石粉部分替代水泥对聚合物粘结砂浆工作性能及力学性能的影响规律,并采用压汞法(MIP)、扫描电子显微镜(SEM)和傅里叶变换红外光谱(FTIR)试验研究砂浆内部孔结构及水化产物微观形貌的变化规律。结果表明:凝灰岩石粉在聚合物粘结砂浆中具有较好的适用性;砂浆强度随石粉替代率的增加呈先增大后减小的趋势,在替代率为15%(质量分数,下同)时,砂浆7 d、28 d抗折强度、抗压强度和粘结强度达到最大值,此时工作性能也较优。当石粉替代率不大于15%时,其对粘结砂浆微细观结构的影响以填充效应和晶核效应为主,可有效改善砂浆内部密实度,且有利于内部孔结构向少害孔和无害孔发展;当石粉替代率为15%时,H_(2)O、OH^(-)、CO_(3)^(2-)等特征振动峰强度最高,即此时内部水化最为充分;当石粉替代率超过15%时,石粉对粘结砂浆工作性能、力学性能和微细观结构均产生不利的影响。

超吸水聚合物对碱激发泡沫混凝土性能的影响

【目的】研究超吸水聚合物(super‐absorbent polymer,SAP)对提升以矿渣和再生微粉为主要材料的碱激发泡沫混凝土性能的影响。【方法】调节SAP预吸NaOH溶液的质量分数和SAP掺量(质量分数,下同),考察其对碱激发泡沫混凝土的流动性、吸水率、凝结时间、导热系数、孔隙结构及强度的影响;借助扫描电子显微镜和傅里叶红外光谱分析,从微观角度揭示SAP对泡沫混凝土性能影响机制。【结果】随着SAP掺量的增加,碱激发泡沫混凝土的流动度、凝结时间和导热系数呈下降趋势,但吸水率增大。SAP的掺入会导致碱激发泡沫混凝土孔隙率增大和孔隙分布的改变,掺入预吸水和预吸质量分数为0.4%的NaOH溶液的SAP后,增大了碱激发泡沫混凝土中孔隙直径大于550μm的孔隙比例;掺入预吸质量分数为0.9%的NaOH溶液的SAP后,则增大了碱激发泡沫混凝土中孔隙直径小于250μm的孔隙比例。适量的掺入SAP可以显著改善碱激发泡沫混凝土的抗压、抗折强度,当SAP预吸质量分数为0.4%的NaOH溶液且掺量为0.10%时,碱激发泡沫混凝土的抗压、抗折强度最高。【结论】SAP预吸NaOH溶液处理后,可以明显改善碱激发泡沫混凝土的工作性能、孔隙结构和力学性能。

早高强单层喷锚衬砌在隧道支护中的应用研究

本文以某隧道斜井为工程依托,对早高强单层喷锚衬砌材料组成及其在斜井中的施作效果进行分析。研究结果表明:早高强单层喷锚衬砌中超微粉复合掺合料的最优混合掺量为30%,联合新型纳米晶胶聚合物应用而使得抗压强度提升15.4%;纳米晶胶聚合物喷射混凝土具有回弹率低、抗渗性能好、强度高等优异特性,其中回弹率为3.4%,28d抗渗性能> P12,6h抗压强度为7.1MPa。本文提出的早高强单层喷锚衬砌施工工艺及工艺参数具有较好的控制效果。