The control of particle size and its distribution has become more and more important both in theory and in practice of emulsion polymerization field. In this study, cationic styrene-acrylate copolymer containing functional monomer was converted into water-soluble polymers by reaction with quaternising agents and acids with the free-soap emulsion polymerization method. The latex was obtained at the existence of nitrogen by the copolymerization of hydrophobic monomer styrene and 2-ethylhexyl acrylate, hydrophilic monomer dimethylaminoethyl methacrylate, modified PVA-0588 as the emulsifiers. The influences of the amount of azoisobutyronitrile initiator, the amount of dimethyl sulphate quaternising agent, reactivity ratio between monomers, charge density and pH value on the preparation process were discussed. The particle size and particle distribution was strongly affected by these factors. The results showed that the latex with narrow particle distribution and mean particle size about 100nm was obtained under redox system by adjusting 33% monomer to become precursor and dropping the rest of 67% monomer, after polymerization, N,N-dimethylamino groups were fully quaternised with dimethyl sulphate to improve the stability of the solutions. The glass temperature of polymer was 58.1°C, as pH values range of solution was 3~5, the stability and charge density of polymer emulsion could improve.
A simple two-dimensional shear deformable finite beam element is developed in order to examine the effect of the high order interpolation on the modes of deformation of the beam cross section using the ANCF finite element. The new element allows for effect of warping that cannot be captured using previously introduced ANCF beam elements, and relaxes the assumption of planar cross section. The displacement field of the new element is assumed to be cubic in the axial direction and quadratic in the transverse direction. Using this displacement field, new shape functions are formulated and include the quadratic of the transverse direction instead of the linear expression. The displacement gradient and transverse strain component obtained using the new higher order element are introduced. Numerical example is presented in order to compare the results obtained using the new finite element and the results obtained using previously developed ANCF finite element. The results reveal that the cross section remains as a curve surface not a planar one.
With the continuous development of printing technology and printing equipments, the quality of newsprint should be improved to meet with all the real demands. Acrylamide copolymer is used in paper-making as process aid and function aid which can effectively improve paper printing adaptability. Preparation and application of polyacrylamide via aqueous copolymerization was studied as dry strength agent in this paper. The polyacrylamide with middle molecular weight and low viscosity was obtained by reacting acrylamide, cationic monomer [2-(acryloyloxy)ethy] -trimethylammonium chloride and N,N-dimethylaminoethyl methacrylate, anionic monomer itaconic acid, active nonionic monomer N-metholacrylamide and crosslinking monomer 1,3,5-triacryloylhexahydro-s-rine, the copolymer was characterized by FT-IR, charge density and molecular weight distribution. On the basis of internal present situation of pulp, the papermaking system with deinking pulp from office waste paper and white water of 1000-1200us/cm conductivity from paper mill were selected for application research. The results show that when the dosage of acrylamide copolymer is 0.8% to the dry weight of pulp and handsheet basis weight is 60g/m2, acrylamide copolymer can show the superior performance to newsprint and receivable cost for paper mill, fluffing speed, tearing strength and internal bonds are respectively improved by 14%, 20% and 30%.
Based on the LuGre friction model, the nonlinear dynamic characteristic of a sucker-rod pumping system of deviated well is simulated. Firstly, the LuGre friction model is introduced, and the values of its six model parameters, which satisfy the engineering’s needs, are obtained according to handbook and computation. Then, the vibration of the rod of sucker-rod pumping system is regarded as an axial vibration of multi-segment flexible rod. The loads analysis of rod element is accomplished by means of the finite element method, and recurrence formulas of load and elastic deformation are derived through the finite difference method. The boundary and initial conditions of the load and deformation are evaluated. In the end, a numerical example is given, where a comparison between the elastic deformation of pumping piston obtained based on LuGre friction model and that obtained based on classical Coulomb friction model is made to show that the LuGre friction model describe the friction of sucker-rod pumping system better.
The purpose of this paper is to investigate the dynamic characteristic of the scissor linear array deployable structure under the coupling action of clearance joints, where the kinematic model of the deployable structure with clearance is established according to the principle of the motion between joint elements. The normal and tangential contact forces between contact components are respectively described using the Flores contact force model and modified Column friction model. In the sequel of this process, the impact forces between the connected components are converted to the mass centers of links connected by this clearance joint, and the converted contact force and additional torque were integrated to the generalized force in motion equations of the deployable structure, and then the effect of joint clearance is introduced to deployable syetem. The simulation results show that the dynamic characteristics of the mechanism are very sensitive to the clearance position, and the movement of a joint clearance will affect the movement of the other joint clearance, which shows that clearance joints in deployable structure have a strong dynamic interaction and all the joints should be modeled as real joints.
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