有机硅/丙烯酸酯共聚物乳液性能的研究

采用反应型乳化剂烷基乙烯基磺酸钠 ( DNS-86)合成了有机硅改性丙烯酸酯共聚乳液 ,考察了乳液的表面张力、稳定性及流变性能。结果表明硅丙乳液的表面张力随有机硅单体用量的增加而减小 ;乳液的冻融稳定性和储存稳定性良好 ,符合涂料的使用要求 ;乳液为非牛顿流体 ,乳液的表观黏度随着有机硅含量的增加而降低。     

PVC/SBS/MBS三元共混体系的力学性能及光学透明性研究

采用冲击实验、拉伸实验、超景深三维显微镜、扫描电镜和分光光度计等手段，对PVC／SBS／MBS三元共混体系的冲击强度、拉伸强度、形态结构以及光学透明性等进行了研究。实验结果表明，MBS能有效改善PVC／SBS共混体系的界面相容性。当SBS和MBS的总量不变时，随着MBS相对含量的增加，共混体系的缺口冲击强度逐渐增加，透光率在m（MBS）／m（SBS）=28／80时达到最大值，光学透明性能最好。     

The viscoplastic properties of crude oil-water interfaces

The breaking of water-in-crude oil emulsions is a major challenge in the conventional petroleum industry, while oil-in-water emulsions present similar issues in commercial oilsands extraction processes. The stability of these emulsions can be attributed to complex rheological properties of the crude oil-water interface. Novel micromechanical techniques are developed that allow direct measurements of interfacial behaviour of emulsion drops. In these techniques, individual emulsion drops are elongated using micropipettes, where one micropipette is shaped into a cantilever for force measurements. As such, the surface behaviour of a drop is recorded in stress-strain experiments. In an alternative technique, the extended drop is released from a micropipette, and its natural, tension-driven relaxation is observed.The surface behaviour of bitumen (a heavy crude oil) emulsion drops in aqueous environments, that include dissolved calcium ions and suspended montmorillonite clays, is studied. The plasticity and other surface properties of these bitumen drops are discussed. A simple, lumped-parameter model is developed to describe the recovery of a bitumen drops to their final non-spherical shapes.     

Computationally efficient solution of population balance models incorporating nucleation, growth and coagulation: application to emulsion polymerization

A computationally efficient solution technique is presented for population balance models accounting for nucleation, growth and coagulation (aggregation) (with extensions for breakage). In contrast to earlier techniques, this technique is not based on approximating the population balance equation, but is based on employing individual rates of nucleation, growth and coagulation to update the PSD in a hierarchical framework. The method is comprised of two steps. The first step is the calculation of the rates of nucleation, growth and coagulation by solving an appropriate system of equations. This information is then used in the second step to update the PSD. The method effectively decomposes the fast and the slow kinetics, thereby eliminating the stiffness in the solution. In solving the coagulation kernel, a semi-analytical solution strategy is adapted, which substantially reduces the computational requirement, but also ensures the consistency of properties such as the number and mass of particles.     

Alkyd emulsions

Various aspects of alkyd emulsion technology have been investigated. The influence of alkyd oil length, acid value and hydroxyl number and type of surfactant used as emulsifier, on shear stability of alkyds emulsions have been studied. It was found that the acid value was the most important alkyd parameter, the stability increasing with increasing oil length. It is also shown that anionic surfactants give emulsions with small droplet sizes at lower concentrations than do nonionics. Polymerizable nonionic surfactants have been tested as emulsifiers and compared with conventional surfactants of the same hydrophilic lipophilic balance (HLB). It was found that surfactants capable of participating in the autoridative curing process give faster drying and improved film hardness compared with nonreactive surfactants. The distribution of driers between the alkyd phase and the water phase has been investigated. It was found that low pH and the use of hydrophilic anionic surfactants, such as sodium dodecyl sulphate, favour partitioning of cobalt into the aqueous phase which is unfavourable with respect to drying properties.     

Cure kinetics and mechanical properties of the blend system of epoxy/diaminodiphenyl sulfone and amine terminated polyetherimide-carboxyl terminated poly(butadiene-co-acrylonitrile) block copolymer

The cure kinetics of blends of epoxy resin (4,4’-tetraglycidyl diaminodiphenyl methane; TGDDM)/curing agent (diaminodiphenyl sulfone; DDS) with ATPEI (amine terminated poly-etherimide) -CTBN (carboxyl terminated poly (butadiene-co-acrylonitrile)) block copolymer (AB type) were studied using differential scanning calorimetry under isothermal conditions to determine the reaction kinetic parameters such as activation energy and reaction constants. Final cure conversion decreased with increasing amount of AB in the blends. A diffusion controlled reaction was observed as the cure conversion increased, and the curing reaction was successfully analyzed by incorporating the diffusion control term in the rate equation for the epoxy/DDS/AB blends. The fracture toughness was improved to about 350% compared to that of the unmodified resin at 30% of AB block copolymer. This is attributed to the formation of co-continuous morphology between the epoxy phase and AB block copolymer phase. By increasing the amount of AB, the modulus of the cured blends decreased, which was due to the presence of CTBN rubbery phases.     

On-line multi-variable predictive control of molar mass and particle size distributions in free-radical emulsion copolymerization

A multi-variable model predictive control (MPC) was formulated to solve control problems associated with a combination of regulation and targeting desired set-points. We investigated the simultaneous control of key polymer properties: the particle size (PSD) and molecular weight distribution (MWD) by manipulating the flow rates of the monomers (styrene, MMA), surfactant, initiator and the temperature of the reactor. A multi-input-multi-output (MIMO) formulation was constructed for the constrained optimal control problem to maximize the width of the PSD (with M_n at a constant set-point), and to maximize the average molar mass. The strategy developed within a gPROMS-API-DCS environment allowed real-time implementation of model-based control of the process. The optimal control problem was implemented via an interface to a dynamic optimization code. Major improvements in process operation and polymer property control resulted on the implementation of our multi-variable MPC algorithm. The manipulation of the four flow rates and the temperature increased the degree of freedom in the system and achieved tighter PSD and MWD control. The on-line performance of MPC for MWD and PSD control was found to be satisfactory.     

Radical entry mechanisms in redox-initiated emulsion polymerizations

The mechanisms and kinetics of radical entry in emulsion polymerizations utilizing redox initiation are investigated using polymerization rate data obtained by reaction calorimetry and electrospray mass spectroscopy analysis of initiator-derived aqueous-phase products. These data have been used to evaluate an initiation scheme for redox-initiated emulsion polymerizations of common monomers such as styrene and methyl methacrylate based around the oxidant, tert-butyl hydroperoxide. Redox initiators are broadly classed by the solubility of their radical products: Hydrophilic radicals enter by propagating to a critical degree of polymerization to become surface-active whilst more hydrophobic radicals may enter particles directly. When direct entry is applicable (the hydrophobic case), initiation efficiency will always be very high.     

反应性乳化剂应用于丙烯酸酯类乳液压敏胶的研制

使用正交试验法设计压敏胶配方,得到用反应性乳化剂参与的AA、HEA、BA和EA、M AA等多元共聚物乳液,研究该聚合物应用于压敏胶的初粘、持粘、剥离强度等力学性能。结果表明,在该体系下引发剂用量、反应温度、AA、反应性乳化剂用量对压敏胶乳液综合性能关系密切,其它各因素影响不明显。得到的优化配方为BA(83%)、AA(1%)、HEA(1%)、MM A和EA的混合单体(15%)。     

耐温耐盐乳状液驱替体系性能研究

对合适HLB值的乳化剂进行了筛选和评价,优选了具有较强稳定性能的乳状液。静态测试结果显示乳状液具有较好的耐温和耐盐性能,随着矿化度的提高,其稳定性能略有降低,但是幅度不大。该乳状液体系具有很高的黏度,渗流阻力能够提高140倍左右,说明乳状液体系能够在高温高盐条件下取得很好的驱替效果。驱替实验还表明乳状液滴与孔喉的匹配性决定了乳状液在多孔介质中的运移能力。