溶剂分子透过HDPE/MPA层状共混物的扩散模型

建立了溶剂分子透过聚合物层状共混物的扩散模型 ,给出了溶剂分子相对有效扩散系数D₀ /D与分散相体积分数、不可透薄片形状参数α以及薄片接头缺口参数δ之间的关系式 .经采用不同值及α值共混物得到的实验数据证明 ,该模型与实验结果吻合良好.     

HDPE／MPA层状容器加工及其阻透性能的研究

本文讨论了HDPE/MPA层状容器的加工以及MPA用量和贮存时间对阻透性的影响,分析了透过滞后、气相和液相透过现象。     

改性HDPE阻隔容器开发

以高密度聚乙烯和尼龙为主要原料，接枝聚乙烯为相容剂，采用吹塑成型工艺制备了具有层状结构的阻隔性容器。通过扫描电子显微镜对阻隔容器壁面的结构形态进行了分析，并对阻隔容器的阻渗性能进行了测定。尼龙分散相在基体中形成了层状分布，对二甲苯的渗透性起到明显的阻隔作用，相容剂质量分数为８％时渗透率最小。将ＨＤＰＥ、ＰＡ、相容剂等经机械混合后，直接熔融挤出吹塑成型的阻隔容器渗透率仅为０．３％。     

温度对HDPE/MPA共混物阻透性能的影响

分析了溶剂分子透过聚合物共混物的溶解-扩散行为,建立了溶剂分子扩散通量与其表观扩散活化能、偏摩尔混合焓以及温度之间的关系式。并采用多种配方的HDPE/MPA共混物,在不同温度下进行渗透实验,结果表明本文建立的关系式与实验数据吻合良好。     

HDPE／EVOH共混阻透容器的研制

将HDPE、EVOH和PE－g-MAH等混合后，吹瓶制成共混阻透容器，考察了EVOH和PE－g-MAH的用量及成型工艺对容器阻透性能的影响。结果表明，较低的增容剂用量和剪切速率及在适当的温度下制备的容器，其阻透性能得到大幅度提高。     

HDPE／PA共混吹塑容器阻渗性能的研究进展

综述了HDPE／PA共混吹塑容器阻渗性能的研究,阐明了分散相PA表态与共混物阻渗性能之间的关系,HDPE／PA共混物的相容性,共混物中组分之间的相对粘度比以及加工条件对阻渗性能的影响,建议今后研究工作应着重探讨流动场对HDE/PA混吹塑容器阻渗性能的影响机理。     

HDPE／PA6共混物注射成型阻隔性容器的研究

研究了制备阻隔性容器的高密度聚乙烯／尼龙６共混物配比，注射成型工艺及其对容器阻隔性能的影响。     

HDPE／PA共混物吹塑容器的结构与性能

利用扫描电子显微镜研究了高密度聚乙烯/尼龙共混物吹塑容器壁的形态结构。通过对阻隔容器壁的二甲苯渗透性能测定,分析了共混物组成及成型加工工艺条件对阻隔容器阻隔性能的影响。     

动态硫化PP／HDPE／EPDM三元共混物的流变性能

本文采用不同的硫化剂，不同的硫化时间，对动态硫化的ＰＰ／ＨＤＰＥ／ＥＰＤＭ三元共混物的流变性能进行了研究。结果表明：１共混体系为假塑体，表现出切力变稀现象；２在低剪切应力下，以Ｍ为硫化剂的粘度与纯机械共混体系的粘度有很大差值，此差值随剪切应力的提高迅速减少；３以ＤＣＰ为硫化剂，体系的粘度低于纯机械共混体系的粘度。     

Oxygen barrier properties of biaxially oriented polypropylene/polyvinyl alcohol blend films

The biaxially oriented PP/PVA blend film was prepared and had the higher oxygen barrier property by about 130 times than that of a biaxially oriented PP film. When the viscosity ratio (η_d(PVA)/η_m(PP)) decreased, the dispersed PVA phase was developed into platelets during stretching process. Oxygen permeability was dependent on the number and size of PVA platelet. However, the Oxygen permeability was not sensitively changed in above 25 wt% of PVA. To obtain excellent barrier property, the optimum amount of plasticizer and initiator was required. A pasticizer was related to the size and degree of crystallization of PVA platelet. An initiator played the role of a compatibilizer. The oxygen barrier was enhanced with increasing the viscosity of PP and draw ratio. The higher viscosity of PP was advantageous for preventing the delamination of a blend film, and the moisture vapor permeability was not affected with the laminar structure. As a result, the biaxially oriented PP/PVA blend film had the potential of substituting for the PVDC coated BOPP film.     

聚合物-溶剂体系中能量对溶剂扩散的影响

The Vrentas-Duda free-volume theory has been extensively used to correlate or predict the solvent diffusion coefficient of a polymer/solvent system.The energy term in the free volume diffusion equation is difficult to estimate,so the energy term was usually neglected in previous predictive versions of the free volume diffusion coefficient equation.Recent studies show that the energy effect is very important even above the glass transition temperature of the system. In this paper, a new evaluation method of the energy term is proposed,that is the diffusion energy at different solvent concentrations is assumed to be a linear function of the solvent diffusion energy in pure solvents and that in polymers under the condition that the solvent in infinite dilution.By taking consideration of the influence of energy on the solvent diffustion,the prediction of solvent diffusion coefficient was preformed for three polymer/solvent systems over a wide range of concentrations and temperatures.The results show an improvement on the predictive capability of the free volume diffusion theory.     

HDPE／UHMWPA层状分散合金的亚微形态,流变性能及体系相容性研究

本文研究了HDPE/UHMWPA共混体系的相容性及各组分的流变性能,据此选取了制备层状分散合金的工艺参数,获得了具有各种层状分散相态的共混物。研究结果表明:在低剪切及分散相粘度大于连续相粘度时,分散相易被层化;体系相容性和外剪切场对层状平板的尺寸及形状有明显的影响。     

Effect of PE-g-MA-Compatibilizer on the Morphology and Mechanical Properties of 70/30 HDPE/ENR Blends

The effects of PE-g-MA as a compatibilizer in binary blends of 70/30 high-density polyethylene/epoxidized natural rubber (HDPE/ENR) have been investigated by means of mechanical analysis and scanning electron microscopy. The special emphasis was given to the role of PE-g-MA in inducing interactions between HDPE and ENR. It has been observed that increasing the amount of PE-g-MA in the blend increases the tensile strength, elongation at break, and impact strength. It is believed that the degree of cross-link increased, which led to improve the interaction between the HDPE and ENR. The optimum stress values are shown in the blend containing 6% PE-g-MA. Scanning electron micrographs (SEM) of the samples also indicated that the addition of compatibilizer decreases the domain size of the dispersed phase. Well-dispersed plastic particles in a rubber matrix were strongly indicated in these samples. The results obtained reveal that the addition of PE-g-MA in HDPE/ENR blend led to an increase in the homogeneity of the blends.     

挤出机螺杆转速对HDPE/MPA共混物结构和阻透性能的影响

从理论上分析了挤出机螺杆转速与聚合物共混物中分散相颗粒数的关系以及螺杆转速对共混物阻透性能的影响 ,实验测定了在不同转速下制得的共混物的阻透性能。并根据阻透性能与结构参数之间的对应关系 ,从渗透实验数据推算出不同转速下共混物内不可透薄片的形状参数。实验表明 ,一般情况下溶剂透过共混物的渗透率随着转速的增加 ,有一个先降后升的变化过程。渗透率最低点对应的转速为最佳转速。分散相体积分数不同 ,其最佳共混转速不同。当共混转速超过临界转速后 ,溶剂渗透率的对数值随转速线性增加。     

Effects of Inclination Angle on Laminar Mixed Convection of a Nanofluid Flowing through an Annulus

Numerical study was done to investigate the effect of inclination angle on the hydrodynamics and thermal parameters of a nanofluid laminar flow throughout an annulus. For Al₂O₃/water nanofluid, profiles of axial velocity, contours of temperature, and secondary flows at the annulus cross sections are presented and discussed at different inclination angles. The results confirm that the axial component of buoyancy forces and secondary flows influences the flow regime. While the axial variation of friction coefficient was affected by the secondary flows for Ri = 0.1, it continuously changes with axial component of buoyancy forces as a function of inclination angle for Ri = 3. The results indicate that the maximum value of heat transfer coefficient obtained at the horizontal condition where the buoyancy forces result the strongest secondary flow.     

Deformation and fracture of polystyrene/polypropylene blends: A simulation study

The mechanical behavior of binary polymer blends polystyrene/polypropylene were studied by a continuous mesoscopic simulation method. The dynamic density functional theory approach embodied in MesoDyn method was adopted to obtain the meso-structures of polymer blends. The output of MesoDyn serves as the input of a micromechanical lattice spring model (LSM), which consists of a three-dimensional network of springs. Mechanical properties, such as young’s modulus and stress distribution can be obtained through applying strain in LSM. Subsequently, a stress-related probabilistic method was applied in LSM to study the fracturing process of materials. The fracture positions were shown in detail which have close relationship with the meso-structures. Due to the significance of interface which has a notable influence on the global mechanical properties of immiscible blends, we proposed a new method to define the stiffness in the interfacial area to study the global stiffness (young’s modulus) of materials. The results show a good agreement with the existing experiments. Besides, we varied the minimum fracture stress (related to toughness) of the interface to investigate the strength of polymer blends. A graphic representation was shown in this work, it indicates that the system with continuous interface perpendicular to the applied strain are more likely to exhibit catastrophic failure. The methods developed in this work provide important tools to predict the mechanical properties of real polymer blends.     

浸渍溶剂的多孔介质提取红霉素的固定床模型

利用浸渍溶剂的多孔介质进行萃取是一种有效的分离方法,本文根据固定床溶剂萃取的特点,假定其过程为内扩散控制,采用扩散传质模型,建立了浸渍溶剂的多孔介质提取红霉素的固定床数学模型。