平面壁附近高分子链的尺寸和形状

The size and the shape of non-reversai random-walking polymer chains near an impenetrable, noninteracting fiat surface are investigated by means of Monte Carlo simulation on the simple cubic lattice. It was found that both size and shape are dependent on the normaLto-surface distance z0 of the first segment of chain. We find that the size and shape of chains, characterized by mean square radius of gyration (S^2) and mean asphericityparameter (A) respectively, show similax dependence on distance z0. Both (S2) and (A) reach the maximum at z0 = 0, then decrease with the increase of z0 and soon reach the minimum values, afterwards they go up continuously and approach to the limit values of free chain. The similar dependence of (S^2) and (A) on z0 can be explained by a positive correlation between A and S^2. However, the dependence of the correlation coefficient CA,S2 on z0 is very complicated and deserves further study. The overall density probability of segments is also investigated. Results show that segments near the surface are relatively less, and the symmetrical distribution disappears when the chain locates near the surface.     

A Reptation-Based Lattice Model with Tube-Chain Coupling for the Linear Dynamics of Bidisperse Entangled Linear Polymer

A reptation-based lattice model for simulating the linear dynamics of entangled linear polymers that accounts for an essential coupling in tube-chain motions during constraint release is proposed. The predictions are tested against a representative set of dynamic oscillatory data on bidisperse polybudadiene (PBd) melts. The special feature of the current model lies in that the motion of the primitive chain coincides exactly with that of the ‘tube,’ so that it is possible to mimic the longitudinal relaxation that is cooperative with the lateral one (i.e., double reptation) during constraint release. The simulation is shown to capture the central feature of constraint release for the investigated system without demanding factorizability for the stress relaxation function, as usually enforced in existing tube theories. Furthermore, the simulation suggests that the longitudinal chain relaxation currently incorporated might account for an important partition of stress relaxation that had customarily been attributed to the effect of double reptation or similar tube motions alone.     

智能型温敏形状记忆高分子材料的研究进展

综述了热致感应型形状记忆高分子材料的工作原理、形成记忆功能的方法及其分类和应用,介绍了热致感应型形状记忆纤维的生产技术和国内外研究发展状况,并对热致感应型形状记忆高分子材料的未来研究发展趋势作以评述。     

高分子共混物分散相尺寸和形状的表征

本文将颗粒大小测定方法引入到高分子共混物的分散相尺寸测定中 ,验证了这是表征分散相尺寸可行的方法。通过对高分子共混物 (PP PA1 0 1 0 )脆性断面的电镜照片进行计算机处理和统计 ,得到分散相的粒径分布。发现各种当量直径 (dF、dP、dC)均较好的符合正态分布 ,并求出了其分布函数 ,还找到了一种参数 (ΨW =dC dF)可以表征颗粒的形状。另外 ,讨论了刻蚀方法对测定结果的影响及误差来源等     

乳液聚合瞬时乳胶粒大小和分布及其控制策略

乳液聚合中瞬时乳胶粒大小及分布与乳胶粒的形成和增长紧密相关,本文在苯乙烯,醋酸乙烯酯乳液聚合中考察了瞬时乳胶粒大小及分布。结果表明,在成核和稳定期乳胶粒增长速率较高,是控制乳胶粒大小及分布的关键阶段,由此提出了对于单体不同水溶性体系控制乳胶粒大小分布的策略,并以实验考核这些策略的合理性。     

热致感应型形状记忆高分子材料及其研究进展

讨论了热致感就型形状记忆高分子材料的记忆原理和对材料的基本要求厅求,介绍了目前已遥产品品种及制备方法,并进一步评述阳了近的研究进展。     

可熔性聚四氟乙烯的球晶尺寸控制方法

对用于降低可熔性聚四氟乙烯球晶尺寸的方法现状进行了描述和介绍,其方法主要是在可熔性聚四氟乙烯中加入高结晶度的成核剂,无定形含氟聚合物或含无定形嵌段的聚合物即球晶最小化剂。     

Monte Carlo simulation of two interpenetrating polymer networks: Structure, swelling, and mechanical properties

The swelling and mechanical properties of various interpenetrating polymer networks (IPNs) were studied. Six networks made from permutations of a moderately crosslinked polyelectrolyte network (ref), a moderately crosslinked neutral polymer network (net1), and a highly crosslinked polyelectrolyte network (net2) were first swollen in water and structural properties such as end-to-end chain lengths and radial distribution functions were compared with the component networks' equilibrium properties. The swelling of composite IPNs was discussed in terms of a balance between the osmotic pressure due to mobile counterions and the restoring force of the network chains, which act in parallel to counteract the osmotic swelling. For the ref-net2 system, the strong stretching of net2 chains increases the network restoring force and the further swelling due to the counterions is suppressed. The swollen networks were then uniaxially stretched, and equilibrium stress-strain plots were obtained up to high extension ratios. The equilibrium volume decreased upon uniaxial extension, and the elastic moduli of IPNs of the A-A type were slightly greater than that of their respective single networks.     

Spontaneous Crystallization in Athermal Polymer Packings

We review recent results from extensive simulations of the crystallization of athermal polymer packings. It is shown that above a certain packing density, and for sufficiently long simulations, all random assemblies of freely-jointed chains of tangent hard spheres of uniform size show a spontaneous transition into a crystalline phase. These polymer crystals adopt predominantly random hexagonal close packed morphologies. An analysis of the local environment around monomers based on the shape and size of the Voronoi polyhedra clearly shows that Voronoi cells become more spherical and more symmetric as the system transits to the ordered state. The change in the local environment leads to an increase in the monomer translational contribution to the entropy of the system, which acts as the driving force for the phase transition. A comparison of the crystallization of hard-sphere polymers and monomers highlights similarities and differences resulting from the constraints imposed by chain connectivity.     

Monte Carlo simulation of complex isomerization. I. Effect of diffusivity on product selectivity

A Monte Carlo method by which actual situations can be approached was developed. The complex isomerization A=B=C in a regular network was simulated, and the effects of intracrystalline diffusivities of molecules on the product selectivity were also investigated.     

粒径对煤矸石填充聚合物复合材料性能的影响

采用不同粒径的煤矸石粉填充高密度聚乙烯制备复合材料,研究了球磨时间对煤矸石粉体粒径的影响和粒径对煤矸石粉填充聚合物复合材料的力学性能的影响。结果表明:粒径对复合材料的性能影响明显,SEM照片显示超细煤矸石粉与HDPE相容性好;当粒径由100目提高到6000目,填充量为30%时,复合材料的弯曲模量提高了30.77%,弯曲强度提高了37.9%,拉伸强度也提高了20.12%,达到增强、增韧的目的。     

粒径对煤矸石填充聚合物复合材料性能的影响

采用不同粒径的煤矸石粉填充高密度聚乙烯制备复合材料,研究了球磨时间对煤矸石粉体粒径的影响和粒径对煤矸石粉填充聚合物复合材料的力学性能的影响。结果表明：粒径对复合材料的性能影响明显,SEM照片显示超细煤矸石粉与HDPE相容性好;当粒径由100目提高到6000目,填充量为30％时,复合材料的弯曲模量提高了30．77％,弯曲强度提高了37．9％,拉伸强度也提高了20．12％,达到增强增韧的目的。     

Monte Carlo simulation of xylene isomerization over zeolite catalysts

The isomerization reaction of xylene was simulated by means of the Monte Carlo method based on the experimentally observed parameters, including the diffusivity, equilibrium adsorption constant and intrinsic rate constant. The dependence of the product selectivity upon the Thiele modulus was examined and the results were satisfactorily consistent with those of the continuous model as well as the experiments. This suggests that the Monte Carlo method is helpful for investigating the nature of shape selectivity in zeolite-catalyzed reactions.     

表面处理方式对纳米SiO2/PS复合粒子粒径及分布的影响

纳米SiO2粒子进行表面处理时所用表面活性剂的种类及用量直接影响二氧化硅/聚苯乙烯(SiO2/PS)复合粒子的粒径及分布。纳米SiO2粒子在超声波场作用下经十六烷基三甲基溴化胺(CTAB)处理后,可在纳米SiO2粒子表面形成单体和引发剂的富集区,在适当条件下引发以纳米SiO2粒子为核心的原位分散聚合反应。当纳米SiO2粒子对CTAB的吸附与初级粒子对聚乙烯吡咯烷酮(PVP)K-30的吸附达到动态平衡时,制备出的SiO2/PS复合粒子表面光滑,分散性好,仅有少量的游离纳米SiO2粒子存在,大部分纳米SiO2粒子被PS包裹。     

环氧聚合型扩链剂的合成及其应用研究

对环氧聚合型扩链剂进展进行了介绍,对合成制备技术进行了概况,叙述其在尼龙6(PA6)、聚对苯二甲酸乙二醇酯/聚对苯二甲酸丁二醇酯(PET/PBT)和聚乳酸(PLA)上的应用情况以及展望了环氧聚合型扩链剂发展的方向。     

水包水多彩涂料彩粒大小与形状的影响因素研究

研究了多彩涂料保护膜形成机理,以及彩粒形状和大小的影响因素。讨论了保护胶体用量和保护胶体中磷酸用量对彩粒大小及形状,以及羟乙基甲基纤维素用量对分散相的黏度以及彩粒大小的影响。     

三元链状分子系统液液平衡的Monte Carlo模拟和分子热力学模型

在格子模型基础上,采用构型偏倚蒸发法（CBVM）对三元链状分子系统的液液平衡进行了Monte Carlo模拟,分别考查了分子链长和链节间相互作用参数对相区的影响。模拟发现,在保持交换能参数一定的情况下,互溶区随高分子之一的链长的增加而减小。在各组分链长不变的情况下,分相区随交换能的减小而增加。修正的Freed模型（RFT）可较满意地再现模拟结果,而Ftory—Huggins模型总是过低地估计互溶区。RFT模型可满意地关联和预测苯-庚烷-二甘醇系统的二元和三元液-液平衡数据。     

Translocation of compact polymer chains through a nanopore

We perform dynamical Monte Carlo simulation to study the forced translocation of compact polymer chains in three-dimensional lattices. The chains are driven through a nanopore connecting two infinite channels by an external field. The scaling properties of average translocation time τ and translocation time distribution (TTD) are studied. The effects of contact energy (?_C), electric field strength (E), and nanopore width (L) on the scaling exponent (α) of average translocation time τ ∼ N^α and the TTD are investigated. For the scaling behavior of τ ∼ N^α, we have found that there is no crossover behavior with weak field strength when the nanopore width is one lattice spacing, which is less than average bond length, while crossover behaviors are observed for larger nanopore widths. The scaling exponent α also depends on contact energy ?_C and electric field strength E. For the TTD, it shifts from the Gaussian to a right-skew distribution with the electric field E increasing for short chains; while for long chains, multi-peak distributions are observed. As a primary and simple model, compact polymer chains are extensively used to capture the structure and thermodynamic properties of proteins, therefore we can investigate the protein translocation by simulating compact chain translocation, and this study will be useful for exploring the complex translocation behaviors of proteins.     

PET聚酯工艺塔的模拟优化

针对生产企业关于PET聚酯工艺塔塔顶凝液EG含量更苛刻的需求,采用化工模拟软件Aspen plus V10,选取NRTL-RK热力学模型,对聚酯工艺塔进行了模拟计算,并和现场数据进行校验,在此基础上,完成了工艺塔的优化分析,结果表明:回流温度控制在55～60℃、回流比1.3、塔板数增加到21～22块,工艺塔顶凝液EG含...