Effect of ethylene-propylene copolymer with residual PE crystallinity on mechanical properties and morphology of PP/HDPE blends

Morphology and mechanical properties of polypropylene (PP)/high density polyethylene (HDPE) blends modified by ethylene-propylene copolymers (EPC) with residual PE crystallinity were investigated. The EPC showed different interfacial behavior in PP/HDPE blends of different compositions. A 25/75 blend of PP/HDPE (weight ratio) showed improved tensile strength and elongation at break at low EPC content (5 wt %). For the PP/HDPE = 50/50 blend, the presence of the EPC component tended to make the PP dispresed phase structure transform into a cocontinuous one, probably caused by improved viscosity matching of the two components. Both tensile strength and elongation at break were improved at EPC content of 5 wt %. For PP/HDPE 75/25 blends, the much smaller dispersed HDPE phase and significantly improved elongation at break resulted from compatibilization by EPC copolymers. © 1995 John Wiley & Sons, Inc.     

Miscibility of linear low density polyethylene (LLDPE)-graft-poly(methyl methacrylate) with poly(vinylidene fluoride) (PVF2) and its application as compatibilizer LLDPE/PVF2 blends

Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to study the miscibility of blends of a graft copolymer of poly(methyl methacrylate) on linear low density polyethylene (LLDPE-g-PMMA, G-3) with poly(vinylidene fluoride)

1 Systematic name: poly(1,1-difluoroethylene).

(PVF₂) and the compatibilization of blends of LLDPE/PVF₂. The specific interaction between PMMA side chains and PVF₂ in G-3/PVF₂ binary blends is weaker than that between the homopolymers PMMA and PVF₂. There are two states of PVF₂ in the melt of a G-3/PVF₂ (60/40, w/w) blend, one as pure PVF₂ and the other interacting with PMMA side chains. The miscibility between PMMA side chains and PVF₂ affects the crystallization of PVF₂. LLDPE-g-PMMA was demonstrated to be a good compatibilizer in LLDPE/PVF₂ blends, improving the interfacial adhesion and dispersion in the latter. Diffusion of PMMA side chains into PVF₂ in the interfacial region reduces the crystallization rate and lowers the melting point (T_m) and the crystallization temperature (T_c) of PVF₂ in the blends.     

群智协同任务分配研究综述

任务分配是群智协同计算和众包中的核心问题之一,即通过设计合理的任务分配策略,在满足任务约束条件下,将群智任务分配给合适的工作者,以提高群智任务的完成效率和结果质量。分析了目前任务分配方法存在的问题,总结并提出了一个通用的任务分配框架,并分别从工作者模型、任务模型、任务分配算法三个方面对国内外相关研究工作进行了分析、归纳和总结。提出了群智协同任务分配研究中的关键问题与今后的研究趋势。     

基于ZigBee的矿用应力监测系统的研究

提出了一种新的煤矿巷道监测方法 ,即采用测力锚杆对巷道顶部深处的应力变化进行定时监测。系统主要分为三部分:传感器节点、通信主站和上位机。传感器节点负责采集和上传数据,数据主站负责管理各传感器节点并存储和上传数据,上位机负责汇总各传感器数据并对其进行分析处理。     

Passive control of uncertain multiple input-delayed systems using reduction method

In order to conveniently analyze stability of uncertain multiple input-delayed closed-loop systems and successfully synthesize passive controllers for a general class of uncertain multiple input-delayed systems with disturbance, the so-called reduction method is applied to the multiple input-delayed systems with parametric uncertainties. A feedback controller associated with the system state and the past control action is designed to guarantee the passivity of the closed-loop systems for all admissible uncertainties. The theoretical findings are illustrated and verified with one numerical example.     

用刚塑性有限元法求解二辊轧管时轧制压力

根据二辊斜轧穿孔变形的特点,对变形区进行了适当的简化,并建立了几何模型,在应用刚塑性有限元法对其稳态轧制变形区的力学特性进行分析基础上,建立了斜轧穿孔过程的泛函、初始速度场,处理了边界条件,求解了轧制压力,并且得到了较高的精度。     

采用激光扫描建模的筒子纱卷绕密度测量方法

为适应智能高质量染色需求,解决当前筒子纱卷绕密度测量精度差、效率低和数字化管控不理想等问题,提出了基于激光位移传感器快速扫描获取数据建立数学模型的筒子纱卷绕密度测量方法.通过控制采样距离和扫描路径及范围,得到充分反映筒子纱形状特征的原始点集.根据不同噪声点的特征和统计学理论,对原始点集加入约束条件实现预处理,通过最小二...     

On the Modification of Hydration Resistance of CaO with ZrO2 Additive

Various ZrO₂/CaO samples were fabricated by cold isostatic pressing and sintered at 1750°C for 4 h. It was observed that the sample with 12% ZrO₂ additive possessed the good hydration resistance and had the lowest apparent porosity of about 0.75%; its weight additive stored after 56 days was less than 0.6 wt%, and it contributed to the occurrence of CaZrO₃ on the surface of CaO. The CaO crucible with 12 mol% ZrO₂ additive did not react with titanium melt during melting TiNi alloy. This provides a support for searching a new refractory with the good hydration resistance for induction melting titanium alloys.     

20%三磷·哒乳油对柑桔红蜘蛛毒力测定及田间药效试验

室内毒力测定结果表明,20％三磷·哒乳油对柑桔红蜘蛛有明显的增效作用,其共毒系数为178.6。1999年经江西进贤和湖南洪江两地田间试验表明,三磷·哒乳油对柑桔红蜘蛛有较好的防治效果,75～100mg／kg处理药后1～3天的防效为90.O％～98.0％,药后7天为82.7％～96.2％,药后15天为56.2％～92.3％,药后25天为51.6％～91.0％。     

云冈石窟立柱岩体长期强度研究

 基于分级加载单轴抗压蠕变试验,研究世界文化遗产云冈石窟9,10,12窟窟前立柱岩体的长期强度,并对其长期承载力学性能进行评价。研究结果表明：(1) 云冈石窟9,10,12窟窟前立柱岩体的岩性主要为砂岩,岩性单一,结构面不发育,属整体块状岩体结构类型,工程地质条件良好。(2) 立柱岩体中粗粒砂岩的长期强度低于中粒、中细粒砂岩的长期强度。其根本原因在于,中粗粒砂岩的胶结物类型是泥质胶结;其中含有微量的蒙脱石,在长期的风化过程中,与水作用后,易发生淋滤作用和溶蚀作用,次生裂隙相对较发育。(3) 高含水量状态下,中粗粒砂岩的长期强度为20.22 MPa,比其在低含水量状态下的长期强度降低44.31%。按云冈石窟立柱应力最大值出现在10窟西柱的上部(1.31 MPa)计,中粗粒砂岩立柱岩体的安全系数为15.4。因此,9,10,12窟窟前立柱岩体的长期承载力学性能良好。建议尽快修复和搭建窟檐,避免雨水对石窟的冲刷,同时还能调节窟内温度与湿度,减轻风化剥蚀。计算9,10,12窟窟前立柱最大可以承载的窟檐质量,供有关建筑设计和文物保护部门参考。这些研究结果和建议对于云冈石窟的保护具有一定的指导意义。