Polycarbonate-linear low density polyethylene blends: Thermal and dynamic-mechanical properties

Blends of polycarbonate (PC) and linear low density polyethylene (LLDPE) of different compositions, in the form of slabs obtained by melt extrusion, have been examined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA).DSC measurements show that the melting, crystallization and glass transition temperatures of the two polymeric components in the blends are slightly affected by the composition. On the contrary, large differences are observed in the melting behaviour of layers cut at various depths, parallel to the slab surfaces of samples. This supports the occurrence of different crystal morphologies and distribution of the two components within the samples. The study of the crystallization kinetics from the melt blends shows that the crystallization processes of LLDPE are affected by the presence of PC.The dynamic mechanical analysis indicates that modulus, transitions and relaxational behaviour of the polymer components are scarcely affected by the composition. Some variations of the damping factor have been interpreted as due to the phase heterogeneity of the system, arising from the processing conditions and rheological behaviour of the blends.     

Caught between historical experience and high hopes: automation atthe Dutch Postal Cheque and Clearing Service, 1950-1965

Since the Netherlands lacks an indigenous computer industry, the article concentrates on the use of computing technologies. It deals specifically with the Dutch giro system, the country's initial step toward automation in the early 1950s. Automation was achieved in 1965. Several organizational processes and the development of computer technology throughout the fifties contributed to the delay of automation and the ultimate choice and implementation of more than 20 IBM 1401 computer systems. The paper sheds light on the importance of studying how computer technology is used as well as how the technologies are developed     

Planar [00. l] disorder in sodium beta alumina

00./and 01./ lattice images are used to show the presence of [OO.l] disorder in alumina. It is shown that both stacking sequence faults and intergrowth are present. The faults are believed to be introduced in the early stages of sintering when spinel block ledges are added out of sequence during growth in the [00. l] direction. The observations show that the planar disorder observed by Bevan et al. [4] cannot be attributed solely to heterophase intergrowth.     

Low-temperature TSD measurements on γ-irradiated polyvinylidene fluoride

As a part of the fundamental study of the relaxational behaviour of the semi-crystalline polymer polyvinylidene fluoride (-(CH₂-C₂) _n -, PVDF), thermally stimulated depolarization (TSD) measurements have been carried out on -irradiated thin films, poled in vacuo. Following irradiation, the total TSD relaxation strength below room temperature is depressed. Mathematical analysis of this region of the TSD spectrum reveals the reduction to be caused by the decrease of the -(glass-transition) relaxation peak. One also observes the irradiation-induced creation of two relaxation peaks, both with higher activation energies than their neighbours. Tentative interpretations for the different components of the relaxation spectrum are proposed.     

Monte Carlo estimation of radionuclide release at a repository scale

Prediction of radionuclide release is a central issue in the performance assessment of nuclear waste repositories. This requires modeling of the radionuclide migration processes through the repository barriers, accounting for the related uncertainties. The present paper illustrates a Monte Carlo simulation-based compartment model in which detailed, local-scale modeling feeds a global-scale analysis of the repository, at reasonable computational expenses. An application to a realistic case study is presented to verify the feasibility of the approach.     

燃煤飞灰的显微颗粒类型与显微结构特征

利用光学显微镜和扫描电子显微镜对不同燃煤煤种和锅炉类型电厂飞灰进行观察研究,建立了燃煤飞灰微颗粒的系统分类方案,并揭示出各类颗粒的显微结构特征,首先根据物质成分将飞灰分出硅铝质,铁质,钙质和炭粒4个组,然后根据微观形貌和内部结构分出16种显微颗粒类型。研究发现空心微珠和子母珠是飞灰中普遍存在的显微颗粒类型,不仅广泛分布于不同粒级的硅铝质颗粒中,而且常见于钙质和铁质颗粒中,发现并命名了多孔微珠这一新的显微颗粒类型;在多种颗粒中广泛分布的次级细小灰球的发现,为飞灰显微结构的成因研究提供了科学依据。     

闪光金粉印花生产实践

为提高金粉印花的产品档次,增加金粉产品的花色品种,通过对金属闪光片用量、网目、粘合剂及其他助剂的优选,金粉闪光片与活性染料共同印花等工艺试验的分析与改进,使闪光金粉印花产品的生产工艺可行,其产品艳丽、别具风格。     

The role of consultant engineers on personnel training and desalination plant operation

The raising countries asking for desalination plants are 0.011:0 normally in trouble for the period of time between taking over of the plant and the first two years of operation.During this period it is very useful to use proper consultants to supervise plant operation and train operating, maintenance and management personnel.In the present paper appropriate schemes of cooperation are outlined togheter with a particullary idea about plant operation control.