Influence of oil contents in dynamically cured natural rubber and polypropylene blends

Mechanical, dynamic, thermal, and morphological properties of dynamically cured 60/40 NR/PP TPVs with various loading levels of paraffinic oil were investigated. It was found that stiffness, hardness, tensile strength, storage shear modulus, complex viscosity, glass transition temperature (T_g) of the vulcanized rubber phase, degree of crystallinity and crystalline melting temperature (T_m) of the polypropylene (PP) phase decreased with increasing loading levels of oil. This is attributed to distribution of oil into the PP and vulcanized rubber domains causing oil‐swollen amorphous phase and vulcanized rubber domains. An increasing trend of elastic response in terms of tension set and damping factor was observed in the TPVs with loading levels of oil in a range of 0–20 phr. It is supposed that a major proportion of oil was first preferably migrated into the PP phase and caused an abrupt decreasing trend of degree of crystallinity and T_m of the PP phase. The dispersed vulcanized rubber domains remained small as particles with a low degree of swelling. Increasing loading levels of oil higher than 20 phr caused a decreasing trend of elongation at break and elastomeric properties. Saturation of oil in the PP phase was expected and the excess oil was transferred to the rubber phase which thereafter caused larger swollen vulcanized rubber domains. The remaining amount of oil was able to separate as submicron pools distributed in the PP matrix. This caused lowering of T_g, T_m, crystallinity of PP phase as well as strength, elastomeric, and dynamic properties of the TPVs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polymer film selection for corrosion protection of data storage magnetic materials

Due to the current requirement of high recording density of hard disk drive, the thickness of DLC layer which is the protective layer is needed to be reduced. Therefore, the corrosion of read-write elements that are fabricated from soft magnetic materials is more critical. During the photolithography process, polymer photoresist is playing the major role on controlling the corrosion of soft magnetic materials. Two different types of polymer photoresists are selected to investigate, noted as wet photoresist and dry photoresist, respectively. Contact angle measurement, AFM and SEM are techniques using to determine the quality of polymer photoresists. Furthermore, the direct corrosion is also studied by using potentiostat/galvanostat-based measurements. The result suggested that the wet photoresist, AZ4999 Clariant, is better as compared to that of dry photoresist. No surface degradation as well as surface defects of the wet photoresist was found after lithography process. The corrosion rate of the specimen coated by this corresponding wet film is found to be only 1.44 x 10(-6) mm/y. In addition, the wet photoresist surface is hydrophobic posed of more than 75 degree of contact angle.     

Lot-sizing and scheduling problem with earliness tardiness and setup penalties

We consider the problem of determining the production lot sizes and their schedules so that the sum of setup cost, holding cost, and tardy cost is minimized. There are n orders waiting to be processed. Each order has its own due date, earliness penalty and tardiness penalty. The production is done in lots, which is the manufacturing of the same product continuously. No early delivery is allowed. Each order is delivered once, on the due date or immediately after the production of the order is completed. We present an algorithm, based on the use of the assignment problem, to optimally solve the problem with zero setup cost. For the problem with setup cost, the Backward Search algorithm is proposed to solve the small size problem. To deal with the large size problem, two heuristics which are Sequencing with Optimal Timing and Genetic Algorithm are presented.     

Mechanistic aspects of silane coupling agents with different functionalities on reinforcement of silica‐filled natural rubber compounds

Silane coupling agents containing different specific functionalities are studied to gain understanding of their roles in silica‐filled natural rubber (NR) compounds. Five different silane coupling agents, that is bis‐(triethoxysilylpropyl) tetrasulfide (TESPT), bis‐(triethoxysilylpropyl) disulfide (TESPD), octyltriethoxysilane, vinyltrimethoxysilane, and bis‐(trimethyl‐silylmethyl) tetrasulfide (TMSMT), are comparatively investigated, by taking the most commonly used TESPT as a reference. The results reveal that alkoxy‐based silanes can effectively reduce the filler–filler interaction and lower compound viscosity owing to the effect of silane‐to‐silica hydrophobation which contributes to better compatibility between silica and NR. The alkoxy‐silanes with a sulfur moiety, that is TESPT and TESPD, show more pronounced improvement in overall properties as a result of filler–rubber interactions. The use of TMSMT which has no alkoxy groups but contains only a sulfur moiety elucidates that there are three reaction mechanisms involved in systems with sulfur‐alkoxy‐based silane. These are as follows: (1) the silane‐to‐silica or silanization/hydrophobation reaction; (2) the silane‐to‐rubber or coupling reaction; and (3) rubber–rubber crosslinking originating from active sulfur released by the polysulfide‐based silane TESPT. These simultaneous reactions are temperature dependent, and show an optimum level at a dump temperature of approximately 140–150°C, as depicted by filler–filler and filler–rubber interactions, as well as mechanical properties of such compounds. POLYM. ENG. SCI., 55:836–842, 2015. © 2014 Society of Plastics Engineers     

Application of nanoporous silicon for a metal-semiconductor-metal visible light photodetector

In this paper we present a study on the application of nanoporous silicon to an optoelectronic device called a nanoporous silicon metal-semiconductor-metal (MSM) visible light photodetector. This device was fabricated on a nanoporous silicon layer which was formed by electrochemical etching of a silicon wafer in a hydrofluoric acid solution under various anodization conditions such as the resistivity of the silicon wafer, current density, concentration of the hydrofluoric acid solution and anodization time. The structure of this device has two square Al/nanoporous silicon Schottky-barrier junctions on the silicon substrate and the electrode spacing is 500 microm. The experiment will study photoresponse and the response time of a nanoporous silicon MSM photodetector which was fabricated on the various porosity of a nanoporous silicon layer. It is found that when devices are fabricated on a higher porosity nanoporous silicon layer, the photoresponse of the device will expand toward the short-wavelength and the bandwidth of the spectrum response will cover visible light. In addition, it is found that the response time of the device decreases.     

Co-presence, collaboration, and control in environmental studies

In this paper, we describe a framework for synchronous collaborative visualization and remote control in the agricultural domain. The framework builds on “Second Life” (SL), a popular networked online 3D virtual world, where users are represented as avatars (graphical self-representations). Co-presence in SL takes the form of instant (real-time) two-way interaction among two or more avatars. The aim of our work is to facilitate co-presence for sharing knowledge and exchanging wisdom about environmental practices. In order to establish a realistic simulated context for communication in SL, virtual counterparts of real devices are created in the virtual world. Specifically, we aim to represent field servers that sense and monitor fields such as rice paddies and vineyards. The Twin-World Mediator (TWM) is developed in order to replicate the behavior of real devices in virtual counterparts, and to facilitate seamless communication between real and virtual world. The TWM is an easy-to-use, extensible, and flexible communication framework. A small study demonstrated how the TWM can support collaboration and experience sharing in the agricultural domain.