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Charles U Pittman - One of the best experts on this subject based on the ideXlab platform.

  • preparation electrical and mechanical properties of vapor grown carbon fiber vgcf vinyl ester composites
    Composites Part A-applied Science and Manufacturing, 2004
    Co-Authors: John P Donohoe, Charles U Pittman
    Abstract:

    Abstract Vapor grown carbon nanofiber (VGCF)/vinyl ester composites were prepared. Their volume electrical properties exhibited percolation behavior with a sharp drop in resistivity occurring between 2 and 3 wt% VGCF loading. Composites made from nitric acid-oxidized VGCF were insulators even at: 15 wt% VGCF loading. Unpolished samples had thin Resin-rich outer layers observed by SEM, which affected their resistivity behavior. The effects of fiber diameter, heat treatment and fiber/Resin Mixing were examined. Incorporating VGCF had little influence on flexural moduli, decreased flexural strengths and T g and increased storage moduli, E ′, both above and below T g .

Qian Bei - One of the best experts on this subject based on the ideXlab platform.

John P Donohoe - One of the best experts on this subject based on the ideXlab platform.

  • preparation electrical and mechanical properties of vapor grown carbon fiber vgcf vinyl ester composites
    Composites Part A-applied Science and Manufacturing, 2004
    Co-Authors: John P Donohoe, Charles U Pittman
    Abstract:

    Abstract Vapor grown carbon nanofiber (VGCF)/vinyl ester composites were prepared. Their volume electrical properties exhibited percolation behavior with a sharp drop in resistivity occurring between 2 and 3 wt% VGCF loading. Composites made from nitric acid-oxidized VGCF were insulators even at: 15 wt% VGCF loading. Unpolished samples had thin Resin-rich outer layers observed by SEM, which affected their resistivity behavior. The effects of fiber diameter, heat treatment and fiber/Resin Mixing were examined. Incorporating VGCF had little influence on flexural moduli, decreased flexural strengths and T g and increased storage moduli, E ′, both above and below T g .

Martin Mckinnon - One of the best experts on this subject based on the ideXlab platform.

  • Fundamental principles of an effective reinforcing roof bolting strategy in horizontally layered roof strata and areas of potential improvement
    'Elsevier BV', 2018
    Co-Authors: Russell Frith, Guy Reed, Martin Mckinnon
    Abstract:

    It is arguable that the development of reinforcing roof bolting systems has largely stagnated in recent times, primarily due to the prevailing industry view that few, if any, further improvements can be made to what currently exists. However, this paper contends that reinforcing roof bolting systems can be further refined by considering both the specific manner by which horizontally bedded roof strata loses its natural self-supporting ability and the specific means by which reinforcing roof bolts act to promote or retain this natural self-supporting ability. The Australian coal industry has insisted on minimising bolt-hole diameter to maximise load transfer and on targeting full-encapsulation by any means necessary for many years. This has led to a significant, albeit unintended, consequence in terms of overall roof bolting effectiveness, namely increased Resin pressures during bolt installation and the associated potential for opening bedding planes that may have, otherwise, remained closed during the bolt installation process. Given that the natural self-supporting ability of roof strata is strongly linked to whether bedding planes are open or closed, logically, minimising Resin pressures should be a significant benefit. This paper focuses primarily on three key issues that relate directly to the function of the roof bolting system itself: (1) the importance of proper Resin Mixing in the context of maximising load transfer strength and stiffness, (2) the importance of minimising Resin pressures developed during bolt installation, and (3) the importance of maximising the effectiveness of the available bolt pre-tension. All mine operators should be invested in improving the individual effectiveness of each installed roof bolt, even by relatively small incremental amounts, so this is an important topic for discussion within the mining community. Keywords: Roof bolts, Strata reinforcement, Partial-encapsulation, Pre-tension, Resin Mixing, Improved bolt effectivenes

Haleh Rasekh - One of the best experts on this subject based on the ideXlab platform.

  • suggested methods for the preparation and testing of various properties of Resins and grouts
    2014
    Co-Authors: Naj Aziz, Ja Nemcik, Ali Mirzaghorbanali, Stephe Foldi, David Joyce, Arash Moslemi, Hooma Ghojavand, Haleh Rasekh
    Abstract:

    In the absence of bolting standards for strata reinforcement in the Australian mines, though individual mines or companies have their in house practices, there remains a visible vacuum in assessing credibly the various properties of chemical Resins and cementitious grouts. Currently, all methods used in evaluating the mechanical properties of both chemical Resins and other bolting reinforcement grouts are dependent on the American, British and South African standards and accordingly there is no uniform and unified methodology of testing. A simplified approach has been discussed to enable mine operators and other interested parties to determine various pertinent properties of chemical Resins and grouts in the bolting system only and this paper describes the various methods used to test a set of Resin properties. A special Resin Mixing Container (RMC) was developed to permit multiple Resin samples to be cast with consistent Resin / grout quality. Various conclusions were drawn from the study enabling a better understanding between suppliers and end users.