Improvement in the Fock test for determining the reactivity of dissolving pulp

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 21-26 ◽  
Author(s):  
CHAO TIAN ◽  
LINQIANG ZHENG ◽  
QINGXIAN MIAO ◽  
CHRIS NASH ◽  
CHUNYU CAO ◽  
...  
Keyword(s):  
Moisture Content ◽  
Sodium Hydroxide ◽  
Constant Temperature ◽  
Carbon Disulfide ◽  
Testing Procedure ◽  
Dissolving Pulp ◽  
Water Bath ◽  
Testing Conditions ◽  
Pulp Sample ◽  
Fock Reactivity

The Fock test is widely used for assessing the reactivity of dissolving pulp. The objective of this study was to modify the method to improve the repeatability of the test. Various parameters that affect the repeatability of the Fock test were investigated. The results showed that Fock reactivity is dependent on testing conditions affecting the xanthation between cellulose and carbon disulfide, such as the moisture content of the pulp sample, sodium hydroxide (NaOH) concentration, xanthation temperature, carbon disulfide dosage, and xanthation time. The repeatability of the test was significantly improved using the following modified testing procedure: air dried sample in the constant temperature/humidity room, xanthation temperature of 66°F (19°C) in a water bath, xanthation time of 3 h, NaOH concentration of 9% (w/w), and 1.3 mL carbon disulfide.

Oxidation of Some Titanium Alloys in Air at Elevated Temperatures

2008 ◽  
Vol 595-598 ◽  
pp. 967-974 ◽  
Author(s):  
E. Godlewska ◽  
M. Mitoraj ◽  
B. Jajko
Keyword(s):  
Thermal Cycling ◽  
Titanium Alloys ◽  
Constant Temperature ◽  
Cross Sections ◽  
Elevated Temperatures ◽  
Mixed Oxides ◽  
Oxidation Mechanism ◽  
Testing Procedure ◽  
Oxidation Products ◽  
Outward Diffusion

This paper presents comparative studies on the performance of two titanium alloys (Ti- 6Al-1Mn, Ti-45.9Al-8Nb) in an oxidizing atmosphere at 700 oC and 800 oC. Testing procedure comprised thermogravimetric measurements at a constant temperature and in thermal cycling conditions (1-h and 20-h cycles at constant temperature followed by rapid cooling). The overall duration of the cyclic oxidation tests was up to 1000 hours. The oxidized specimens were analyzed in terms of chemical composition, phase composition, and morphology (SEM/EDS, TEM/EDS, XRD). The extent and forms of alloy degradation were evaluated on the basis of microscopic observation of specimen fractures and cross-sections. Selected specimens were examined by means of XPS, SIMS and GDS. Oxidation mechanism of Ti-46Al-8Nb was assessed a two-stage oxidation method using oxygen-18 and oxygen-16. Apparently, the oxidation of this alloy proceeded in several stages. According to XPS, already after quite short reaction time, the specimens were covered with a very thin oxide film, mainly composed of aluminum oxide (corundum). A thicker layer of titanium dioxide (rutile) developed underneath. These two layers were typical of the oxidation products formed on this alloy, even when tested in thermal cycling conditions. In general, the scale had a complex multilayer structure but it was thin and adherent. Under the continuous layer of titania, there was a fine-grained zone composed of mixed oxides. The alloy/scale interface was marked with niobium-rich precipitates embedded in a titanium-rich matrix. There were some indications of secondary processes occurring under the initial continuous oxide layers (e.g. characteristic layout of pores or voids). Thickness of inner scale layers clearly increased according to parabolic kinetics, while that of the outer compact layer (mainly TiO2) changed only slightly. The distribution of oxygen isotopes across the scale/alloy interface indicated two-way diffusion of the reacting species – oxygen inward and metals outward diffusion. Silicon deposited on Ti-6Al-1Mn alloy positively affected scale adhesion and remarkably reduced alloy degradation rate.

Research of Artificial Rumen Constant Temperature Water Bath Based on Fuzzy Logic Controller

2014 ◽  
Vol 602-605 ◽  
pp. 2487-2490
Author(s):  
Xi Wu Li ◽  
Bo Xu
Keyword(s):  
Fuzzy Control ◽  
Constant Temperature ◽  
Fuzzy Logic Controller ◽  
Control Unit ◽  
Bath Temperature ◽  
Water Bath ◽  
Dynamic Responses ◽  
Test Operation ◽  
Constant Temperature Water Bath ◽  
Temperature Water

In the artificial rumen device constant temperature water bath temperature control for model and parameter uncertainty is proposed that 89S51 microcontroller as the control core, using fuzzy control algorithm, realized thermostatically control of water bath temperature. This paper presents the overall system architecture and design philosophy of fuzzy control unit and associated circuits. Systematic simulation and test operation showed that: the good dynamic responses of the system, high precision control, strong robustness, achieve better control of the water bath temperature.

Correlation Between Fock Reactivity and Intrinsic Viscosity of Dissolving Pulp During Cellulase Treatment

2019 ◽  
Vol 39 (4) ◽  
pp. 296-303 ◽  
Author(s):  
Shanshan Liu ◽  
Huili He ◽  
Xin Fu ◽  
Yingchao Wang ◽  
Qiang Wang ◽  
...  
Keyword(s):  
Intrinsic Viscosity ◽  
Dissolving Pulp ◽  
Cellulase Treatment ◽  
Fock Reactivity

scholarly journals A Comparison of Two Heated Water-Bath Humidifiers

1975 ◽  
Vol 3 (1) ◽  
pp. 41-47 ◽  
Author(s):  
C. A. Shanks ◽  
J. M. Gibbs
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Absolute Humidity ◽  
Water Bath ◽  
Delivery Tube ◽  
Artificial Airway ◽  
Heated Water ◽  
Heating Wire ◽  
Selection Of ◽  
Independent Heat

The performance of two heated water-bath humidifiers was examined in terms of airway temperatures and humidities. These were the simple heated tank [Marshall and Spalding, 1953) and the Fisher and Paykel No. 328 (Spence and Melville, 1972), both of which had the potential to deliver gases at temperatures above 40°C, and with a moisture content in excess of 50 mg/litre. The major advantage of the No. 328 was its heating wire in the delivery tube. This lessened or prevented condensation within the tube, and allowed the water bath to be maintained at lower temperatures. Independent heat controls for the water bath and the delivery tubing allow precision of humidities in the gases provided for inspiration through an artificial airway. When condensation is prevented, the temperature of the saturated gases leaving the humidifier limits the absolute humidity supplied. Monitoring and adjustment of airway temperature of the patient then allows selection of temperature and relative humidity in the inspired gas.

scholarly journals Geopolymer Stabilisation of Unfired Earth Masonry Units

2014 ◽  
Vol 600 ◽  
pp. 175-185 ◽  
Author(s):  
Daniel Maskell ◽  
Andrew Heath ◽  
Pete Walker
Keyword(s):  
Compressive Strength ◽  
Moisture Content ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Large Scale ◽  
High Moisture Content ◽  
High Moisture ◽  
Load Bearing ◽  
Disproportionate Collapse ◽  
Masonry Units

Contemporary domestic structures typically use masonry units that are approximately 100mm thick. There is interest in using commercial methods of manufacture to produce earthen bricks that have a similar form factor to conventional masonry The large scale adoption of thin walled unfired earth masonry is dependent on its suitability for use in a load bearing application. High moisture content leading to full saturation, for example as a result of flooding, is a concern for unstablised earth construction, especially as wall thickness reduces. The greatest barrier for earth masonry adoption is the durability of the material when affected by high moisture content. Accidental and intentional wetting of a 100mm thick load bearing unfired earth wall could lead to disproportionate collapse. The paper presents initial findings from an investigation into the use of geopolymer mechanism as a method of stabilisation. The use of geopolymer mechanism was chosen as a possible method of improving the water resilience. Soil that is used for commercial extruded fired brick production was chosen. The soil was selected as the precursor (source of the required silica and alumina) and this was mixed with various sodium hydroxide and sodium silicate activators. Specimens were tested both in their dry sate as well as following 24 hours of submersion in water. Compressive strength of cylinders after saturation, was used as an indicator of effective stabilisation. The maximum dry compressive strength achieved was 10.4N/mm2 with the addition of 5% sodium hydroxide and 20% sodium silicate after curing at 105°C. The most significant contributor to the strength gain was the addition of sodium silicate. Although some of the cylinders were able to be tested under fully saturated conditions the strengths achieved were negligible and insufficient for structural application. The potential for geopolymers as a method of stabilising unfired earth bricks is discussed with respect to the compressive strengths achieved.

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