Thermographic Study of Elastomers III. Peculiarities of Crystallization of Natural Rubber

Abstract Thermographic (DTA) study reveals two independent melting regions of natural rubber crystallites and a gap between them which is determined by a sharp difference in the rates of the crystallization process. Crystallites formed at a low temperature (− 25° C) and at room temperatures are distinguished by the degree of development, but pertain to the same crystallographic form. High temperature crystals play the role of seed in low temperature crystallization. During the melting of low temperature crystallites of natural rubber, they recrystallize with a rise in the melting point (without reaching, however, room temperatures). The appearance of this phenomenon on the thermograms is determined by the relation between rates of crystallization and of heating in the course of the experiment. The rate of crystallization of natural rubber and the relative amount of crystallites formed at − 25° C were studied by DTA; the effect of rubber plasticization on these magnitudes was noted.

Download Full-text

Using a low temperature crystallization process to prepare anatase TiO2 buffer layers for air-stable inverted polymer solar cells

Energy & Environmental Science ◽

10.1039/b922373h ◽

2010 ◽

Vol 3 (5) ◽

pp. 654 ◽

Cited By ~ 44

Author(s):

Jen-Hsien Huang ◽

Hung-Yu Wei ◽

Kuan-Chieh Huang ◽

Cheng-Lun Chen ◽

Rui-Ren Wang ◽

...

Keyword(s):

Solar Cells ◽

Low Temperature ◽

Crystallization Process ◽

Polymer Solar Cells ◽

Anatase Tio2 ◽

Buffer Layers ◽

Low Temperature Crystallization ◽

Inverted Polymer Solar Cells ◽

Temperature Crystallization

Download Full-text

Improved calcium sulfate recovery from a reverse osmosis retentate using eutectic freeze crystallization

Water Science & Technology ◽

10.2166/wst.2012.540 ◽

2013 ◽

Vol 67 (1) ◽

pp. 139-146 ◽

Cited By ~ 4

Author(s):

D. G. Randall ◽

R. Mohamed ◽

J. Nathoo ◽

H. Rossenrode ◽

A. E. Lewis

Keyword(s):

Low Temperature ◽

Reverse Osmosis ◽

Calcium Sulfate ◽

Crystallization Process ◽

Eutectic Temperature ◽

Water Recovery ◽

Recovery Rates ◽

Low Temperature Crystallization ◽

Operating Temperatures ◽

Temperature Crystallization

A novel low temperature crystallization process called eutectic freeze crystallization (EFC) can produce both salt(s) and ice from a reverse osmosis (RO) stream by operating at the eutectic temperature of a solution. The EFC reject stream, which is de-supersaturated with respect to the scaling component, can subsequently be recycled back to the RO process for increased water recovery. This paper looks at the feasibility of using EFC to remove calcium sulfate from an RO retentate stream and compares the results to recovery rates at 0 and 20 °C. The results showed that there was a greater yield of calcium sulfate obtained at 0 °C as compared with 20 °C. Operation under eutectic conditions, with only a 20% ice recovery, resulted in an even greater yield of calcium sulfate (48%) when compared with yields obtained at operating temperatures of 0 and 20 °C (15% at 0 °C and 13% at 20 °C). The theoretical calcium recoveries were found to be 75 and 70% at 0 and 20 °C respectively which was higher than the experimentally determined values. The EFC process has the added advantage of producing water along with a salt.

Download Full-text

Tensile Rupture of Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3547249 ◽

1970 ◽

Vol 43 (2) ◽

pp. 222-228 ◽

Cited By ~ 44

Author(s):

A. G. Thomas ◽

J. M. Whittle

Keyword(s):

Tensile Strength ◽

Critical Temperature ◽

Low Temperature ◽

Carbon Black ◽

Natural Rubber ◽

Growth Process ◽

Abrupt Change ◽

Main Chain ◽

Low Temperature Crystallization ◽

Temperature Crystallization

Abstract The dependence of tensile strength of a number of vulcanizates on temperature has heen studied. A critical temperature θc is found for natural rubber at which an abrupt change in strength occurs. This temperature depends on degree of crosslinking and also on the nature of the vulcanizing system. The presence of carbon black filler increases the strength above θc but has little influence on the value of θc or the strength at temperatures below it. The behavior can be explained qualitatively in terms of a change in mechanism of rupture from essentially a tear process above θc to a crack growth process below it. The influence of vulcanizing system is mainly due to changes in the nature of the crosslink rather than changes in regularity of the main chain as shown by the rate of low temperature crystallization.

Download Full-text

Role of SrTiO3 Seed Layer on Low-temperature Crystallization of Pb(Zr, Ti)O3 Films Prepared by Metalorganic Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-1034-k10-28 ◽

2007 ◽

Vol 1034 ◽

Author(s):

Ji-Won Moon ◽

Naoki Wakiya ◽

Takanori Kiguchi ◽

Tomohiko Yoshioka ◽

Tanaka Junzo ◽

...

Keyword(s):

Low Temperature ◽

Seed Layer ◽

Chemical Vapor ◽

Pzt Film ◽

Pzt Films ◽

Low Temperature Crystallization ◽

Seed Layer Thickness ◽

Temperature Crystallization ◽

Seed Layers

AbstractRole of SrTiO3 seed layer on low-temperature crystallization of Pb(Zr, Ti)O3 (PZT) film was investigated. The SrTiO3 seeds were prepared by pulsed laser deposition (PLD) with the temperature range of 400-600 °C and PZT films were prepared by thermal MOCVD. The pyrochlore free PZT films can be successfully crystallized at around 340 °C on SrTiO3 seed layers by thermal MOCVD. It was found that the role of SrTiO3 seed layer is not only pyrochlore suppression but also perovskite promotion. It is also considered that crystallinity, surface coverage and seed layer thickness are important parameters for low-temperature crystallization and electrical properties of PZT films.

Download Full-text