Thermal Expansion and Glass Transition Behaviour of Thin Polymer Films with and without a Free Surface Via Neutron Reflectometry

1998 ◽  
Vol 543 ◽  
Author(s):  
D. J. Pochan ◽  
E. K. Lin ◽  
S. Satija ◽  
S. Z. D. Cheng ◽  
Wen-Li Wu
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Free Surface ◽  
Film Thickness ◽  
Coefficient Of Thermal Expansion ◽  
Neutron Reflectometry ◽  
Bilayer Films ◽  
Fluorinated Polyimide ◽  
Expansion Behavior ◽  
Before And After

AbstractThe thermal expansion of thin deuterated polystyrene (dPS) films supported on energetically repulsive, fluorinated polyimide (PI) substrates (PI/dPS bilayer) was measured via neutron reflectometry as a function of initial dPS film thickness. Film thickness was measured before and after capping with a top layer of the same repulsive, high glass transition polyimide that comprised the substrate layer (PI/dPS/PI trilayer) in an attempt to observe any effects of the dPS free surface in the bilayer geometry. Bulk thermal expansion behavior, characterized by a discontinuous change in coefficient of thermal expansion (CTE) at the glass transition (Tg), is observed in films with thickness > 70 rim. For thicknesses between 70 nm and 40 nm a transition is seen from bulk behavior in bilayer films to glassy thermal behavior in the trilayer films persisting up to 20 °C above the bulk Tg. In films with thickness < 40 nm the bulk glassy CTE persists well above the bulk Tg for both bilayer and trilayer films

Applicability of Iron Phosphate Glass Medium for Loading NaCl Originated From Seawater Used for Cooling the Stricken Power Reactors

2013 ◽  
Author(s):  
Hidekazu Kobayashi ◽  
Ippei Amamoto ◽  
Takuma Yokozawa ◽  
Teruo Yamashita ◽  
Takayuki Nagai ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Phosphate Glass ◽  
Glass Formation ◽  
Coefficient Of Thermal Expansion ◽  
Glass Melting ◽  
Glass Network ◽  
Iron Phosphate ◽  
Chemical Durability ◽  
Raw Material

As the part of investigation for immobilization of the sludge as one of the radioactive wastes arising from the treatment of contaminated water at Fukushima Dai-ichi nuclear power plant, applicability of vitrification method has been evaluated as a candidate technique. The aim of this study is to evaluate the influence of NaCl as one of the main constituents of sludge, on glass formation and glass properties. Two kinds of iron phosphate glass (IPG) media in the xFe2O3-(100-x)P2O5, with x = 30 and 35 (mol%) were chosen and the glass formation, structure and properties including density, coefficient of thermal expansion, glass transition temperature, onset crystallization temperature and chemical durability of NaCl-loaded IPG were studied. The results are summarized as follows. Sodium chloride, NaCl could be loaded into IPG medium as Na2O and Cl contents and their loading ratio could be up to 19 and 15 mol%, respectively. Majority of Cl content of raw material NaCl was thought to be volatilized during glass melting. Loading NaCl into IPG induces to depolymerize glass network of phosphate chains, leads to decrease both glass transition and onset crystallization temperatures, and to increase coefficient of thermal expansion. NaCl-loaded IPG indicated good chemical durability in case of using 35Fe2O3-65P2O5 medium.

The Effect of Thermal History on Porcelain Expansion Behavior

1989 ◽  
Vol 68 (9) ◽  
pp. 1313-1315 ◽  
Author(s):  
C.W. Fairhurst ◽  
D.T. Hashinger ◽  
S.W. Twiggs
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Room Temperature ◽  
Heating Rates ◽  
Thermal Expansion Data ◽  
Temperature Range ◽  
Expansion Behavior

Porcelain-fused-to-metal restorations are fired several hundred degrees above the glass-transition temperature and cooled rapidly through the glass-transition temperature range. Thermal expansion data from room temperature to above the glass-transition temperature range are important for the thermal expansion of the porcelain to be matched to the alloy. The effect of heating rate during measurement of thermal expansion was determined for NBS SRM 710 glass and four commercial opaque and body porcelain products. Thermal expansion data were obtained at heating rates of from 3 to 30°C/min after the porcelain was cooled at the same rate. By use of the Moynihan equation (where Tg systematically increases in temperature with an increase in cooling/heating rate), the glass-transition temperatures (Tg) derived from these data were shown to be related to the heating rate.

Highly transparent polyhydroxyimide/TiO2 and ZrO2 hybrid films with high glass transition temperature (Tg) and low coefficient of thermal expansion (CTE) for optoelectronic application

2017 ◽  
Vol 5 (33) ◽  
pp. 8444-8453 ◽  
Author(s):  
Shun-Wen Cheng ◽  
Tzu-Tien Huang ◽  
Chia-Liang Tsai ◽  
Guey-Sheng Liou
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Expansion Coefficient ◽  
Coefficient Of Thermal Expansion ◽  
High Glass Transition Temperature ◽  
Hybrid Films ◽  
Optoelectronic Application ◽  
Low Thermal Expansion

Highly transparent polyhydroxyimide/TiO2 and ZrO2 hybrids films with high glass transition temperature and low thermal expansion coefficient for optoelectronic application.

Hygrothermal Behavior of Advanced Polymers Above Water Boiling Temperatures

2014 ◽  
Vol 136 (1) ◽  
Author(s):  
Changsoo Jang ◽  
Bongtae Han
Keyword(s):  
Thermal Expansion ◽  
Moisture Content ◽  
Coefficient Of Thermal Expansion ◽  
Measurement Data ◽  
Hybrid Procedure ◽  
Boiling Temperature ◽  
Hygrothermal Behavior ◽  
Expansion Behavior ◽  
Wide Range ◽  
Moisture Conditions

Hygroscopic and thermal expansion behavior of advanced polymers is investigated when subjected to combined high temperature and moisture conditions. An enhanced experimental–numerical hybrid procedure is proposed to overcome the limitations of the existing methods when used at temperatures above the water boiling temperature. The proposed procedure is implemented to measure the hygrothermal strains of three epoxy molding compounds and a no-filler underfill over a wide range of temperatures including temperatures beyond the water boiling temperature. The effects of moisture content on the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are evaluated from the measurement data. A formulation to predict the Tg change as a function of moisture content is also presented.

Rheological and Thermomechanical Properties of Meso and Non-Porous Silica Filled Epoxy Composites

2015 ◽  
Vol 815 ◽  
pp. 67-71
Author(s):  
Gang Li ◽  
Peng Li Zhu ◽  
Tao Zhao ◽  
Rong Sun ◽  
Daniel Lu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Mesoporous Silica ◽  
Coefficient Of Thermal Expansion ◽  
Porous Silica ◽  
Thermomechanical Properties ◽  
Epoxy Composites ◽  
Silica Microspheres ◽  
Silica Filler

In the present study, epoxy based composite filled with meso and non-porous silica microspheres with similar size were prepared respectively and their rheological and thermo-mechanical properties were studied systematically. The results showed that the mesoporous silica/epoxy composites showed much higher viscosity, storage modulus and glass transition temperature (Tg) while lower coefficient of thermal expansion (CTE) than did epoxy composites with nonporous silica particles, which could be attributed to the stronger interface interaction between the mesoporous silica filler with larger specific surface area (BET) and the epoxy matrix.

Thermal Expansion Behavior and Characteristic of SiCp/Al Composites

2011 ◽  
Vol 287-290 ◽  
pp. 658-661 ◽  
Author(s):  
Xian Liang Zhou ◽  
Duo Sheng Li ◽  
Ai Hua Zou ◽  
Xiao Zhen Hua ◽  
Zhi Guo Ye ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Size Range ◽  
Coefficient Of Thermal Expansion ◽  
Pure Aluminum ◽  
Annealing Process ◽  
Ceramic Mold ◽  
Range Space ◽  
Thermal Expansion Behavior ◽  
Expansion Behavior ◽  
Al Matrix

SiCp/Al composites were fabricated by ceramic mold freedom infiltration and pressureless infiltration, respectively. The microstructure and phases are analyzed by metallurgical microscope and coefficient of thermal expansion of SiCp/Al composites were tested by thermal dilatometer. The results show that SiCp/Al composites are compact and uniform. SiC particles were dispersed uniformly in Al matrix, and SiCp segregation was not found in composites. Under a certain SiCp size range, space between SiCp decreases with decreasing of SiCp size, and CTE of SiCp/Al composites also decreases with decreasing of particles size. Compared with CTE of composite with pure aluminum as matrix, CTE of composite with ZL101 as matrix is less. Under the annealing process, CTE of SiCp/Al composites with ZL101 as matrix is less than that with the solution and aging, which indicated that its dimensional stability of resisting to temperature fluctuation is better, and thermal expansion behavior and characteristic of SiCp/Al composites are also better.

scholarly journals Evaluation of the coefficient of thermal expansion of human and bovine dentin by thermomechanical analysis

2012 ◽  
Vol 23 (1) ◽  
pp. 03-07 ◽  
Author(s):  
Murilo Baena Lopes ◽  
Zhuoqun Yan ◽  
Simonides Consani ◽  
Alcides Gonini Júnior ◽  
Anderson Aleixo ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Third Molar ◽  
Weight Changes ◽  
Incisor Tooth ◽  
Test Environment ◽  
Material Interface ◽  
Human Teeth ◽  
Thermal Expansion Behavior ◽  
Expansion Behavior

The mismatch of thermal expansion and contraction between restorative materials and tooth may cause stresses at their interface, which may lead to microleakage. The present work compared the coefficient of thermal expansion (CTE) with the thermomechanical behavior of human and bovine teeth and determined if the CTE is a suitable parameter to describe tooth behavior. Fifteen human third molar and 15 bovine incisor tooth slices (6×5×2 mm) were allocated to 3 groups according to the test environment: G1 - room condition, G2 - 100% humidity, G3 - desiccated and tested in dry condition. Each specimen was weighed, heated from 20 to 70ºC at 10ºC min−1 and reweighed. The CTE was measured between 20 and 50ºC. Fresh dentin (human -0.49% ± 0.27, bovine -0.22% ± 0.16) contracted on heating under dry condition. Under wet conditions, only human teeth (-0.05% ± 0.04) showed contraction (bovine 0.00% ± 0.03) accompanied by a significantly lower (p<0.05) weight loss than in dry specimens (human 0.35% ± 0.15, bovine 0.45% ± 0.20). The desiccated dentin expanded on heating without obvious weight changes (0.00% ± 0.00). The CTE found was, respectively, in dry, wet and dissected conditions in ºC-1: human (-66.03×10-6, -6.82×10-6, 5.52×10-6) and bovine (-33.71×10-6, 5.47×10-6, 4.31×10-6). According to its wet condition, the dentin showed different CTEs. The thermal expansion behavior of human and bovine dentin was similar. A simple evaluation of the thermal expansion behavior of tooth structure by its CTE value may not be appropriate as a meaningful consideration of the effects on the tooth-material interface.

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