scholarly journals Stability of Crystal Nuclei of Poly (butylene isophthalate) Formed Near the Glass Transition Temperature

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1099
Author(s):  
Silvia Quattrosoldi ◽  
Nadia Lotti ◽  
Michelina Soccio ◽  
Christoph Schick ◽  
René Androsch
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Growth Temperature ◽  
Thermal Characteristics ◽  
Maximum Temperature ◽  
Nucleation Time ◽  
Maximum Temperatures ◽  
Nuclei Number

Tammann’s two-stage crystal-nuclei-development method is applied for analysis of the thermal stability of homogenously formed crystal nuclei of poly(butylene isophthalate) (PBI) as well as their possible reorganization on transferring them to the growth temperature, using fast scanning chip calorimetry. Crystal nuclei were formed at 50 °C, that is, at a temperature only slightly higher than the glass transition temperature, and developed to crystals within a pre-defined time at the growth temperature of 85 °C. The number of nuclei, overcritical at the growth temperature, was detected as a function of the transfer-conditions (maximum temperature, heating rate) by evaluation of the developed crystal fraction. For different size-distributions of crystal nuclei, as controlled by the nucleation time, there is detected distinct reduction of the nuclei number on heating to maximum temperatures higher than about 90 to 110 °C, with the latter value holding for longer nucleation time. Longer nucleation allows for both increasing the absolute nuclei number and generation of an increased fraction of larger nuclei. Heating at 1000 K/s to 140–150 °C causes “melting” of even the most stable nuclei. While direct transfer of crystal nuclei from the nucleation temperature (50 °C) to the growth temperature (85 °C) reveals negligible effect of the transfer-heating rate, in-between heating to higher temperatures is connected with distinct nuclei-reorganization above 85 °C on heating slower than 1000–10.000 K/s. The performed study not only provides specific valuable information about the thermal characteristics of crystal nuclei of PBI but also highlights the importance of proper design of Tammann’s nuclei development experiment for analysis of nuclei numbers. With the evaluation of critical rates of temperature-change for suppression of non-isothermal formation of both nuclei and crystals, the kinetics of crystallization of the slow crystallizing PBI is further quantified.

Phase transition in non-crystalline solids viewed from heating

1995 ◽  
Vol 398 ◽  
Author(s):  
K. Nakayama ◽  
K. Kojima ◽  
N. Takahashi ◽  
Y. Masaki ◽  
A. Kitagawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Transient Phase ◽  
Disordered Structures ◽  
Fragmentation Processes ◽  
Scaling Rule

ABSTRACTThe heating-rate dependence of crystallization temperature, Tc, and the glass transition temperature, Tg, is studied from the view points of nucleation and fragmentation processes in disordered structures. Tc and Tg are expected to increase monotonically with heating rate. Such behaviors of Tc and Tg are classified into four characteristic regions with respect to the heating rate. Results are summarized in the Transient Phase Diagram where Tc and Tg are given as a function of heating rate. The scaling rule in the Transient Phase Diagram is given.

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.

Modification of the Mechanical Behavior in the Glass Transition Region of Poly(lactic acid) (PLA) through Catalyzed Reactive Extrusion with Poly(carbonate) (PC)

2015 ◽  
Vol 1119 ◽  
pp. 292-295
Author(s):  
Vu Thanh Phuong ◽  
Maria Beatrice Coltelli ◽  
Irene Anguillesi ◽  
Patrizia Cinelli ◽  
Andrea Lazzeri
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Transition Region ◽  
Reactive Extrusion ◽  
Maximum Temperature ◽  
Glass Transition Region ◽  
The One ◽  
Poly Carbonate

In order to improve the thermal stability of PLA based materials it was followed the strategy of blending it with a polymer having a higher glass transition temperature such as poly (carbonate) of bisphenol A (PC) . PLA/PC blends with different compositions were by melt extrusion produced also in the presence of an interchange reaction catalyst, tetrabutylammonium tetraphenylborate (TBATPB) and triacetin. The dynamical mechanical thermal characterization showed an interesting change of the storage modulus behavior in the PLA glass transition region, evident exclusively in the catalyzed blends. In particular, a new peak in the Tan δ trend at a temperature in between the one of PLA and the one of PC was observed only in the blends obtained in the presence of triacetin and TBATPB. The height and maximum temperature of the peak was different after the annealing of samples at 80°C. The data showed an interesting improvement of thermal stability above the PLA glass transition, this was explained keeping into account the formation of PLA-PC copolymer during the reactive extrusion. Furthermore, the glass transition temperature of the copolymer as a function of composition was studied and the obtained trend was discussed by comparing with literature models developed for copolymers.

Study of the Glass Transition Temperature of (Se100-xBix)90Te10 (x = 0, 0.5, 1, 1.5, 2, 2.5, 3) Alloys

2011 ◽  
Vol 316-317 ◽  
pp. 55-58 ◽  
Author(s):  
Deepshikha Sharma ◽  
Saneel K. Thakur
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Network Model ◽  
Differential Analysis ◽  
X Ray Diffraction ◽  
Glass Transition Temperatures ◽  
X Ray ◽  
Xrd Studies

Alloys of (Se100-xBix)90Te10 (x =0, 0.5, 1, 1.5, 2, 2.5, 3 at.%) were prepared by using a conventional melt-quench technique. The samples under investigation were characterized using X-ray diffraction (XRD) and differential analysis (DTA) at a heating rate of 10K/min. It was found, from the XRD studies, that the alloys were amorphous in nature. The glass transition temperatures of the alloys were found to increase with increasing bismuth content. This increase in the glass transition temperature was explained on the basis of a chemically ordered network model.

From ultrafast to slow: Heating rate dependence of the glass transition temperature in metallic systems

2016 ◽  
Vol 96 (12) ◽  
pp. 454-460 ◽  
Author(s):  
Stefan Küchemann ◽  
Goodwin Gibbins ◽  
Joe Corkerton ◽  
Eleanor Brug ◽  
Jonas Ruebsam ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Rate Dependence ◽  
Slow Heating ◽  
Metallic Systems

Some Properties of the Glass Transition in the Amorphous Sb-As-S-Se-I System

2007 ◽  
Vol 555 ◽  
pp. 165-170
Author(s):  
F. Skuban ◽  
S.R. Lukić ◽  
D.M. Petrović ◽  
Mirjana Šiljegović
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Specific Heat ◽  
Heating Rate ◽  
Glass Composition ◽  
Transition Process ◽  
Abrupt Increase ◽  
Pseudobinary System

Transformations of glasses from the multicomponent pseudobinary system (As2Se3)100−x(SbSI)x were analyzed from the aspect of determining the glass transition temperature Tg, activation energy of the process Et, and characteristic changes of the specific heat. The established dependence of Tg on glass composition and heating rate served as the basis for determining the activation energy of glass transition process Et. An abrupt increase in the specific heat cp at the glass transition temperature was analyzed with the aim of classifying the materials according to the criterion of the so-called 'fragility'. It was found that the investigated glasses, i.e. their melts, belong to the group of thermodynamically 'strong' melts.

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