scholarly journals Correlations between dynamic fragility, activation energy and glass transition temperature in polymeric composite materials: An overview from literature

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Heitor Luiz Ornaghi Junior 1 ◽  
Matheus Poletto 2 ◽  
Felipe Gustavo Ornaghi 3
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Composite Materials ◽  
Glass Transition Temperature ◽  
Transition Region ◽  
Polymeric Composite ◽  
Polymeric Composite Material ◽  
Reinforcement Effect ◽  
Polymeric Composite Materials

Here, it is compiled data from literature for glass transition temperature (Tg) and activation energy (Ea) for different types of polymeric composite materials. A correlation among both parameters and dynamic mechanical curves is analyzed in terms of reinforcement effect and its correlation with the glassy and elastomeric moduli, as well the wideness of the main transition region. Besides, all results are discussed in terms of dynamic fragility. The results indicate that the glass transition temperature has not a direct relation with reinforcement effect promoted both in the glassy and/or elastomeric moduli. Moreover, the dynamic fragility concept seems do not be applied in polymeric composite materials since in the glass transition region the format of the storage, loss and tan delta curves vary strongly, depending on the specific polymeric composite material family.

scholarly journals Buckling and vibration analysis of shape memory laminated composite beams under axially heterogeneous in-plane loads in the glass transition temperature region

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Nilesh Tiwari ◽  
A. A. Shaikh
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Boundary Conditions ◽  
Shape Memory ◽  
Transition Region ◽  
Shape Memory Polymer ◽  
Shear Deformation Theory ◽  
Effect Of Temperature ◽  
Glass Transition Region

AbstractBuckling and vibration study of the shape memory polymer composites (SMPC) across the glass transition temperature under heterogeneous loading conditions are presented. Finite element analysis based on C° continuity equation through the higher order shear deformation theory (HSDT) is employed considering non linear Von Karman approach to estimate critical buckling and vibration for the temperature span from 273 to 373 K. Extensive numerical investigations are presented to understand the effect of temperature, boundary conditions, aspect ratio, fiber orientations, laminate stacking and modes of phenomenon on the buckling and vibration behavior of SMPC beam along with the validation and convergence study. Effect of thermal conditions, particularly in the glass transition region of the shape memory polymer, is considerable and presents cohesive relation between dynamic modulus properties with magnitude of critical buckling and vibration. Moreover, it has also been inferred that type of axial loading condition along with the corresponding boundary conditions significantly affect the buckling and vibration load across the glass transition region.

Hygrothermal Behavior of T700 and T300 BMI Used for Advanced Polymeric Composite

2012 ◽  
Vol 476-478 ◽  
pp. 632-635 ◽  
Author(s):  
Shuang Wang ◽  
Wei Fang Zhang ◽  
Yu Chen ◽  
Yu Fen Wu
Keyword(s):  
Compressive Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Surface Morphology ◽  
Water Absorption ◽  
Failure Mode ◽  
Polymeric Composite ◽  
Compressive Properties ◽  
Hygrothermal Behavior

The mechanism of hydrothermal ageing was investigated for T700/ BMI 5428 and T300/QY8911 by studying its glass transition temperature, tensile/compressive properties, changes of surface morphology absorbed in water with 100°C temperature. Results show that the glass transition temperature getting lower with the rate of water absorption. The tensile/compressive strength of composite decreased in the humid and heat environments, although with the identical failure mode.

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

scholarly journals Recycled Glass Fibres from Wind Turbines as a Filler for Poly(Vinyl Chloride)

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Krzysztof Lewandowski ◽  
Katarzyna Skórczewska ◽  
Kazimierz Piszczek ◽  
Włodzimierz Urbaniak
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Composite Materials ◽  
Glass Transition Temperature ◽  
Impact Strength ◽  
Vinyl Chloride ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Poly Vinyl Chloride

This paper presents the method of using glass fibre with carbon deposit (GFCD), derived from the recycling of wind turbine blades, for production of composite materials based on poly(vinyl chloride) (PVC). Composite materials containing from 1 to 15 wt% of GFCD were produced by plasticising with a plastographometer and then by pressing. The processability and performance were studied. Mechanical properties in static tension, impact strength, and thermal stability were determined. Glass transition temperature was also determined by means of the dynamic mechanical thermal analysis (DMTA). The GFCD percentage of up to 15 wt% was found not to slightly affect the change in the processability, thermal stability, and glass transition temperature. PVC/GFCD composite materials are characterised by a definitely greater elastic modulus with simultaneous decrease of tensile strength and impact strength. An analysis with scanning electron microscopy revealed good adhesion between the filler and the polymer matrix.

scholarly journals The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin

2016 ◽  
Vol 39 (1) ◽  
pp. 13-25
Author(s):  
Karol Monkos
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscous Flow ◽  
Solvent Interactions ◽  
Model Free ◽  
Free Volume Model ◽  
Wide Range ◽  
Different Temperatures

Abstract The paper presents the results of viscosity determinations on aqueous solutions of ovalbumin at a wide range of concentrations and at temperatures ranging from 5°C to 55°C. On the basis of these measurements and three models of viscosity for glass-forming liquids: Avramov’s model, free-volume model and power-law model, the activation energy of viscous flow for solutions and ovalbumin molecules, at different temperatures, was calculated. The obtained results show that activation energy monotonically decreases with increasing temperature both for solutions and ovalbumin molecules. The influence of the energy of translational heat motion, protein-protein and protein-solvent interactions, flexibility and hydrodynamic radius of ovalbumin on the rate of decrease in activation energy with temperature has been discussed. One of the parameters in the Avramov’s equation is the glass transition temperature Tg. It turns out that the Tg of ovalbumin solutions increases with increasing concentration. To obtain the glass transition temperature of the dry ovalbumin, a modified Gordon-Taylor equation is used. Thus determined the glass transition temperature for dry ovalbumin is equal to (231.8 ± 6.1) K.

The Influence of Gamma Radiation on the Glass Transition of Hydroxyapatite/Poly L-Lactide Composite

2007 ◽  
Vol 555 ◽  
pp. 497-502
Author(s):  
Dejan Miličević ◽  
S. Trifunović ◽  
N. Ignjatović ◽  
E. Suljovrujić
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Relaxation ◽  
Absorbed Dose ◽  
Gel Permeation Chromatography ◽  
Chain Scission ◽  
Scanning Calorimetry ◽  
Dsc Measurements

Hydroxyapatite/poly L-lactide (HAp/PLLA) is a composite biomaterial which has been widely utilized for substitution and reparation of the hard bone tissue. It is well known that gamma irradiation has been successfully employed in the modification/sterilization of such porous composites and that it has advantages over other procedures. In this study, differential scanning calorimetry (DSC) measurements were made to investigate the influence of the radiation on glass transition behavior and structural relaxation, as well as to estimate the activation energy for this process. The apparent activation energy ΔH* for structural relaxation in the glass transition region was determined on the basis of the heating rate dependence of the glass transition temperature Tg. Furthermore, the results were correlated with those obtained by gel permeation chromatography (GPC). Our findings support the fact that the radiation-induced chain scission in the PLLA phase is the main reason for the decrease of the glass transition temperature and/or activation energy with the absorbed dose.

On the Possibility to Observe a Compensation Effect around the Glass Transition Temperature

2006 ◽  
Vol 514-516 ◽  
pp. 1462-1466
Author(s):  
Rodica M. Neagu ◽  
José N. Marat-Mendes ◽  
Eugen R. Neagu
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Compensation Effect ◽  
Depolarization Current ◽  
Exponential Factor ◽  
Relaxation Parameters ◽  
Maximum Current ◽  
Thermally Stimulated Depolarization

Compensation has been reported for the relaxation parameters: the activation energy W and the pre-exponential factor τ0, determined from the Thermal Sampling of Thermally Stimulated Depolarization Current technique. Below the glass transition it is assumed that the relaxation time follows an Arrhenius equation. In the vicinity of glass transition temperature an experimental thermogram may be analyzed using the Vogel-Fulcher-Tamman-Hesse (VFTH) or the Williams- Landel -Ferry equation. In this article we use the VFTH relationship to study the compensation effect in the range of glass transition. For an elementary peak obtained by TS there is a relationship between the activation energy W, the temperature of the maximum current Tm, the VFTH temperature, the compensation temperature Tc and the compensation time τ c. We employ this relationship for a basic analysis of the compensation effect in the temperature range around Tg. By numerical simulations, and assuming parameters similar to those measured experimentally, we show that it is possible to observe a compensation point in some well defined conditions

scholarly journals The Dynamic Constants of Unidirectional Fibrous Composites at the Glass Transition Region as Obtained from the Interphase Concept

2018 ◽  
Author(s):  
Emilio Sideridis ◽  
John Venetis
Keyword(s):  
Composite Material ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Transition Region ◽  
Loss Factor ◽  
Intermediate Phase ◽  
Mechanical Analysis ◽  
Fibrous Composites ◽  
Glass Transition Region

Dynamic mechanical analysis (DMA) is a versatile technique that complements the information given by the more traditional thermal analysis techniques such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermal mechanical analysis (TMA). Dynamic constants such as storage modulus, loss modulus, and loss factor are temperature dependent and provide information about interfacial bonding between reinforced fibre and polymer matrix of composite material. To study the above mentioned properties at the glass transition region, for unidirectional fibrous composites reinforced with continuous fibers a reliable model was applied. In particular, the composite material was considered as composed of three phases with the intermediate phase between matrix and fibres, the interphase, to have variable properties depending on those of main phases and the mode of preparation of the overall material. The glass transition temperature is defined as the point at which the specific volume versus temperature curve changes abruptly slope marking the region between rubbery polymer and glassy polymer nature. Hence, the behaviour of unidirectional fibrous composites was investigated at this region. Examination of the glass transition temperature, which constitutes an upper limit for the structurally important glassy region through the loss factor, was performed by its consideration as a combination of glass transition temperature of matrix and interphase.

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.

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