Table of Contents
What is the glass transition temperature of a polymer?
The glass transition temperature is the temperature range where the polymer substrate changes from a rigid glassy material to a soft (not melted) material, and is usually measured in terms of the stiffness, or modulus.
Which polymer has higher glass transition temperature?
These types of interactions increase the rigidity of polymeric material therefore increase the glass transition temperature. Polyvinyl chloride has higher Tg than polyethylene and Nylon-6 also has higher transition point than polyolefin.
What is the Tg of PTFE?
PTFE is a thermoplastic polymer, which is a white solid at room temperature, with a density of about 2200 kg/m3 and a melting point of 600 K (327 °C; 620 °F). At temperatures above 650–700 °C (1,200–1,290 °F) PTFE undergoes depolymerization.
Do amorphous polymers have a glass transition temperature?
Amorphous solids don’t melt suddenly when they’re heated. Instead, they reach a range of temperatures over which the material becomes less glassy and more rubber-like or vice versa. As a result, amorphous polymers don’t have a melting point — they have a glass transition temperature, or Tg.
What is the difference between glass transition and melting temperature?
The main difference between glass transition temperature and melting temperature is that glass transition temperature describes the transition of a glass state into a rubbery state whereas melting temperature describes the transition of a solid phase into a liquid phase.
Why glass transition is second order transition?
There is no latent heat of glass transition. The temperature keeps going up. But the temperature doesn’t go up at the same rate above the Tg as below it. Because the glass transition involves change in heat capacity, but it doesn’t involve a latent heat, this transition is called a second order transition.
Does PTFE have a glass transition temperature?
From literature, PTFE has two beta transition at approximately 19°C and 31°C and a glass transition at approximately 126°C [Nasa].
How do you calculate glass transition temperature?
3.2. 1 Glass transition temperature. Glass transition temperatures of cyclic and linear PS were determined by DSC. For linear PS, the dependence of Tg on molar mass can be expressed by Tg = [1/Tg + K/Mw]−1, where K is a polymer-dependent constant and Mw is the weight average molar mass.
What is the transition temperature of vinyl chloride?
Both the glass transition temperature and the melting point of poly (vinyl chloride have been found to increase as the temperature at which the ample is polymerized is decreased). The glass transition temperature changes from about 70°C. for polymer prepared at 125°C. to about 100°C. for polymer prepared at −80°C.
What is the solubility parameter of vinylidene chloride?
Density ρ g mL-1 1.67 – 1.77 1.71 Solubility Parameter δ MPa1/2 19.9 – 20.2 20.0 Molar Cohesive Energy Ecoh J mol-1 23200 – 22500 22800 Glass Transition Temperature Tg K 254, 295 Molar Heat Capacity Cp J (mol K)-1 104 – 117 112
What causes the glass transition temperature to change?
The glass transition temperature changes from about 70°C. for polymer prepared at 125°C. to about 100°C. for polymer prepared at −80°C. It is believed the increase in percentage of syndiotactic structure which results from decreasing the polymerization temperature is responsible for the change in glass transition temperature.
What are the thermal properties of polycarbonate transition point?
Thermal Properties 4・1 Transition Point 4・1・1 Glass Transition Point (Secondary Transition Point) The glass transition point of polycarbonate obtained from the inflection point of refractive index is 141~149℃, as shown in Fig. 4・1・1‐1.