What is the Tg of PP?
What is the Tg of PP?
The temperature at the border from the rubbery state to the solid state (called the glass state) is called its “glass transition temperature”. The glass transition temperature is generally indicated as Tg….
| Name of plastic | Tg |
|---|---|
| Polypropylene | 0�C |
| Polyvinyl chloride | 87�C |
| Polystyrene | 100�C |
| ABS | 80 to 125�C |
What is isotactic syndiotactic and atactic?
The key difference between atactic isotactic and syndiotactic polymer is that the atactic polymers have their substituents in a random manner and isotactic polymers have their substituents in the same side, whereas the syndiotactic polymers have their substituents in an alternating pattern.
What does Tg mean in plastics?
There is a certain temperature(different for each polymer) called the glass transition temperature, or Tg for short. When the polymer is cooled below this temperature, it becomes hard and brittle, like glass. Some polymers are used above their glass transition temperatures, and some are used below.
What is isotactic polymer?
Isotactic polymers are composed of isotactic macromolecules (IUPAC definition). In isotactic macromolecules all the substituents are located on the same side of the macromolecular backbone. An isotactic macromolecule consists of 100% meso diads. Polypropylene formed by Ziegler–Natta catalysis is an isotactic polymer.
What is Tg of PE?
[7–11], based on direct study of wholly amorphous linear PE, that the Tg of PE is −80°C from one hand, and from the other, that branched PE is supposed to have a much higher Tg value (corresponding to the β-relaxation peak), one can consider the extrapolated Tg value of −23°C from branched PE samples as the Tg of …
How is TG calculated?
Tg is typically calculated by using a half-height technique in the transition region. The heating rate and sample heat history are a couple of factors that may affect the test result. Depending on the equipment capability, DSC can be used for a wide range of thermoplastic and thermoset polymers.
What is isotactic in chemistry?
Isotactic – An isotactic polymer is one in which all of the pendant groups are located on the same side of the hydrocarbon backbone chain. A popular form of polypropylene that is commonly marketed is an example of an isotactic polymer.
Is PVC isotactic?
Structure of PVC There are a number of different ways in which chloroethene molecules can combine together to form long polymer chains. This structure is known as isotactic polyvinyl chloride.
What is the Tg of PVC?
Thermal and fire Traditional product PVC has a maximum operating temperature around 60 °C (140 °F) when heat distortion begins to occur. Melting temperatures range from 100 °C (212 °F) to 260 °C (500 °F) depending upon manufacture additives to the PVC.
What is the Tg of HDPE?
The data in Figure 1 indicates the Tg of the HDPE sample to be approximately -111 ˚C. For comparison, the same sample was run under conventional DSC conditions at 10 ˚C/ min.
How are isotactic polymers?
Atactic, Isotactic, and Syndiotactic Polymers Atactic polymers form from radical chain polymerization. These polymers have branches that result from hydrogen abstraction processes. Both isotactic and syndiotactic forms of polymers are produced with catalysts designed by K. Ziegler of Germany and G.
What does isotactic mean in chemistry?
isotactic in American English (ˌaisəˈtæktɪk) adjective. Chemistry (of a polymer) having the same configuration at successive, regularly spaced positions along the chain.
What is the isotacticity of polypropylene?
Most polypropylene used in various textile products is produced from isotactic polymers. Isotacticity of polypropylene has significant influence on tape or fiber property. Only iso- and syndiotactic polymer have sufficient molecular order to create polycrystalline structure and hence acceptable physical and tensile properties for oriented tapes.
What is the difference between isotactic and Syndiotactic PP?
Untill a decade ago all PP produced was isotactic and the catalysts were heterogeneous. Homogeneous catalysts opened the way to syndiotactic PP and this material can be less opaque and stronger than isotactic PP. The catalyst and the concomitant technology have undergone drastic changes over the years.
Why are some polymers called isotactic?
It is not because of the equal orientation that the polymer is called isotactic; isotactic refers to the absolute configuration of this carbon atom at the moment it was made and because the repeat unit is C2 the methyl groups are oriented to the same side.
Does isotactic polypropylene crystallization produce spherulites?
According, to Varga revision [3] when isotactic polypropylene is crystallized from the melt, is monitored by polarizing optical microscope, birefrengent spherulites are produced, growing radially at a constant rate under isothermal conditions.
