What is the Tg of polypropylene?
Glass Transition Temperature of some Polymers
| Polymer | Tg (K)a,b |
|---|---|
| Polypropylene (PP) | 260 (239) |
| Polyethylene (HDPE)* | 148* (148, 186, 238) |
| Polymethylacrylate (PMA) | 283 (285) |
| Polypropyleneglycol (PPG) | 198 (205) |
Would polystyrene have a higher or lower glass transition temperature than polypropylene?
Since both polymers are 25% crystalline, they will exhibit behavior similar to curve B in Figure 15.18. However, polystyrene will have higher melting and glass transition temperatures due to the bulkier side group in its repeat unit structure, and since it has a higher weight-average molecular weight.
What is the glass transition temperature of polystyrene?
100 °C
Forms produced
| Properties | |
|---|---|
| Glass transition temperature | 100 °C |
| Vicat softening point | 90 °C |
| Coefficient of thermal expansion | 8×10−5 /K |
| Specific heat capacity (c) | 1.3 kJ/(kg·K) |
Why polypropylene has higher glass transition temperature than polyethylene?
Chain flexibility: Chain flexibility is one of the important factor, which affects Tg. Bulky group attached to polymer backbone also reduces flexibility of chain backbone therefore polypropylene has higher Tg than polyethylene.
Does polyethylene have a glass transition temperature?
Polyethylene (PE) has been and is the most common and most studied polymer. Nevertheless, there is still no full consensus among researchers about such a basic property as the value of its glass transition temperature T g. Values as different as around −25°C and −120°C are reported [1] and Immergut, E. H.
Why polyethylene has lower Tg than polystyrene?
Tg of polyethylene is low because of its high flexibility and the absence of side groups. Additionally PE is semicrystalline due to its realtively simple and symmetrical structure, teherfore it remains tough and exhibits plastic behavior between Tg and Tm.
What factors affect glass transition temperature?
Factors Affecting Tg
- Molecular Weight – In straight chain polymers, increase in MW leads to decrease in chain end concentration resulting in decreases free volume at end group region – and increase in Tg.
- Molecular Structure – Insertion of bulky, inflexible side group increases Tg of material due to decrease in mobility,
What is high impact polystyrene made of?
HIPS is a modified form of polystyrene: Polystyrene (PS) plastic is a naturally transparent thermoplastic material that is available in several forms. The most basic form of PS is general purpose PS (GPPS), also known as crystal PS. GPPS is a result of styrene monomer polymerization and it is a transparent product.
How strong is high impact polystyrene?
High Impact Polystyrene Properties and Material Options
| UNITS | HIGH IMPACT POLYSTYRENE | |
|---|---|---|
| Tensile strength | psi | 3,500 |
| Tensile elongation at break | % | 55 |
| Flexural modulus | psi | 310,000 |
| Izod impact (notched) | ft-lbs/in of notch | 2.8 |
Is high impact polystyrene amorphous?
HIPS (High Impact Polystyrene), also known as PS (Polystyrene), is an amorphous thermoplastic material, used in lower heat applications. It is categorized as a standard material, and offers ease of processing, high impact strength, and stiffness.
How is high impact polystyrene made?
HIPS is a high impact strength material: This form of PS typically is produced by adding around 5-10% rubber or butadiene copolymer. This increases the toughness and impact strength of the polymer and results in a very stiff product ideal for packaging applications.
What does a high glass transition temperature mean?
The polymer molecules move freely around each other. This transition point is called the glass transition temperature. The lower slope below the Tg is due to the lower heat capacity for the amorphous polymer. Above the Tg, the rubbery, flexible polymer has a higher heat capacity.
What are the factors affecting the glass transition temperature of polymers?
If value of entropy is high, then value of Tg is also high. Increase in pressure of surrounding leads to decrease in free volume and ultimately high Tg. Other factors like branching, alkyl chain length, bond interaction, flexibility of polymer chain, film thickness etc. also have significant impact on glass transition temperature of polymers.
What is high impact polystyrene (HIPS)?
HIPS: High impact polystyrene contains usually 5 to 10% rubber (butadiene) and is used for parts which require high (er) impact resistance. HIPS is a graft copolymer having polystyrene sidearms.
How to increase the heat resistance of polystyrene?
To increase the heat resistance, styrene is sometimes copolymerized with small amounts of maleic anhydride or it is copolymerized with this monomer to an alternating structure. The copolymer poly (styrene-co-maleic anhydride) (PSMA) has a higher T g than pure polystyrene (400 – 430 K), improved heat resistance and high dimensional stability.
What is glass transition temperature (Tg)?
The glass transition temperature is generally indicated as Tg. Tg is a physical quantity that is determined by the type of plastic. By knowing the value of Tg, it is possible to estimate the time required for the molded item to cool inside the cavity and the molded item temperature at which it can be ejected from the mold.
