Glass transition temperature (Tg) is a term used in materials science and polymer chemistry to describe the temperature at which an amorphous polymer transitions from a glassy, brittle state to a more rubbery, flexible state. At temperatures below Tg, the polymer is in a solid, glassy state and is brittle and inflexible. Above Tg, the polymer becomes more flexible and elastic, and can deform under stress. The glass transition temperature is an important property of thermoplastics as it can affect their mechanical properties, processability, and durability.
Glass transition temperature (Tg) of starch
The glass transition temperature (Tg) of starch can vary depending on the type of starch and its physical state, such as granular or gelatinized form. Generally, the Tg of native granular starches ranges from about 50 to 70°C, while the Tg of gelatinized starches is lower and can range from about 40 to 60°C. The Tg can also be affected by factors such as moisture content, plasticizers, and chemical modifications.
The glass transition temperature (Tg) of tapioca starch can vary depending on factors such as moisture content, processing conditions, and any modifications made to the starch. However, in general, the Tg of tapioca starch is around 60-70°C. This means that below this temperature, tapioca starch is in a glassy state, and its molecules are rigid and brittle. Above this temperature, tapioca starch becomes more flexible and rubbery, and its molecules can begin to flow and rearrange themselves, which is important for its use as a thermoplastic material.
Natural, dry starch typically has a high glass transition temperature (Tg) and melting temperature (Tm), which can make it brittle and unsuitable for use in plastics. In order to overcome these issues, plasticization and modification techniques are often employed to reduce the Tg and Tm of starch, making it more flexible and versatile as a material.