High heat resistant fibre
High heat resistant fibre is a fibre developed to overcome the low heat resistance of PVC fibre, and can be curled using electron irons at home. It can also resist high temperatures because its main material is polyester which has a melting point of 260C. It also has flame retardant properties.
Real hair forms a curl well at a high temperature of around 200C but high heat resistant fibre forms a curl well at a low temperature of around 140C. When curling high heat resistant fibre at a higher temperature, you can get a stronger curl if you eliminate the iron while maintaining the curl and then cooling it for 10 seconds.