With the continuous increase in the amount of PBT resin, the defects such as poor flame retardancy, insufficient heat deformation temperature, and insufficient notch impact strength of PBT materials are becoming increasingly apparent. In order to make up for the shortcomings in the performance of pure PBT resin and expand its application fields, relevant personnel continuously modify it. At present, there are three main types of PBT modified products in China: glass fiber reinforced, flame retardant modified, and blended alloy modified. 
1、 Enhanced modification
Adding glass fiber to PBT not only maintains the original advantages of PBT resin, such as chemical resistance and processability, but also significantly improves its mechanical properties and overcomes the sensitivity of PBT resin to gaps.
2、 Flame retardant modification
PBT is a crystalline aromatic polyester. Without the addition of flame retardants, its flame retardancy belongs to UL94HB level. Only by adding flame retardants can it reach UL94V0 level.
Commonly used flame retardants include halogen based flame retardants such as bromide, Sb2O3, phosphides, and chlorides, with the most common being decabromodiphenyl ether, which has always been the main PBT flame retardant. However, due to environmental reasons, European countries have long banned its use, and various parties are looking for its alternatives. However, there has been no performance advantage over decabromodiphenyl ether alternatives.
Nevertheless, as a trend, halogen-free flame retardant technology has received attention from major companies in recent years. Compared with existing halogen based PBTs, they have low density, excellent electrical properties, and the same mechanical properties as existing materials. However, due to the lack of economically practical and ideal substitutes, halogenated flame retardant products still dominate the market.
3、 Blended alloy modification
The main purpose of blending PBT with other polymers is to improve notch impact strength, improve warping deformation caused by molding shrinkage, and improve heat resistance. Blending is widely used domestically and internationally to modify it. The polymers used for blending modification of PBT mainly include PC, PET, etc. This type of product is mainly used in automobiles, electronics, and electric tools. The proportion of fiberglass varies, and its application fields also vary.
1 PC/PBT alloy
Advantages: Polycarbonate (PC) has excellent performance and can be melted and blended with PBT in any ratio at temperatures greater than the glass transition temperature of PC by 150 ℃. The blended PC/PB alloy can not only overcome the shortcomings of insufficient processability and wear resistance in PC molding, but also make up for the shortcomings of insufficient impact strength, impact resistance, and heat resistance in PBT notches.
2 PET/PBT alloy
Advantages: Polyethylene terephthalate (PET) and PBT have similar solubility parameters and chemical structures. The mixed system of the two has good compatibility, with only one glass transition temperature Tg appearing
3 Blending PBT with other polymers
In addition to the aforementioned materials, some materials with good compatibilization effects, such as PU, PP, ABS, SBS, EPDM, POE, ASA, EVA, elastomer, etc., have also been attempted to melt blend and modify PBT. There are also biodegradable biological resins PBS, PCL, and PBT blended to produce environmentally friendly PBT alloys.