Several factors influence polymer modified bitumen (PMB) in asphalt modification systems. Key factors include the type and concentration of polymer used, the compatibility of the polymer with the bitumen, the processing temperature during modification, and the mixing time. Additionally, the properties of the base bitumen, such as its viscosity and chemical composition, play a crucial role. Environmental conditions, such as temperature and humidity, can also affect the performance and durability of PMB in asphalt applications.