When exploring the characteristics of hot - melt adhesives in low - temperature environments, "embrittlement" is a key issue. Generally, hot - melt adhesives tend to become brittle due to low temperatures.
Hot - melt adhesives are mainly composed of polymers, tackifiers, waxes, and other components. In a low - temperature environment, the mobility of polymer molecular chains is significantly reduced, and the movement of chain segments becomes difficult. This causes a significant decrease in the original flexibility and elasticity of the hot - melt adhesive, and a notable increase in brittleness.
Take EVA hot - melt adhesive as an example. When the ambient temperature drops below 0°C, its hardness rises rapidly, and its flexibility decreases sharply. In winter in the northern regions, if products bonded with EVA hot - melt adhesive are placed outdoors, affected by the low temperature, the hot - melt adhesive is prone to brittle cracking, resulting in the failure of the bonded parts.
However, not all hot - melt adhesives are extremely prone to embrittlement at low temperatures. Through special formulations and modifications, some hot - melt adhesives can maintain good flexibility in low - temperature environments. For example, adding specific plasticizers or elastomers to the hot - melt adhesive formula can improve its low - temperature performance. Pressure - sensitive hot - melt adhesives, due to their special molecular structure, can still maintain a certain degree of elasticity and flexibility at low temperatures, making them suitable for scenarios with high requirements for low - temperature performance.