Food grade PC244R basic innovative plastic, flame retardant grade in the United States
Category:
Rubber and plastic/engineering plastic/PC
Model:
Brand:
Basic Innovative Plastics&# 40; United States&# 41
Retail Price
24.60USD
重量
kg
- Product Description
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Description :
Food grade PC244R basic innovative plastic, flame retardant grade in the United States
Stress cracking phenomenon of PC products
Stress cracking refers to a complex failure behavior in which plastic products undergo premature cracking and failure when exposed to chemical media and stress simultaneously. It is related to various factors such as environmental effects, material properties, and molding methods. Regarding the stress cracking of PC materials, research by Masami Tomikawa, Yukihiko Sato, and others in Japan has shown that the local orientation of polycarbonate macromolecules causes microcracks in the parts. These microcracks can be eliminated by heat treatment when no gaps are formed due to fragmentation; Under the influence of the environment and external forces, microcracks continue to grow and develop, resulting in cracks that have formed voids and become irreparable fracture damage.
It is generally believed that during the molding of polycarbonate, the molecular chains are forced to orient, and orientation is difficult due to the presence of benzene rings on the polycarbonate molecular chains. After molding, the oriented chains tend to return to their natural state. However, due to the freezing of the entire molecular chain and the mutual influence between the large molecular chains, residual stress exists in the product; At the same time, polycarbonate also has intermolecular forces and entanglement forces, namely anti cracking forces, which depend on the length of the molecular chains, the number of entanglements between chains, and the intermolecular forces.
When the anti cracking ability and internal stress are balanced, the product will not crack. However, when the anti cracking ability is less than the internal stress, the product will be qualified during molding but crack after being stored for a period of time. Briefly summarized as: benzene ring on molecular chain - forming orientation - internal stress appearing after product forming - when internal stress and crack resistance are balanced - qualified product - when internal stress exceeds crack resistance - product cracking.
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Key words:- Food grade PC244R
