PP-R管材脆性剖析及处理办法(国外英文资料).docVIP

PP-R管材脆性分析及解决措施(国外英文资料) The resulting crystals are larger and have higher crystallinity. Due to the different speed of crystallization of the inner and outer wall of the tube, different crystallization degree can produce stress concentration and influence the performance of pipe. 3.2??? The anti-shock properties of PP - R tubes are improved through annealing process The cooling process results in the brittleness of the PP - R tube, which is caused by the different velocity of the inner and outer wall. Therefore, it is possible to reduce the velocity of the lining of the tube and the speed of the crystal velocity in the inner and outer wall of the tube. The low melting point of the PP is closely aligned with the molecular chain of the PP, and the size of the spherocrystal grows as the heat increases. At the same time, because the absorption of heat increases the motion between the molecules, it reduces the tension stress caused by crystallization. Therefore, through annealing technology, the anti-shock performance of the pipe can be improved effectively, and the PP -r tube can be achieved through online annealing and off-line annealing. 3.2.1, online annealing process Pp-r pipe production line with 4 section cooling water tank, vacuum extruder extrusion PP - R tube embryos after sizing set in the first quarter vacuum cooling phase, and the vacuum cooling shower through cooling box section 2, 3, closed cooling water, and water tank zhongtong with 100 ℃ constant temperature heat flow, on-line annealing, finally through the fourth quarter the vacuum tank for cooling, pipe cutting and packing. 3.2.2, offline annealing process In order to realize the offline annealing, the cart is made for the shelf, which is 5 meters long, 1.5 meters wide and 1.5 meters high, separated by a three-layer hollowed-out partition. Normal rolled off the production line of pp-r pipes placed in four layers trolleys, about 2000 meters per car placed pp-r pipe, push carts with pp-r pipe into a cl