1. Acrylic is a thermoplastic plastic, which will cause serious deformation of the mirror surface if used under high temperature for a long time. The deformation temperature of acrylic is 100 ℃, and the continuous use temperature cannot be higher than 90 ℃. Acrylic material itself contains polar side methyl, which has obvious hygroscopicity, and the hygroscopicity is 0.3% – 0.4%. Acrylic will expand after moisture absorption, resulting in the deformation of the mirror surface. Before forming, the acrylic plate must be dried, and the drying condition is to dry at 80 ℃ – 85 ℃ for 4-5 hours. The acrylic mirror must be kept dry in the use environment, and must not be used in the bathroom, outdoor and other humid environment.
2. Acrylic has effective and obvious non-Newtonian fluid characteristics within the temperature range of molding processing. The melt viscosity will obviously decrease with the increase of shear rate, and the melt viscosity is also sensitive to the change of temperature. Therefore, for the molding process of polymethylmethacrylate, increasing the molding pressure and temperature can significantly reduce the melt viscosity and obtain better fluidity.
3. The temperature at which acrylic begins to flow is about 160 ℃, and the temperature at which acrylic begins to decompose is higher than 270 ℃, with a wide processing temperature range.
4. Acrylic melt viscosity is high, cooling rate is fast, and the product is easy to produce internal stress. Therefore, the process conditions are strictly controlled during molding, and post-processing is also required after molding.
5. Acrylic is an amorphous polymer, with small shrinkage and its variation range, generally about 0.5% – 0.8%, which is conducive to forming plastic parts with high dimensional accuracy.
6. Acrylic has good cutting performance, and its profile can be easily machined to various required sizes.
1.亚克力是一种热塑性塑料,长时间在高温环境下使用会导致镜面严重变形,亚克力的变形温度为100℃,连续使用温度不能高于90℃。亚克力材料本身含有极性侧甲基,具有明显的吸湿性,吸湿率在0.3%-0.4%。亚克力吸湿后会膨胀,导致镜面变形,成型前必亚克力板材须干燥,干燥条件是80℃-85℃下干燥4-5h,一定要保持亚克力镜子使用环境的干燥,绝不能在卫生间、室外等湿气重的环境中使用。
2.亚克力在成型加工的温度范围内具有效明显的非牛顿流体特性,熔融粘度随剪切速率增大会明显下降,熔体粘度对温度的变化也很敏感。因此,对于聚甲基丙烯酸甲酯的成型加工,提高成型压力和温度都可明显降低熔体粘度,取得较好的流动性。
3.亚克力开始流动的温度约160℃,开始分解的温度高于270℃,具有较宽的加工温度区间。
4.亚克力熔体粘度较高,冷却速率又较快,制品容易产生内应力,因此成型时对工艺条件控制要求严格,制品成型后也需要进行后处理。
5.亚克力是无定形聚合物,收缩率及其变化范围都较小,一般约在0.5%-0.8%,有利于成型出尺寸精度较高的塑件。
6.亚克力切削性能甚好,其型材可很容易地机加工为各种要求的尺寸。