Hu Hu giúp đệ với!!!!
Đệ đang làm bài luận mà vốn tiếng anh thì nghèo nàn, dịch mãi ko được đoạn nói về bản chất hóa học của polycarbonate. Ức chế nhắm.Các huynh giúp đệ với. Đoạn văn ấy đây :
Polycarbonates got their name because they are polymers having functional groups linked together by carbonate groups (-O-(C=O)-O-) in a long molecular chain.
Also carbon monoxide was used as a C1-synthon on an industrial scale to produce diphenyl carbonate, being later trans-esterified with a diphenolic derivative affording poly (aromatic carbonate)s.
Taking into consideration the C1-synthon polycarbonates can be divided into poly(aromatic carbonate)s and poly(aliphatic carbonate)s. The second one, poly(aliphatic carbonate)s are a product of the reaction of carbon dioxide with epoxides, which owing to the thermodynamical stability of carbon dioxide requires the use of a catalyst. The working systems are based on porphyrins, alkoxides, carboxylates, salens and beta-diiminates as organic, chelating ligands and aluminium, zinc, cobalt and chromium as the metal centres. Poly(aliphatic carbonate)s display promising characteristics, have a better biodegradability than the aromatic ones and could be employed to develop other specialty polymers.
One type of polycarbonate plastic is made from bisphenol A (BPA). This polycarbonate is a very durable material, and can be laminated to make bullet-proof "glass", though “bullet-resistant” would be more accurate. Although polycarbonate has high impact-resistance, it has low scratch-resistance and so a hard coating is applied to polycarbonate eyewear lenses. The characteristics of polycarbonate are quite like those of polymethyl methacrylate (PMMA; acrylic), but polycarbonate is stronger, usable in a larger temperature range but also more expensive. This polymer is highly transparent to visible light and has better light transmission characteristics than many kinds of glass. CR-39 is a specific polycarbonate material — although it is usually referred to as CR-39 plastic — with good optical and mechanical properties, frequently used for eyeglass lenses.
Thank các huynh!
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