经常有人问某种容器能不能泡茶，或者用微波炉加热。如果是玻璃或者陶瓷容器，泡茶加热当然没问题。可如果是塑料容器呢？
其实，瓶装饮料和矿泉水塑料瓶底部，或者其他塑料制品的底部常有如下所示的“循环”标志。这些数字是通知我们制成饮料瓶的化学物品，从而我们也可以知道是否能用这些容器放心地加热。
1 聚对苯二甲酸乙二醇脂
2 高密度聚乙烯
3 聚氯乙烯
4 低密度聚乙烯
5 聚丙烯
6 聚苯乙烯
7 其它所有未列出的树脂和混合料
示例：
“1”代表PET (聚对苯二甲酸乙二醇酯)
一般的矿泉水、碳酸饮料和功能饮料瓶都用这一材质。其耐热至70℃易变型长时间重复使用可能会释放出有害物质。高温天气尽量不要把矿泉水长期寄存在露天或车里，也不要直接把开水冲进矿泉水歧骘。
“2”代表HDPE (高密度聚乙烯)
常见白铯药瓶、清洁用品、沐浴产品，不要循环使用。
“3”代表PVC (聚氯乙烯)
常见雨衣、建材、塑料膜、塑料盒等。可塑性优良，价钱廉价。只能耐热81℃，高温时容易有不好的物质产生，很少被用于食品苞装。
“4”代表LDPE (低密度聚乙烯)
目前市场上的保鲜膜、塑料膜等多用这种材质，但它耐热性不强，建议大家在将食物放入微波炉加热前，取下苞裹着的保鲜膜。
“5”代表PP (聚丙烯)
微波炉餐盒采纳这种材质制成，耐130℃高温，透明度差，这是可以放进微波炉的塑料盒，在小心清洁河重复使用。
“6” 代表PS (聚苯乙烯)
有些餐盒盒体以5号PP制造，但盒盖却以6号PS(聚苯乙烯)制造，PS透明度好，但不耐高温，所以不能与盒体一并放进微波炉。
“7” 其它所有未列出的树脂和混合料
总结：如果在塑料容器上看到数字“5”或者“PP”，放心的加热吧。如果是其他标志，小心了，加热后可能产生有毒物质...
English References:
What Do Recycling Symbols on Plastics Mean?
Sometimes it seems like modern America is one colossal plastic palace. The versatile material is in our cars, toys, packaging, clothing, home goods, food utensils, medical devices and so much more. It is also littering our streets, clogging our waterways and choking marine life. Many plastics can be readily recycled, but how do consumers make sense of all the different types and rules?
Number 1 Plastics
PET or PETE (polyethylene terephthalate)
Found in: Soft drink, water and beer bottles; mouthwash bottles; peanut butter containers; salad dressing and vegetable oil containers; ovenable food trays.
Recycling: Picked up through most curbside recycling programs.
Recycled into: Polar fleece, fiber, tote bags, furniture, carpet, paneling, straps, (occasionally) new containers
PET plastic is the most common for single-use bottled beverages, because it is inexpensive, lightweight and easy to recycle. It poses low risk of leaching breakdown products. Recycling rates remain relatively low (around 20%), though the material is in high demand by remanufacturers.
Number 2 Plastics
HDPE (high density polyethylene)
Found in: Milk jugs, juice bottles; bleach, detergent and household cleaner bottles; shampoo bottles; some trash and shopping bags; motor oil bottles; butter and yogurt tubs; cereal box liners
Recycling: Picked up through most curbside recycling programs, although some allow only those containers with necks.
Recycled into: Laundry detergent bottles, oil bottles, pens, recycling containers, floor tile, drainage pipe, lumber, benches, doghouses, picnic tables, fencing
HDPE is a versatile plastic with many uses, especially for packaging. It carries low risk of leaching and is readily recyclable into many goods.
Number 3 Plastics
V (Vinyl) or PVC
Found in: Window cleaner and detergent bottles, shampoo bottles, cooking oil bottles, clear food packaging, wire jacketing, medical equipment, siding, windows, piping
Recycling: Rarely recycled; accepted by some plastic lumber makers.
Recycled into: Decks, paneling, mudflaps, roadway gutters, flooring, cables, speed bumps, mats
PVC is tough and weathers well, so it is commonly used for piping, siding and similar applications. PVC contains chlorine, so its manufacture can release highly dangerous dioxins. If you must cook with PVC, don't let the plastic touch food. Also never burn PVC, because it releases toxins.
Number 4 Plastics
LDPE (low density polyethylene)
Found in: Squeezable bottles; bread, frozen food, dry cleaning and shopping bags; tote bags; clothing; furniture; carpet
Recycling: LDPE is not often recycled through curbside programs, but some communities will accept it. Plastic shopping bags can be returned to many stores for recycling.
Recycled into: Trash can liners and cans, compost bins, shipping envelopes, paneling, lumber, landscaping ties, floor tile
LDPE is a flexible plastic with many applications. Historically it has not been accepted through most American curbside recycling programs, but more and more communities are starting to accept it.
Number 5 Plastics
PP (polypropylene)
Found in: Some yogurt containers, syrup bottles, ketchup bottles, caps, straws, medicine bottles
Recycling: Number 5 plastics can be recycled through some curbside programs.
Recycled into: Signal lights, battery cables, brooms, brushes, auto battery cases, ice scrapers, landscape borders, bicycle racks, rakes, bins, pallets, trays
Polypropylene has a high melting point, and so is often chosen for containers that must accept hot liquid. It is gradually becoming more accepted by recyclers.
Number 6 Plastics
PS (polystyrene)
Found in: Disposable plates and cups, meat trays, egg cartons, carry-out containers, aspirin bottles, compact disc cases
Recycling: Number 6 plastics can be recycled through some curbside programs.
Recycled into: Insulation, light switch plates, egg cartons, vents, rulers, foam packing, carry-out containers
Polystyrene can be made into rigid or foam products -- in the latter case it is popularly known as the trademark Styrofoam. Evidence suggests polystyrene can leach potential toxins into foods. The material was long on environmentalists' hit lists for dispersing widely across the landscape, and for being notoriously difficult to recycle. Most places still don't accept it, though it is gradually gaining traction.
Number 7 Plastics
Miscellaneous
Found in: Three- and five-gallon water bottles, 'bullet-proof' materials, sunglasses, DVDs, iPod and computer cases, signs and displays, certain food containers, nylon
Recycling: Number 7 plastics have traditionally not been recycled, though some curbside programs now take them.
Recycled into: Plastic lumber, custom-made products
A wide variety of plastic resins that don't fit into the previous categories are lumped into number 7. A few are even made from plants (polyactide) and are compostable. Polycarbonate is number 7, and is the hard plastic that has parents worried these days, after studies have shown it can leach potential hormone disruptors.
