Why some lab plastic consumables made by PP and some made by PS material?

Polypropylene (also known as PP) and polystyrene (also identified as PS) are two types of commonly used polymers in plastic laboratory consumables. PP and PS are similar in many applications, but there are some inherent differences between them that make them more appropriate for specific applications.

PP is a thermoplastic polymer. It is commonly used to manufacture plastic laboratory supplies such as beakers, bottles, flasks, specimen containers, test tubes, and many others. Polypropylene is exceptionally tough, unbreakable, flexible and resistant to many chemicals, acids, and bases. It also has a high level of heat resistance. Depending on the grade, polypropylene has a melting point of 130℃, up to 171℃. Many polypropylene products are autoclavable due to this high level of heat resistance. In contrast with polystyrene products, which are disposed of after only a single use, polypropylene can be reused over and over again. Therefore, polypropylene products can be considered as cost-effective alternatives to their glass equivalent. The durability, high chemical resistance, and high level of temperature tolerance of polypropylene products make them very versatile in many laboratory and industrial applications.

PS is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum. At room temperature, polystyrene is normally a solid thermoplastic, but can be melted at higher temperature for extrusion, then resolidified. Polystyrene is great for general sample storage and transport and is commonly used in lab supplies such as test tubes, microplates, and petri dishes due to is glass level transparency. It is a highly used plastic all over the world because it is usually offered at a lower price than many other plastics. Polystyrene is environmentally friendly because it can be recycled. Although polystyrene offers some resistance to acids and bases, it is not as resistant against some chemicals as polypropylene. Polystyrene cannot withstand heat above 100°C and are disposed after only a single use.

how to distinguish between PP and PS?

• The difference in sound: PS material is tougher, the percussion sound is clearer. PP sound is dull because the PP material has adequate toughness but lacks hardness.
• The difference in appearance: PS can be quite clear, PP is not, but it still has the appearance of frosted glass.
• The difference in texture: PP has good toughness, while PS is more rigid.

Generally speaking, the same thickness of PP and PS products, transparency: PS>PP, hardness: PS>PP, toughness PP>PS.