Properties of Laboratory Plastics
Customers of The Lab Depot frequently ask what laboratory plastics should be used for various needs. To help answer that question, the staff at The Lab Depot has put together some information regarding laboratory plastics and their specific uses. Low Density Polyethylene (LDPE) LDPE is a very useful and popular plastic for laboratory work. Although it is quite flexible, it is almost unbreakable. Generally it is translucent to opaque. LDPE is chemically not reactive at room temperature but, over time, it may be slowly attacked by concentrated oxidizing agents. Various organic solvents may soften or swell LDPE but it has excellent resistance to dilute and concentrated acids, alcohols, bases and esters. LDPE has limited resistance to hydrocarbons – both aliphatic and aromatics – as well as poor resistance to halogenated hydrocarbons and mineral oils. Temperatures up to 90 degrees C may be used for short time periods and 80 degrees C may be maintained continuously without damage to this material; -50 degrees C is the minimum temperature recommended. Autoclaving is not recommended. A wide range of laboratory plastics apparatus is manufactured from LDPE including bottles, wash bottles, carboys, tanks, and many other items that require a robust material in the lab. High Density Polyethylene (HDPE) HDPE exhibits a somewhat higher chemical resistance than LDPE. It is harder and more opaque and it can withstand rather higher temperatures, 120 degrees C for short periods, 110 degrees C continuously. Autoclaving is not recommended. It is used in many blow molding of laboratory items such as bottles and large containers. HDPE has good resistance to acids, bases, alcohols, aldehydes, esters, hydrocarbons, ketones, and oils – both minerals and vegetables.Polymethylpentene (PMP or TPX) PMP or TPX is highly transparent, resistant to impact, extremely rigid and it will withstand temperatures of up to 200 degrees C for short periods and 180 degrees C continuously. It may be autoclaved. It is particularly useful in the manufacture of volumetric apparatus such as flasks, beakers and measuring cylinders. It is susceptible to attack by strong oxidizing agents over long periods of time and some chlorinated solvents may cause swelling or softening. PMP has excellent resistance to acids, bases, alcohols, minerals oils, and good resistance to aldehydes and esters. Only limited resistance is evident with hydrocarbons, ketones and oxidizing agents. Polypropylene (PP) PP is a translucent plastic that exhibits excellent mechanical properties. One major advantage of this type of laboratory plastic is its higher temperature resistance which is 135 degrees C. It is autoclaveable. Although largely unreactive chemically the presence of the methyl groups makes it slightly more susceptible to attack by strong oxidizing agents than HDPE. PP has excellent chemical resistance to acids, bases, alcohols, minerals oils, and minor attack from aldehydes, esters, ketones and aliphatic hydrocarbons. PP is very suitable for items that require frequent sterilization such as trays and instrument jars. Polyvinylchloride (PVC) PVC is a plastic that is used, primarily, for the manufacture of tubing. It is soft and pliable, generally transparent, with a bluish tint. It is attacked by many organic solvents but has a very good resistance to oils and it has a low permeability to gases. PVC is not recommended for use above 70 degrees C.Polycarbonate (PC) PC has excellent dimensional stability with a high impact strength which is maintained over a wide temperature range. It is very suitable for the manufacture of laboratory safety shields, vacuum desiccators and centrifuge tubes. PC may be autoclaved with a maximum continuous working temperature of 130 degrees C, and 140 degrees C for short periods of time. This plastic is soluble in many organic solvents and has poor resistance to acids, bases, esters, and – as mentioned – most organic solvents with the exception of oils where the resistance is fair to good. Polystyrene (PS) PS is a rigid, hard, very transparent material with good dimensional stability. The maximum continuous temperature for its use is 60 degrees C, 70 degrees C for short periods of time. Many disposable laboratory plastics products such as petri dishes and pipets are manufactured from PS. The material has good chemical resistance to many aqueous solutions, but is soluble in many of the aromatic and halogenated solvents.