Choosing laboratory plasticware with the right chemical compatibility
Plasticware is required for a variety of laboratory processes but an understanding of plastic chemical compatibility - its physical properties, and how this impacts compatibility with the chemicals the plasticware has contact with, is essential.
This blog provides an overview of the most common types of plasticware used within the laboratory environment, a summary of the key characteristics of each, and advice on which substances they are most and least suited for to ensure labware has the correct plastic chemical compatibility.
Polypropylene, often abbreviated to PP, is a translucent rigid polymer that is capable of withstanding temperatures between -20 to +135°C. Due to its robust nature it is typically used for the manufacture of a wide range of general laboratory items such as beakers, bottles, jugs and cylinders to name but a few. As it is autoclavable at 121°C, items manufactured from this material can be sterilized and in addition bottles and containers of this material can be used to support the sterilization of the contents within. The material has excellent chemical resistance across a range of substances including several acids such as salicylic acid, sulphuric acid and moderate concentrations of hydrochloric acid. However, there are a number of substances for which it is not suited including toluene, acetone and nitrobenzene and benzene.
Polytetrafluoroethylene, often abbreviated to PTFE, is an opaque rigid polymer with a much greater working temperature range than all other plastics as it can be used between –200 and +260°C. It has an unrivalled resistance to almost all chemicals too so is an ideal material for the most challenging of user applications. This material is typically used to make bottles, beakers and stirrers for use in more demanding laboratory applications.
Polyfluoroalkoxy, often abbreviated to PFA, is a translucent flexible form of PTFE. It has the same valuable properties as PTFE above but its clarity and flexibility make it ideal for the manufacture of bottles, typically those used for trace metal analysis.
Low Density Polyethylene (LDPE)
Low Density Polyethylene, often abbreviated to LDPE, is a translucent pliable polymer with a narrow temperature range of -50 to +80°C, so unsuitable for autoclaving. Its flexibility makes products manufactured from it virtually unbreakable. It is ideal for use where a flexible product is needed such as for wash bottles and other similar dispensing bottles. It has good resistance to most chemicals, however there are a number of substances for which it is not suitable including hexane and benzene.
High Density Polyethylene (HDPE)
High Density Polyethylene, often abbreviated to HDPE, is a translucent polymer which unlike LDPE is far more rigid in nature. It is suitable for use in temperatures that range between -100 to +120°C and like plasticware made of LDPE it cannot be autoclaved. It has a good level of chemical resistance and its high tensile strength makes it very tough. It is often used for bottles where a rigid structure is required.
Polymethylmethacrylate, Acrylic (PMMA)
Polymethylmethacrylate, Acrylic, often abbreviated to PMMA, is a transparent rigid polymer with a narrow temperature range between - 60 to +50°C and cannot be autoclaved. It has only a moderate chemical resistance (it is not suitable for use with butyl acetate and acetone for example) but is very tough and is typically used for radiation shields where both excellent visibility and protection are required.
Polymethylpentene (PMP / TPX)
Polymethylpentene, often abbreviated to PMP or TPX, is a transparent rigid polymer. It has a low density and a high clarity and often used in the manufacture of plastic laboratory ware such as beakers and cylinders where a high level of clarity is specifically beneficial. It has a broad temperature range between -180 to +145°C and can be autoclaved at 121°C. It has good to excellent chemical resistance although care is still required with a number of substances including benzene.
Polystyrene, often abbreviated to PS, is a transparent rigid polymer. It has a narrow temperature range of between -40 to +90°C, cannot be autoclaved and is brittle in nature. However, it has excellent clarity and is often used to manufacture medical containers and tubes where visibility of the contents is important. It has only moderate chemical resistance but can be used with certain acids including lower concentration sulphuric acid.
Polycarbonate is a transparent rigid polymer with a broad temperature range between -135 to +135°C, so is suitable for autoclaving at 121°C. It has moderate chemical resistance but most importantly possesses a high impact strength and is therefore typically used for safety shields and other such protective equipment. Care should be taken when exposing this polymer to many substances as it has only moderate chemical resistance, so can’t be used with highly concentrated sulphuric acid or acetone for example.
Polyvinylchloride is a polymer with one of the narrowest temperature ranges of plasticware commonly found in the lab at between -25 to +70°C. It is therefore not autoclavable. PVC has moderate chemical resistance and can be either rigid or flexible and coloured or clear in nature. It is typically used for general everyday laboratory support products such as trays and troughs.