We realize aspects of the services we provide can get technical and our clients and contacts have a wide variety of experience within the field of materials science. To help you better understand how our services relate to your needs, we’ve created this glossary of common terms and phrases.
- Amorphous: In general, amorphous means without form. In materials science and related fields, an amorphous solid is a substance that lacks the definite structure of a crystal. The atoms and molecules in amorphous solids don’t align in a lattice pattern. These substances include glass, gel and thin films. Many polymers are classified as amorphous.
- Chirality: Chiral molecules are those for which there is another identical molecule arranged as a mirror image. Consider chiral molecules as human hands – the left is a mirror image of the right. Achiral molecules are symmetrical – when reflected, their structure is the same.
- Crystallinity: The degree to which a substance’s molecules and atoms align. The more crystalline the substance, the less amorphous it is. Highly crystalline materials are harder, tougher, and more durable than amorphous materials. Polymers, like polyethylene, have a high degree of crystallinity and are therefore durable materials.
- Fluoropolymers: As the name suggests, these are polymers that contain fluorine atoms. The original fluoropolymer, tetrafluoroethylene, was discovered by accident and is now known by its brand name, Teflon. In general, fluoropolymers are high-performance plastics used in a variety of intense fields.
- Glass transition temperature: The temperature at which a polymer changes from a hard material to a soft, rubbery substance. This isn’t the same as the melting point, nor is it truly a distinct temperature: It is a range over which the polymer chains increase mobility.
- Hydrolysis: The process of breaking chemical bonds using water. Hydrolysis is a chemical reaction of a substance with water. In contrast, dissolution of a material in water is a physical process.
- Melt phase: The fancy way of describing the process when a substance transitions from a crystalline solid to an amorphous liquid. Through heat or pressure, the molecules become less ordered and solid material liquefies.
- Melting point: The temperature at which the melt phase occurs. This temperature will vary from substance to substance.
- Molecular weight: A number that is related to the length and number of monomer repeat units that comprise a polymer. A polymer material typically has polymer chains of various lengths, not all the same length. As a result,it is common to talk about the average molecular weight.
- Monomer and co-monomer: A monomer is a molecule that can bond with others of the same kind to form a polymer chain. Two different monomers that bond together are co-monomers. Monomers have polyfunctionality, which means they can form chemical bonds to at least two other monomers.
- Morphology: This refers to the physical properties of a substance, like shape, size, composition and phase distribution.
- Plasticizers: Substances that may be added to a material to increase its flexibility and resilience. Water can be a plasticizer when added to clay. Materials scientists can add plasticizing molecules to PVC, for example, to make the plastic more pliable and suitable for different uses.
- Polymer: Our namesake, a polymer is a chain of monomers bonded together chemically. Some assume polymers are all synthetic, but that isn’t the case. Some naturally-occurring polymers include rubber, which can be enhanced and altered to optimize certain properties. With that said, many synthetic materials like plastics and gels are polymers.
- Polydispersity: Essentially, the degree to which objects in a mixture have varying size, shape and weight. A uniform mixture contains identical objects, whereas a mixture with a high degree of dispersity contains widely different objects. In the case of polymers, polydispersity is a description of the range of molecular weights that exist in the material.
- Solvent: A substance that can dissolve another substance. Once a substance dissolves into a solvent, the resulting mixture is called a solution.
- Tensile strength: The ability of a substance to resist breaking from a pulling force. A material has high tensile strength if it takes a great force to cause it to snap simply by pulling on it. A steel beam has high tensile strength, while a wet noodle has low tensile strength.
- Thermal stability: A substance’s ability to resist breaking down under intense heat. The higher the temperature it can withstand, the higher the thermal stability. When the heat is too high, it will break chemical bonds and change the substance’s properties.
- Thermoplastics: Plastics that become pliable under the application of heat and then harden again when cool. One key characteristic is that they can be remelted and molded over and over again, unlike thermosets.
- Thermosets: Once a thermoset is produced, it cannot be remelted and molded through heat. Any additional heat could only risk damaging the substance. If thermoplastics are like ice cream – can be melted and solidified over and over again – thermosets are like cookies. Too much heat and they will burn or char.
- Toughness: The materials science equivalent of the ability to take a punch. Toughness refers to a substance’s ability to absorb energy without suffering structural damage or fracturing.
- Viscoelasticity: A substance that demonstrates properties of both a fluid and an elastic solid. Silly putty is one example – it conforms to its container over time, like a fluid, but it stretches and returns to its original shape, like an elastic solid.
- Viscosity: Viscosity is the resistance of a material to flow. A fluid that is highly resistant to flow, like honey or molasses, has high viscosity. Water has low viscosity – it flows freely. A substance’s viscosity may change depending on the temperature.
That isn’t an exhaustive list of every term you’ll come across, but it does address some of the more technical terms. If we’ve left something off the list you feel we should add please comment below and we will gladly expand our glossary.
If you need help understanding a polymer-related term or a polymer material contact us and our experts will get you the answers you require.