Tech Talk Blog

The molecular forces and chemical bonding are important to understand the physical properties the bulk polymer exhibits. The covalent bonding in a polymer system is one of the strongest and significant forces and is often referred as primary bonding. A list of common covalent bonds and the energy associated with the bonds are listed below:

This list shows the dissociation (bond breaking) energy to predict which bonds will break first when a polymer is overheated or modified by plasma or UV. For example, the carbon (C) chlorine (Cl) bond will dissociate before a C-H bond in a PVC polymer.

Secondary bonding forces are also important as they can affect the material’s physical properties, such as surface tension, viscosity, friction, volatility, and solubility. The secondary forces are as follows:

Blends are the physical blend of polymers. Unlike a copolymer that is chemically mixed, polymer blends are mixed before or during molding operations. Yet, polymer blends can be just as useful and cost effective as copolymers or terpolymers. The physical property of a blend is determined by the physical properties of each ingredient and miscibility. If the compounds are miscible, the mixture will remain uniformly blended (homogenous). If the compounds are not miscible, the each mixture will separate into its respective phase. It would be here that the physical properties of the material would be compromised if the adhesion between the compounds is poor. Fortunately, if two immiscible polymer need to be blended, an additive can be used or a polymer can be grafted to one of the originals.

If you want to know a little bit more, watch our Plastics Technology 101 Seminar and other videos in our Video Learning Center.