A thermoplastic resin, by its nature, offers mechanical properties that can provide a molded part its durability, strength, impact resistance and myriad features. When increased durability is required, filler materials can be added to the resin that can improve certain properties.
Fillers can be used in blow molding, blown film, extrusion, injection molding and thermoforming.
Fiber-reinforced materials continue to gain traction as weight reduction continues to be a trend in automotive and aerospace. Compounders continue to research new options to enhance the properties of materials.
Polycarbonates are a popular selection due to their temperature resistance. TPEs can offer molders flexibility and impact resistance. Nylon offers strength, while acrylic’s key feature is transparency.
As processors work with a part’s geometry and application, they may find that one resin works well. When the performance of the standard resin needs to be increased, an additive such as a fiber reinforcement or some other material can increase the resin’s needed qualities.
Glass remains the most common additive in resins for many injection molding shops. Glass fibers can offer significantly more strength and rigidity when compared to the performance of unfilled resins.
However, for every action, there is an equal and opposite reaction. With the increase in strength, there is an increase in brittleness. Glass-filled parts perform best when they are just supporting weight and are not subjected to high-impact stress.
The fill percentages can range from just over 10 percent to more than 40 percent. Glass can be used in a number of resins, including BS, acetal, PC, liquid crystal polymer, PBT, PET, PPS, nylon and some high-performance materials, including PEEK and PEI.
Generally, there isn’t a financial benefit to added glass as a filler, but there are some disadvantages that must be considered. When glass is added in the matrix, its fibers can also change the flow of a base resin as well as restricting shrink rate.
Other options are used less often. Small percentages of ceramic filler or mineral-enhanced additives can be used to enhance temperature resistance in parts. This can increase strength, while also making parts more brittle. As a result, these parts can crack or chip on impact.
Talc, calcium carbonate and carbon fiber also are used for added strength, with carbon fiber a key component in creating light-weight automotive parts that offer strength and durability. Going forward, compounders will continue to develop new filler options to meet their customers’ needs.