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Resources Blog How to select the right resin

Plastic is a key material in the production of electronics devices, medical instruments, automotive components, and consumer appliances. Its popularity has come from its practicality, flexibility, and lower production costs in many applications.

Resin Plastic Injection Moldings

Understanding raw materials

According to a recent study from Grand View Research, “the global injection molded plastics market size was valued at USD 265.1 billion in 2020 and is expected to expand at a compound annual growth rate (CAGR) of 4.6% from 2021 to 2028.” The packaging segment dominated the overall revenue share as of 2021(30.6%), but increasing consumption in automotive components, electronic enclosures, consumer appliances, and medical sectors are also driving a lot of the growth moving forward. Major players like BASF SE, Eastman Chemical Company, Dow Chemical, SABIC, DuPont, and LyondellBasell have contributed to the development of a large selection of resins from which to choose. Considering that material selection is one of the most important factors in creating quality plastic parts, how do you choose the right plastic resin for your injection molding?


US Plastic Injection Moldings Market - GVR


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In plastic injection moldings, thermoplastics are heated, then cooled in a mold to form a part. Thermoplastics comprise the majority of the manufactured polymer resins on the market today used in the injection molding process. With over 85,000 material options for plastic injection molding to choose from, deciding which thermoplastic is best for the job can become overwhelming.

The Thermoplastics Rectangle by the International Association of Plastics Distribution can help you start (see bottom of post for illustration). The IAPD website also offers a quick review of the properties for different resins.


Commodity, engineering, or specialty resins …

Thermoplastics are categorized by family and type. They fall into three broad categories or families: commodity resins (typically the least expensive), engineering resins (very expensive with higher mechanical and thermal properties), and specialty or high-performance resins (most expensive, not commonly used, really tough and lightweight, most common in the aerospace industry). The three resin families have different morphologies, each divided into two categories: amorphous and semi-crystalline. Amorphous resins have less shrinkage after cooling; they have better transparency and work well on products that have tight tolerances. However, they are also brittle and can’t withstand chemicals. Semi-crystalline resins, on the other hand, are opaque; they have a higher resistance to abrasion and chemicals and are less brittle but have high rates of shrinkage.


… additives and fillers

There is one more area to resin manufacturing: additives and fillers. The properties of a resin can be altered by adding other materials to it. Additives and fillers can make plastics cleaner, safer, and stronger, and can increase their lifecycle – think plasticizers, flame retardants, UV stabilizers, antioxidants, etc. To help keep costs low, manufacturers can use additives or fillers to impart additional qualities to affordable materials at a lower cost or reduce material costs by lowering resin consumption. There are continuous advances in additives and, more recently, in bio-based additives.


The 6 questions to ask when selecting the right resin

Now you know enough to start asking the right questions for your resin. It’s important to understand that different applications have different material needs when it comes to plastic injection moldings. Here are some questions to ask:

1. What is the intended purpose of the part?

  • Purpose of the part/product
  • Weight and dimensions requirements
  • Longevity desired
  • Environment it will be used in

2. What key attributes should the finished product have in terms of strength?

  • Hardness - Impact and mechanical resistance to indentation measured on the (Shore) Durometer Scale
  • Flexibility – ability to bend without breaking
  • Resistance desired:
    • Heat resistance
    • Chemical resistance
    • Electrical resistance
    • Wear resistance
    • Moisture resistance
    • Friction resistance

3. What specific functionalities or qualities do you want the finished product to have?

  • Water absorption
  • Elasticity
  • Ductility
  • Transparency
  • Dimensional stability
  • Insulation properties
  • Heat deflection / distortion

4. Are there special aesthetic considerations?

  • Texture or finish (glossy, soft to the touch, etc)
  • Colorization properties
  • Customization of surfaces (embossing, print, ready for glue or metal)

5. Do any regulatory requirements apply?

  • FDA, RoHS, REACH and NSF certifications
  • Food safe
  • Safe for use by children

6. What cost makes sense for this part?

Frequent and ongoing advances in polymer science make it important to work with a partner that has experience with a variety of resins and applications and has the right equipment to vigorously test your first article and pre-production samples. Click here to learn more about how Chainlogix can support quality manufacturing for your plastic injection molding projects.

At Chainlogix, we’ve spent years cultivating relationships with proven suppliers and securing the most competitive prices for our clients. We proudly offer the best custom-tailored solutions in the business, and with exceptional customer care that places a high emphasis on human relationships and connections. We serve clients across a broad range of markets including industrial and consumer electronics, industrial machinery, telecommunications, lighting, and construction. Our services encompass all areas of the procurement process such as:

  • Product development, design, and NPI
  • Sourcing
  • Production
  • Logistics
  • Supply and demand planning

Call Chainlogix at 833-874-6635 to learn more about how we can provide the parts, components, or final products you need.


Visit the IAPD website at to access the helpful guides shown below.