Resin Vs. Plastic: Understanding The Core Differences For Better Material Selection

In the huge system of materials science, resin, as an extremely important class of polymer materials, occupies a pivotal position in our daily life and in various fields of industrial production. However, many people often confuse resin with plastic, making it difficult to distinguish between the two. Next, let’s take a closer look at this unique material, from its definition, properties, types, to its advantages and disadvantages, and its wide range of applications.

What is Resin?

Resin can be divided into natural resins and synthetic resins, and are a class of organic polymers. Under normal conditions, they are mostly in solid or semi-solid form, insoluble in water, but can be dissolved in specific organic solvents. During processing, the resin is hardened by heating or by adding a curing agent. Phenolic resin and polyester resinare widely used in industries such as art creation, aerospace and automotive manufacturing.

The unique properties of resin

• Strength and hardness: Different types of resin vary greatly in strength and hardness. Epoxy resin, for example, have excellent strength due to their high crosslinking density.
• Lightweight: The low density of the resin makes it an indispensable material for the aerospace and automotive industries.
• Flexibility: Polyurethane resin have outstanding flexibility due to their unique molecular structure.
• Biocompatible: Some resins are safe for use in the medical field due to their good compatibility with human tissues.
• Weather resistance: Different resins have different weather resistance, and acrylic resins have excellent performance in light resistance.
• Corrosion resistance: Fluorocarbon resins are chemically stable and can effectively resist the erosion of various chemicals.
• Processability: The resin has good plasticity and can be processed into products of various shapes and sizes.
• Thermoplastic vs. thermoset: Some resins can be both repeatedly softened and cured under certain conditions.
• Environmental protection: With the deepening of the concept of environmental protection, the research and development of environmentally friendly resin products has become a new trend.

Physical properties of resin

1. Condition: Resin exists in a wide variety of forms, including solid, liquid, and gelatinous forms.
2. Color: It can take on a wide variety of colors, both transparent and opaque.
3. Density: From low density to high density, there is a wide range of resin products.
4. Hardness: It has a wide range of hardness, from soft to hard.
5. Texture: To the touch, some resins are smooth, while others are more viscous.
6. Transparency: Transparency ranges from transparent to opaque.
7. Gloss: Some resin products have a shiny luster.
8. Thermal conductivity: In general, resins have low thermal conductivity and good insulating properties.
9. Electrical insulation: This property allows it to be used in scenarios where reduced conductivity is required.
10. Melting Point: The melting point of a resin varies depending on the type and additives.

The chemical properties of the resin

• Polymerization: Resin is formed by polymerization through a specific chemical reaction.
• Cross-linking: The cross-linking reaction can significantly enhance the strength and stability of the resin.
• Solubility: The solubility of the resin varies in different solvents.
• Reactivity: The resin can react with a curing agent or catalyst to achieve a change in performance.
• Chemical resistance: There are differences in the chemical resistance of resins due to different formulations and types.
• Thermal decomposition: At high temperatures, the resin decomposes.
• Oxidation resistance: Some resins can still maintain good stability in an oxidizing environment.
• Hygroscopicity: The hygroscopicity of a resin has an impact on its dimensional stability and mechanical properties.

Type of resin

1. Epoxy resin: Known for its high strength and durability, it is widely used in construction, electronics and other industries.
2. Polyurethane resin: It has good flexibility and toughness, and is often used in the manufacture of shoe soles, sofas and other products.
3. Polyester resin: It has good mechanical properties and chemical resistance, and is widely used in the field of shipbuilding.
4. Silicone: It has excellent heat resistance and electrical insulation, and is mostly used for sealing electronic devices.
5. Acrylic resin: Transparent and weather-resistant, often used in the production of outdoor billboards.
6. Phenolic resin: Outstanding heat resistance and electrical insulation, it is an ideal material for manufacturing electrical enclosures.

Advantages of resin

• Corrosion resistance: After proper treatment, the corrosion protection performance of the resin is excellent.
• High strength: Resin has higher strength than traditional materials.
• Abrasion resistance: The resin has high hardness and good wear resistance.
• Insulation: In the electrical field, the insulating properties of resins play an important role.
• Processability: Various processing methods such as injection molding enable the resin to be made into a variety of products.
• Low cost: Overall, the cost of resins is relatively low.
• Lightweight: Resins are lighter in weight compared to materials such as metal and concrete.

Disadvantages of resin

1. Flammability: Some resins are flammable and have certain safety hazards.
2. Coating difficulty: When coating work, the resin surface is prone to problems such as bubbles.
3. Difficulty of recycling: It is difficult to recycle resin waste.
4. Brittleness: In general, the resin texture is brittle.
5. Temperature sensitivity: Most resins are difficult to withstand high temperatures.
6. UV sensitivity: With long-term exposure to ultraviolet light, the resin is susceptible to damage.

Uses of resin

• Medical and health: Absorbent resins are widely used in the medical field, such as diapers, wound dressings, etc.
• Coatings and varnishes: Resins are used as a substrate for coatings and varnishes to protect surfaces.
• Adhesives: Resins have excellent adhesion properties and are an important component of various adhesives.
• Plastic products: The production of many plastic products is inseparable from resins.
• Fibers: Resin fibers play an important role in the manufacture of textiles and synthetic leather.
• Electronics: used in the manufacture of various electronic components, such as circuit boards.
• Building materials: Resins are also key raw materials in architectural coatings and adhesives.
• Printing inks: Resins ensure that the ink adheres firmly to the printing surface.

What is Plastic?

In our daily lives, plastics can be found everywhere. From drinking water bottles to the casings of electronic products, we cannot do without them. So, what exactly is plastic? Plastic is essentially a synthetic or semi-synthetic material, the main component of which is polymer. It is not only lightweight, but also very durable and flexible. Most importantly, it has low production costs. These advantages have quickly led to the widespread use of plastics in various fields. Currently, the raw materials for the production of most modern plastics come from fossil fuels.

Unique properties of plastics

1. Flexibility: Can be easily molded into various shapes, whether it is a large plastic water tank or a small and exquisite ornament. ​
2. Durability: Wear-resistant and impact-resistant, like everyday plastic tables and chairs, not easily damaged by bumps and sun exposure. ​
3. Lightweight: Conducive to transportation and packaging, can reduce the difficulty and cost of handling. ​
4. Insulation: Good electrical insulation and thermal insulation, wire sheaths and insulation containers often use this property. ​
5. Chemical resistance: Can resist most chemicals, laboratory reagent bottles are often made of plastic. ​
6. Versatility: By adjusting the formula and process, it can meet different specific needs. ​
7. Low cost: Suitable for large-scale production, favored by many companies. ​
8. Waterproof: In pipes and outdoor equipment, it can effectively prevent moisture.

Physical properties of plastic

• Melting point: It varies according to different types of plastics, such as polyethylene and polypropylene have different melting points.
• Density: From low-density foam to high-density engineering plastics, the span is large.
• Stiffness: There are soft as plastic bags and hard as plastic cutting boards.
• Transparency: It can be transparent for beverage bottles, but also opaque for toy production.
• Permeability: Some plastics are permeable to gases and liquids, depending on the type.

Chemical properties of plastics

1. Chemical resistance: It can store chemicals and resist acids and corrosive substances.
2. Stability: Sensitive to temperature and light, easy to age at high temperature and exposure to sun.
3. Flammability: Most of them are flammable and release harmful gases, so pay attention to fire prevention when using.
4. Degradation: The rate of degradation depends on the type and environment, and some of them are refractory to degradation in the natural environment.
5. Solubility: Different plastics have unique solubility properties in different solvents.
6. Reactivity: Depending on the chemical composition, it reacts with other substances under certain conditions.
7. Recyclability: Due to the complex composition, it is difficult to recycle.

Main types of plastic

1.General plastics:

• PE (polyethylene): Including HDPE, LDPE, etc.
• PP (polypropylene): High rigidity, heat resistance
• PVC (polyvinyl chloride): Two types of hard and soft
• PS (polystyrene): Transparent, easy to process

2.Engineering plastics:

• PA (nylon): Wear resistance, high strength
• PC (polycarbonate): Impact resistance, transparent
• POM (polyoxymethylene): High rigidity, low friction
• PET (polyethylene terephthalate): High mechanical strength

3.Special plastics:

• PTFE (polytetrafluoroethylene): High temperature resistance, low friction
• PEEK (polyetheretherketone): High temperature resistance, high strength
• PI (polyimide): Extreme environmental stability

advantages of plastic

Plastic materials offer significant advantages in a number of ways:

1. Convenient processing: Suitable for injection molding, extrusion and other molding processes
2. Light weight, high strength: The specific strength is better than most metal materials
3. Design freedom: Complex geometries can be formed
4. Cost-effective: The cost advantage of mass production is obvious
5. Versatility: Special properties can be obtained through modification
6. Corrosion resistance: Resistant to a variety of chemical media
7. Insulation properties: Excellent electrical insulation properties
8. Shock and noise reduction: Good damping characteristics

Disadvantages of plastic

There are also several restrictions on the use of plastic materials:

• Limited heat resistance: Long-term use temperatures are usually below 150°C
• Creep tendency: Prone to deformation under long-term load
• Aging problem: Reduced performance due to light, heat, and oxygen
• Recycling challenges: The sorting and recycling system is not yet perfect
• Dimensionally stable: High coefficient of thermal expansion
• Surface hardness: Most varieties are easy to be scratched
• Environmental concerns: Difficult degradation of traditional varieties

Uses of plastic

Plastics are used in a wide range of modern industries:

1.Packaging industry:

Food packaging: PE film, PET bottle

Transport packaging: PP turnover box, foam cushioning material

2.Automobile manufacturing:

Interior parts: ABS, PP

Functional parts: PA tubing, POM gear

3.Electrical & Electronics:

Shell: ABS, PC/ABS alloy

Insulators: PVC cable, PE film

4.Architectural Field:

Pipe: PVC-U, PP-R

Profile: PVC doors and windows

Insulation material: EPS, XPS

5.Medical Devices:

Disposables: PP, PE

Precision instruments: PC, PEEK

6.Daily necessities:

Household items: PP, PS

Children’s products: ABS, TPE

7.Agricultural Applications:

Mulch: LDPE

Irrigation pipe: HDPE

8.Sports Equipment:

Protective equipment: PC, ABS

Sports equipment: carbon fiber reinforced plastic

Resin vs. Plastic: Core Differences

The following is a table comparing the differences between resins and plastics, organized based on key dimensions such as composition, properties, and processing methods:

Contrast Dimensions	Resin	Plastic
Definition	High molecular polymer, in a broad sense, refers to the raw materials of plastic substrates	Plastic materials made of resin as the main component and plasticizers, fillers, etc.
Element	Natural resin (rosin, amber) or synthetic resin (polyethylene, polyvinyl chloride, etc.)	Resin (40%-100%) + additives (plasticizers, stabilizers, colorants, etc.)
Form	Liquid, semi-solid or solid when not processed; solidified after processing	The finished product is solid (thermoplastics can be repeatedly heated to soften, and thermosetting resins cannot be reshaped after solidification)
Processing method	Thermoplastic resins can be melted and processed, and thermosetting resins need to be solidified and molded	Injection molding, extrusion molding, blow molding and other processes
Physical properties	Corrosion resistance, good insulation, high strength (such as epoxy resin)	Lightweight, impact resistant, easy to shape, but poor heat resistance (most plastics are easy to deform at high temperatures)
Chemical properties	High chemical activity (uncured), stable after curing	Good chemical stability (some plastics have poor solvent resistance)
Thermal properties	Thermoplastic resins can be repeatedly heated to soften, and thermosetting resins are heat-resistant after curing	Thermoplastic plastics can be repeatedly processed, and thermosetting plastics cannot be reshaped after curing
Typical uses	Coatings, adhesives, electronic packaging, high-performance composite materials (such as carbon fiber resins)	Daily necessities (plastic bags, toys), industrial parts (safety helmets), packaging materials, medical equipment
Environmental protection	Natural resins are biodegradable, and some synthetic resins are difficult to degrade	Traditional plastics are difficult to degrade (“white pollution”), and degradable plastics are gradually developing
Cost	High-performance resins (such as epoxy resins) are more expensive	Low production cost, suitable for large-scale applications
Processing flexibility	Thermosetting resins cannot be reshaped after curing, while thermoplastic resins can be processed repeatedly	Thermoplastic plastics can be repeatedly heated and molded, suitable for the production of complex shapes
Typical product examples	Epoxy resin (paint), phenolic resin (bakelite), unsaturated polyester (fiberglass)	Polyethylene (plastic bags), polycarbonate (safety helmets), ABS plastic (electrical housings)

Summary of key differences:

• Definition and Composition: Resins are natural or synthetic polymers; plastics are synthetic with additional additives.
• Processing Methods: Resins require curing; plastics are processed through molding techniques.
• Form and State: Resins are often liquid or semi-solid; plastics are solid.
• Uses: Resins are used in coatings, adhesives, and composites; plastics are used in packaging, construction, and consumer goods.
• Properties: Resins generally have higher hardness and density, while plastics are more flexible and durable.

When to choose resin over plastic?

Resin should be preferred over plastic in the following 7 situations:

1. When high-strength bonding is required (e.g., structural bonding, resin adhesion is 3-5 times higher than plastic)
2. When the operating temperature exceeds 150°C (thermosetting resins can withstand temperatures up to 200-500°C, plastics are generally below 150°C)
3. Electronic precision packaging requirements (resin CTE can be adjusted to <20ppm/°C, plastic is generally 50-100ppm/°C)
4. Strong corrosive environment (fluoropolymer is resistant to 98% concentrated sulfuric acid, and the annual corrosion rate is <0.01mm)
5. Ultra-thin coating (UV resin can achieve 10μm coating, plastic spraying is difficult to be less than 100μm)
6. Medical implant requirements (medical silicone resin passes cytotoxicity level 0 test)
7. High-end surface treatment (resin can achieve mirror gloss GU>95, plastic is affected by weld marks)

Key to Choice: When better temperature resistance, adhesion, corrosion resistance, precision, or biocompatibility are required, resins should be used, even at a high cost. Common application scenarios (such as packaging, daily necessities) are more suitable for plastics.

When should you choose plastic over resin?

Plastics should be preferred over resins in the following situations:

1. When large-scale production is required (plastic injection molding is efficient and has a short cycle)
2. Cost-sensitive products (the price of general plastic raw materials is usually 1/3-1/2 of that of resins)
3. Require complex three-dimensional modeling (plastics have good fluidity and are suitable for making fine structural parts)
4. Short-term use or disposable products (such as packaging bags, beverage bottles, etc.)
5. When materials need to be recyclable (thermoplastics can be repeatedly melted and recycled)
6. Require flexibility or impact resistance (such as PE, PP and other plastics have better toughness than most resins)
7. Use in normal temperature environments (plastics have stable performance in the range of -40℃~120℃)

Choice key: When pursuing production efficiency, cost advantages, freedom of modeling or recyclability, plastics are a more economical and practical choice. However, resins should still be considered in scenarios with special requirements for temperature resistance and strength.

Choosing the Right CNC Machining Parts Factory

When looking for a CNC machining parts factory, there are quite a few things to look out for. First of all, it is necessary to examine the technical level of the factory in climb milling and conventional milling, especially multi-axis CNC machining technology. You know, a factory that specializes in high-precision CNC machining can make the machined parts have a smooth and flat surface and accurate dimensions. If you want to process parts made of aluminum, plastic, titanium, etc., it is best to choose a factory that is experienced in aluminum CNC machining, CNC plastic machining, and CNC titanium machining.
Take auto parts processing as an example, many auto parts have extremely high requirements for precision, not only the size is not bad, but the surface finish is also very critical. If you find a factory that is skilled in multi-axis CNC machining and high-precision machining, you can meet these requirements and produce high-quality parts.

Conclusion

Figuring out the difference between resins and plastics can go a long way in choosing the right material. The performance of resin is superior and stable, such as in the aerospace field, many key components will use resin materials. Plastics have diverse functions and relatively low costs, and are widely used in daily necessities, such as plastic cups and plastic bags.
When choosing materials, we have to take into account the actual needs and also consider the impact on the environment. If it is the production of single-use packaging products, plastic may be more suitable; If you want to make products that require the highest levels of performance, resins are a better choice.
In short, in order to achieve the best results in the machined product, it is important to cooperate with a professional multi-axis CNC machining and high-precision CNC machining factory. With their professional technology and rich experience, they can help us solve various processing problems and ensure product quality.

Contact us now to get exclusive CNC machining solutions!
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Team LongSheng

This article was written by various LongSheng contributors. LongSheng is a leading resource on manufacturing with CNC machining, sheet metal fabrication, 3D printing, injection molding,metal stamping and more.