5 Critical Mistakes in Plastic and Rubber Processing That Shorten Product Lifespan

Photo: servet photograph / Unsplash

Processing plastics and rubber requires precise adherence to technological parameters. Even seemingly minor deviations—such as insufficient drying of granules, incorrect injection temperature, or improper dosing of stabilizers—can cause cracks, loss of elasticity, or reduced resistance to chemicals. These defects often manifest only after months of use, when repairs are costly or impossible. This article focuses on five common mistakes that jeopardize the quality and lifespan of final products and demonstrates how to eliminate them using proper procedures and additives.

1. Improper Storage Conditions: How Temperature and Humidity Damage Materials

Plastics and rubber are sensitive to their environment, and although they are often considered durable materials, their long-term lifespan depends on adhering to proper storage conditions. The most common mistake is exposing materials to extreme temperatures—whether high or low. For example, polyolefins (such as polyethylene or polypropylene) can lose mechanical strength at temperatures above 40 °C, while some types of rubber become hard and brittle at temperatures below 0 °C. Equally critical is humidity: hygroscopic polymers (e.g., polyamides) absorb water, leading to property degradation, swelling, or even microcracks.

The ideal storage temperature for most plastics and rubbers ranges between 15–25 °C, with relative humidity below 60 %. Materials should be stored in their original packaging, protected from direct sunlight, and kept separate from chemicals that could cause contamination or chemical reactions. For rubbers, it is also important to avoid contact with ozone, which accelerates aging—storage areas should therefore not contain sources of ozone, such as electric motors or UV lamps.

2. Ignoring Additive and Polymer Compatibility: Why Materials Degrade Prematurely

When processing plastics and rubber, additives (stabilizers, plasticizers, fillers, colorants) are often added to improve their properties. However, a mistake occurs when the compatibility of these additives with the specific polymer is not verified. For example, some plasticizers used in PVC can migrate to the surface, causing stickiness or loss of elasticity, while improperly selected stabilizers can accelerate material degradation due to UV radiation or heat.

Before selecting additives, it is essential to perform compatibility tests, not only with the polymer but also with other components of the mixture. It is also important to adhere to the recommended dosage – excessive amounts of additives can lead to undesirable reactions, such as gas formation, color changes, or reduced mechanical strength. For rubbers, it is crucial to verify whether additives affect the vulcanization process, as this could result in insufficient crosslinking and thus poorer physical properties of the final product.

Photo: servet photograph / Unsplash

3. Overheating material during processing: How high temperatures destroy polymer structure

Processing plastics and rubber often requires elevated temperatures, whether during molding, injection, extrusion, or vulcanization. However, overheating the material is one of the most common causes of polymer degradation. At temperatures above the recommended range, thermal degradation occurs, manifesting as color changes, odor, loss of mechanical properties, or bubble formation. For example, polypropylene begins to degrade at temperatures around 280 °C, while some types of rubber may release toxic gases when overheated.

To minimize risks, it is crucial to adhere to the temperature profiles recommended by the material manufacturer and regularly calibrate processing machinery. For thermoplastics, it is important to monitor the residence time of the melt in the plasticizing unit—long delays lead to degradation even at relatively low temperatures. For rubber, it is necessary to control the temperature and duration of vulcanization, as insufficient or excessive crosslinking results in products with inferior properties. The use of thermal stabilizers can help, but it does not replace proper setting of process parameters.

4. Inadequate Cleaning and Contamination: How Impurities Shorten Product Lifespan

Material contamination with foreign substances is a frequent but often underestimated cause of premature failure in plastic and rubber products. Impurities can originate from insufficiently cleaned processing machinery, contaminated raw materials, or improper storage. For example, residues of previous material in the extruder can cause melt heterogeneity, leading to defects in the product structure. In rubber, foreign particles (dust, metal filings) can act as initiation points for cracks or accelerate material aging.

Prevention of contamination begins with thorough cleaning of processing equipment between individual batches, especially when switching to a different type of polymer. It is recommended to use cleaning compounds or purging materials to remove residues of the previous material. Raw materials should be stored in sealed containers and handled in a clean environment. For critical applications (e.g., medical or food products), it is advisable to perform regular purity checks of raw materials using standard testing methods such as microscopic analysis or spectroscopy.

Photo: servet photograph / Unsplash

5. Neglecting Proper Dosage of Flame Retardants and Stabilizers

When processing plastics and rubber, it is crucial to adhere to precise dosing of additives, particularly flame retardants and stabilizers. These substances protect the material from degradation caused by heat, UV radiation, or oxidative processes, but their effectiveness depends on the correct concentration. Too low a dosage leads to insufficient protection, while excessive amounts can cause undesirable reactions, such as deterioration of mechanical properties or color changes. For example, in polypropylene, an excess of HALS stabilizers (hindered amine light stabilizers) can lead to the formation of undesirable by-products that accelerate material aging.

Dosing should be based on the technical specifications provided by the additive manufacturer and verified using standard testing methods. It is also recommended to regularly check the homogeneity of the mixture to prevent local excess or deficiency of the additive. In practice, the use of automated dosing systems has proven effective, as they minimize human error. For critical applications, such as components for the automotive or electrical industries, it is advisable to perform accelerated aging tests on samples to verify the long-term stability of the material.

6. Incorrect Setting of Injection and Compression Molding Parameters

Processing parameters such as temperature, pressure, cycle time, and injection speed have a fundamental impact on the quality and lifespan of plastic and rubber products. Excessively high pressure or injection speed can cause internal stress in the material, leading to cracks or deformations. Conversely, insufficient pressure or low temperature can result in incomplete mold filling, causing defects such as cold joints or inadequate layer adhesion. For rubber, the correct setting of vulcanization temperature and time is particularly critical, as insufficient vulcanization reduces mechanical resistance, while over-vulcanization leads to material brittleness.

To minimize errors, it is essential to adhere to the recommended processing parameters from the polymer manufacturer and regularly calibrate machinery. Modern injection and compression molding machines allow precise setting and real-time monitoring of parameters, which helps prevent defects. For complex shapes or thin-walled products, it is recommended to perform simulation analyses of material flow, which can identify potential issues before production begins. It is also important to regularly check the condition of molds and tools, as wear can negatively affect product quality.

7. Insufficient Attention to Post-Processing and Surface Finishing

After the actual shaping of plastics and rubbers, further steps such as bonding, painting, welding, or surface finishing often follow, which can significantly affect the product's lifespan. Incorrect surface finishing, such as insufficient degreasing before painting, leads to poor coating adhesion and premature peeling. For rubber products, improper bonding can cause delamination or loss of elasticity. Another common issue is the use of unsuitable solvents or cleaning agents, which can damage the polymer structure or cause corrosion of metal inserts.

To ensure long-term durability, it is crucial to follow technological procedures for post-processing. Before bonding or painting, the surface must be thoroughly cleaned and activated, for example, using plasma treatment or chemical primers. For rubber, it is important to select an adhesive compatible with the specific polymer type and adhere to the recommended curing conditions. When welding plastics, care must be taken to use the correct temperature and pressure to avoid material degradation. It is always advisable to conduct adhesion tests and mechanical resistance tests on samples before proceeding to mass production.

Do you need to ensure consistent quality for your plastic or rubber products?

Every raw material requires an individual approach – from selecting the right additives to optimizing processing conditions. GCG Group provides detailed technical data sheets and safety data sheets (SDS) for all supplied materials and advises on the selection of suitable stabilizers, plasticizers, or processing additives for your specific application. Contact us – or browse our catalog of over 1,300 products.