Comprehensive Evaluation and Testing of Polymer Materials
In modern industry, polymer materials are among the most widely used materials. They can be seen everywhere—thermal insulation foam in construction, plastic parts in cars, composite materials for aerospace applications, insulating coatings in electronic devices, as well as films for packaging and catheters in medical instruments. These materials are indispensable.
Why are polymer materials so popular? Because they have many advantages. They are lightweight, which reduces the overall weight of products; they are not easily corroded, allowing for longer use; they are easy to process, capable of being made into various shapes; and they have good insulation properties, making them particularly useful in the electronics field. Currently, over 400 million tons of polymer materials are produced globally each year, and their usage continues to increase.
However, polymer materials can encounter many troubles in practical use. For example, fluctuating temperatures, frequent friction, contact with chemical liquids, and prolonged exposure to sunlight can all affect their performance. Over time, the materials may crack, lose strength, and in severe cases, become unusable. Previously, a car manufacturer had to recall thousands of vehicles due to insufficient impact resistance of plastic bumpers; a medical device company faced safety issues during use due to not testing the corrosion resistance of polymer catheters. Therefore, comprehensive and accurate testing of polymer materials is particularly important, as it is the key to ensuring product quality and safety of use, and also promotes new material research and industrial standard advancements.
1. What Aspects Should Polymer Material Testing Measure?
Polymer material testing does not look at a single indicator; instead, it takes multiple aspects into account, mainly including physical properties, chemical properties, mechanical properties, and environmental adaptability.
1.1 Physical Property Testing
Physical properties primarily look at basic indicators such as density, melting point, transparency, and permeability. For example, in the case of polyethylene film used for packaging, its density must be measured; the higher the density, the better the film's barrier properties, which helps preserve food. Its ability to permeate oxygen and water vapor must also be measured to select the appropriate film according to different packaging needs. In the electronics field, polymer insulating materials need to have their dielectric constant and volume resistivity measured to ensure that no leakage occurs in high-voltage environments.
1.2 Chemical Property Testing
Chemical property testing primarily assesses the chemical stability of the material and the safety of its components. Infrared spectroscopy analysis is a common method that can accurately distinguish the components of materials and check whether additives within the materials may migrate out. For example, PVC plastic used in children's toys must be tested for excess phthalate plasticizers, which could enter the child's body through the skin, posing health risks. Furthermore, the material's ability to resist chemical corrosion must be tested by soaking it in acidic or basic solutions or organic solvents, observing changes in weight, size, and appearance. Polymer coatings used in chemical pipelines must maintain good adhesion and corrosion resistance after being soaked in 30% sulfuric acid solution for 1000 hours.
1.3 Mechanical Performance Testing
The mechanical performance is related to whether the material can withstand external forces, mainly measuring tensile strength, impact strength, bending strength, and hardness. Taking the polypropylene composite material used for automobile door panels as an example, specialized machines should be used to measure its tensile strength, which must reach at least 30 MPa, and the elongation at break must also be above 5%, so that it is not easily cracked when closing the door; in a low-temperature environment at -40°C, the impact strength must also be measured, requiring an impact energy exceeding 5 kJ/m² to prevent the material from becoming brittle and breaking in low winter temperatures. For polymer waterproof membranes used in construction, the peel strength with the substrate must be measured, requiring at least 1.5 N/mm to avoid the waterproof layer falling off and causing leaks.
1.4 Environmental Adaptability Testing
Environmental adaptability testing simulates the harsh environments that materials may encounter during use to observe changes in performance over long-term use. Aging testing is a very important item, including thermal aging, ultraviolet aging, and damp heat aging. Thermal aging involves placing the material in an oven at 120°C for 1000 hours to measure whether its mechanical performance has declined; ultraviolet aging uses ultraviolet lamps to simulate sunlight exposure, observing whether the material changes color or cracks; damp heat aging involves placing the material in an environment at 85°C and 85% humidity to see if it becomes moldy. For example, polymer back sheets used in photovoltaic modules must maintain good insulation and weather resistance after 2000 hours of ultraviolet aging testing to ensure the photovoltaic components last for 25 years.
2. Development of Polymer Material Testing Technologies
As polymer materials become increasingly advanced, testing technologies are also continuously upgraded, becoming smarter and more accurate, with the ability to achieve online testing.
In the past, to test materials, samples had to be taken off the production line, cut to standard sizes, and then tested, which was not only time-consuming but also did not provide timely information about changes in the materials during production. Now, with the introduction of online testing technologies, the situation is different. On plastic film production lines, laser thickness gauges can scan the thickness of films in real time, achieving an accuracy of ±1 μm; once the thickness exceeds the standard, the control system will automatically adjust the machine parameters. Near-infrared spectroscopic online analyzers can analyze the components of the polymer melt within 10 seconds, promptly checking whether the additive content is appropriate to avoid affecting product performance.
In terms of microscopic testing, scanning electron microscopes and atomic force microscopes play significant roles. Scanning electron microscopes can reveal the presence of nanoscale cracks on the surface of aged rubber materials, which can lead to a decrease in material strength; atomic force microscopes can measure the surface roughness of materials, with smoother surfaces resulting in tighter bonding between coatings and substrates, enhancing wear resistance. Additionally, dynamic mechanical analysis technology can measure the storage modulus and loss factor of materials within a temperature range from -150°C to 200°C, accurately determining the glass transition temperature of materials, indicating at what temperature materials will transition from hard to soft. For example, PVC materials undergo this change around 80°C.
Moreover, intelligent testing systems have emerged, making testing more efficient and data more accurate. Some testing institutions have established "Polymer Material Testing Cloud Platforms," linking data from equipment such as tensile testers, aging boxes, and spectrometers. This system can automatically collect test data and generate reports. Through AI algorithms, data trends can be analyzed; if the tensile strength of a certain batch of materials falls by 5% consecutively three times, the system will automatically alert the staff, making it convenient to investigate issues with raw materials or processes. Machine learning technology can also predict the performance of new materials by analyzing vast amounts of testing data, quickly revealing the performance of new materials and reducing the R&D cycle from six months to one month.
3. The Important Significance of Polymer Material Testing
3.1 Helping Enterprises Optimize Production and Reduce Costs
For enterprises, conducting resin material tests can optimize production processes and reduce costs. A company that produces plastic pipes previously faced issues due to the extrusion temperature being too low, resulting in uneven plasticization of the pipes and inadequate tensile strength, with a product qualification rate of only 75%. After identifying the problem through testing, they adjusted the extrusion temperature from 180°C to 195°C, and the product qualification rate rose sharply to 99%, also reducing waste and saving over 2 million yuan annually. Moreover, testing used polymer materials can ascertain if these materials can be reused. For instance, a packaging company tested the viscosity of recycled PET plastic, mixing the qualified recycled material with new material in a 3:7 ratio, resulting in packaging bottles with performance comparable to those made from pure new materials and a 15% reduction in raw material costs.
3.2 Promoting New Material Research and Development
In the field of new material research and development, testing can validate research results and expedite the application of new technologies. Biodegradable polymer materials, such as PLA and PBAT, are currently very popular, and testing their degradation performance is crucial. To assess their degradation rate in environments like soil and seawater under composting conditions, the degradation rate must exceed 90% within 180 days to meet environmental standards. A research team developed biodegradable medical sutures that, through in vitro degradation testing and in vivo biocompatibility testing, proved capable of degrading on their own after wound healing, eliminating the need for removal. The testing data also provide a basis for formulating new material standards. For example, China's standard "GB/T 38082-2019 for Biodegradable Plastic Shopping Bags" was established based on a substantial amount of degradation performance testing data, specifying requirements for the degradation rate and heavy metal content of shopping bags.
3.3 Promoting High-Quality Development of the Industry
A unified and standardized testing system can drive high-quality development in the industry. Presently, major countries and regions worldwide have polymer material testing standards, such as the EU's EN standards, the USA's ASTM standards, and China’s GB standards. These standards standardize testing methods and indicators, preventing inferior products from disrupting the market. In the medical device sector, China’s "GB/T 16886 Biological Evaluation of Medical Devices" series of standards clearly outlines testing methods for the cytotoxicity, sensitization, and genetic toxicity of medical polymer materials, ensuring that every medical polymer product undergoes strict safety assessments. Additionally, once testing technologies achieve international recognition, China’s polymer material products can be exported more effectively. For instance, a company's polymer waterproof membrane passed the EU CE certification test, complies with the EN 13707 standard, and successfully entered the European market, resulting in a 30% increase in annual export volume.
4. Conclusion
With the increasing application of polymer materials in high-end manufacturing, new energy, and biomedicine, the demands for testing technologies are also rising. In the future, not only will it be necessary to assess whether materials meet standards, but also to accurately predict material performance and monitor changes throughout the entire lifecycle of the material. There may be a "Material Health Monitoring System" that integrates the Internet of Things, for example, by installing sensors in aerospace polymer components to monitor stress changes in real-time. Additionally, there will be a "Testing Data Traceability Platform" based on blockchain to ensure that testing data cannot be tampered with.
In summary, the testing of polymer materials not only maintains the safety baseline of products but also promotes the development of the material industry towards high quality and high added value. Only by conducting thorough testing can polymer materials be safely used in more critical areas, providing strong support for the innovative development of modern industry.