Environmental stress cracking on thermoplastic materials: redefine, design and improve new testing instruments combining mechanical stress and chemical immersion in alkaline environments

Background
Plastics are widely used in chemical industries due to their better corrosion resistance to acids, bases, and heat compared to metals, especially in highly concentrated acid and bases at high temperatures. Even though plastics do not corrode in the same way and their service life is still longer than that of other material types, they are also affected by these environments.

At RISE (a state-owned, independent research institution), we have extensive experience in researching the effects of corrosive environments on plastics, to make them safer and more durable.

One of our focus areas is based on a combination of medium/highly concentrated alkali environments combined with high temperatures, and mechanical stress. The combination of these variables is called environmental stress cracking (ESC), still a big issue within the chemical industries. ESC causes around 15-30% of all plastic breakdowns in tough environments, e.g., failures in different types of polypropylene (PP) in high-heat, alkaline conditions under mechanical stress.

Industrial collaboration: Funded by our Membership Research Consortia (MRC), you will work with different companies providing materials, insights and feedback.

Your impact: Help redesign tools that predict plastic failures, improving safety and efficiency for industries.

Description

Your mission:
Redesign and refine the ESC-rig apparatus for slow, creep-like tests that combine mechanical stress, chemical immersion (in alkaline solutions), and high temperatures.

Improve the ESC-rig apparatus to measure stress or creep with the help of displacement sensors, while PP are exposed to high temperatures and alkaline solutions.

Goals:
Make the ESC-rig apparatus reliable enough to make repetitive sets of experiments and give significant results.

Verify the suitability of the rig for investigating how the crystallinity of PP and highly corrosive exposures impact the service life of stress exposed materials.

Validate with advanced analysis: measuring these differences by characterizing materials tested in the redesigned ESC-rig with optical, mechanical, thermal or chemical analysis

Qualifications
Mechanical/Electrical Engineering, Machine Design, Mechatronics, or similar with an interest in polymers, materials and chemistry.

Skills bonus: Experience in testing rigs, sensors, or lab analysis.

Terms
Number of students: 1
Start time: January 2026
Estimated time required: 20 weeks
Scope: 30 hp
Location: Kista, Stockholm
Compensation: 1333 SEK per credit (hp) after project completion and approval. 

Contact: Chao Zheng (chao.zheng@ri.se), RISE, Department of Corrosion and Material Durability, Unit: Infrastructure and Energy

Welcome with your application!
Submit your CV and grade transcripts. Interviews ongoing. Candidates are encouraged to send in their application as soon as possible.

Keywords: Environmental Stress Cracking, Polymer, Plastic, Testing Rig, Sensor, Material, Chemistry, Electrical, Machine, Mechanical, Industry Collaboration