Environmental Stress Cracking Research Articles

Chemical resistance testing of plastics – Material compatibility of detergent and disinfectant products

Surface cleaning and disinfection is a key part of breaking the chain of transmission and reducing the risk of healthcare associated infections (HAIs). However, if cleaning and disinfectant formulations are incompatible with surface materials, frequent application can cause premature failure of plastics due to Environmental Stress Cracking (ESC). Material compatibility should be considered when selecting cleaning and disinfecting products. This study evaluates the tendency of 2-in-1 wet wipes to cause ESC in commonly found healthcare plastics. Eight ready-to-use 2-in-1 wet wipes were evaluated for their ability to cause ESC in 13 plastic surfaces in accordance with BS EN ISO-22088-3. Polymers were exposed to fluid extracted from wipes at a fixed strain of 0.5% for 7 days and assessed for cracking, crazing, and tensile strength in accordance with ISO 527-2:2012. All 2-in-1 wet wipes tested contained ESC agents, although the severity of ESC varied. Products with higher pH (>8.0) were responsible for 74% of failures, with 22 of the 39 tested plastics visibly cracking. Although the primary active in all tested wipe formulations were Quaternary Ammonium Compounds (QACs), formulations that included small/medium amines or alcohol demonstrated a greater propensity for plastic cracking. Each disinfectant formulation exhibits a unique spectrum of microbial efficacy and unique potential to cause surface damage. This may result in device failures and recalls that could compromise patient and staff safety. BS EN ISO-22088-3 can support material compatibility assessments of disinfectant and detergent products before they come to market.

Nanostructure characterisation of welded polyethylene using small angle X-ray scattering

Polyethylene (PE), a common thermoplastic polymer, is gaining prominence in the construction and packaging industries due to its exceptional mechanical properties, chemical resistance, safety, and integrity. However, internal defects can occur during manufacturing and throughout its service life. Neglecting this problem results in the disposal of plastic and, consequently, the accumulation of plastic waste and environmental issues, which have caused much criticism. A common method to repair the thermoplastics is welding, which introduces seams and localized thermal residual stress fields resulting in areas where damage can nucleate, potentially leading to cracks and failure over time. These cracks often start at the nanoscale and propagate to larger length scales until failure occurs. The objective of this research paper is to develop welding processes, with improved integrity and lifespan for PE. Additionally, it aims to investigate and assess the impact of PE welding on parent materials at nano- and micron-scales, to understand limitations that are challenging to overcome in such welding processes. The study involves joining PE panels together under various pre-heating and post-cooling conditions, followed by evaluating the environmental stress cracking resistance of the welds and the durability of the repaired components. The crystallinity and morphology of the PE material in the weld area and its surrounding regions were analysed using Small Angle X-ray Scattering (SAXS), and the findings were compared with results obtained from optical microscopy and Differential Scanning Calorimetry. The study concludes that SAXS results offer exceptional information about the parent PE and weld material within the welding zone.

Investigating the effect of compatibilizers on environmental stress cracking resistance in polypropylene/low density polyethylene blends

The present study focuses on the effect of octylphenoxy poly(ethyleneoxy)ethanol (IGEPAL CA 630) on the environmental stress cracking resistance (ESCR) of blends of polypropylene (PP) and low-density polyethylene (LDPE) at different weight fractions without and with the addition of two compatibilizers, corresponding to styrene-ethylene-butylene-styrene (SEBS) copolymer and styrene-ethylene-butylene maleate (SEBS-g-MA). Compression molding was used after mixing the melt in a Brabender internal mixer to create the blends. ESCR of the blends was determined by exposing the blends to a solution of IGEPAL CA 630 the presence of stress. Mechanical (tensile) and thermal properties are extracted to evaluate the effect of adding the compatibilizers SEBS and SEBS-g-MA to the blend. In the environmental stress cracking (ESCR) tests, the time to failure increases with increasing PP content, despite PP's greater resistance to ESCR than LDPE. The addition of SEBS-g-MA to the blend significantly improves the flexibility and ESCR performance of PP/LDPE blends with specific weight fractions.

Relation of craze to crack length during slow crack growth phenomena in high‐density polyethylene

AbstractThe craze‐crack mechanism occurring in high‐density polyethylene (HDPE) causing slow crack growth and environmental stress cracking is investigated in detail with respect to the relation of crack length and the related craze zone. This is essential for the understanding of the resulting features of the formed fracture surface and their interpretation in the context of the transition from crack propagation to ductile shear deformation. It turns out that an already formed craze zone does not inevitably result in formation of a propagating crack, but could also undergo ductile failure. For the examination, the full notch creep test (FNCT) was employed with a subsequent advanced fracture surface analysis that was performed using various imaging techniques: light microscopy, laser scanning microscopy, scanning electron microscopy, and X‐ray micro computed tomography scan. FNCT specimens were progressively damaged for increasing durations under standard test conditions applying Arkopal, the standard surfactant solution, and biodiesel as test media were used to analyze the stepwise growth of cracks and crazes. From considerations based on well‐established fracture mechanics approaches, a theoretical correlation between the length of the actual crack and the length of the preceding craze zone was established that could be evidenced and affirmed by FNCT fracture surface analysis. Moreover, the yield strength of a HDPE material exposed to a certain medium as detected by a classic tensile test was found to be the crucial value of true stress to induce the transition from crack propagation due to the craze‐crack mechanism to shear deformation during FNCT measurements.Highlights Progress of crack formation in high‐density polyethylene is analyzed by different imaging techniques Determined growth rates depend on distinction between craze zone and crack The ratio of the present crack to the anteceding craze zone is validated theoretically The transition from crack propagation to ductile shear deformation is identified An already formed craze zone may still fail by ductile mechanisms

Blending Modification Technology of Insulation Materials for Deep Sea Optoelectronic Composite Cables

The insulation layer of deep-sea optoelectronic composite cables in direct contact with high-pressure and highly corrosive seawater is required for excellent water resistance, environmental stress cracking resistance (ESCR), and the ability to withstand high DC voltage. Although high-density polyethylene (HDPE) displays remarkable water resistance, it lacks sufficient resistance to environmental stress cracking (ESCR). This article is based on a blend modification approach to mixing HDPE with different vinyl copolymer materials (cPE-A and cPE-B). The processing performance and mechanical properties of the materials are evaluated through rheological and mechanical testing. The materials’ durability in working environments is assessed through ESCR tests and water resistance experiments. Ultimately, the direct current electrical performance of the materials is evaluated through tests measuring space charge distribution, direct current resistivity, and direct current breakdown strength. The results indicate that, in the polyethylene blend system, the rheological properties and ESCR characteristics of HDPE/cPE-A composite materials did not show significant improvement. Further incorporation of high melt index linear low-density polyethylene (LLDPE) material not only meets the requirements of extrusion processing but also exhibits a notable enhancement in ESCR performance. Meanwhile, copolymerized polyethylene cPE-B, with a more complex structure, proves effective in toughening HDPE materials. The material’s hardness significantly decreases, and when incorporating cPE-B at a level exceeding 20 phr, the composite materials achieve excellent ESCR performance. In a simulated seawater environment at 50 MPa, the water permeability of all co-modified composite materials remained below 0.16% after 120 h. The spatial charge distribution and direct current resistivity characteristics of the HDPE, cPE-A, and LLDPE composite systems surpassed those of the HDPE/cPE-B materials. However, the HDPE/cPE-B composite system exhibited superior dielectric strength. The application of composite materials in deep-sea electro–optical composite cables is highly promising.

Understanding environmental stress cracking in the Bell Test at the notch region

AbstractThe Bell Test (ASTM‐D1693) is commonly used to accelerate part failure in order to evaluate resin selection for applications like piping and tanks where environmental stress cracking is possible, even though the method tends to offer less than desirable repeatability. The working hypothesis for this new study with polyethylenes was that the variability seen in failure times may be attributed to a higher sensitivity of the phase morphology primarily at or near the surfaces of a notch than more commonly referenced bulk descriptors of a polymer, affecting stresses and the localized absorption of the preferred stress cracking agent. Using an organic dye tracer to monitor penetration of stress cracking agent into the polymer along with image analysis for the notch dimensions and a load cell, the local aspects of the mechanism were evaluated for up to four grades of polyethylene of varying crystallinity. By this detailed analysis, it was revealed that for failure to occur by ESC, influences in the polymer by absorption of the stress cracking agent preceded the changes in stresses in the specimen, contrary to original expectation. There was an imminent rate increase in both stresses and notch expansion once absorption of the surfactant reached a critical concentration. This critical nature was shown to be dependent on the crystallinity of the polymer under observation, considering the size/arrangement of crystals present and entanglements formed through the amorphous contents to dictate the rate by which IGEPAL can be absorbed into a polyethylene specimen. The results of this study validate the need for greater focus on polymer properties at the notch rather than the bulk of the specimen, though more techniques for providing analysis of these properties at the notch surfaces are needed for future improvements to the mechanism.Highlights Bromocresol dye acts as a novel visualization aid in tracking IGEPAL CO‐630 sorption Crystallinity was related to a plasticization threshold for absorption of IGEPAL Accelerated increase in internal stresses follow absorption. Variability of the Bell Test was related to crystalline properties at the notch

Polycarbonate-based hybrid ternary blend with regulated silica dispersion and distribution towards high environmental stress crack resistance, high strength and high toughness

Polycarbonate (PC) has a very low environmental stress crack resistance (ESCR). This work aims at increasing its ESCR as well as its tensile strength and toughness via a hybrid ternary blend (HTB) which is composed of PC, hydroxyl-rich polyvinyl butyral (PVB) and hydroxyl-rich silica (SiO2). Selective distribution and fine dispersion of SiO2 in the dispersed phase (PVB) through hydrogen bonding between the PVB and SiO2 endows the HTB with high ESCR, tensile strength and toughness. Two processes are compared to develop the HTB. One is composed of two steps: the SiO2 is dispersed in the PVB dissolved in anhydrous ethanol; after the removal of the ethanol, the resulting (PVB/SiO2) is then blended with the PC in the molten state. The other process is composed of a single step: PVB, SiO2 and PC are directly blended in the molten state. The two-step process yields better properties: The PC/(PVB-10/SiO2-2) containing 10 wt% of PVB and 2 wt% of SiO2 shows higher melt flow index, tensile strength and toughness. More importantly, its ESCR in carbon tetrachloride is 5 times that of the PC. We envision that this work provides a new perspective to the theory of HTB, and opens a promising route to prepare high-performance PC with excellent practicality.

Improving the performance of post-consumer resin feedstocks for rigid packaging applications: A pilot-scale assessment

Various market, environmental and political drivers encourage the use of more post-consumer resin (PCR) high-density polyethylene (HDPE) in rigid packaging. However, PCR HDPE performs poorly compared to virgin HDPE, particularly in blow-moulded bottles for cleaning products which often show inadequate resistance to environmental stress cracking. In this study we evaluate and compare additives representing various strategies designed to improve the mechanical performance of PCR HDPE. Two commercially available recycled HDPE PCRs were extruded with eight candidate additives and the bottle performance of the best performing blends were tested in extrusion blow moulding trials. FTIR analysis revealed polypropylene contamination in one PCR although rheology and thermal properties were very similar. The use of strain hardening modulus as a selection criterion for pilot scale trials was demonstrated. The results revealed that particulate additives may have negative effects while polyolefin additives are more likely to succeed at the pilot scale.

Microstructure and Tensile Properties of Melt-Spun Filaments of Polybutene-1 and Butene-1/Ethylene Copolymer.

Polybutene-1 with form I crystals exhibits excellent creep resistance and environmental stress crack resistance. The filaments of polybutene-1 and its random copolymer with 4 mol% ethylene co-units were produced via extrusion melt spinning, which are expected to be in form I states and show outstanding mechanical properties. The variances in microstructure, crystallization-melting behavior, and mechanical properties between homopolymer and copolymer filaments were analyzed using SEM, SAXS/WAXD, DSC, and tensile tests. The crystallization of form II and subsequent phase transition into form I finished after the melt-spinning process in the copolymer sample while small amounts of form II crystals remained in homopolymer filaments. Surprisingly, copolymer filaments exhibited higher tensile strength and Young's modulus than homopolymer filaments, while the homopolymer films showed better mechanical properties than copolymer films. The high degree of orientation and long fibrous crystals play a critical role in the superior properties of copolymer filaments. The results indicate that the existence of ethylene increases the chain flexibility and benefits the formation of intercrystalline links during spinning, which contributes to an enhancement of mechanical properties. The structure-property correlation of melt-spun PB-1 filaments provides a reference for the development of polymer fibers with excellent creep resistance.

On the environmental stress cracking of a vibration-welded polycarbonate (PC)-based nanocomposite

In the present study, the environmental stress cracking resistance (ESCR) of a vibration-welded polycarbonate (PC) nanocomposite filled with 1 vol.-% nanosilica was comprehensively investigated with the help of an online optical crack measurement approach. The experimental results reveal that the improvement of the ESCR strongly depended on the stress cracking agents (SCAs) used. In deionized (DI) water, addition of nanosilica leads to a significant increase in the ESCR of neat PC. In contrast, the enhancement of the ESCR in isopropanol after incorporating nanosilica is marginal. This observed improvement is attributed to the much more plastic deformations and micro cavities induced by the nano-sized particles during fracture of the materials, which are elucidated through the optical analysis.

Effect of Annealing Process and Molecular Weight on the Polymorphic Transformation from Form II to Form I of Poly(1-butene).

Poly(1-butene) (PB-1) resin has excellent mechanical properties, outstanding creep resistance, environmental stress crack resistance and other excellent properties. However, PB-1 resin experiences a crystal transformation for a period, which seriously affects the production efficiency and directly restricts its large-scale commercial production and application. The factors affecting the crystal transformation of PB-1 are mainly divided into external and internal factors. External factors include crystallization temperature, thermal history, nucleating agent, pressure, solvent induction, etc., and internal factors include chain length, copolymerization composition, isotacticity, its distribution, etc. In this study, to avoid the interference of molecular weight distribution on crystallization behavior, five PB-1 samples with narrow molecular weight distribution (between 1.09 and 1.44) and different molecular weights (from 23 to 710 k) were chosen to research the influence of temperature and time in the step-by-step annealing process and molecular weight on the crystal transformation by differential scanning calorimetry (DSC). When the total annealing time was the same, the step-by-step annealing process can significantly accelerate the rate of transformation from crystal form II to I. PB-1 samples with different molecular weights have the same dependence on annealing temperature, and the optimal nucleation temperature (i.e., low annealing temperature, Tl) and growth temperature (i.e., high annealing temperature, Th) were -10 °C and 40 °C, respectively. At these two temperatures, the crystal form I obtained by step-by-step annealing had the highest content; other lower or higher annealing temperatures would reduce the rate of crystal transformation. When the annealing temperature was the same, crystal form I first increased with annealing time tl, then gradually reached a plateau, but the time to reach a plateau was different. The crystalline form I contents of the samples with lower molecular weight increased linearly with annealing time th. However, the crystalline form I contents of the samples with higher molecular weight increased rapidly with annealing time th at the beginning, and then transformation speed from form II to form I slowed down, which implied that controlling Tl/tl and Th/th can tune the different contents of form I and form II. At the same Tl/tl or Th/th, with increasing molecular weight, the transformation speed from form II to form I via the step-by-step annealing process firstly increased and then slowed down due to the competition of the number of linked molecules and molecular chain mobility during crystallization. This study definitely provides an effective method for accelerating the transformation of poly(1-butene) crystal form, which not only has important academic significance, but also has vital industrial application.

Failure Analysis of Abnormal Cracking of the Track Circuit Reader Antenna Baffle for High-Speed Trains.

The track circuit reader (TCR) is an important part of train control systems. This paper reports a failure of the TCR antenna baffle, which is used to prevent the TCR antenna from being struck by foreign objects. The designed service life of the baffle is 4.8 million kilometers, but serious cracking was found during routine maintenance after only 0.67 million kilometers of operation. In order to avoid the hidden danger brought by the incident to the safe operation of the train, it is necessary to conduct a complete failure analysis of the failed TCR antenna baffle. Therefore, a comprehensive investigation of the base material, cleaning agents, crack morphologies, etc., was carried out, and the failure environment of the antenna baffle was verified by experiment. The final results show that the environmental stress cracking is the root cause of the failed antenna baffle, and the multiple bubbles produced by the formed process of the antenna baffle are another important cause. According to the conclusions, the solutions to prevent the reoccurrence of such failures are proposed. After these solutions are adopted, the number of failed antenna baffles is greatly reduced, which fully proves the correctness of this analysis.

Environmental stress cracking of chemically aged HDPE-100 gas pipe under impact fracture mode

Environmental stress cracking of chemically aged HDPE-100 gas pipe under impact fracture mode

Improving the consistency of environmental stress cracking resistance testing for polyethylenes

AbstractThis paper explores a novel modification to the Bell Test (ASTM‐D1693) for minimizing its variability in failure time by the introduction of heat notching. The new notching technique for assessing environmental stress cracking resistance was evaluated with four different grades of polyethylene and compared to results using the ASTM standard for notching. Differences in both the failure time and the associated variability were witnessed with this technique, evaluated at various annealing conditions between the cold crystallization temperature and crystal melting temperature of a polyethylene. Best results were found using the midpoint temperature between these two conditions for the heated blade. Localized elastic moduli for the notched samples were obtained by force mapping via atomic force microscopy, showing decreased crystallinity content at the point of concentrated stress was favored for more consistent failure times. The work highlights the critical nature of local phase morphology at the notch in the assessment of environmental stress cracking resistance.

Assessment of Commercially Available Polyethylene Recyclates for Blow Molding Applications by a Novel Environmental Stress Cracking Method.

The transition to a circular economy has a major impact on waste management and the reuse of materials. New mandatory recycling targets for plastics will lead to a high availability of recyclates. For these recyclates, useful applications need to be found. One potential application for recyclates is blow molding bottles as packaging for non-food contents. This study investigates commercially available post-consumer high-density polyethylene recyclates together with virgin blow molding grades in terms of their short-term mechanical properties and environmental stress cracking resistance. While the short-term mechanical properties showed only slightly lower performance than the tested virgin grades, the overall environmental stress cracking failure times of the recyclates were much lower compared to virgin materials, even though the crack-growth kinetics could be similar. Although neither the tensile nor the notched impact strength results of the two polyethylene recyclates revealed large differences, the stress intensity-factor-dependent crack-growth rates of both materials were significantly different.

Molecular dynamics study of the environmental stress cracking agent assisted cavitation in linear and branched polyethylene

We used molecular dynamics (MD) simulation to investigate whether an environmental stress cracking (ESC) agent would help the cavitation process in linear polyethylene (LPE) and branched polyethylene (BPE) by examining the free volume hole size and spatial distributions at the [PE]-[ESC agent] interfaces. The BPE models used contained 10 and 82 butyl/hexyl branches/1000 backbone carbons and the ESC agent used was nonyl ethoxylate (NE) at concentrations 0.001–1.4 wt%. The results show that there exist no significant changes in the packings of LPE and BPE chains, as characterized by their radial distribution functions (RDFs), in the presence of NE regardless its concentration. However, molecular packings at the [PE]-[NE] interfaces vary with NE concentration. In particular, ethylene (E) segments of NE, compared to the ethylene oxide (EO) segments, exhibit stronger association with LPE and BPE chains. We used the Voronoi tessellation method to determine the size and spatial distributions of free volume holes at the [PE]-[NE] interfaces and found that more and larger free volume holes formed around the E-segments than the EO-segments. And such effect was found to be more pronounced in the case of LPE chains than the BPE chains. We further investigated the free volume holes coalescence dynamics using the Fourier mode analysis. The number of frequency modes and the corresponding intensities of the E-segments were significantly higher than those of EO-segments, suggesting that E-segments exhibited a higher tendency to form more and larger free volume holes. This suggests that [PE]-[E-segments] interfaces have a higher chance to form larger voids (i.e., cavitation, a feature of brittle failure that is experimentally observed in ESC). The tendency intensified with increasing NE concentration but was reduced by the presence of short chain branches. The high mobility of terminal carbons in the short chain branches is believed to suppress the formation of large free volume holes at the [PE]-[E-segments] interfaces by absorbing the newly formed free volume by that of the terminal carbons.

Failure analysis on abnormal cracking of polycarbonate plates used in the gearbox oil level gauge for high-speed train

The gearbox of bogie is the core transmission component of the high-speed train. Once its parts have problems, this will cause hidden danger to the running of the train. Therefore, the safety of the gearbox parts must be paid special attention. The failed samples studied in this paper were the polycarbonate (PC) plates used in the gearbox oil level gauge and seven PC plates were found failure during routine maintenance for a certain type of high-speed train. Among them, five plates had cracks parallel to the oil level and close to the middle area, while other two plates had cracks near the circular arc area and lay at an angle of 45° with the level line. In order to find out the root cause of their failure, a variety of material analysis methods were used to examine the properties of the materials, and the fracture morphologies were studied in detail by means of macro and micro observations. The analysis results show that the causes of the failed PC plates could be divided into two types, one was caused by environmental stress cracking and thermal fatigue and the other was caused by forced installation when the length of the PC plate was a little larger. According to the correct determination of the failure causes, the pertinent countermeasures like length reduction of the PC plate and spraying special transparent coating on the PC plate have been put forward, which have been proven very effective after execution.

Simulation of micro cracks introduced by environmental stress in amorphous plastics

Environmental stress crack resistance (ESCR) is a major problem especially for amorphous polymers. The interaction between aggressive substances and both mechanical external and residual stresses can lead to a fracture of the plastic part. In a previous study, a method was developed to measure the ESCR. The specimens are bent over a circular jig to introduce external stresses and a softener is applied as aggressive substance. After a certain time, the samples fracture giving a measure for the ESCR. In this study, this method is under further investigation using the example of acrylonitrile butadiene styrene. Before the sample fractures, there are several micro cracks visible on the surface. The growth of these micro cracks was measured by dye penetrant testing and the shape of the cracks was determined with computer tomographic measurements. From these measurements, artificial samples were constructed for a simulation. Through the simulation, the stresses in the samples were determined to get an insight into the failure mechanism of the samples. It has been shown that the number of the micro cracks in a sample is constant at all times even though there is a great variation in the number of cracks in the different samples. The cracks grow almost linearly with time. This means that all cracks initiate in one specimen at the same time and in the following phase these cracks grow while no more new cracks initiate. This can be explained by the simulation showing that the stress accumulates at the tips of the cracks and the tensile stress at the surface of the specimens decreases. These results were compared with the results from a stress relaxation test which also showed a decrease in the tensile stress at the surface with time, hence verifying the simulative results.

The Aging Performance of PVDF in Acid Oil and Gas Medium

In the process of transporting oil and gas, the service performance of thermoplastic pipes will decline due to the multiple influences of medium, temperature, and pressure. In order to study the service performance changes of PVDF pipes under oil and gas transportation conditions, the high-temperature autoclave is used to simulate the service state of the pipe in the mediums. The PVDF samples are exposed to simulated oil and gas mediums for 1 week, 3 weeks, 5 weeks, and 7 weeks under 60 °C and 90 °C conditions. After the exposure test, the physical and chemical properties of the PVDF pipe are tested and compared with the initial samples. Compared with the initial sample, the sample quality after the exposure test has a slight increase, with growth rates of 2% and 3% at 60 °C and 90 °C, respectively. Meanwhile, the tensile strength of the samples is about 13% and 21% lower than that of the initial sample, respectively. According to the microscopic morphology analyses, there are some crack defects on the surface of the sample after the exposure test. Through infrared analysis, it is shown that no molecular chain breakage, crosslinking, or other reactions are found after the exposure test. The above analysis shows that the PVDF sample has slight penetration and swelling during the exposure test. However, due to the large force between the PVDF molecules, its mechanical properties have a small downward trend, showing excellent environmental stress crack resistance.

Environmental stress cracking of 3D-printed polymers exposed to concrete

Increasing demand for complex concrete shapes in architecture has triggered the use of digital fabrication methods for producing non-standard formworks. To this end, polymer extrusion 3D printing has already shown promising results in a range of research projects. However, 3D-printed polymer formworks can suffer from sudden failures during casting, which are generally associated with the pressure exerted by the wet concrete on the thin plastic formworks. Such failures can however be substantially accelerated by the corrosive effects of the wet concrete paste on some 3D-printed thermoplastics, a phenomenon that has not been studied in depth so far. This paper first reviews the state of the art of 3D-printed polymer formworks and their applications in architecture. It focuses on the failures caused by formwork pressure and synthesizes the various solutions to this problem reported in the literature. Beyond this, additional results are introduced to provide a guideline for thermoplastic selection in 3D-printed formworks. Common thermoplastics are presented, and their behaviour during concrete casting is documented. This behaviour can be analysed through ultimate strength and creep tests performed in three-point bending on 4 × 10 × 100 mm 3D-printed polymer samples, both in dry state and exposed to an alkaline solution of pH 13, typical for cementitious materials. The tests show that contact with the alkaline solution leads to a rapid strength loss in some thermoplastics. This effect is particularly pronounced with PLA and its blends, for which the strength loss over 10 min is more than 80 % compared to dry samples. Other thermoplastics, such as ABS, ASA, HIPS, Nylon, PVA and ABS/PC have shown more limited or in some cases no deterioration under the same conditions. The material-specific mechanism of deterioration is environmental stress cracking in contact with the alkaline solutions and it occurs in all 3D printing orientations and loading directions where tensile stresses occur. • Polymer extrusion 3D printing is used to fabricate complex formworks for concrete. • 3D-printed polymer formworks can suffer sudden failures during concrete casting. • High pH and hydrostatic pressure can reduce the strength of some polymers by 80 %. • This is a material-specific phenomenon known as environmental stress cracking.