Polymer Liner Research Articles

Polymer Liners with Cu-MWCNT based HCTSVs to Reduce Crosstalk Effects

Polymer Liners with Cu-MWCNT based HCTSVs to Reduce Crosstalk Effects

Review of the Hydrogen Permeation Test of the Polymer Liner Material of Type IV On-Board Hydrogen Storage Cylinders.

Type IV hydrogen storage cylinders comprise a polymer liner and offer advantages such as lightweight construction, high hydrogen storage density, and good fatigue performance. However, they are also characterized by higher hydrogen permeability. Consequently, it is crucial for the polymer liner material to exhibit excellent resistance to hydrogen permeation. International organizations have established relevant standards mandating hydrogen permeation tests for the liner material of type IV on-board hydrogen storage cylinders. This paper provides a comprehensive review of existing research on hydrogen permeability and the hydrogen permeation test methods for the polymer liner material of type IV on-board hydrogen storage cylinders. By delving into the hydrogen permeation mechanism, a better understanding can be gained, offering valuable references for subsequent researchers in this field. This paper starts by thoroughly discussing the hydrogen permeation mechanism of the liner material. It then proceeds to compare and analyze the hydrogen permeation test methods specified by various standards. These comparisons encompass sample preparation, sample pretreatment, test device, test temperature and pressure, and qualification indicators. Then, this study offers recommendations aimed at enhancing the hydrogen permeation test method for the liner material. Additionally, the influence of test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material is discussed. Finally, the influences of the test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material are discussed. Future research direction on the hydrogen permeability and hydrogen permeation test method of the liner material of the type IV hydrogen storage cylinder has been prospected.

A comprehensive assessment of energy storage options for green hydrogen

The current study investigates suitable hydrogen storage technologies for hydrogen produced by renewable energy resources in a green manner. Type-I, III, and IV high-pressure tanks, adsorbent storage, metal hydride storage and chemical storage options are investigated and compared based on their hydrogen storage capacities, costs, masses and greenhouse gas (GHG) emissions. The results of this study show that in a Type-IV hydrogen storage tank (i.e., composite material tank of carbon fiber with thermoplastic polymer liners), increasing the tank pressure from 100 bar to 800 bar increases the hydrogen holding capacity by 457.7%. Regarding the environmental impact, the lowest GHG emissions appear to be the lowest for liquid hydrogen storage with an average of 3.5 CO2eq/kg-H2 while the respective emissions become the highest in metal hydride storage tanks as 113.6 CO2eq/kg-H2. Furthermore, hydrogen storage capacity for Type-IV tanks varies from 1.94 kg at 100 bar to 15.69 kg at 1500 bar in a 250 L tank. In chemical hydride storage tanks, the stored H2 mass will be 40.75 kg for 100 L, 128.39 kg for 200 L, 216.03 kg for 300 L, 303.67 kg for 400 L, 391.31 kg for 500 L and 478.96 kg for 600 L, respectively. Moreover, hydrogen storage, distribution and dispensing are considered critically important in hydrogen logistics and the results of this study will help better guide policymakers to establish effective policies and increase renewable energy penetration in the energy market.

Review of Decompression Damage of the Polymer Liner of the Type IV Hydrogen Storage Tank.

The type IV hydrogen storage tank with a polymer liner is a promising storage solution for fuel cell electric vehicles (FCEVs). The polymer liner reduces the weight and improves the storage density of tanks. However, hydrogen commonly permeates through the liner, especially at high pressure. If there is rapid decompression, damage may occur due to the internal hydrogen concentration, as the concentration inside creates the pressure difference. Thus, a comprehensive understanding of the decompression damage is significant for the development of a suitable liner material and the commercialization of the type IV hydrogen storage tank. This study discusses the decompression damage mechanism of the polymer liner, which includes damage characterizations and evaluations, influential factors, and damage prediction. Finally, some future research directions are proposed to further investigate and optimize tanks.

The Effect of Cooling Rates on Thermal, Crystallization, Mechanical and Barrier Properties of Rotational Molding Polyamide 11 as the Liner Material for High-Capacity High-Pressure Vessels

The rapid development of hydrogen fuel cells has been paralleled by increased demand for lightweight type IV hydrogen storage vessels with high hydrogen storage density, which raises the performance requirements of internal plastic liners. An appropriate manufacturing process is important to improve the quality of polymer liners. In this paper, DSC, WAXD, a universal testing machine and a differential pressure gas permeameter were used to investigate the effect of the cooling rate of the rotational molding polyamide 11 on the thermal, crystallization, mechanical and barrier properties. The cooling rate is formulated according to the cooling rate that can be achieved in actual production. The results suggest that two PA11 liner materials initially exhibited two-dimensional (circular) growth under non-isothermal crystallization conditions and shifted to one-dimensional space growth due to spherulite collision and crowding during the secondary crystallization stage. The slower the cooling process, the greater the crystallinity of the specimen. The increase in crystallinity significantly improved the barrier properties of the two PA11 liner materials, and the gas permeability coefficient was 2-3-fold higher than at low crystallinity. Moreover, the tensile strength, the tensile modulus, the flexural strength, and the flexural modulus increased, and the elongation at break decreased as the crystallinity increased.

Modeling and Characterization of Annealing-Induced Cu Protrusion of TSVs With Polyimide Liner Considering Diffusion Creep Behavior

Polymer liner has been used in through-silicon-vias (TSVs) for smaller parasitic capacitance and better thermo-mechanical performance. For the application in heterogeneous integrated systems, it is critical to study the thermal reliability of such TSVs in both theoretical modeling and experimental characterization. Among the numerous reliability challenges, the Cu protrusion phenomenon of TSVs is one of the most severe issues, which can lead to cracks and delamination in integrated systems. In this article, the annealing-induced Cu protrusion of polyimide (PI) liner TSVs is studied by experiments and simulations. PI-TSVs are fabricated and the Cu protrusion at various annealing conditions is characterized. Finite element analysis (FEA) is carefully carried out taking into account the diffusion creep rate model, and the deviations between FEA and experiment results of protrusion heights are less than 3%. Besides, the deformation procedure and the creep behavior of Cu pillars during annealing are analyzed. Based on the proposed FEA model, comprehensive parametric analyses are conducted to study the effects of different annealing conditions on the Cu protrusion heights, which are helpful to understand and improve the thermal reliability of PI-TSVs.

Development of an image processing algorithm (IPA‐Delfin) for the digital reconstruction of composite overwrapped pressure vessels

AbstractWet filament winding has been established as the primary manufacturing process for overwrapped pressure vessels. However, the prediction of the mechanical performance of pressure vessels is still not sufficiently accurate, mostly due to process‐induced deviations within the laminate structure. In this work, we present an image processing algorithm (IPA‐Delfin) that enables the real‐time generation of a digital reconstruction based on the actual geometry and position of the placed roving. A Type‐IV pressure vessel is analyzed under real manufacturing conditions. Our approach allows the measurement of the overlapping degree of roving within the laminate and the prediction of gaps. The results show that the fiber‐band width and the overlapping area vary significantly when the roving is placed directly on the vessel's polymer liner. A more constant and uniform fiber‐band width and overlapping area were observed when the filament winding took place on the previously placed roving. Hence, the IPA‐Delfin can be potentially used for the generation of digital twins of composite overwrapped pressure vessels.

Progressive failure analysis and burst mode study of type IV composite vessels

ABSTRACT The lightweight high-pressure hydrogen storage vessels composed of polymer liner and composite reinforced layers have attracted more and more attention. In this research, a 2D axisymmetric finite element model was proposed to predict the damage evolution, failure strength and failure mode of the composite overwrapped pressure vessels, in which a user subroutine UMAT based on Hashin failure criteria was introduced to simulate the progressive damage properties of the composite material. The FE models are validated by comparison with the experimental results, and the error between the numerical simulation results and the experimental results was within 10%. It is found that vessels with different lay-up schemes might burst in different locations. Parametric studies are performed to obtain a critical ratio of hoop and helical layers to keep the vessel burst in safe mode.

Effects of interfaces and ordered microstructures on thermal properties of graphene flakes/polyethylene composites

AbstractThe lightweight type IV hydrogen storage tanks put forward higher requirements for the thermal properties of the polymer liners. To improve the thermal properties, graphene flakes (GFs) were used as fillers to reinforce high‐density polyethylene (HDPE). The effects of the interfaces between GFs and polymer matrix and the ordered microstructures on the thermal properties of composites were discussed. The results showed that the ordered arrangement of the composite microstructures can significantly improve its thermal conductivity (kc). At 0.5 wt% GFs loading, the ordered composite kc reached 6.052 W/(m K), corresponding to 11.8 times that of unoriented pure HDPE. The effect of interfaces on kc was qualitatively analyzed by scratching GFs on the cross‐section of the composites. Although GFs form continuous networks with high kc in the polymer matrix, the interface defects between GFs and HDPE matrix lead to increased interfacial thermal resistance at high GFs concentrations. Therefore, the thermal enhancement coefficient of the composites decreases with the increase in GFs concentration. Moreover, mixing GFs can increase the initial thermal degradation temperature of the composites by 15.9 °C and the Vicat softening point by 1.6 °C. This work will provide an essential reference for the application of polymers in type IV tanks.

Polymer liner pipelines as a robust and cost-efficient solution

Polymer liner pipelines as a robust and cost-efficient solution

Impact of Polymer Liners on Crosstalk Induced Delay of Different TSV Shapes

The performance of a through silicon via (TSV) based 3D integrated circuit technology is primarily dependent on the choice of an appropriate liner material. The most commonly used liner material, SiO2, is undergoing considerable reliability challenges such as coefficient of thermal expansion (CTE) mismatch, scallop formation, and interfacial delamination related problems. Therefore, TSVs employed with a polymer liner have achieved significant attention in recent years due to their low dielectric constant and excellent step coverage along the via surface that can effectively reduce thermal stress and crosstalk induced delay. This paper presents a comprehensive and accurate RLGC model for different via shapes, considering the impact of various liner materials on the crosstalk induced delay. Considering an accurate via geometry and material properties at 32 and 45 nm technology, the proposed equivalent RLGC parameters include the cumulative effects of TSV metal, liner, bump, and the silicon substrate. The aforementioned parameters are used to model a novel T-type equivalent electrical network of cylindrical, tapered, and coaxial TSVs considering a coupled driver-via-load (DVL) setup. The proposed equivalent models of different via shapes are used to demonstrate the worst-case crosstalk induced delay in TSVs under the influence of various liner materials. Considering a tapered TSV, a significant improvement in crosstalk induced delay at 32 nm w.r.t. 45 nm technology is observed as 53.5%, 33.76%, and 19.12% at aspect ratios of 2.4, 3, and 4, respectively for the BCB liner.

Analysis of the Integration of Aramid Fiber Tension Struts in a Box-shaped Pressure Vessel

Shared vehicle architectures for fuel cell electric vehicles (FCEVs) and battery electric vehicles (BEVs) allow significant cost reduction in development and production by enabling economies of scale. Therefore, a box-shaped design for a type 4 pressure vessel is developed, which allows an efficient storage of hydrogen in conventional battery design spaces. For a load capable design, the top and bottom of the tank wall are connected with tension struts made of aramid fibers. Based on an analytical design, the geometry of the vessel is defined and a manufacturing process is developed using tufting as key technology for the insertion of the aramid fiber tension struts. The load transfer between the CFRP tank wall and the tension struts is crucial for the mechanical strength of the containment. Fiber loops are evaluated by guiding the tension struts through the CFRP tank wall and deflecting the load. In tensile tests, strengths of at least 1720 MPa are measured for this configuration. The tightness of the containment is ensured by a polymer liner and its adhesion to the struts. The interface between aramid fiber struts and the liner is investigated on strut-level analytically and in experiments. Different shear moduli of the investigated polymers show a major influence on the shear stress in the liner. For the application in the tension-braced pressure vessel, liner materials with the lowest possible modulus should be used to reduce the stress peaks in the liner. Finally, a design corridor for the dimensions of the tension struts and preferred material properties for the liner can be derived. For the investigated material, a strut diameter of 1 mm with a strut spacing of 3 to 5 mm is recommended.

Investigation of Crosstalk Issues for MWCNT Bundled TSVs in Ternary Logic

The investigation of crosstalk issues for coupled through silicon vias (TSVs) in ternary logic is presented in this study. The crosstalk issues are analyzed for coupled TSVs utilizing multi-walled carbon nanotube (MWCNT) as conductive filler, and polymer liners such as polyimide, polypropylene carbonate (PPC), benzocyclobutene (BCB) as insulating materials. For the coupled TSVs, the electrical equivalent circuit model is used to investigate the crosstalk which is driven by the ternary inverter. Based on the Hewlett simulation program with integrated circuit emphasis (HSPICE) simulations, the effects of crosstalk such as functional and dynamic crosstalk for proposed TSVs are compared with single-walled CNT (SWCNT) TSVs. Furthermore, the other performance parameters such as power dissipation, power delay product (PDP), and energy delay product (EDP) are investigated. The crosstalk effects of the proposed model are also examined for various TSV heights. It is noticed that the BCB based coupled MWCNT TSVs provide a significant improvement in crosstalk at reduced TSV height. It is also noticed that the proposed TSVs improved the overall performance up to 30.21% compared to the SWCNT based TSVs. Hence, the MWCNT based TSVs with BCB liner are most suitable for ternary logic integrated circuits (ICs) over the conventional TSVs.

An equation for hole-spanning design of underground cast iron pipes lined with polymeric liners

Defects such as through-wall holes may significantly affect the performance of cast iron pipes lined with polymeric liners. Literature review reveals that the hole spanning design formulae in the Appendix X1 of ASTM F1216 (2016), also adopted in AWWA (2019), produce conservative results for holes with diameters smaller than the cut-off value defined in ASTM F1216 (2016) and AWWA (2019) for partially and fully deteriorated pipes but unconservative results for holes with diameters larger than the cut-off value, and the effect of holes on the mechanical behaviors of lined water pipes has not been thoroughly investigated. This paper aimed to address the issue in the hole spanning design formulae in ASTM F1216 (2016) and AWWA (2019), and numerically investigated and quantified the effect of holes in cast iron host pipes on the performance of lined pipes. A wide range of pipe dimensions, hole diameters, liner modulus, liner wall thickness, internal pressure and friction coefficients at the interface between the cast iron pipe and liner were considered. An equation for the maximum stresses in polymeric liners was derived based on the numerical results. It was found that the maximum stress in the polymeric liner increases with the diameter of the hole in the cast iron pipe until the hole size reaches a threshold level where the effect of hoop stresses takes over and the maximum stress will tend to plateau. It was also found that increasing the friction coefficient, the ratio of pipe modulus to liner modulus and the liner wall thickness will reduce the maximum stress in the liner. The outcome of this study can assist engineers in more accurate hole spanning design of polymeric liners for deteriorated cast iron pipes and quantifying the size of an unacceptable hole for a given host pipe and a liner product.

Plastic pollution risks in bioretention systems: a case study

ABSTRACT We investigated plastic pollution in soil-based stormwater bioretention systems (BRS), which are potentially important pollutant receptors and pathways. Our integrated study is the first of its kind, focusing on plastic abundance, size fractionation, composition, and interactions with urban metrics (including housing density and auxiliary stormwater treatment infrastructure) in BRS filter media. Our results revealed that mesoplastic (MEP) and microplastic (MP) concentrations in BRS are comparable with those reported in other stormwater systems (e.g. wetlands) as well as soils in other land use areas (e.g. agriculture). Distributional sampling within the BRS revealed MP abundances do not change with horizontal distance from the inlet to the outlet. However, MEP abundances drastically decreased towards the outlet, indicating plastic accumulation within BRS. This is important because MEPs can breakdown into MPs which can affect BRS function as well as mobilise downstream. Yet our data uncovered more complex mechanisms involved in BRS plastic fate, with composition data revealing that MPs are not simply breakdown products of MEPs but are instead derived from different sources. Composition, morphology and colour analysis confirmed that BRS polymer liners are a key source of MPs and MEPs in soil filter media. Multivariate analysis of the data with urban design metrics showed gross pollutant traps are effective at decreasing MP concentrations in BRS but not as effective at controlling MEPs. Our results point to complex plastic transmission and accumulation pathways in BRS. Interception measures can partially alleviate plastic risk, but more work is needed to elucidate plastic long-term fate in BRS.

Reliability based failure assessment of deteriorated cast iron pipes lined with polymeric liners

Defects may appear or further develop in cast iron pipes lined with polymeric liners in the form of surface corrosion pits/patches, through-wall holes, gaps, longitudinal cracks, circumferential cracks and/or failed joints etc. This paper examines the performance of deteriorated cast iron pipes lined with polymeric liners using probabilistic analysis. The deterioration of lined cast iron pipes includes corrosion of cast iron pipes together with creep and creep rupture of polymeric liners. Various potential failure modes of lined pipes and the uncertainties of key physical parameters, including geometries, deterioration models and material properties of the pipe and liner, dimensions of the defects in the pipe and loading conditions etc., in probabilistic failure assessment of lined pipes are considered. The probability of failure of each lined pipe is calculated over its lifetime and a sensitivity analysis is also conducted to identify the most influential parameters on the failure probability of the lined pipe. It is found that the coefficients for the rupture strength and the creep retention factors of the liners are most influential on the probability of failure of the lined pipes.

The Influence of Decontamination Procedures on the Surface of Two Polymeric Liners Used in Prosthodontics.

Polymeric liners are materials commonly used in prosthodontics to reshape denture surfaces contacting the soft tissues of the oral cavity. The aim of the study was to determine the impact of different cleaning methods on two polymeric materials used in prosthodontics as non-adhesive permanent liners. The material for the research consisted of samples made from Mollosil Plus (Detax, Ettlingen, Germany)—direct polysiloxan liner; and Plastitanium (Pressing Dental, San Marino, Republic of San Marino)—an injection-molded liner. A total of 198 samples were made, 99 of each assessed material. They were exposed to different cleaning methods—a toothbrush, a toothbrush and soap, a toothbrush and toothpaste (BlendaMed, Procter&Gamble, Cincinnati, OH, USA), a toothpaste and denture cleaning paste (Protefix Hygiene Denture Paste, Queisser Pharma, Germany), denture cleansing tablets (Protefix Hygiene Cleaning Tablets, Queisse Pharma, Germany), and a disinfecting spray (Aftermat, Port Jefferson Station, New York City, NY, USA)—for 1 min, 5 min, 10 min, and 15 min. The image acquisition was performed with scanning electron microscopy and samples were analyzed for the homogeneity of their surfaces—the presence of holes, grooves, precipitate, and small and large separating pieces of the material marking departures from this homogeneity. For each type of damage, one point was given. Continuous data from two groups were compared with Mann–Whitney U testing. Due to a small sample size and distribution of variables other than normal, to compare more than two groups, Kruskal–Wallis testing with post hoc analysis (Dunn test with Bonferroni correction) was used. Categorical data were compared with the chi-square test and the Fisher’s exact test. The Mollosil Plus material should be decontaminated with the use of a toothbrush or toothbrush with soap, while Plastitanium material should be disinfected. Plastitanium samples are more susceptible to damage during the decontamination procedures than Mollosil Plus.

Development of Abaqus WCM plugin for progressive failure analysis of type IV composite pressure vessels based on Puck failure criterion

The type IV composite pressure vessels (CPVs) are used as a reliable solution for storing compressed gas but still require research and development to reach commercial advancements. The main two challenges in the design of CPVs are: a) debonding of liner and composite shell during the curing process, and b) accurate finite element modeling of the thickness and angle variation of helical layers at the dome regions. In this study, debonding of composite shell from polymeric liner and bosses due to the temperature variations during the curing process is simulated by using bilinear cohesive law. Regarding the second challenge, the Abaqus WCM plugin is used to model the actual geometry of two-liter type IV CPV’s domes by defining and controlling manufacturing parameters. The UVARM subroutine is developed to apply stress analysis and predict the damage initiation using the Maximum Stress, Tsai-Wu, Tsai-Hill, Hashin, and Puck failure criteria. Also, a USDFLD subroutine is written to implement progressive failure analysis using the Puck failure criterion with sudden material degradation model. The numerical axial and radial displacements as well as burst pressure results are compared with the experimental results available in the literature. A good correlation is observed between the finite element and experimental results. Also, numerical results showed that the initial debonding gap due to curing does not affect the progressive damage of the composite shell.

Equations for gap-spanning design of underground cast iron pipes lined with thermosetting polymeric liners

Polymeric spray and cured-in-place-pipe liners have attracted the attention of water utilities as alternatives for renovation of deteriorated cast iron pipes. Circumferential defects, in the form of existing gaps, ring fractures or failed joints, may exist in cast iron pipes and they may significantly influence the performance of the lined pipes under applied loads. Literature review showed that limited research has been conducted to investigate the effect of circumferential defects. This paper aims to comprehensively examine the mechanical performance of polymer lined cast iron pipes with circumferential defects, using finite element analyses, and derive equations based on the finite element results for engineering design. Three different failure modes, namely, lining through existing gaps in pressurized host pipes, formation of gaps for pressurized lined pipes subjected to axial movements, and pressurized lined pipes with ring fractures under bending, are comprehensively studied. After validation of the developed numerical models for each of the failure modes, parametric studies were conducted considering different pipe properties, liner properties, loading conditions and interface properties. Equations were then derived based on the numerical results using non-linear regression for the three failure modes to facilitate the use of the results in practice. It was found from this study that for all three modes a reduction in the ratio of the cast iron pipe modulus to liner modulus will result in an increase in the normalized maximum stress, which is defined as the ratio of the maximum stress to internal pressure in the liner. This effect is most significant for formation of gaps for pressurized lined pipes subjected to axial movements and pressurized lined pipes with ring fractures under bending. It was also found that by increasing the friction coefficient or reducing the ratio of liner wall thickness to pipe diameter, the normalized maximum stress in the liner increases. Among the three failure modes, the normalized maximum stress in the liner for formation of gaps for pressurized lined pipes subjected to axial movements was affected the most.

Performance of Hydrogen Storage Tanks of Type IV in a Fire: Effect of the State of Charge

The use of hydrogen storage tanks at 100% of nominal working pressure (NWP) is expected only after refuelling. Driving between refuellings is characterised by the state of charge SoC <100%. There is experimental evidence that Type IV tanks tested in a fire at initial pressures below 1/3 NWP, leaked without rupture. This paper aims at understanding this phenomenon. The numerical research has demonstrated that the heat transfer from fire through the composite overwrap at storage pressures below NWP/3 is sufficient to melt the polymer liner. This melting initiates hydrogen microleaks through the composite before it loses the load-bearing ability. The fire-resistance rating (FRR) is defined as the time to rupture in a fire of a tank without or with blocked thermally activated pressure relief device. The dependence of a FRR on the SoC is demonstrated for the tanks with defined material properties and volumes in the range of 36–244 L. A composite wall thickness variation is shown to cause a safety issue by reducing the tank’s FRR and is suggested to be addressed by tank manufacturers and OEMs. The effect of a tank’s burst pressure ratio on the FRR is investigated. Thermal parameters of the composite wall, i.e., decomposition heat and temperatures, are shown in simulations of a tank failure in a fire to play an important role in its FRR.