High-modulus Polyethylene Fibres Research Articles

Mechanical characterization procedure of HMPE fiber for offshore mooring in deep waters

For several offshore installations, especially those for exploration of offshore resources, such as Floating Production Storage and Offloading (FPSO), the stability of subsea pipelines and exploration risers are closely related to the mooring system. High performance polymeric fibers have been used in recent decades for offshore mooring, more recently polyester has been challenged by advancement in ultra-deep waters due to its considerable elongation. A candidate fiber for lower elongation mooring systems is high modulus polyethylene (HMPE). The work describes mechanical characterization procedures in high modulus polyethylene fibers envisioning the possibility of offshore mooring systems made entirely with HMPE, which allow deeper water depths, as well as stability to the pipelines. As a result, the fiber is suitable for mechanical strength and linear tenacity. It still shows good performance in abrasion resistance, and loss of inelastic portions in cyclic loads. However, the behavior in creep, due to its slightly high strain rates, restricts its use, but recent fibers known as "Low creep" can be studied, allowing complete mooring systems made with HMPE.

Experimental investigation on service safety and reliability of full-scale HMPE fiber slings for offshore lifting operations

In recent years, high modulus polyethylene (HMPE) fiber slings have been increasingly used in marine transportation and installation projects due to their numerous advantages including lighter than steel ropes, easily handling operation, and no fish hooks et al. Due to the complex behavior of fiber ropes, an effective bedding-in method is necessary to proposed to stabilize the sling length and ensure the safety and reliability of offshore lifting operations. This study proposes a detailed procedures and techniques for evaluating the creep behaviors and load elongation properties of full-scale slings with a normal breaking strength of 10,000 kN. The experimental results reveal that the HMPE exhibits the viscoelastic-viscoplastic behavior and load history effect. Based on the experimental results, the crucial mechanical parameters such as Young's modulus and static stiffness of the HMPE sling are established. A bedding-in procedure of HMPE slings is proposed to remove the structural elongation and to ensure the stability of the length of the sling. The present results have been applied and verified on the evaluation of the slings in Sewol Salvage Engineering. The results can serve as a reference for the application of HMPE slings in offshore lifting operations.

Experimental measurement for dynamic tension fatigue characteristics of HMPE fibre ropes

This paper presents a full-scale experimental investigation for the fatigue properties of HMPE (high-modulus polyethylene) fibre ropes under dynamic loads. Three ropes with different constructions have been tested under various loading averages, amplitudes and periods. The results indicate that the stability of the inner structure plays an important role in fatigue resistance. Therefore, the 2 × 12 braided HMPE rope with more strands of a smaller diameter generally showed a longer fatigue life. An existing empirical equation is validated against the available data and the present experimental results, while a poor agreement is found in the cases of long loading periods. On this account, an equation is further proposed by taking into account the influences of loading period and rope configuration. After setting a proper base for the logarithm of failure time, a good convergence for the iterative fitting in the regression calculation and reasonable agreement against the experimental results have been found.

Dynamic stiffness of braided HMPE ropes under long-term cyclic loads: A full-scale experimental investigation

This paper presents a full-scale experimental investigation to study the nonlinear dynamic stiffness of high-modulus polyethylene (HMPE) fibre rope under long-term cyclic loading. Three kinds of ropes with different constructions and diameters were selected as test samples. The influences of mean load and load amplitude on axial stiffness and the corresponding evolution process were respectively studied. The experimental results showed that various braided ropes' dynamic stiffness was slightly different, which was mainly caused by the different twist angles. Furthermore, the non-dimensional stiffness of small-scale rope was lower than the large samples to some extent. This should be related to the small-scale ropes without an outer jacket were much softer and thus had more distinct deformation. The validations against two existing empirical expressions have also been performed. The results pointed out that these equations had some errors predicting the evolution procedure of the dynamic stiffness and the magnitude of small-scale sample's stiffness. On these accounts, a set of empirical expressions, taking into account braid constructions, diameter and input load conditions, has been newly derived. The comparison against the present experimental results proved its good reliability.

Yarn on yarn abrasion performance of high modulus polyethylene fiber improved by graphene/polyurethane composites coating

As a high-performance fiber, high modulus polyethylene fiber (HMPE) has been widely used in the rope industry. However, due to its low melting point and poor thermal conductivity, it tends to break under the conditions of repeated yarn on yarn abrasion during tension-tension fatigue or tension-bending fatigue. This paper puts forward a method to improve the yarn on yarn abrasion performance of HMPE using a functional graphene/polyurethane composites coating (FG/PU) and discussed the influence of yarn tension, abrasion frequency on the yarn on yarn performance. Based on the yarn morphology and abrasion temperature observation, the failure mechanism was discussed. The experimental results show that the FG/PU coating obtained can improve the yarn on yarn abrasion performance obviously, especially in the case of high-frequency and large tension condition.

Computer vision and thermal monitoring of HMPE fibre rope condition during CBOS testing

Fibre rope usage in deep sea lifting operations is gaining more prominence in recent times. With rope minimum break loads (MBL) comparable to that of their steel wire counterparts, the use of high modulus polyethylene (HMPE) ropes is seen as a viable option for use in subsea construction cranes. The ropes are worn out during use and visual inspection remains one of the main methods of determining whether a fibre rope is to be retired from use, therefore a natural extension is condition monitoring through computer vision. Creep and temperature are constraining with HMPE ropes and should be monitored continuously, particularly when the rope is cyclically bent over sheaves. Additionally, interpreting the thermal history of the rope during use could give insight into deterioration. In this paper, a condition monitoring system based on combined computer vision and thermal monitoring is used during cyclic bend over sheave tests performed on 560 kN break load of 12 strand braided HMPE ropes. New monitoring features such as local length and width through computer vision algorithms combined with surface thermal monitoring and global elongation are presented and their effectiveness as condition monitoring features is assessed.

Thermal properties of polypropylene and high modulus polyethylene fibers reinforced concretes

Abstract Concrete is one of the materials most used by the construction industry. Reinforcing this material with fibers is a technique used to improve its mechanical properties. Steel and polymer fibers are the main types used in this application and there are few studies about the influence of polymer fibers on the thermal properties of concrete. In order to analyze this influence, the present work carried out thermal conductivity, thermal expansion, and compressive strength after exposure to a temperature of 200 °C on specimens made of concrete with addition of polypropylene (PP) fibers and concrete with addition of high modulus polyethylene (HMPE). It was also conducted thermogravimetric analysis (TGA) on PP and HMPE fibers. The results show that the addition of polymer fibers alters the thermal properties of the concrete, reducing its thermal expansion, for example.

Lifetime prediction of high-modulus polyethylene yarns subjected to creep using the Larson–Miller methodology

The aim of the present work is to apply the Larson–Miller technique for the study of the mechanical behavior under creep of high-modulus polyethylene (HMPE) fibers focused on use as in offshore mooring ropes. Creep is known to be a long-term phenomenon, so in most cases, reproducing such experiments in real time is not feasible, and as the life span of anchoring systems must be in the order of decades, accelerated tests are required to verify the long-term mechanical behavior of the material. The methodology using the Larson–Miller parameter is a well-documented and powerful technique for materials’ lifetime prediction, although seldom applied to polymeric materials. It involves in performing accelerated (high temperature and/or loads) creep tests to determine the parameters that are later used to estimate the rupture time of the material under constant load. It is concluded that the Larson–Miller technique is efficient for calculating the lifetime of HMPE subjected to creep.

The Fracture Resistance Of The Endodontically Treated Molar Teeth With MOD Preparations Restored With Different Types Of Composit Material

Compared to teeth with healthy pulps, root filled teeth are considered more susceptible to fracture. The present study was directed toward improving the effect of using flowable composite with or without polyethylene fiber reinforcement on fracture resistance of the endodontically treated mandibular molars with MOD preparations. Thirty sound extracted human mandibular molars were randomly assigned to three groups (n=10). All teeth were root filled and MOD cavity preparation were created.Group (1) was restored with a dentine bonding system(DBS: SE Bond) and composite resin( CR). In group (2), flowable composite resin ( Protect liner F) was used before restoring teeth with CR. In group (3) leno woven ultra high modulus polyethylene ribbon fiber ( Ribbond, Seattle, WA. USA) was inserted into the cavities in a buccal to lingual direction and teeth were then restored with DBS and CR. After finishing and polishing the specimens were stored in 100% humidity at 37C° for 1 day. Compressive loading of the teeth was performed using a universal testing machine at a crosshead speed of 0.5 mm min "' . the mean load necessary to fracture the samples were recorded in newtons (N) and were subjected to analysis of variance (ANOVA) and Tukey test. The results showed that the used of flowable composite resin under composite restorations had no effect on fracture resistance of root filled molars teeth with MOD preparation . while the used of polyethylene fjtffer under composite restorations in root filled teeth with MOD preparations significantly, increased fracture strength .
 Aim
 To evaluate the effect of using flowable composite with or without ultra high modulus polyethylene fiber reinforcement on fracture resistance of root filled mandibular molars with mesio - occluso-distal(MOD) preparations.

Influence of the towline material: Steel or high-modulus polyethylene on towing gear design and tug deck fittings

The traction force or bollard pull and specific function of a tugboat determine the size of its towing gear and deck fittings. These dimensions must enable the tug to carry out a manoeuvre safely. This article considers proposals made in the implementing regulations for calculating the length and diameter of the towline. It analyses the possibility of using high-modulus polyethylene fibre and the way it would affect the design of the towing gear and deck fittings, including the fairleads and bits. It would be useful if regulations provided further guidance on towline length for port tugs. The final part of this study analyses the solutions informed by a sample of 51 port tugs, the majority of which are escort tugs.

Mechanical behaviour of HMPE and aramid fibre ropes for deep sea handling operations

This paper describes the mechanical behaviour of ropes used for deep sea oceanographic operations. First the requirements of deep sea handling ropes are presented. Two high performance fibres are commonly used, aramid co-polymer and high modulus polyethylene (HMPE), and these are then compared. Results from tests on single fibres and 50 ton break load braided ropes are presented, which show that the initial stiffness of a new HMPE rope increases with load level in a bedding-in process resulting from both molecular alignment and construction reorientation. The aramid rope is less sensitive to this effect and shows a high stiffness from first loading. Measurements made at sea on oceanographic ropes of both materials using an elastic recoil method are presented, and apparent modulus values are consistent with laboratory measurements. Once both ropes have been fully bedded-in the HMPE is significantly stiffer, particularly under dynamic loads. Creep tests indicate that aramids creep less quickly than HMPE under constant loads over a 6 h period at 20 °C. Bending over sheave tests indicate longer lifetimes for the aramid but further tests on wet aramid are required to complete this conclusion.

Modelling creep tests in HMPE fibres used in ultra-deep-sea mooring ropes

Due to its low density and high strength, HMPE (high modulus polyethylene) fibres are being increasingly used in synthetic ropes for offshore mooring. Nevertheless, the occurrence of creep at sea temperature can be a shortcoming for its practical use. Creep tests performed at different load levels in a sub-system of the HMPE rope (yarn) are frequently used as a first step to obtain some information about the susceptibility to creep deformation at a given temperature. The present paper is concerned with the phenomenological modelling of creep tests in HMPE yarns. In this macroscopic approach, besides the classical variables (stress, total strain), an additional scalar variable related with the damage induced by creep process is introduced. An evolution law is proposed for this damage variable. The predicted lifetimes and elongations of HMPE specimens in creep tests at different load levels and room temperature are compared with experimental results showing a good agreement.

Tensile fatigue behaviour of PBO fibres

Poly(p-phenylene benzobisoxazole) (PBO) fibres are finding increasing applications on account of their exceptional stiffness and strength. This article presents results from tests on single PBO filaments, to characterize their intrinsic behaviour under quasi-static and cyclic tensile loading. Scanning electron microscopy is used to show the fibrillation mechanism leading to failure. Results are compared to data for polyester, aramid and high modulus polyethylene fibres. PBO fibres show shorter fatigue lifetimes than the other fibres when maximum stress is expressed as a percentage of quasi-static break load, but the absolute stress values applied are much higher for an equivalent lifetime.

Influence of different reinforcing materials on the rheology of provisional restorations.

The effects of adding different ratios (0.5, 1, 5, 10, 20 and 40%) of zirconium oxide powder (ZrO) and ultra high modulus polyethylene fibers (PE) (0.5, 1, 2 and 4%) on the rheology mean value of autopolymerizing acrylic resin was investigated using Rotary Viscometer. Also the effect of temperature on the rheology mean values of reinforced acrylic resin were studied and analyzed. Mean values, student t-test and paired sample t-test also was analyzed. From our results it is obvious that the rheology mean value of acrylic resin (group I) is increased by increasing the ratio of ZrO. There is no significant difference between acrylic resin and group II (zirconium oxide group) at 0.5, 1 and 5% ZrO, but at 10 and 20% ZrO there is significant difference. For PE group (group III), the rheology mean value of acrylic resin is increased by increasing the ratio of PE from 0.5 to 2% when measured at different temperatures 20, 25 and 30 C. There is no significant difference between acrylic resin and group III at 0.5% PE, but at 1% and 2% PE there is a significant difference. In this study 40% ZrO and 4% PE had been eliminated from this study because the formed mixtures were friable and could not be molded. The rheology mean values were also affected by increasing the temperature from 20 to 30 C.

Inelastic behavior and fracture of high modulus polymeric fiber bundles at high strain-rates

The tensile behavior and fracture mechanisms of poly(phenylene terephthalamide) (PPTA) and high modulus polyethylene (HMPE) fiber bundles were studied at high strain-rates using a tension Kolsky bar. For all fiber bundles investigated, a significant amount of strain energy was found to be dissipated by inelastic processes in addition to that due to fracture. The differences in microstructure and properties between the fibers were shown to have a noticeable influence on the inelasticity and fracture behavior in PPTA fiber bundles. No significant strain-rate effect on inelastic behavior and maximum strength was found in HMPE fiber bundles. Scanning electron micrographs of the fracture surfaces of PPTA fiber showed that the failure occurs mainly by fibrillation resulting in pointed breaks, and showed no fundamental difference in fracture mechanism at quasi-static and high strain-rates. However, the fracture mechanism in the HMPE fiber was different at quasi-static and high strain-rates, crazing was dominant at high strain-rates and plate formation under quasi-static conditions. This difference was more substantial in HMPE fibers with lower degree of crystalline order, which suggested that the inelastic behavior is governed by a precise mechanism of load transfer between the crystalline and amorphous phases present in HMPE fibers as a function of loading rate. At high strain-rates, HMPE fibers appear to be able to dissipate more strain energy than PPTA fibers due to this intrinsic change of deformation mechanism. Our results also support the idea that the mechanical behavior of a PPTA fiber bundle is inherently statistical including variations in strength distribution and alignment of the individual filaments.

Surface modification of ultra high modulus polyethylene fibers by an atmospheric pressure plasma jet

AbstractTo improve their adhesion properties, ultra high modulus polyethylene (UHMPE) fibers were treated by an atmospheric pressure helium plasma jet (APPJ), which was operated at radio frequency (13.56 MHz). The surface properties of the fibers were investigated by X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and contact angle measurement. The surface dyeability improvement after plasma treatments was investigated using laser scanning confocal microscopy (LSCM). The adhesion strengths of the fibers with epoxy were evaluated by microbond tests. In addition, the influence of operational parameters of the plasma treatment including power input and treatment temperature was studied. XPS analysis showed a significant increase in the surface oxygen content. LSCM results showed that the plasma treatments greatly increased fluorescence dye concentrations on the surface and higher diffusion rate to the fiber center. The tensile strength of UHMPE fiber either remained unchanged or decreased by 10–13.6% after plasma treatment. The contact angle exhibited a characteristic increase in wettability, due to the polar groups introduced by plasma treatment. The microbond test showed that the interfacial shear strengths (IFSS) increase significantly (57–139%) after plasma treatment for all groups and the optimum activation is obtained at 100°C and 5 W power input. SEM analysis showed roughened surfaces after the plasma treatments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Aging of surface properties of ultra high modulus polyethylene fibers treated with He/O 2 atmospheric pressure plasma jet

To investigate the relationship between aging of the treatment effect and the gas composition of atmospheric pressure plasma treatment, ultra high modulus polyethylene (UHMPE) fibers were selected as a model fiber to study the aging behavior of fiber surface treated by atmospheric pressure plasma jet (APPJ) with pure helium, helium + 1% oxygen, and helium + 2% oxygen. Atomic force microscopy showed increased surface roughness, while X-ray photoelectron spectroscopy revealed increased oxygen contents after the plasma treatments. The plasma treated fibers had lower contact angles and higher interfacial shear strengths to epoxy than those of the control fiber. Adding 1% of O 2 to helium increased effectiveness of the plasma in polymer surface modification and suppressed aging after the treatment, while adding 2% of O 2 had a negative effect on the APPJ modification results and accelerated aging. In addition, no significant difference in single fiber tensile strength was observed between the control and the plasma treated fibers.

The effect of fiber insertion on fracture resistance of endodontically treated molars with MOD cavity and reattached fractured lingual cusps

In this study, the effect of flowable composite reinforced with a leno wave ultra high modulus (LWUHM) polyethylene fiber (Ribbond) on fracture resistance of endodontically treated molars with MOD cavity and lingual cuspal fracture was evaluated. Sixty sound extracted human mandibular molars were randomly assigned to six groups (n = 10). Group 1 served as control. Teeth in groups 2-6 received root canal treatment and a MOD cavity preparation. Teeth in group 2 were kept unrestored. Lingual walls of specimens in groups 3-6 were fractured at the CEJ and reattached (C&B Super-Bond). Group 3 was kept unrestored, and group 4 was restored with a composite resin (CR) (AP-X). In group 5, a flowable resin (FR, Protect Liner F) and in group 6, a Ribbond in combination with FR were inserted inside the cavity before CR restoration. After finishing and polishing, the specimens were subjected to compressive loading perpendicular to the occlusal surface at a crosshead speed of 1 mm/min. The mean load necessary to fracture were recorded in Newton and the results were statistically analyzed. MOD cavity preparation reduced fracture resistance of endodontically treated teeth (p < 0.05). Fracture resistance of rebonded fractured specimens was found to be similar to that of the nonfractured samples (p > 0.05). Use of LWUHM polyethylene fiber Ribbond increased fracture strength of endodontically treated molar teeth with MOD cavity preparation and cuspal fracture (p < 0.05). As a result, it was concluded that the insertion of Ribbond inside the cavity has a positive effect on fracture strength of endodontically treated molar teeth with MOD cavity preparation and cuspal fracture.

Novel Methods for Obtaining High Modulus Aliphatic Polyamide Fibers

Super high modulus polyethylene fibers can be created by converting high molecular weight flexible PE chains into highly oriented and extended chain conformations. However, unlike polyethylene, aliphatic polyamides have very high cohesive energy and therefore cannot be easily drawn and highly oriented. This review addresses this fundamental problem by analyzing various novel approaches that can be used to suppress hydrogen bonding in these types of polyamides. Plasticization of such polymers with ammonia, iodine, salts, and Lewis acids, as well as dry spinning, wet spinning, and gel spinning, are discussed. Specialized techniques that involve vibrational zone drawing and annealing as well as laser heating zone drawing and annealing are also reviewed. Some of these methods definitely lead to remarkable improvements in initial modulus and other mechanical properties. The development of recombinant spider silk proteins as well progress in spinning these materials is also reported. The advantages and disadvantages of all of these processes are then summarized.

The effect of fibre insertion on fracture resistance of root filled molar teeth with MOD preparations restored with composite

To evaluate the effect of using flowable composite with or without leno woven ultra high modulus polyethylene fibre reinforcement on fracture resistance of root filled mandibular molars with mesio-occlusodistal (MOD) preparations. Sixty sound extracted human mandibular molars were randomly assigned to five groups (n = 12). Group 1 did not receive any preparation. From groups 2 to 5, the teeth were root filled and MOD preparations were created. Group 2 remained unrestored. Group 3 was restored with a dentine bonding system (DBS; SE Bond, Kuraray, Japan) and composite resin (CR) (AP-X; Kuraray). In group 4, flowable composite resin (Protect Liner F; Kuraray) was used before restoring teeth with CR. In group 5, leno woven ultra high modulus polyethylene ribbon fibre (Ribbond, Seattle, WA, USA) was inserted into the cavities in a buccal to lingual direction and the teeth were then restored with DBS and CR. After finishing and polishing, the specimens were stored in 100% humidity at 37 degrees C for 1 day. Compressive loading of the teeth was performed using a universal testing machine at a crosshead speed of 0.5 mm min(-1). The mean load necessary to fracture the samples were recorded in newtons (N) and were subjected to analysis of variance (ANOVA) and Tukey post-hoc test. The mean load necessary to fracture the samples in each group were (in N): group 1: 1676.75 +/-154.63(a), group 2: 376.51 +/- 37.36(b), group 3: 733.23 +/- 133.33(c), group 4: 786.48 +/- 145.34(c), group 5: 943.63 +/- 121.15(d). There were statistically significant differences between the groups annotated with different letters. (i) Use of flowable composite resin under composite restorations had no effect on fracture resistance of root filled molar teeth with MOD preparations, (ii) use of polyethylene ribbon fibre under composite restorations in root filled teeth with MOD preparations significantly increased fracture strength.