Ultra-high Modulus Polyethylene Research Articles

An Alternative Method for Incorporating Fiber Meshes in Complete Upper Dentures

The most commonly used material for constructing complete dentures is polymethyl methacrylate (PMMA). However, the strength characteristics of PMMA, such as impact strength and fatigue strength, are poor, and fracturing of PMMA dentures is a common problem in prosthodontic practice. Reinforcing PMMA with various materials, such as carbon fibers, glass fibers (fiberglass), and ultrahigh modulus polyethylene fibers, has been suggested to strengthen the denture-base material. A common problem encountered when packing the resin on these specimens is fiber slippage beyond the denture edges. The present study proposes an alternative method of incorporating fiber meshes into complete dentures, whereby a thin filament of self-polymerizing resin at the perimeter of the fiber mesh is produced, giving a clear and stable shape to the mesh that fits the upper jaw cast. During placement of the shaped mesh on the cast, a positive-negative relationship is created between the mesh and cast, which immobilizes the mesh during the incorporation process.

A testing device to investigate the properties of strain-hardening, cement-based composites (SHCC) under impact shear loading

Strain-hardening, cement-based composites (SHCC) are a novel class of fiber-reinforced concretes which exhibit high tensile strain capacity and crack control prior to failure localization, making them suitable for application as strengthening layers or as main materials for construction elements exposed to severe loading and environmental conditions. As opposed to their tensile properties, the shear performance of SHCC has been only scarcely investigated. In the context of structural strengthening against dynamic actions such as impact loading, the paper at hand describes the development, implementation, and testing of a shear testing setup for ductile cementitious composites. The development of the testing setup had as its target its integration in a gravity-driven Split-Hopkinson tension bar (SHTB) and required both finite element modeling and experimental testing. The numerical modeling aimed at a detailed parameter study of the device geometry, boundary conditions, and notch configuration of the material specimens as well. The experimental program implied both quasi-static and impact shear experiments on normal-strength SHCC made with ultrahigh-modulus polyethylene (UHMWPE) fibers. Both the numerical and experimental analyses demonstrated the inapplicability of one-dimensional wave analysis in deriving specimen shear response. This was solved by applying high-speed optical measurements with subsequent digital image correlation (DIC), which also allowed the accurate evaluation of the fracture modes related to load history. The study highlighted the pronounced influence of loading and boundary conditions on the specimens’ response and demonstrated the necessity of complementary numerical analyses to derive the constitutive relationships of SHCC. Furthermore, it serves as basis for further device optimization in respect of structural and inertial effects.

Обзор технологий производства сверхвысокомолекулярного полиэтилена

The review of existing technologies of production and processing of ultra-high molecular weight polyethylene, as well as areas of its application, is presented. Ultra high modulus polyethylene has high performance characteristics – wear resistance, low friction coefficient, high corrosion and chemical resistance and high fracture toughness. These unique properties of ultra high modulus polyethylene distinguish it from other varieties of polyethylene.

Effect of Fiber Reinforcement on Fracture Resistance and Fracture Toughness for Long Span Provisional Restorations

Aim of the work: This study was aimed to determine the effect of fiber reinforcement on the fracture load and toughness of long span provisional restorations. Materials and method: Two types of commercially available provisional materials were selected Protemp™4 and Structur3. Two mechanical tests were performed to evaluate the fracture load and fracture toughness for each material. Twenty samples of four units, fixed partial dentures were fabricated to evaluate the fracture loading of both materials. The samples of each group were further subdivided into two equal subgroups (10 samples each). The first subgroup served as control, without fiber reinforcement while, the second subgroup included the addition of ultrahigh modulus polyethylene fibers (UHMPE) which is delivered pre-impregnated by the manufacturer. An electronic scale were used to pre-weight the fibers, then cut to a predetermined length (2.0mm) before incorporation in the resin mix to represent 3% weight of the control sample. For fracture toughness test, twenty rectangular samples (2.5X5X25 mm) from each material were fabricated. Ten samples for each subgroup were used with and without addition of the fibers. The samples were soaked before testing in artificial saliva for 14 days and then were thermocycled for 2500 cycles between 5oC and 55oC.Conclusions: Structur3 provisional material showed higher fracture load and fracture toughness mean values than Protemp™ 4. Fiber impregnation into provisional restorations enhanced the fracture load significantly but did not show the same improvement with the fracture toughness.

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 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.

Influence of treatment duration on hydrophobic recovery of plasma‐treated ultrahigh modulus polyethylene fiber surfaces

AbstractOne of the major disadvantages of ultrahigh modulus polyethylene (UHMPE) fibers is their low surface energy which makes them difficult to adhere to most of the resins used in composites. Therefore, UHMPE fibers are often treated with plasmas to improve their surface properties. However, aging of plasma treatment effect is a major concern for plasma‐treated fibers. In this study, UHMPE fibers were treated for 30, 60, 90, and 120 s with Ar/O2 plasma on a dielectric barrier discharge device. The change of the surface properties and adhesion characteristics of the fibers were investigated immediately after and 30 days after the plasma treatments using X‐ray photoelectron spectroscopy, contact angle measurement, scanning electron microscopy, and micro‐bond tests. Results show that aging of the plasma treatment effect was suppressed by increasing the plasma treatment duration. The interfacial shear strengths were increased from 4 MPa to 5.9, 7.8, 9.2, and 7.6 MPa for the 30, 60, 90, and 120 s treatment groups, respectively. After 30 days' aging, the IFSS for the 30, 60, 90, and 120 s treatment groups lowered 24, 22, 10, and 9%, respectively. Increasing the plasma treatment time will increase the thickness and saturation degree of the oxidized layer on the polymer surfaces, which might hinder the migration of the hydrophobic polar functional groups from the surface to the bulk of the polymer after the plasma treatment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

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

Influence of twist and filament location in a yarn on effectiveness of atmospheric pressure plasma jet treatment of filament yarns

A twist free polyethylene terephthalate (PET) filament tow and ultrahigh modulus polyethylene (UHMPE) filament tows with 0, 1, 2, and 3 twist/cm are used as model systems to investigate the penetration of atmospheric pressure plasma jet modification effects through a single yarn. The change in surface wettability is determined using static contact angle measurements. Morphological and chemical changes on the fiber surface are characterized by scanning electron microscopy and X-ray photoelectron microscopy. The adhesion improvement is analyzed by micro-bond pullout test. For the PET filament tow, the fibers from the middle layer tend to have poorer treatment effect than those from the top and the bottom layers in terms of surface roughness, wettability and surface chemical composition change. For the UHMPE yarns, as the twist level increases, the plasma treatment is less effective in improving the fiber surface chemical composition, wettability and interfacial shear strength to epoxy due to the tightened yarn structure.

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.

Effect of absorbed moisture on the atmospheric plasma etching of polyamide fibers

A potential problem for the atmospheric pressure plasma treatment is that the moisture absorbed by the substrate may influence plasma surface modification processes. This study evaluated the effect of moisture regain on the surface morphology change of polyamide fibers by plasma etching. Polyamide 6, poly( p-phenylene terephthalamide) (PPTA, aromatic polyamide), wool (polyamide 2), and ultrahigh modulus polyethylene (UHMPE, polyamide infinity) fibers, were selected to represent various polyamide molecular structures. The fibers were plasma treated at three moisture regains corresponding to three different relative humidity levels (10, 65, and 100%). Scanning electron microscope (SEM) showed that no apparent morphology change was observed on the surface of UHMPE and PPTA fibers. Under the nano-scale surface analysis of atomic force microscopy (AFM), however, rougher surface of UHMPE and PPTA fibers appeared with elevated relative humidity or higher moisture regain. In terms of polyamide 6 and wool, SEM images revealed that compared to the slight plasma etching effect of fibers with the lowest moisture regain, a thin surface layer of the treated fibers with higher moisture regain was partially or completely peeled off. It may be concluded that fiber moisture regain plays an important role in atmospheric pressure plasma etching of polyamide fibers, which may be mainly due to the interaction between the absorbed water and the polymer molecules. It can be concluded that the etching rate of atmospheric pressure plasma for a polymer depends on its moisture regain, intermolecular forces, crystallinity, and molecular structure.

Influence of environmental moisture on atmospheric pressure plasma jet treatment of ultrahigh-modulus polyethylene fibers

One of the main differences between low-pressure and atmospheric-pressure plasma treatments is that there is little moisture involved in the low-pressure plasma treatment, although moisture could exist at the wall of the vacuum chamber or react with the substrate after plasma treatment, while in the atmospheric-pressure plasma treatment moisture exists not only in the environment but also in any hygroscopic substrate. In order to investigate the influence of environmental moisture on the effect of atmospheric pressure plasma treatment, ultra-high-modulus polyethylene (UHMPE) fibers were treated using an atmospheric-pressure plasma jet (APPJ) with 10 l/min helium gas-flow rate, treatment nozzle temperature of 100°C and 5 W output power. The plasma treatments were carried out at three different relative humidity levels, namely 5, 59 and 100%. After the plasma treatments, the surface roughness increased while the water-contact angle decreased with increasing relative humidity. The number of oxygen containing groups increased as the environmental moisture content increased. The interfacial shear strength of the UHMPE fiber/epoxy system was significantly increased after the plasma treatments, but the moisture level in the APPJ environment did not have a significant influence on the adhesion properties. In addition, no significant difference in single fiber tensile strength was observed after the plasma treatments at all moisture levels. Therefore, it was concluded that the environmental moisture did not significantly influence the effect of atmospheric-pressure plasma treatment in improving interfacial bonding between the fiber and epoxy. The improvement of the interfacial shear strength for the plasma-treated samples at all moisture levels was mainly due to the increased surface roughness and increased surface oxygen and nitrogen contents due to the plasma etching and surface modification effect.

Influence of temperature and relative humidity on aging of atmospheric plasma jet treatment effect on ultrahigh-modulus polyethylene fibers

The aging effects of atmospheric pressure plasma treated fiber surfaces are important for storage and processing of the fibers. One of the high-performance fibers, ultrahigh modulus polyethylene (UHMPE) fiber, was chosen as a model system to investigate the aging process of atmospheric pressure plasma jet (APPJ) treated fibers surfaces 0, 7, 15 and 30 days after initial plasma treatment. The fiber was first plasma-treated and then stored at temperatures varying from −80 to 80°C on the same relative humidity (RH, 0%) and on RH of 0%, 65% and 100% at the same temperature of 20°C. Immediately after the plasma treatment, scanning electron microscope (SEM) showed the roughened fiber surface. X-ray photoelectron spectroscopy analysis showed changed surface chemical compositions. Contact-angle measurement showed increased surface wettability and microbond test showed an increase in IFSS. With increasing relative humidity or decreasing temperature, the IFSS value decreased and the contact angle increased more slowly. However, after 30 days, the IFSS values and contact angles reached a similar level for all groups. Moisture showed no effect on the single fiber tensile strengths during aging. The reasons for the observed aging behavior could be that decreasing temperature or increasing relative humidity hindered the surface rearrangement of polymer chains after plasma treatment.

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.

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.

The flexural behavior of denture base reinforced by different contents of ultrahigh-modulus polyethylene fiber

Denture base made from acrylic resin (polymethyl methacrylate, PMMA) was reinforced by different contents of ultrahigh-modulus polyethylene fiber (UHMPEF). The flexural strength of the denture base was tested, the failure modes and microstructures were investigated with a scanning electron microscope (SEM). The results indicate that 3.5wt% UHMPEF increased the ultimate flexural strength of the denture base.

Interphase formation and structure in phenolic composites containing ultra-high modulus polyethylene fibre

The acid-catalysed cure reaction of a phenolic resin at 80°C results in the trapping of water as micron-sized spherical domains within the resin. When untreated commercial ultra-high modulus polyethylene (UHMPE) fibre is used as reinforcement with this resin, the water is trapped at the interface due to the poor wet-out of the fibre by the resin. This produces low interfacial shear strengths. A short radio frequency plasma treatment of the fibre in oxygen or water increases the shear strength by more than a factor of 2. The water liberated on resin cure is not trapped at the interface of the plasma-treated fibres, due to the enhanced wet-out of the fibre by the phenolic resin prior to cure. The plasma-treated UHMPE shows surface restructuring by XPS over a period of a week, but there is no loss of interfacial shear strength when the phenolic composite is fabricated, consistent with rapid reorientation of the carbonyl and carboxyl functionality in the presence of the resin.

Modified shear lag model for fibers and fillers with irregular cross-sectional shapes

For fibers with irregular cross sections such as ultrahigh modulus polyethylene (UHMPE) fibers and ribbon-like carbon fibers, the original shear lag model would not provide accurate calculations for interfacial shear stress because it assumes a circular fiber cross section. In this study, a modified shear lag model is proposed to calculate the interfacial shear stress that reflects the change of fiber cross-sectional shape. Microbond test on a UHMPE fiber/epoxy system was used for verification of the model. The difference between the interfacial shear strength (IFSS) calculated using the modified model and that using the original model assuming an equivalent fiber diameter was found to be as high as 15% and it linearly increased as the irregularity of the cross-sectional shape increased. When the irregularity constant exceeds 1.12, the error in IFSS involved in using the original shear lag model and an equivalent fiber diameter is greater than 10%.

The aging of atmospheric plasma-treated ultrahigh-modulus polyethylene fibers

The aging effects of atmospheric plasma treatments on UHMPE fibers are studied. UHMPE fibers are treated for 0.5 and 1 min with He/O2/air gas and for 2 and 4 min with He/air gas by atmospheric pressure plasma on a capacitively coupled device at a frequency of 5 kHz. The samples are tested for fiber/epoxy interfacial shear strength at time intervals of 0, 3, 15 and 30 days after initial plasma treatment. Scanning electron microscopy shows micro-cracks on each set of treated fibers, which is not affected by aging over the 30 day study. Interfacial shear strengths (IFSS) for plasma-treated fibers are 2–3 times as high as that of the control. The IFSS for the plasma treated fibers remains constant up to 15 days and then decreases afterwards. XPS Analysis shows a slight increase in atomic concentration of oxygen and nitrogen for each plasma-treated sample. For the He/O2/air plasma-treated samples, XPS analysis shows an observable increase in C–OH bonds, C=O bonds and COOH bonds, while for the He/air plasma-treated samples, there is a slight increase in C–OH and O=C–O bonds. After 30 days, a decrease in oxygen content for all plasma-treated samples is manifested.

Atmospheric pressure helium + oxygen plasma treatment of ultrahigh modulus polyethylene fibers

Ultrahigh modulus polyethylene fibers were treated with atmospheric pressure helium + oxygen plasma in a capacitively coupled device at a frequency of 7.5 kHz. The fibers were treated for 0, 0.5, 1, 1.5, and 2 min. The surfaces of the fibers treated with He + O2 plasma were etched and micro-cracks were formed. XPS analysis showed a 65ndash213% increase in oxygen content on the surfaces of all plasma-treated fibers, except for the 1.5 min group. An increase in the concentration of C—O and the appearance of C=O bonds on the surfaces of plasma-treated fibers were observed. In the micro-bond test, He + O2 plasma-treated groups had a 65–104% increase in interfacial shear strength over that of the control. The tensile strength of the fibers was either unchanged or decreased by 10–13% by the plasma treatments.