scholarly journals Effects of Composite Formulation on Mechanical Properties of Biodegradable Poly(Propylene Fumarate)/Bone Fiber Scaffolds

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Xun Zhu ◽  
Nathan Liu ◽  
Michael J. Yaszemski ◽  
Lichun Lu
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Sodium Chloride ◽  
Benzoyl Peroxide ◽  
Ultimate Strength ◽  
Testing Machine ◽  
Compressive Modulus ◽  
Fractional Factorial ◽  
Materials Testing ◽  
Poly Propylene

The objective of our paper was to determine the effects of composite formulation on the compressive modulus and ultimate strength of a biodegradable, in situ polymerizable poly(propylene fumarate) (PPF) and bone fiber scaffold. The following parameters were investigated: the incorporation of bone fibers (either mineralized or demineralized), PPF molecular weight, N-vinyl pyrrolidinone (NVP) crosslinker amount, benzoyl peroxide (BP) initiator amount, and sodium chloride porogen amount. Eight formulations were chosen based on a resolution III two-level fractional factorial design. The compressive modulus and ultimate strength of these formulations were measured on a materials testing machine. Absolute values for compressive modulus varied from 21.3 to 271 MPa and 2.8 to 358 MPa for dry and wet samples, respectively. The ultimate strength of the crosslinked composites varied from 2.1 to 20.3 MPa for dry samples and from 0.4 to 16.6 MPa for wet samples. Main effects of each parameter on the measured property were calculated. The incorporation of mineralized bone fibers and an increase in PPF molecular weight resulted in higher compressive modulus and ultimate strength. Both mechanical properties also increased as the amount of benzoyl peroxide increased or the NVP amount decreased in the formulation. Sodium chloride had a dominating effect on the increase of mechanical properties in dry samples but showed little effects in wet samples. Demineralization of bone fibers led to a decrease in the compressive modulus and ultimate strength. Our results suggest that bone fibers are appropriate as structural enforcement components in PPF scaffolds. The desired orthopaedic PPF scaffold might be obtained by changing a variety of composite formulation parameters.

Crosslinking Characteristics of an Injectable Poly(Propylene Fumarate)/ β-Tricalcium Phosphate Paste and Mechanical Properties of the Crosslinked Composite for Use as a Biodegradable Bone Cement

1998 ◽  
Vol 530 ◽  
Author(s):  
S.J. Peter ◽  
P. Kim ◽  
A.W. Yasko ◽  
M.J. Yaszemski ◽  
A.G. Mikos
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Compressive Strength ◽  
Bone Cement ◽  
Tricalcium Phosphate ◽  
Weight Percent ◽  
Compressive Modulus ◽  
Gel Point ◽  
Handling Characteristics ◽  
Poly Propylene

AbstractWe investigated the crosslinking characteristics of an injectable composite paste of poly(propylene fumarate) (PPF), N-vinyl pyrrolidinone (N-VP), benzoyl peroxide (BP), sodium chloride (NaCl), and β-tricalcium phosphate (β-TCP). We examined the effects of PPF molecular weight, N-VP/PPF ratio, BP/PPF ratio, and NaCl weight percent on the crosslinking temperature, heat release upon crosslinking, gel point, and the composite compressive strength and modulus. The maximum crosslinking temperature did not vary widely between formulations, with the absolute values falling between 38 and 48 °C, and was much lower than that of 94°C for poly(methyl methacrylate) bone cement controls tested under the same conditions. The total heat released upon crosslinking was decreased by an increase in PPF molecular weight and a decrease in N-VP/PPF ratio. The gel point was effected strongly by the PPF molecular weight, with a decrease in PPF molecular weight leading to a more rapid gel point. An increase in initiator concentration had the same effect to a lesser degree. The time frame for curing was varied from 1 -121 minutes, allowing the composite to be tailored to specific applications. The compressive strength and compressive modulus values increased with decreasing N-VP/PPF, increasing NaCl content, and increasing BP/PPF ratio. For all formulations, the compressive strength values fell between 1 and 12 MPa, and the compressive modulus values fell between 23 and 265 MPa. These data suggest that injectable PPF/β-TCP pastes can be prepared with handling characteristics appropriate for clinical orthopaedic applications and that the mechanical properties of the cured composites are suitable for trabecular bone replacement.

scholarly journals Poly(Propylene Fumarate)–Hydroxyapatite Nanocomposite Can Be a Suitable Candidate for Cervical Cages

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Yong Teng ◽  
Hugo Giambini ◽  
Asghar Rezaei ◽  
Xifeng Liu ◽  
A. Lee Miller ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Moduli ◽  
Failure Load ◽  
Polymeric Composite ◽  
Materials Testing ◽  
Bulk Materials ◽  
Suitable Candidate ◽  
Salt Leaching ◽  
Wide Range ◽  
Poly Propylene

A wide range of materials have been used for the development of intervertebral cages. Poly(propylene fumarate) (PPF) has been shown to be an excellent biomaterial with characteristics similar to trabecular bone. Hydroxyapatite (HA) has been shown to enhance biocompatibility and mechanical properties of PPF. The purpose of this study was to characterize the effect of PPF augmented with HA (PPF:HA) and evaluate the feasibility of this material for the development of cervical cages. PPF was synthesized and combined with HA at PPF:HA wt:wt ratios of 100:0, 80:20, 70:30, and 60:40. Molds were fabricated for testing PPF:HA bulk materials in compression, bending, tension, and hardness according to ASTM standards, and also for cage preparation. The cages were fabricated with and without holes and with porosity created by salt leaching. The samples as well as the cages were mechanically tested using a materials testing frame. All elastic moduli as well as the hardness increased significantly by adding HA to PPF (p < 0.0001). The 20 wt % HA increased the moduli significantly compared to pure PPF (p < 0.0001). Compressive stiffness of all cages also increased with the addition of HA. HA increased the failure load of the porous cages significantly (p = 0.0018) compared with nonporous cages. PPF:HA wt:wt ratio of 80:20 proved to be significantly stiffer and stronger than pure PPF. The current results suggest that this polymeric composite can be a suitable candidate material for intervertebral body cages.

Analysis of mechanical properties of different volleyballs

2019 ◽  
Vol 233 (2) ◽  
pp. 292-300
Author(s):  
Florian Schneider ◽  
Kerry MacDonald ◽  
Doug Reimer ◽  
Angela D Melnyk ◽  
Thomas R Oxland
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Significant Influence ◽  
High Velocity ◽  
Testing Machine ◽  
Sampling Frequency ◽  
Coefficient Of Restitution ◽  
Materials Testing ◽  
Compression Force ◽  
Gauge Pressure

Concussions are becoming an increasingly important issue in sports, especially in an area like volleyball that, until recently, seemed less prone to such injuries. The purpose of this study was to determine the coefficient of restitution and basic mechanical properties of standardized volleyballs, including stiffness and hysteresis, dependent on different influencing factors. A drop test was performed to calculate the coefficient of restitution based on the time of flight of the ball between the first and second bounce. This was detected using a microphone with a sampling frequency of 44.1 kHz. To determine the mechanical properties, a materials testing machine applied a compression force until a deformation of 50 mm was achieved. These data were sampled with a frequency of 12.5 kHz. The results showed that the three analysed factors in this study, including the ball model, gauge pressure, and incident velocity, had a significant influence on the coefficient of restitution. Therefore, the amount of energy dissipation during an impact situation at low velocities was significantly different within the tested sample of official standardized volleyballs. The stiffness and hysteresis of the volleyballs also varied significantly. These basic mechanical findings raise an interesting question as to whether the investigated factors are appropriate to predict forces acting on the head during a high velocity collision (25–30 m/s), ultimately resulting in a risk of concussion.

scholarly journals Improving the shape stability and enhancing the properties of layer dependent material extruded biodegradable polylactic acid for thin implants

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alper Ekinci ◽  
Xiaoxiao Han ◽  
Andrew Gleadall ◽  
Andrew Allan Johnson
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Polylactic Acid ◽  
Testing Machine ◽  
Degree Of Crystallinity ◽  
Annealed Specimen ◽  
Future Research ◽  
Shape Stability ◽  
Tensile Testing Machine ◽  
Content Type

Purpose This paper aims to establish an appropriate annealing method, which is necessary for shape stability and to evaluate their potential degradation performance of 1-, 3- and 5-layer material extruded polylactic-acid specimens by enhancing their thermal and mechanical properties. Design/methodology/approach The distortion of each layered printed specimen subjected to degradation was calculated in x- and y-direction. Each layered specimen was subjected to annealing at 70°C, 80°C and 90°C for 2 h and at 80°C for 1, 4, 8 and 16 h. Thermal, molecular weight and mechanical properties were calculated using, differential scanning calorimetry, gel permeation chromatography and tensile testing machine, respectively. Findings In the x-direction, distortion was 16.08 mm for one-layer non-annealed printed specimens and decreased by 73% and 83% for 3- and 5-layer, respectively, while each layered non-annealed specimen subjected to degradation at 37°C for one month. Within the outlined study, annealing treatment enhances properties such as the degree of crystallinity (%χ) up to 34%, Young’s modulus (E) by 30% and ultimate tensile strength by 20% compared to the non-annealed specimens. Practical implications The future research accomplishments will be concentrated on the design, development and optimisation of degraded biomedical implants using material extrusion thin films including drug delivery system and fixation plates. Originality/value The printed thin specimens subjected to degradation were investigated. This research developed a new understanding of the effect of the annealing temperature and time on the mechanical, thermal and molecular weight properties for each layered specimen.

Failure of an Advanced Five Layers RT800 Composite

2015 ◽  
Vol 760 ◽  
pp. 299-304
Author(s):  
Vasile Gheorghe ◽  
Florin Teodorescu-Draghicescu ◽  
Dora Raluca Ionescu
Keyword(s):  
Mechanical Properties ◽  
Glass Fibers ◽  
Testing Machine ◽  
Experimental Tests ◽  
Specific Weight ◽  
Materials Testing ◽  
Bending Tests ◽  
Three Point Bending ◽  
Median Part ◽  
Glass Mat

This paper presents mechanical properties of five layers RT800 glass mat laminate impregnated with polyester resin and subjected to three-point bending tests until break. The RT800 glass mat used as reinforcement presents randomly disposed short glass fibers with 845 g/m2specific weight. From the cured plate, twenty specimens have been cut and placed on a three-point bending device and tested using a materials testing machine with servo hydraulic command. The specimens have been carried out at Compozite Ltd Brasov and the experimental tests have been accomplished at SC INAR SA Brasov and Transilvania University of Brasov. Outstanding mechanical properties of this kind of material have been found in which the specimens have suffered delamination mainly in their median part.

scholarly journals Properties Enhancement of High Molecular Weight Polylactide Using Stereocomplex Polylactide as a Nucleating Agent

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1725
Author(s):  
Purba Purnama ◽  
Muhammad Samsuri ◽  
Ihsan Iswaldi
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Crystallization Behavior ◽  
Testing Machine ◽  
Nucleating Agent ◽  
Mechanical And Thermal Properties ◽  
Nucleating Agents ◽  
Thermal And Mechanical Properties ◽  
X Ray ◽  
Universal Testing

As one of the most attractive biopolymers nowadays in terms of their sustainability, degradability, and material tune-ability, the improvement of polylactide (PLA) homopolymer properties by studying the utilization of stereocomplex polylactide (s-PLA) effectively and efficiently is needed. In this sense, we have studied the utilization of s-PLA compared to poly D-lactide (PDLA) homopolymers as a nucleating agent for PLA homopolymers. The mechanical and thermal properties and crystallization behavior of PLA homopolymers in the presence of nucleating agents have been evaluated using a universal testing machine, differential scanning calorimeter, and X-ray diffractometer instruments, respectively. PDLA and s-PLA materials can be used to increase the thermal and mechanical properties of poly L-lactide (PLLA) homopolymers. The s-PLA materials increased the mechanical properties by increasing crystallinity of the PLLA homopolymers. PLLA/s-PLA enhanced mechanical properties to a certain level (5% s-PLA content), then decreased them due to higher s-PLA materials affecting the brittleness of the blends. PDLA homopolymers increased mechanical properties by forming stereocomplex PLA with PLLA homopolymers. Non-isothermal and isothermal evaluation showed that s-PLA materials were more effective at enhancing PLLA homopolymer properties through nucleating agent mechanism.

Mechanical properties of the dog renal capsule

1976 ◽  
Vol 40 (2) ◽  
pp. 164-170 ◽  
Author(s):  
L. A. Herbert ◽  
W. C. Chen ◽  
A. Hartmann ◽  
J. C. Garancis
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Ultimate Strength ◽  
Spontaneous Rupture ◽  
Materials Testing ◽  
Kidney Volume ◽  
Maximum Strain ◽  
Renal Capsule ◽  
Force Unit ◽  
Anterior Posterior

The renal capsule is an important determinant of whole kidney volume/pressure relationships. To gain further insights into its possible role we examined the mechanical properties of the dog renal capsule using standard materials testing procedures. From each of four locations on the kidney surface, the following mechanical properties of the renal capsule were determined: elastic modulus (force/unit of cross-sectional area theoretically required to double the length of the specimen), tensile stiffness (force/unit width theoretically required to double the length of the specimen), ultimate strength (stress at time of fracture of the specimen), and maximum strain (percent strain at time of the fracture of the specimen). We found that the elastic modulus of the renal capsule from all capsular sites was substantially greater than values previously reported for dog aorta. The stiffness of the capsule covering the anterior-posterior surface of the kidney was found to be about 50% greater than the stiffness of the capsule covering the lateral and polar surfaces of the kidney. The ultimate strength of the anterior-posterior capsule was significantly greater than that of the lateral or polar capsule. This finding may explain the clinical observation that the spontaneous rupture of the renal capsule and parenchyma associated with the acute swelling of transplant rejection is confined almost exclusively to the lateral and polar portions of the renal capsule and cortex. The mean maximum strain at each capsular site was about 35%. This degree of circumferential expansion corresponds to about a doubling of kidney volume. Thus, this observation suggests that the renal capsule is at risk to undergo spontaneous rupture when renal volume increases of this magnitude are observed.

Barbed versus smooth poly- propylene three-loop pulley sutures for repair of canine gastrocnemius tendon

2014 ◽  
Vol 27 (06) ◽  
pp. 436-440 ◽  
Author(s):  
T. A. Harper ◽  
M. A. Mitchell ◽  
M. S. McFadden ◽  
B. Heggem Perry ◽  
B. S. Perry
Keyword(s):  
Tensile Strength ◽  
Testing Machine ◽  
Tendon Repair ◽  
Barbed Suture ◽  
Materials Testing ◽  
Gap Formation ◽  
Failure Loads ◽  
Poly Propylene ◽  
Polypropylene Sutures

SummaryObjective: To compare the ultimate tensile strength (UTS) and load to 1 and 3 mm gap formation of smooth (3-metric) and knotless barbed (4-metric) polypropylene sutures placed in a three-loop pulley pattern for canine gastrocnemius tendon repair.Study design: In vitro.Sample size: Thirty-three paired bonetendon units with one of each pair assigned to each suture type. Barbed suture size was based on previously published materials testing results.Methods: Each unit was placed in a servohydraulic testing machine and tested under single cycle tensile loading until repair failure.Results: There was a significantly higher UTS for smooth polypropylene compared to the barbed polypropylene repairs. The loads resulting in 1 and 3 mm gaps for the barbed repairs were consistently significantly less than the corresponding smooth polypropylene repair values.Conclusion: The knotted smooth polypropylene repair was consistently stronger than the knotless barbed polypropylene repair when placed in a three-loop pulley pattern for gastrocnemius repair.Clinical significance: Knotless barbed polypropylene suture should not be considered equivalent to knotted smooth polypropylene of comparable tensile strength when placed in a three-loop pulley pattern for canine gastrocnemius tendon repair. The low failure loads of the barbed repair are probably due to failure of the barbs to anchor consistently throughout the tendon in the knotless configuration.

The Influence of Sintering Temperature on the Mechanical Properties and Microstructure of Carbon Nanotubes/Zirconia/Hydroxyapatite Biocomposites

2013 ◽  
Vol 423-426 ◽  
pp. 38-42
Author(s):  
Ai Min Li ◽  
Kang Ning Sun ◽  
Run Hua Fan
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Fracture Surface ◽  
Bending Strength ◽  
Electronic Materials ◽  
Sintering Temperature ◽  
Testing Machine ◽  
Materials Testing ◽  
Hot Pressing Sintering

Carbon nanotubes/zirconia/hydroxyapatite biocomposites was prepared by hot-pressing sintering under Ar atmosphere. The influence of sintering temperature on the mechanical properties and microstructure of carbon nanotube/zirconia/hydroxyapatite biocomposites was studied. We tested the bending strength and fracture toughness by universal electronic materials testing machine. The component of the composites was tested by XRD. The fracture surface of the composites was observed by SEM. The results indicate that the bending strength and fracture toughness of the composites is lower when the sintering temperature is lower than 1200°C. The difference of bending strength and fracture toughness at 1200°C and 1300°C is little. The number of them has risen markedly than the low temperature which reached to189.2MPa and 1.8MPa·m-1/2 respectively. The composition of the composites is mainly of hydroxyapatite, zirconia, carbon nanotubes, and a small amount of calcium phosphate, which indicated that part of the hydroxyapatite has decomposed. SEM photographs show that the fracture surface of the composites sintered at 1200 °C and 1300 °C is ductile fracture status and has bigger density.

The compressive strength of articular cartilage

1998 ◽  
Vol 212 (4) ◽  
pp. 273-280 ◽  
Author(s):  
A J Kerin ◽  
M R Wisnom ◽  
M A Adams
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Articular Cartilage ◽  
Testing Machine ◽  
Mechanical Damage ◽  
Materials Testing ◽  
Bovine Articular Cartilage ◽  
Creep Loading ◽  
Force Displacement

Articular cartilage provides the smooth bearing surfaces in freely moving (synovial) joints. Its mechanical properties are important because structural failure of cartilage is closely associated with joint disorders, including osteoarthritis. Some mechanical properties of cartilage are well characterized, but little is known about its compressive strength. A technique for measuring cartilage compressive strength is evaluated, and an overview of experiments which relate strength to stiffness and tissue hydration is given. Specimens of bovine articular cartilage-on-bone, approximately 15 mm square, were loaded on a hydraulic materials testing machine using flat impermeable indentors. Linear-ramp loading/unloading cycles of 1 s duration, and of increasing severity, were applied until failure was evident on force-displacement graphs. Some specimens were tested following a 30 min period of creep loading. Inkstaining and histology were used to locate the site of initial damage to each specimen. Specimen failure occurred first in the cartilage surface layer at a nominal applied stress of 14–59 MPa (mean 35.7 MPa). Mechanical properties were little affected by specimen or indentor size, provided both remained within defined limits, and compressive strength could be measured to an accuracy of approximately ±5 per cent. Compressive stiffness was a significant predictor of strength, but only if it was measured at high levels of stress. Strength increased following creep-induced water loss, and initial mechanical damage could propagate under moderate cyclic loading. This technique for measuring cartilage compressive strength has potential for investigating the causes of cartilage failure in vivo

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