Effect of Temperature and Strain Rate on the Flexural Behavior of Wood-Polypropylene Composites

The mechanical properties of wood-polypropylene composites exhibit typical viscoelasticity. However, there is little information on the mechanical properties of wood-polypropylene composites related to temperature and time, which limits the use of wood-polypropylene composites as structural components. Here, the effect of time (strain rate) and temperature on the flexural properties and the master curve of the storage modulus used to predict the long-term performance of wood-polypropylene composites were investigated. The results showed that the flexural strength and modulus increased linearly with the increase of wood contend, which can increase by 134% and 257% respectively when the mass fraction of wood powder reached 45%. Moreover, there was a positive linear relationship between flexural strength and ln strain rate, while the flexural strength and modulus decreased as temperature elevated. The storage modulus as a function of frequency (time) and temperature confirmed this trend. To evaluate the long-term performance, the storage modulus master curve was constructed and the respective activation energy was calculated, which revealed that the long-term performance of the samples depended on the matrix and the addition of an appropriate amount of wood powder was beneficial to improve their durability.

Download Full-text

Experimental Assessment of Mechanical Properties of Geo-grid Reinforced Material and Long-Term Performance of GT/HDPE Composite

Advanced Composite Materials ◽

10.1163/156855108x345252 ◽

2008 ◽

Vol 17 (3) ◽

pp. 247-258 ◽

Cited By ~ 3

Author(s):

Jung Min Seo ◽

Kyung Ho Min ◽

Beong Bok Hwang ◽

In Chul Lee ◽

Jayasekara Vishara Ruchiranga ◽

...

Keyword(s):

Mechanical Properties ◽

Experimental Assessment ◽

Long Term Performance ◽

Term Performance

Download Full-text

Optical cements: Influence of mechanical properties on long-term performance

Precision Engineering ◽

10.1016/0141-6359(80)90057-4 ◽

1980 ◽

Vol 2 (2) ◽

pp. 73-75 ◽

Cited By ~ 1

Author(s):

P.G. Hunt

Keyword(s):

Mechanical Properties ◽

Long Term Performance ◽

Term Performance

Download Full-text

Time-dependent degree of conversion, Martens parameters, and flexural strength of different dual-polymerizing resin composite luting materials

Clinical Oral Investigations ◽

10.1007/s00784-021-04091-4 ◽

2021 ◽

Author(s):

Matthias Kelch ◽

Bogna Stawarczyk ◽

Felicitas Mayinger

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Resin Composite ◽

Practical Importance ◽

Degree Of Conversion ◽

Polymerization Reaction ◽

Indentation Modulus ◽

Fixed Dental Prostheses ◽

Long Term Performance ◽

Term Performance

Abstract Objective To investigate the degree of conversion (DC), Martens hardness (HM), elastic indentation modulus (EIT), and biaxial flexural strength (BFS) of six dual-polymerizing resin composite luting materials initially and after 2 and 7 days of aging. Materials and methods Specimens fabricated from Bifix QM (BIF; VOCO), Calibra Ceram (CAL; Dentsply Sirona), DuoCem (DUO; Coltène/Whaledent), G-CEM LinkForce (GCE; GC Europe), PANAVIA V5 (PAN; Kuraray Europe), and Variolink Esthetic DC (VAR; Ivoclar Vivadent) (n = 12 per material) were light-polymerized through 1 mm thick discs (Celtra Duo, Dentsply Sirona). DC, HM, and EIT were recorded directly after fabrication, and after 2 and 7 days of aging. As a final test, BFS was measured. Univariate ANOVAs, Kruskal–Wallis, Mann–Whitney U, Friedman, and Wilcoxon tests, and Weibull modulus were computed (p < 0.05). Results While CAL presented low DC, HM, EIT, and BFS values, DUO and BIF showed high results. Highest Weibull moduli were observed for VAR and DUO. DC and Martens parameters increased between the initial measurement and 2 days of aging, while aging for 7 days provided no further improvement. Conclusions The choice of dual-polymerizing resin composite luting material plays an important role regarding chemical and mechanical properties, especially with patients sensitive to toxicological issues. DUO may be recommended for bonding fixed dental prostheses, as it demonstrated significantly highest and reliable results regarding DC, HM, and BFS. As DC and HM showed an increase in the first 48 h, it may be assumed that the polymerization reaction is not completed directly after initial polymerization, which is of practical importance to dentists and patients. Clinical relevance The chemical and mechanical properties of dual-polymerizing resin composite luting materials influence the overall stability and long-term performance of the restoration.

Download Full-text

Comparison of Long-Term Strength Development of Steel Fiber Shotcrete with Cast Concrete Based on Accelerator Type

Materials ◽

10.3390/ma13245599 ◽

2020 ◽

Vol 13 (24) ◽

pp. 5599

Author(s):

Kyong Ku Yun ◽

Seunghak Choi ◽

Taeho Ha ◽

Mohammad Shakhawat Hossain ◽

Seungyeon Han

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Steel Fiber ◽

Strength Reduction ◽

Strength Development ◽

Fiber Reinforced ◽

Cast Concrete ◽

Long Term Performance ◽

Term Performance

This study analyzed the effect of accelerating agents, such as aluminate, cement mineral, and alkali-free accelerators, on the long-term performance of steel-fiber-reinforced shotcrete. The shotcrete performance was studied based on the type and amount of steel fiber added. Performance tests were performed to identify the accelerator providing better long-term performance to the steel-fiber-reinforced shotcrete. Changes in strength and flexural performance over time were investigated. The compressive strength and flexural strength tests on 1-, 3-, 6-, 12-, and 24-month-old test specimens were performed, wherein 37 kg of steel fiber was added to the cement mineral and aluminate mixes, and 40 kg of steel fiber was added to the alkali-free mix. The 1-month compressive strength result of all the test variables satisfied the Korea Expressway Corporation standard. The compressive strength of the cast concrete and shotcrete specimens increased with age, demonstrating a strength reduction, particularly in the 24-month-old shotcrete specimens. Thus, the shotcrete performance may deteriorate in the long-term. In the 24-month-old specimen, substantial flexural strength reduction was observed, particularly in the aluminate and alkali-free specimens. The relative strength of the specimens was compared with that of the cast concrete mold specimens. The results suggest the use of alkali-free accelerators, considering the long-term performance of tunnels and safety of workers. Moreover, increasing the steel fiber performance rather than the amount of low-performance steel fiber must be considered.

Download Full-text

AN ANALYSIS OF THE PERFORMANCE OF DECONSTRUCTED TIRES FOR USE AS PADS IN RAILROAD TRACKS

Journal of Civil Engineering and Management ◽

10.3846/13923730.2014.914098 ◽

2016 ◽

Vol 22 (6) ◽

pp. 739-746 ◽

Cited By ~ 2

Author(s):

Miguel SOL-SÁNCHEZ ◽

Fernando MORENO-NAVARRO ◽

Maria Carmen RUBIO-GÁMEZ

Keyword(s):

Mechanical Properties ◽

Dynamic Stiffness ◽

Crumb Rubber ◽

Fatigue Tests ◽

Excellent Performance ◽

Railroad Tracks ◽

Engineering Work ◽

Long Term Performance ◽

Term Performance

The use of end-of-life (EOL) tires is now widespread in civil engineering work. In most cases, the tires are shredded and recycled as crumb rubber. However, this research focuses on an alternate method in which EOL tires were deconstructed to manufacture rail pads. In other words, their outer layer was removed, which made it possible to benefit from the mechanical properties of the tires without having to grind them up. The performance of the recycled tire rubber was analyzed by means of static and dynamic stiffness tests as well as by fatigue tests. The results reflected the long-term performance of the material. Also analyzed was the deterioration of its properties after various thermal and anti-ageing treatments. The results obtained were compared with those of commercial crumb rubber rail pads. The excellent performance of the rail pads made from deconstructed EOL tires shows the high potential of this material for use in railroad tracks.

Download Full-text