Impact strength of an experimental polyurethane- based polymer

Abstract

The impact strength of a newly developed experimental polyurethane-based polymer which is derived from palm oil (Experimental PU) was compared with denture polymers; heat-cured and self cured polymethyl methacrylate (PMMA) and Eclipse ® , light-activated urethane dimethacrylate prosthetic resin system. Ten specimens were prepared using heat-cured PMMA (Meliodent ® Heat Cure, Heraeus Kulzer, Germany), self cured PMMA (Meliodent ® Rapid Repair, Heraeus Kulzer, Germany), Eclipse ® baseplate resin (Dentsply, USA) and Experimental PU material. Specimens were prepared following manufacturer's instructions except for the Experimental PU material where it was prepared in bulk and sectioned to the desired dimension, 64 x 6 x 4 mm. A 'V' notch of approximately 0.8mm in depth was machine cut across the 6mm width. Prior to the Charpy type impact test, specimens were soaked in a water bath for 50 hours at 37ºC. Eclipse ® baseplate resin showed the highest impact strength (2.73 kJ/m 2 ±0.54) followed by Meliodent ® Rapid Repair (2.50kJ/m 2 ±0.65), Meliodent ® Heat Cure (1.96kJ/m 2 ±0.42) and Experimental PU (1.04kJ/m 2 ±0.29). One-way ANOVA showed significant interaction between materials (p<.05) and Tukey HSD revealed that Experimental PU exhibited significantly lower impact strength compared to other materials. Meliodent ® Rapid Repair was not significantly different from Meliodent ® Heat Cure and Eclipse ® baseplate resin. It can be concluded that the Experimental PU exhibited the lowest impact strength while Eclipse ® baseplate resin the highest.

Effect of thermocycling on the flexural and impact strength of urethane‐based and high‐impact denture base resins

“…Polyurethanes are segmented polymers that have both soft and hard segments, providing both flexibility and toughness characteristics 4 . In a urethane dimethacrylate polymer, the long aliphatic polyether segment in the repeated unit provides improved chain flexibility, which may explain the improved toughness of urethane dimethacrylate‐based materials 4 . Some commercially available aliphatic urethane dimethacrylate polymers have shown significantly higher flexural strengths than other resins 22 with the increased strength attributed to the lower molecular weight and molar volume of urethane dimethacrylate resin monomers that would increase the initial methacrylate functionality of the unpolymerised resin.…”

“…12 reported that Microbase, which is also a polyurethane polymer base, had a mean impact strength value of 6.3 kj/m 2 . Only one study evaluated the impact strength of Eclipse resin 4 , and the mean value obtained was 2.73 kj/m 2 . It has been reported that depending on the loading configuration (Izod or Charpy), the specimen dimensions and the presence of notches and their geometry, the impact test can result in different values of impact strength 17 .…”

Influence of incorporation of ZrO₂ nanoparticles on the repair strength of polymethyl methacrylate denture bases

“…[28][29][30] Although flexural stresses that are counteracted by the flexural strength of the material are a constant phenomenon during mastication, impact strength is also required to prevent accidental dropping or falling of the dentures. Because dentures have frenal notches and some scratches on the denture surface that act as common stress concentrated areas and consequently reduce the strength of the dentures, 31 a Charpy-type impact test was selected for this study, and V-shaped notches were created in the specimens in order to simulate denture borders.…”

“…The existence of a V-notch confirmed that the specimens were broken at the same point during testing. 31,42 Therefore, the surface design did not significantly affect the repairs' impact strength.…”

The Effect of Nano- ZrO2 and nano-Al2O3 Reinforcement on Flexural and Impact Strength of Repaired Acrylic Denture Base

“…Also, the effect of alumina (Al 2 O 3 ) addition has been reviewed and reported a positive impact on the properties of acrylic resin (38) . Although flexural stresses that are counteracted by the flexural strength of the material are a constant phenom enon during mastication, impact strength is also required to prevent fracture upon accidental dropping or falling of the dentures (39) .…”