Conventional Water Bath Research Articles

Effect of Zirconium Oxide Nano-Fillers Addition on Transverse Strength And Impact Strength of Heat-Polymerized Acrylic Resin, An in Vitro Study

Aim: The purpose of this study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentration (1.5%, 3%, 5% and 7%) on the transverse strength and impact strength of heat-polymerized acrylic resin. Materials and Methods: Zirconium oxide powders with different concentrations (1.5%, 3%, 5% and 7%) were incorporated into heat-cure acrylic resin (PMMA) and processed with optimal condition (2.5:1 Powder/monomer ratio, conventional packing method and water bath curing for 2 hours at 95˚C) to fabricate test specimens of PMMA of dimensions (65 x 10 x 2.5mm) for the transverse strength and (60 x 7 x 4mm) for impact strength. PMMA without additives was prepared as a test control. Two types of mechanical tests; transverse strength and impact strength were carried out on the samples. The recorded values transverse strength in (MPa) and impact strength in (J) were collected, tabulated and statistically analyzed. One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups which are statistically significant when the P value ≤ 0.05. Results: Addition of Zirconium oxide nanofillers to PMMA significantly increased the transverse strength and impact strength Conclusion: Zirconium oxide nanofillers added to PMMA has a potential as a reliable denture base material with increased transverse strength and impact strength. According to the results of the present study, the best mechanical properties were achieved by adding 7%wt ZrO2 concentration.

Inactivation and recovery kinetics of Escherichia coli O157:H7 treated with ohmic heating in broth

In order to explore the inactivation effect of ohmic heating on bacteria, inactivation and recovery kinetics of Escherichia coli O157:H7 treated with ohmic heating in broth were studied and compared with conventional water bath heating. During the heating process, the temperature of E. coli broth treated with ohmic heating increased linearly with the increasing of time, while in water bath heating, the temperature increased linearly with heating time at first, and then the increase became slower gradually. Temperature-inactivation profiles showed that the inactivation history of ohmic heating was different from that of water bath heating. The modified Gompertz model was better to fit the inactivation experimental data, while the modified Logistic model worked better to fit the recovery curves. Model parameters analysis showed that E. coli cells treated with ohmic heating had longer lag phase in recovery compared to that of water bath heating, which might be related to non-thermal effect of ohmic heating.

Ultrasonic-microwave synergistic extraction of paprika pigment

Paprika was soaked in n-hexane to extract paprika pigment by using ultrasonic and microwave assisted extraction (UMAE). The effects of different operating variables were investigated and the extraction condition was optimized through orthogonal design: ultrasonic power of 50 w, microwave power of 240 w, powder-solvent ratio of 1: 25 (g/mL), microwave time of 600 s, paprika particle size of 60 mesh. At these conditions, the color value of 147 of paprika pigment was reached. Compared with the conventional water bath extraction method, UMAE has the advantages of shorter extraction time and higher efficiency, which may be related to the effect of UMAE on destroying the cellular structure of paprika.

Evaluation of Impact Strength of Dental Acrylic Resins by Incorporation of TiO2 Nanoparticles Using Two Different Processing Techniques

The present study aims to evaluate the impact strength of PMMA incorporated with TiO2 nanoparticles by two different processing techniques i.e. water bath and microwave processing techniques. A total of 80 samples made of PMMA were divided into four groups. Each group includes 20 samples with group I and II comprising of samples made of normal acrylic resin and acrylic resin reinforced with 1 wt% TiO2 nanoparticles processed with conventional water bath technique respectively, groups III and IV include normal acrylic resin and acrylic resin reinforced with 1 wt% TiO2 processed using microwave technique respectively. The specimens were tested for impact strength using IZOD pendulum impact tester. The impact energy values obtained were analyzed statistically. The results through one-way ANOVA showed a high mean impact strength with group IV samples (23.13) and lowest with respect to group I (19.42) with highest statistical significance (p < 0.001). A post hoc Tukey test intergroup analysis showed a statistically significant difference between group I and other groups, whereas there was no statistical significance associated with other intergroup comparisons. PMMA with its current drawbacks in the physical and mechanical properties requires modifications to make it an ideal denture base material. The current investigation evaluates that a high mean impact strength with samples made of PMMA incorporated with TiO2 nanoparticles processed by microwave technique was obtained when compared with normal acrylic resins processed by water bath technique. The methodology of current study can be used while processing of denture bases for patients to evaluate the effect of oral environment on inclusion of TiO2 nanoparticles with microwave processing in a clinical setup. This could help in reducing the amount of fractures associated with heavy load masticatory stresses and improving the mechanical properties in denture bases. How to cite this article: Kumar CA, Kumar CR, Vamshikiran K, et al. Evaluation of Impact Strength of Dental Acrylic Resins by Incorporation of TiO2 Nanoparticles Using Two Different Processing Techniques. J Contemp Dent Pract 2019;20(10):1184-1189.

Flexural and Surface Properties of PMMA Denture Base Material Modified with Thymoquinone as an Antifungal Agent.

To evaluate the effect of addition of different concentrations of thymoquinone (TQ) on the flexural strength, elastic modulus, surface roughness, and hardness of PMMA denture base material. A total of 160 rectangular specimens were prepared from heat-polymerized acrylic resin, with dimensions of 65 × 10 × 2.5 mm3 for flexural strength testing and 10 × 20 × 3 mm3 for surface property testing. The specimens were divided into eight groups of 20 specimens: one control group without addition of TQ and seven test groups prepared by adding TQ to acrylic powder in concentrations of 0.5, 1, 1.5, 2, 2.5, 3, and 5 wt%. The polymer was added to the monomer before being mixed, packed, and processed using the conventional water bath method. A universal testing machine was used to measure flexural strength and elastic modulus. A profilometer and a Vickers hardness tester were used to measure surface roughness and hardness, respectively. One-way ANOVA and the Tukey-Kramer multiple-comparison test were used for statistical analysis, with statistical significance at p ≤ 0.05. Addition of TQ to PMMA denture base material significantly decreased flexural strength and elastic modulus at high concentrations (p < 0.01), while no significant differences were observed at low concentrations (0.5%, 1% TQ) in comparison with the control group. At high TQ concentrations, surface roughness increased while hardness decreased (p < 0.0001), and no significant differences were observed at low concentrations (0.5%, 1% TQ) in comparison with the control group. The most favorable addition values were 0.5% and 1% TQ in all TQ groups. Addition of TQ did not affect the flexural and surface properties of PMMA denture base material at low concentrations (0.5%, 1% TQ) and could be incorporated into PMMA denture base material as an antifungal agent.

Effect of Resin Stages on the Dimensional Accuracy of Denture base cured by long and short curing method in a conventional water bath

Acrylic resin is the most widely used material in prosthetic dentistry and itsdimensional accuracy is most important factor in successfulness denture constructer.The aim of this study was to investigate the dimensional changes of denture baseacrylic cured by long and short curing method by using conventional water bath.60 maxillary wax bases were made and randomly assigned in 3 groups specimensaccording to the stringy, dough like and rubbery stages of the acrylic resin cured by:1-long curing cycle: curing the resin at 74 C° for 9 hours.2-Short curing cycle: processing the resin at 74 C° for 1 1/2 hour and at 100 C° for1/2 hour. Results were submitted to ANOVA and Turkey’s test and it showedthat in short curing cycle, the dough like stages presented values (0.193 mm)with statistically significant difference (P&lt;0.05) when compared with the stringy(0.246mm) and rubbery (0.240 mm) stages.While for the long curing cycle the dough stage presented values (0.199mm) withstatistically significant difference (P&lt;0.05)when compared with stringy (0.230mm)and rubbery (0.239mm) St

Effect of Henna Addition on the Surface Roughness and Hardness of Polymethylmethacrylate Denture Base Material: Anin vitroStudy

This study aimed to evaluate the effect of the addition of various henna-which can have antifungal properties-on the surface roughness and hardness of polymethylmethacrylate (PMMA) denture base material.A total of 99 rectangular-shaped (10 × 20 × 3 mm3) specimens were prepared from heat-cured acrylic resin and divided into one control group without the addition of henna and five test groups, which were prepared by adding Yamanihenna powder to polymer at concentrations of 1, 2.5, 5, 7.5, and 10 wt%. The polymer was added to the monomer, mixed, packed, and processed using the conventional water bath method. After processing, specimens were finished and polished, then kept in distilled water for 48 ± 2 hours. A profilom-eter and Vickers hardness tester were used to measure surface roughness and hardness respectively. Statistical data analysis was conducted via Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM, USA). The independent sample t-test was used and p ≤ 0.05 was considered statistically significant.The addition of henna at varying concentrations significantly increased the surface roughness values (p ≤ 0.01) while decreasing hardness (p ≤ 0.0001). The most favorable addition value was 1% henna between all henna groups.The addition of henna to the acrylic resin may negatively affect the surface properties of PMMA acrylic denture base.Antimicrobial denture with minimum deterioration effects on its physical properties could be achieved with henna addition to denture base material in low concentration. However, 1% henna showed the best results between the henna groups as regards roughness and hardness values.

Polysaccharide blended whey protein isolate-(WPI) hydrogels: A physicochemical and controlled release study

Design and characterization of composite whey protein isolate (WPI) hydrogels are gaining interest due to their utilization as controlled delivery matrices for bioactive agents. In this study, black carrot extract (BC) loaded composite WPI hydrogels, containing xanthan (XN), pectin (PC) and gum tragacanth (GT) were prepared by conventional water bath (CV) and infrared (IR) assisted microwave heating (MW). Release and swelling experiments were conducted at pH 7.0 phosphate buffer solution for 24 h. Highest swelling ratio (SR) was observed at CV XN hydrogels and only XN hydrogels showed a distinct increase in SR (17.85%) with respect to WPI hydrogels containing no additional polymer (10.55%) (p < 0.05). CV WPI hydrogels having no added polysaccharide showed the highest release percent (77.81%). CV PC, XN and GT hydrogels with release ratios of 37.15%, 32.79% and 29.39%, respectively, were capable of retarding release with respect to sole WPI hydrogels (p < 0.05). MW increased the release rates of all polymer added hydrogels. Nuclear Magnetic Resonance (NMR) relaxometry was used to understand the polymer-water interactions in the samples. Therefore, transverse relaxation times (T2) and self-diffusion coefficients (SDC) of each hydrogel were measured. Increasing T2 and SDC values of CV XN samples were associated with better gel characteristics. Scanning electron microscope (SEM) images revealed the microstructural differences between the heating and polymer types. Mathematical modelling of release behaviors of hydrogels was also conducted to estimate diffusion coefficients. Moreover, this study introduces the effects of MW-IR heating on the physiochemical and controlled release behavior of WPI-GT composite hydrogels for the first time.

Rheological and structural properties of fish scales gelatin: Effects of conventional and ultrasound-assisted extraction

ABSTRACTIn this study, the rheological and structural properties of extracted fish scales gelatin by conventional water bath (CWB) and ultrasound-assisted water bath (UWB) at different temperatures (60°C, 70°C and 80°C) were studied. Rheological behaviours showed that the extracted fish scales gelatin by UWB at 60°C possessed the highest storage modulus (5000 Pa), gelation point (22.94°C), melting point (29.54°C), and apparent viscosity than the others. X-ray showed that high temperature and ultrasound reduced the triple-helix content of fish scales gelatin along with decreasing gelling properties. Atomic force microscopy showed that the largest aggregates could be observed in the surface of UWB60. Therefore, UWB proved to be a promising technology in the extraction of high-quality fish gelatin.

Comparison of the flexural strength of polymethyl methacrylate resin reinforced with multiwalled carbon nanotubes and processed by conventional water bath technique and microwave polymerization.

Purpose:This in vitro study was done to compare the flexural strength of polymethyl methacrylate resin reinforced with multiwalled carbon nanotubes (MWCNTs) and processed by conventional water bath technique and using microwave energy.Materials and Methods:A total of 180 acrylic resin specimens measuring 65 mm × 10 mm × 2.5 mm were fabricated, with conventional water bath groups and microwave group having ninety specimens each. Ninety specimens were divided into thirty specimens as control and subgroups containing 0.025% MWCNTs and 0.050% MWCNTs with thirty specimens each. The specimens were tested for flexural strength by three-point bending test on universal testing machine. The statistical analysis was done using Student's t-test and one-way analysis of variance, and the intercomparison between each group was done using Tukey's post hoc analysis.Results:The mean flexural strength of specimens cured by water bath technique was 95.563 MPa and microwave technique was 118.416 MPa. Control Group B possesses highly significant increase in flexural strength than Control Group A with P < 0.01. Unpaired Student's t-test showed that Subgroup B1 and Subgroup B2 possess highly significant increase in flexural strength than Subgroup A1and Subgroup A2.Conclusion:Heat polymerized denture base resin with and without reinforcement of MWCNTs and polymerized by microwave technique possess higher flexural strength than heat polymerized fiber reinforced denture resin polymerized by water bath technique. MWCNTs could be used as an effective reinforcement material for denture base resin polymerized by either water bath technique or microwave energy.

Effect of Modified Nano Hydroxyapatite Fillers Addition on Some Properties of Heat Cured Acrylic Denture Base Materials

Background: Poly (methylmethacrylate) is not ideal in every aspect and has disadvantages such as insufficient surface hardness, increase water sorption and poor impact resistance and the latter being the primary cause of fracture of denture base resins. The aim of this study was to evaluate the effect of addition of silanized nano- hydroxyapatite (HA) on some properties of heat cured acrylic denture base material. Materials and methods: HA nano particles were first silanized with i§MPS (tri methacryloxypropyletrimethoxy silane coupling agent) then ultrasonicated with methylmethacrylate (monomer) to disperse agglomerated nano particles and mixed with polymer. 2% by wt of HA nano particles was selected as the best concentration that added to the denture base material according to the pilot study.(100) specimens were prepared by conventional water bath processing technique and divided to two groups: 50 specimens for control group or 0% HA and 50 for experimental group or 2% HA then each group was subdivided to five groups with 10 specimens for each test: impact strength, transverse strength, surface hardness, surface roughness, water sorption and water solubility. Results: highly significant increase in impact strength and surface hardness after addition of 2% HA nano particles but not significant decrease in water sorption whereas solubility was significantly decreased. Surface roughness was significantly increased as compared with control group but remained within the acceptable limit less than 2i­m. HA nanoparticles addition highly decreased the transverse strength value. Conclusion The addition of 2% HA nano particles considerably improved the impact strength, surface hardness and had positive effect on water sorption and solubility. Whereas the same concentration tend to highly decreased transverse strength and increase surface roughness.

Developing an Effective Method to Determine the Heat Transfer Model in Fish Myofibrillar Protein Paste with Computer Simulation Considering the Phase Transition on Various Dimensions

Abstract Numerical simulation was performed to evaluate thermal patterns of Alaska pollock (AP) surimi paste depending on the dimension and the phase transition of sol to gel during conventional water bath cooking. AP surimi paste (76 and 80 % moisture) was molded into 2, 3.5, and 5 cm cubes and heated at 90 °C. Three simulation models were developed: using average thermal properties in the cooking temperature range from 20 to 90 °C (model A); the thermal properties at the average temperature of each dimension (model B); and the thermal properties including the phase transition region of each dimension (model C). Model A showed a relatively large deviation between the simulation and experiment. Model B reflected the effect of dimension on gelation and showed better fitness (maximum RMSE=5.01 °C). The highest fitness (maximum RMSE=1.67 °C) was observed with model C reflecting both dimension difference and a phase transition.

Effect of Zirconium Oxide Nano-Fillers Addition on Mechanical Properties of Heat-Polymerized Acrylic Resin

Purpose: The mechanical strength of polymethyl methacrylate (PMMA) remains far from ideal for maintaining the longevity of denture. The purpose of this study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentration (1.5, 3, 5 and 7%) on the flexural strength, fracture toughness, and hardness of heat-polymerized acrylic resin. Materials and methods: Zirconium oxide powder with different concentrations (1.5, 3, 5 and 7%) were incorporated into heatcure acrylic resin (PMMA) and processed with optimal condition (2.5:1 Powder/monomerratio, conventional packing method and water bath curing for 2 hours at 95˚C) to fabricate test specimens of PMMA of dimensions (50 ×30 × 30 mm) for the flexural strength, fracture toughness, and (50 ×30 × 30 mm) were fabricated for measuring hardness. PMMA without additives was prepared as a test control. Three types of mechanical tests; flexural strength, fracture toughness and hardness were carried out on the samples. The recorded values of flexural strength in (MPa), fracture toughness in (MPa.m1/2), and hardness (VHN) were collected, tabulated and statistically analyzed.One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups which are statistically significant when the P value ≤ 0.05. Results: Addition of Zirconium oxide nanofillers to PMMA significantly increased the flexural strength, fracture toughness and hardness.Conclusion: These results indicate that Zirconium oxide nanofillers added to PMMA has a potential as a reliable denture base material with increased flexural strength, fracture toughness, and hardness. According to the results of the present study, the best mechanical properties were achieved by adding 7%wt ZrO2 concentration.

Estimation of the linear dimensional changes of autoclave cured acrylic resin with multiple palatal depths and investment materials

Background: Dimensional changes of acrylic denture bases after polymerization results in need for further adjustments or even ends with technical failure of the finished dentures. The purpose of this study was to estimate the linear dimensional changes for different palatal depths when using multiple investment materials and polymerization techniques. Materials and methods: Ninety upper complete denture bases were constructed for this study. They were divided into two main groups according to the polymerization methods: conventional water bath and experimental autoclave (short and long cycles). Each main group was further subdivided into three subgroups according to the palatal depth (shallow, medium and deep). Furthermore, for each palatal depth; complete denture bases were invested either with dental stone or laboratory silicone. For each upper complete denture, measurements of linear dimensional changes were done by fixation of metallic screws on the tissue surface of the denture base. The distances were measured by using travelling microscope with an accuracy of 0.001 %. The data were statistically analyzed using three way analysis of variance (ANOVA) for three variables, which were (palatal depth, investments and polymerization techniques), LSD test and student T test for comparisons between groups. Results: There were significant improvements in the dimensional accuracy of denture bases cured with autoclave compared with water bath. Also, silicone investments were a successful alternative to stone, study data shows that short autoclave processing with silicone reduces the magnitude of the linear dimensional changes. On the other hand, long autoclave processing and stone investments were better than silicone in reducing dimensional changes. Conclusion: The findings of this study indicates that the use of autoclave processing in acrylic curing is a promising alternative to the conventional water bath and leads to better dimensional stability for the finished dentures in all oral configurations and palatal depths. Also, Silicone is more preferable than stone, although it's not as strong investing materials when compared with stone.

The influence of adding of modified ZrO2-TiO2 nanoparticles on certain physical and mechanical properties of heat polymerized acrylic resin

Background: The mechanical and physical properties of Polymethyl methacrylate (PMMA) don’tfulfill the entire ideal requirements of denture base materials. The purpose of this study was to produce new modified polymer nanocomposite (PMMA /ZrO2-TiO2) andassess itsimpact strength, transverse strength and thermal conductivity in comparison to the conventionalheat polymerized acrylic resin. Materials and Methods: Both ZrO2 and TiO2nano fillers were silanized with TMSPM (trimethoxysilyl propyl methacrylate) silane coupling agent before beingdispersed by ultrasonication with the methylmethacrylate (monomer) and mixed with the polymer by means of 2% by weight in (1:1) ratio, 60 specimens were constructed by conventional water bath processing technique and divided into 2 groups: 30 specimens for control group 0% nanofillers and 30 specimens for experimental group 2% of (1:1) ZrO2 and TiO2nano fillers then each group was subdivided into3 sub-groups according to the test to be conducted with 10 specimens for impact, transverse and thermal conductivity test. Results: The interaction of TMSPM silane and the nanofillers was confirmed by FT-IR (Fourier Transform Infra-red spectrophotometer). High significant increase in impact strength (9.838) Kj/m2 and transverse strength (101.705) N/mm2 and non-significant increase in thermal conductivity (0.286) W/m.C° of heat cured acrylic resin of the new polymer nanocomposite were observed. Conclusions: The addition of 2 wt.% of ZrO2:TiO2 by means of 1:1 ratio considerably improved the impact and transverse strength and had a positive effect on the thermal conductivity.

Evaluation of direct transesterification of microalgae using microwave irradiation

Nannochloropsis sp. wet biomass was directly transesterified under microwave (MW) irradiation in the presence of methanol and various alkali and acid catalyst. Two different types of direct transesterification (DT) were used; one step and two step transesterification. The biodiesel yield obtained from the MWDT was compared with that obtained using conventional method (lipid extraction followed by transesterification) and water bath heating DT method. Findings revealed that MWDT efficiencies were higher compared to water bath heating DT by at least 14.34% and can achieve a maximum of 43.37% with proper selection of catalysts. The use of combined catalyst (NaOH and H2SO4) increased the yield obtained by 2.3-folds (water bath heating DT) and 2.87-folds (MWDT) compared with the one step single alkaline catalyst respectively. The property of biodiesel produced by MWDT has high lubricating property, good cetane number and short carbon chain FAME’s compared with water bath heating DT.

Determination of Acrylic Denture Resin Surface Roughness by Different Processing Techniques

Background: Poly (methyl methacrylate) (PMMA) seems to be the most commonly used material in the construction of denture base due to its advantages. However, it is still far from being ideal in fulfilling the physical and mechanical properties. Therefore, attempts to improve the properties of PMMA were taken by the researcher through many ways The purpose of this study was to estimate the effect of different processing techniques on surface roughness of acrylic base denture resin. Materials and Methods: A total sample of (50) specimens were prepared; these specimens were divided into 3 main processing techniques, and 5 experimental sub-groups (n=10): Group (A), acrylic denture base material processed by conventional water bath technique (74C for 1 and half hours then boiled for 30 min; Group (B), acrylic resins processed by microwave oven at (500 Watts) for 3 min; Group (C) samples processed by autoclave device with 3 different timing set up : (C1) for l0 min, (C2) for 20 min and (C3) for 30 min. This is done to make a comparison of different autoclave polymerization conditions on the surface roughness of denture base resin. Results: Statistically, there was no significant difference between the traditional water bath group technique and an autoclave system when the specimen processed at (121C/210Kpa) for 30 min. However, there was a statistically significant difference compared to other experimental groups. Conclusion: The autoclave processing technique could be the new alternative system to process the acrylic resin base material alongside the conventional methods. The experimental group prepared by autoclave system at (121C/21Kpa) for 30 min showed an improvement in the surface roughness compared to microwave and water bath techniques.

Cone restraining and head-only electrical stunning in broilers: Effects on physiological responses and meat quality

Two experiments were conducted to evaluate a new electrical stunning system for broilers. The objective of the first experiment was to evaluate the behavioral, neural, and physiological responses of 27 broilers after head-only electrical stunning while their bodies were restrained in cone-shaped holders. In the second experiment, quality of meat from 30 broilers after head-only electrical stunning in a cone-shaped restrainer was compared with that from 30 broilers stunned in a conventional water bath. Broilers were restrained in the cone with their heads positioned to facilitate a correct stun, followed by a neck cut by hand. After stunning, each broiler displayed a tonic phase, followed by minimal brain activity during bleeding. On average, heart rate was 258 ± 51 beats/min before stunning. The heart was observed to malfunction after cutting. According to the correlation dimension analyses, the score remained low. Within a confidence limit of 95%, taking into account the number of birds with a reliable electroencephalogram (n = 27), the chance of an effective stun and exsanguination with all broilers lies between 0.90 and 1.00 using a sinusoidal AC current of 264 ± 29 mA (∼130 V). After a brief learning period, operators were able to easily position the broilers in the cone in a commercial setting. The pH after chilling was 0.5 units lower (P < 0.05) in the head-only stunned group compared with the group stunned in a conventional water bath. After head-only stunning, 60% of breast fillets showed no blood splashes and 3% showed severe blood splashes compared with 20 and 27% after conventional water bath stunning. No differences in temperature and color were observed between the 2 groups. It is concluded that broilers could be restrained in a cone, followed by correct head-only stunning, neck-cutting, and unconscious shackling afterward under laboratory and commercial slaughterhouse conditions. When this procedure was used, meat quality was better compared with broilers stunned in the conventional water bath.

Effect of Zirconium Oxide Nano-Fillers Addition on the Flexural Strength, Fracture Toughness, and Hardness of Heat-Polymerized Acrylic Resin

Purpose: The mechanical strength of polymethyl methacrylate (PMMA) remains far from ideal for maintaining the longevity of denture. The purpose of this study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentration (1.5%, 3%, 5% and 7%) on the flexural strength, fracture toughness, and hardness of heat-polymerized acrylic resin. Materials and methods: Zirconium oxide powders with different concentrations (1.5%, 3%, 5% and 7%) were incorporated into heat-cure acrylic resin (PMMA) and processed with optimal condition (2.5:1 Powder/monomer ratio, conventional packing method and water bath curing for 2 hours at 95。C) to fabricate test specimens of PMMA of dimensions (50 × 30 × 30 mm) for the flexural strength, fracture toughness, and (50 × 30 × 30 mm) were fabricated for measuring hardness. PMMA without additives was prepared as a test control. Three types of mechanical tests; flexural strength, fracture toughness and hardness were carried out on the samples. The recorded values of flexural strength in (MPa), fracture toughness in (MPa.m1/2), and hardness (VHN) were collected, tabulated and statistically analyzed. One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups which are statistically significant when the P value ≤ 0.05. Results: Addition of Zirconium oxide nanofillers to PMMA significantly increased the flexural strength, fracture toughness and hardness. Conclusion: These results indicate that Zirconium oxide nanofillers added to PMMA has a potential as a reliable denture base material with increased flexural strength, fracture toughness, and hardness. According to the results of the present study, the best mechanical properties were achieved by adding 7%wt ZrO2 concentration.

Experimental Study on the Disposal of Polymer Flooding Produced Water of Oilfield by Microwave Radiation

Microwave treating polymer flooding produced water of oilfield (PFPWO) is a new technology in the sewage treatments. Compare the effect of treating water samples by conventional water bath heating and microwave radiation, and analysis the microwave radiation power and time on the effect of treatment by experiment. The result shows that the disposed effect of microwave radiation is better than conventional water bath heating for PFPWO, and there exists a best power and time. It can be seen that microwave treatment has a good prospect for promoting.