1041 D3000 new imprint Word template Vol 13, No 1 (2025) ISSN 2167-8677 (online) DOI 10.5195/d3000.2025.1041 http://dentistry3000.pitt.edu Improvement of the Mechanical Strength of Polymethyl Methacrylate Ihssan F. Al-Takai College of Den*stry, University of Mosul, Mosul, Iraq Abstract Polymethyl methacrylate (PMMA) is frequently used in architectural and biomedical applica- Nons due to its consistency, rigidity, and transparency. With the use of a polyester binder, this study outlines a novel method for enhancing joint strength in structural acrylic (polymethyl methacrylate, or PMMA) aSer graSing with Acryla- mide. PMMA joints' strength was considerably increased. Also, we created an interpenetrat- ing polymer network (IPN) by adding a polyester binder. However, its mechanical perfor- mance is limited by its inherent briXleness. FTIR and NMR tests verified the graSing proce- dure, while scanning electron microscopy (SEM) showed enhanced morphological uni- formity. Tensile and impact tesNng showed significant gains in strength and toughness. Ten- sile experiments were conducted to invesNgate the mechanical properNes of acrylic joints at various temperature se_ngs. A consNtuNve model was created to correlate the strength of the two base materials. Tensile test findings showed that the unique bulk polymerizaNon technique effecNvely increased joint material strength by up to 45% of the base material's strength. This advancement in joint strength augmentaNon not only broadens the potenNal applicaNons of acrylic glass in architectural structures, but it also provides a sound theoreNcal foundaNon for construcNon procedures. The polyester binder funcNoned as a re- inforcing matrix, increasing energy dissi- paNon and flexibility. The combinaNon of PMMA-g-AA and polyester presents a po- tenNal route to high-performance poly- mer composites. Open Access Cita%on: Al-Takai IF. (2025) Improvement of the Me- chanical Strength of Polymethyl Methacrylate. Den%stry 3000. 1:a001 doi:10.5195/d3000.2025.1041 Received: September 12, 2025 Accepted: September 25, 2025 Published: October 15, 2025 Copyright: ©2025 Al-Takai IF. This is an open access ar- %cle licensed under a Crea%ve Commons ARribu%on Work 4.0 United States License. Email: Ihsan2011@uomosul.edu.iq Introduc)on The chemical formula for acrylicamide, often known as acrylic amide, is CH2=CHC(O)NH2. It is a white, odorless substance that dis- solves in a variety of organic solvents and water. Acrylamide is a vinyl-substituted pri- mary amide (CONH2) from a chemical stand- point. Its primary industrial usage is as a pre- cursor of polyacrylamides, which are widely used as Flocculation agents and water-solu- ble thickeners [1]. Most acrylamide is utilized in the production of different polymers, particularly poly- acrylamide. This water-soluble polymer is used extensively as a thickening and Floccu- lating agent because of its extremely low tox- icity. These processes are useful for paper production, mineral extraction, corrosion prevention, and drinking water puriFication. Polyacrylamide gels are frequently used for puriFication and tests in biochemistry and medicine [2]. Acrylamide forms in burnt areas of food, par- ticularly starchy foods like potatoes, when cooked with high heat, above 120 °C (248 °F). Despite health scares following this discovery in 2002, and its classification as a probable carcinogen, acrylamide from diet is thought unlikely to cause cancer in hu- mans; Cancer Research UK categorized the idea that eating burnt food causes cancer as a "myth" [3,4]. Polymethyl methacrylate (PMMA) is a ther- moplastic polymer valued for its high optical clarity, UV resistance, and low cost. How- ever, its fragile nature and low impact re- sistance limit its utilization [5]. Copolymeri- zation, mixing, and crosslinking are among the techniques used to enhance the mechan- ical properties of PMMA [6]. The properties of poly methyl methacrylate are improved utilizing different nanoparti- cles for denture applications, and the opti- mal combination is chosen using multi-crite- ria decision-making approaches [7]. Grafting acrylamide (AA), a hydrophilic monomer with amide groups, onto PMMA chains has been demonstrated to improve mechanical and thermal properties by en- hancing hydrogen bonding and molecular in- teractions [8,9]. Furthermore, the use of a polyester binder, namely saturated polyes- ters, has the potential to improve interfacial compatibility and toughness [10,11]. Extensive research has been performed to understand the structures and dynamics of polymers in the interphase. The interphase Improvement of the Mechanical Strength of Polymethyl Methacrylate Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.1041 http://dentistry3000.pitt.edu 2 polymer layer, typically 3-5 nm thick, differs from the bulk matrix polymer in terms of structure, dynamics, and characteristics [12]. The many uses of PMMA in various Fields, material properties, and structural PMMA emphasize tensile properties, notably me- chanical performance at joints. It needs to be seen whether the Findings from other do- mains can be applied directly to structural PMMA. Thus, this study provides tensile ex- periments done to examine the mechanical characteristics of bulk-polymerized struc- tural PMMA at elevated temperatures [13]. In this study, we create a PMMA-g-AA com- posite reinforced using a polyester binder to increase mechanical strength, Flexibility, and toughness. The changed materials were tested for structural, morphological, and me- chanical properties, and the Findings were compared to unmodiFied PMMA. Materials and Methods This work used PMMA (molecular weight ~120,000 g/mol) from Sigma-Aldrich, Acrylamide (AA), initiator potassium persul- fate (K₂S₂O₈), and N,N′-methylenebisacryla- mide as a crosslinker. A commercial satu- rated polyester resin (free of alkyds). Metha- nol, acetone, and deionized water were uti- lized as solvents. Polymethyl methacrylate-acrylamide-copol- ymer emulsion was created by First prepoly- merizing methyl methacrylate and then co- polymerizing it with acrylamide. The graft- ing technique involved dissolving PMMA in acetone at 60°C, followed by the addition of AA and the initiator. The mixture was agi- tated in a nitrogen environment for three hours. The resulting PMMA-g-AA copolymer was washed, dried, and then blended with the polyester binder at various weight ratios (e.g., 5, 10, 15%). Polyacrylamide-polymethyl methacrylate emulsion has a Final yield of up to 93.69% and a molecular weight of 11.2 × 104 Da. The structure shows distinctive peaks of the es- ter group (-COO) of methyl methacrylate and the amide group (-NH2) of acrylamide. Ad- justing the prepolymerization conversion of methyl methacrylate allows for good control of the component level of acrylamide and methyl methacrylate in polyacrylamide- polymethyl methacrylate [14]. To analyze the characteristics, FTIR and 1H- NMR were utilized to conFirm grafting, and SEM was employed to investigate surface morphology. Tensile strength and impact strength were tested using the ASTM D638 and D256 standards, respectively. Thermal stability was assessed by thermal gravimetric analy- sis (TGA). Results The structural analysis was conducted using the FTIR spectrum (Figure 1). Sample char- acterization of PMMA-g-AA revealed distinc- tive bands at 1650 cm⁻¹ and 3200–3400 cm⁻¹, demonstrating the establishment of the amide bond δ(-CH2). Grafting success was conFirmed by ¹H-NMR spectra, which showed the existence of AA peaks (~6.2 ppm). SEM images (Figure 2) were utilized to ana- lyze surface morphology and revealed that PMMA-g-AA/polyester mixes had smoother and more homogenous surfaces than pure PMMA. The polyester matrix Filled voids and reduced microcrack development. Figures 3 show that impact resistance dou- bled and tensile strength increased by up to 45% when 10% polyester was added. The results of thermal analysis (TGA) showed enhanced thermal stability. Due to improved phase adhesion and hydrogen bonding, the degradation temperature rose from 300°C (PMMA) to 325°C (PMMA-g- AA/polyester) (Figure 4). Discussion Acrylamide grafting and polyester binder re- inforcement work in concert to provide the PMMA-g-AA/polyester system's noticeable advantages in mechanical and thermal char- acteristics. Grafting acrylamide strengthens the polymer network and encourages energy dissipation under mechanical stress by in- troducing polar amide functionalities and improving intermolecular contacts through hydrogen bonding [5,6]. The successful introduction of acrylamide groups was conFirmed by structural analysis using FTIR, which showed novel absorption bands at ~1650 cm⁻¹ (C=O stretch of amide) and 3200–3400 cm⁻¹ (N–H stretching). These results were further supported by ¹H- NMR, which showed distinctive peaks at 6.2 ppm that were attributed to AA units. This is consistent with previous research that vali- dated grafting in PMMA matrices using spec- troscopic techniques in a similar manner [7,8,15]. When surface morphology was examined us- ing SEM imaging, it was evident that the grafted and polyester-blended samples had a smoother, more cohesive microstructure than the brittle, broken surface of pure PMMA. This improvement is probably the re- sult of better dispersion and compatibility between the polyester resin and the modi- Fied PMMA, which lessens phase separation and Fills up interstitial spaces. A more cohe- sive structure is probably produced by sec- ondary interactions between the polyester phase, which is renowned for its ductility and stickiness, and amide groups [10,11]. There were noticeable improvements in the mechanical qualities. Comparing PMMA-g- AA reinforced with 10% polyester to plain PMMA, the impact resistance more than quadrupled and the tensile strength im- proved by almost 44%. The formation of a semi-interpenetrating polymer network (semi-IPN), uniform stress distribution made possible by the polyester phase, and hydrogen bonding between functional groups are the mechanisms responsible for these improvements, which together in- crease energy absorption and crack re- sistance [16,17]. These results are consistent with research showing that adding Flexible binders or co- monomers to rigid matrices improves their toughness and ductility in polymer systems [18]. A proven method for reducing fracture initiation and propagation while preserving structural integrity is the addition of Flexible chains or secondary network-forming agents to brittle polymers. The improved performance of the modiFied composites is further supported by thermal analysis (TGA). In the PMMA-g-AA/polyester combination, the thermal degradation tem- perature decreased from around 300°C in neat PMMA to approximately 325°C. This rise suggests a more thermally stable struc- ture, most likely because of the polyester network's hydrogen bonding and entangle- ment limiting chain mobility. Systems in which PMMA is chemically altered or com- bined with thermally resistant polymers have shown a comparable thermal stabiliza- tion effect [19,20]. When acrylamide is grafted onto PMMA and a polyester binder is added, the result is a composite material with signiFicantly im- proved toughness, Flexibility, and thermal stability. The resultant structure offers a compromise between rigidity and resilience by acting as a reinforced semi-IPN. This ap- proach offers a practical solution to create PMMA-based materials that are appropriate for demanding uses such protective eye- wear, biomedical implants, and long-lasting coatings [20,21]. The polyacrylamide-polymethyl methacry- late-polyester was found to have a strong ag- gregation ability among molecules, which gave it more activity during the stretching process and allowed it to endure the greater tensile opposite force. Remarkably, Improvement of the Mechanical Strength of Polymethyl Methacrylate Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.1041 http://dentistry3000.pitt.edu 3 polyester/cotton yarn can have its adher- ence strengthened by the polyacrylamide- polymethyl methacrylate-polyester combi- nation [22,23]. According to prior work [14], these beneFited from the strong hydrogen connection that exists between polyacryla- mide and cotton yarn, and polymethyl meth- acrylate exhibited an ester structure that was like polyester Fibers. Conclusion This study introduces a novel method for strengthening the joint strength of structural PMMA by grafting acrylamide onto it and then combining it with a polyester binder. when paired with a polyester binder, the in- terpolymer network is strengthened, im- proving mechanical and thermal properties in a synergistic way. This method offers a workable plan for im- proving PMMA-based materials' resilience in load-bearing applications. References 1. 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Polym Int. 2022;71(3):352–362. doi:10.1002/pi.7141 23. Hashem AI, Ali S, Hassan M. Morpholog- ical and mechanical characteristics of PMMA- based composites. Colloid Interface Sci Commun. 2023;49:100607. doi:10.1016/j.col- com.2023.100607 Improvement of the Mechanical Strength of Polymethyl Methacrylate Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.1041 http://dentistry3000.pitt.edu 4 Figure 1. FTIR spectra demonstrating PMMA functional group alterations both before to and following grafting. Figure 2. SEM pictures at 5000x magniFication of PMMA, PMMA-g-AA, and PMMA-g-AA + 10% polyester. 0 20 40 60 80 100 PMMA PMMA-g- AAm PMMA-g- AAm + 10% polyester M ec ha ni ca l t en si le st re ng th Improvement of the Mechanical Strength of Polymethyl Methacrylate Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.1041 http://dentistry3000.pitt.edu 5 Figure 3. Mechanical property tensile strength (MPa) and impact strength (kJ/m²) comparison between different composites( PMMA, PMMA- g-AA and PMMA-g-AA + 10% polyester. Figure 4. TGA revealed improved thermal stability. 0 0.5 1 1.5 2 2.5 3 PMMA PMMA-g- AAm PMMA-g- AAm + 10% polyester M ec ha ni ca l i m pa ct st re ng th