Papers by Keyword: Polymethyl Methacrylate (PMMA)

Abstract: Polymethylmetharylate (PMMA) has been widely used for aircraft canopies and transparent structural components, and processed into various parts through vacuum forming. In this study, the effects of forming speed and deformation characteristics on thickness uniformity during high-temperature vacuum forming of PMMA were analyzed. First, creep tests and high-temperature tensile tests were conducted at the specimen level to quantitatively distinguish between creep deformation and plastic deformation. Creep tests were performed under constant temperature and load conditions, and strain was measured through Digital Image Correlation. For plastic deformation analysis, tensile tests at room temperature and elevated temperatures were carried out to compare yield strength and elongation changes. To analyze thickness uniformity during the forming process, rectangular-shaped parts were fabricated using vacuum forming under various conditions where temperature and forming speed are key variables. After forming, thickness uniformity and surface transparency of the products were measured. Additionally, internal structural changes according to forming speed and temperature conditions were analyzed, and a comprehensive evaluation of material stability was performed.

Abstract: In this study, the thermomechanical behavior of PMMA(poly-methyl methacrylate) during high-temperature vacuum forming was analyzed through both experimental and computational approaches. The material behavior of PMMA was modeled as a temperature and strain-rate dependent viscoplastic response, coupled with time-dependent creep deformation. The creep behavior was represented by the Norton–Bailey power law (Eq. 1), while the constitutive model for the strain rate and temperature-dependent stress-strain behavior was implemented in ABAQUS via a user subroutine (UHARD). The forming process was simulated by using ABAQUS/Standard VISCO solver, incorporating vacuum pressure loading and clamping conditions. The numerical framework enables effective analysis of deformation behavior under thermomechanical forming conditions and provides a basis for process-oriented modeling of PMMA vacuum forming.

Abstract: Polymethylmethacrylate (PMMA) cement has been used in orthopedics for more than 70 years. The advantages of PMMA bone cement include high compressive strength, stickiness, deformable ability and rapid self-setting. But the heat produced during polymerization would hinder the recovery. In order to improve the properties, in this research we added tetracalcium phosphate (TTCP) into polymethylmethacrylate cement as TP cement. A serious of characterizations including thermal property study, compression strength and micor-CT evaluation were carried out. According to the results, the polymerization heat was significantly reduced for the TP cement. The compressive strength was also enhanced with TTCP addition. TP-10 had better properties. As to thermal tests, TP-40 showed better results. Micro CT was used to monitor the composition inside the materials, and the results showed that TTCP was well dispersed in the PMMA matrix. The composite PMMA bone cement adding with tetracalcium phosphate seemed to be a potential candidate as low temperature product.

Abstract: In this study, novel composites materials composed of polymethyl methacrylate (PMMA) reinforced ZrO₂-Al₂O₃-SiO₂ filler system were developed. Zirconia-alumina-silica filler system were synthesized through sol-gel technique. Chitosan and trimethoxypropilsilane (TMPS) were used to modify the composites system. The resulting composites material were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and hardness test. SEM images displayed the composites particles in nanometer size with minor agglomeration. The XRD results revealed the presence of cubic and tetragonal phase of zirconia and also monoclinic silica phases in the composites system. These crystallographic characteristic could affect the mechanical properties of the composites. The hardness value for un-modified composites was 15.27 ± 0.25 VHN and for TMPS 19.43 ± 1.89 VHN and chitosan modification 18.75 ± 2.05 VHN, respectively. Therefore, these novel composites materials composed of PMMA reinforced filler system of zirconia-alumina-silica would provide the potential to apply in dental technology.