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The impact of pressure-assisted thermal processing (PATP) on selected polymeric food packaging materials was studied. Two commercially available packaging materials called APP (combination of biaxially oriented and PVdC coated polyester with a sealing layer against polypropylene) and BPE (combination of biaxially oriented polyester with coextruded barrier film of the structure polyethylene/EVOH/m-polyethylene) were pressurized at 600 MPa for 10 min, at 70°C. The impact of combined pressure-heat treatment on the change of packaging materials was assessed by SEM (Scanning Electron Microscopy). In addition, visual examination was performed for the treated APP and BPE materials. The results showed that the combined extreme pressure-heat treatments can compromise the integrity of both packaging materials. Opaque areas, delaminations and dark spots were a general consequence of the pressure-assisted thermal processing of tested packaging materials.

Replacing weak soil layer by a gravel cushion is a usual consolidation method, wich has been improved lately by inserting in the gravel cushion reinfocements, analogical to concrete reinforcement, aiming to increase the bearing capacity of the foundation soil. This paper presents some aspects regarding geosinthetical materials behaviour used to reinforced the gravel cushion as much as the effect on stresses distribution and displacements in gravel and surrouding soil. This study has been conducted trough experimental tests and numerical analysis. The conducted analysis is statical and nonliniar. The calculus of the study consists of: displacements of the soil, the values of the stresses in inner part of the gravel layer and in the geosinthetic materials. Noticing that the disposal of the reinforcements leads to decrease stresses and displacements values at the foundation level but also at the gravel layer base.

The purpose of this study is associated to the investigation of the acrylic teeth denture base resin interface with invasive tests such as tensile testing. 30 large size artificial acrylic first upper molars (Spofadent Plus_Spofa Dental) were milled to 30 acrylic cylinders. The cylinders were randomly assigned in three experimental groups, so that 10(ten) cylinders were distributed to each one of the three (3) experimental sample groups. The bonding flat surfaces of the cylinders were submitted to a different treatment: Group 1: (control group_without treatment), Group 2: Benzene, Group 3: Toluene. For the chemical treatment procedures, organic solvents with 98.9% chemical purity were used. The bonding test samples were realized according to ADA specification No. 15, using a self-cured denture base repair resin (Duracryl–Spofa Dental, Kerr Company). Each sample was stored for 30 days in distilled water and in tensile tested at 1 mm/min speed. The mean values of the tensile bond strength test registered were statistically significant among groups, ranging from 26.5 MPa (group 1) to 23.13 MPa (group 3). The results of this study suggest the fact that the chemical treatment with the mentioned organic solvents improves not in a significant manner the adhesion of the acrylic teeth to the denture base resin.

The effects of stearic acid treated dolomite (Sa-Dol) on the mechanical, morphological and thermal properties of polypropylene (PP) composite were studied. Prior treatment, raw dolomite was ground in planetary mill using different grinding time to obtain the submicron size (under 10mm). Particle size and specific surface area of dolomite was analyzed and validated using particle size analyzer (Malvern Mastersizer) and Brunauer-Emmett-Teller (BET) method respectively. Dolomite with five filler loadings (5, 10, 15, 20 & 25%) were mixed with PP thermoplastic and were compounded using hot melt blending method. Fourier Transform Infrared (FTIR) spectroscopy confirms the successful of filler treatment using stearic acid according to the new peak at 2917 cm--1 attributed to the alkyl group that represented the addition of C-H bond. Tensile properties indicated that tensile strength of PP/Dol decreased with the increasing of filler loading for both systems. The elongation at break decreased with filler loading and showed better and improved result after treatment with stearic acid. The incorporation of stearic acid coated filler into PP matrix enhanced the break elongation of the composites that makes the composites more ductile. Morphological analysis using Scanning Electron Microscopy (SEM) proved better interfacial adhesion and less agglomeration of dolomite filler after treatment with stearic acid at low filler loading (5 wt.%).

The purpose of this study was to determine the three-dimensional coating thickness of two scan sprays used in labside digitalization. An assembly consisting of a CoCr tooth with a standard full ceramic crown preparation and a three-dimensionally printed PLA base was duplicated twenty times out of type IV plaster. The plaster models were digitized using a three-dimensional scanner and reference virtual models were acquired (REF). A homogenous coat of spray A was applied on all models and the models were rescanned. After digitalization, the models were steam cleaned and the same technique was used for spray B. The reference scans were compared separately with the scans of group A and B. The resulting data was analyzed with the Student unpaired t-test (a = .05). While there were significant intergroup differences in the three-dimensional comparison of the root mean square of deviations, both scan sprays showed acceptable coating thicknesses for clinical use.

This investigation concerns the preparation of binary PPR/SEBS and PPR/SBS blends by melt mixing procedure with the goal of studying the effect of thermoplastic elastomers on performance of polypropylene random copolymer (PPR) in the extrusion and injection molding processes. Effect of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and poly(styrene-b-butadiene-b-styrene) (SBS) respectively on the mechanical and thermal properties of PPR have been investigated. The melt processability, melt flow index (MFI), tensile properties, VICAT softening temperature (VST), heat deflection temperature (HDT), Shore hardness and IZOD measurements highlighted that SEBS is more efficient than SBS.

The paper concerns current engineering in plastics processing, the present day studies focusing on the rational solving of problems and on logical reasoning, on the usage of modern mathematical methods in leading and taking decisions, on the usage of instruments which have significantly changed and the development of business: computers, the internet, artificial intelligence. The practice uses engineering techniques by creating mathematical models. Appealing to scenarios ensures the improvement of decisions, involving answers on the improvement of quality and the rational usage of available human and financial resources. The research results are materialized through the development and effective use of a mathematical model in which the incoming data packets are obtained at a quantifiable levels of risk.

The obturators are prostheses used to close palatal defects after maxillectomy, to restore masticatory function and to improve speech, deglutition and esthetics. The most commonly used materials in manufacturing maxillary obturator prosthesis are the acrylic resins. The aim of the paper is to present experimental compression and traction tests in order to determine the material properties of Meliodent® Heat Cure produced by Heraeus Kulzer GmbH Germany. This is a two component heat curing polymer used for manufacturing fixed and removable prosthetic devices. Test results show that the average compressive strength of the samples is 94 MPa, while the average compression modulus for all resin samples tested was calculated at 716 MPa. The average ultimate tensile strength of the samples is 58.72 MPa and the average modulus of elasticity for all resin samples tested was determined to be 4213 MPa.

The loss or absence of an eye creates not only a functional disability, but also an important psychological impact on an individual’s social and professional life. Ocular prostheses are maxillofacial prosthetic devices which are generally custom made to replace a lost eye. Polymethyl methacrylate (PMMA) is the most common material used for manufacturing ocular prostheses. The main component of the ocular prostheses is the artificial iris that needs to be identical to the healthy one. For this reason manufacturing the iris is a challenging task for the maxillofacial anaplastologist. The main procedure used in manufacturing the iris is the manual painting technique which can be time consuming and susceptible to error, mainly regarding the color matching. The subject of this article describes an alternative technique of manufacturing the iris. This technique involves using a digital photographing image of the healthy eye which is edited and printed on photographic paper and it seems to offer good esthetic results being less complicated compared to the conventional manual painting technique. The main deficiency of the method is the color distortion which appears after the iris is embedded in the ocular prosthesis. This is caused by an alteration of the photographic paper during the final polymerization stage of the ocular prosthesis which takes place at high temperature.

Tracheal stenosis is a condition where the trachea narrows or becomes constricted as a result of a laryngotracheal trauma, prolonged tracheal intubation, high tracheostomy or systemic diseases.A possible treatment for tracheal stenosis is tracheal reconstruction with costal cartilage grafts that are implanted into the anterior tracheal wall. In order to secure the graft cartilage to the tracheal sidewalls we can use differnt synthetic resorbable materials, such as polylactic acid and polyglycolic acid, that allow anchoring of the costal cartilage to the tracheal wall. The aim of this paper is to present a fixation device for fixing the cartilage graft on the tracheal side walls. This device is designed using a synthetic resorbable material and allows anchoring of the costal cartilage to the tracheal wall using microscrews made of resorbable material.