Search results

The main purpose of polymeric mixtures manufacturing is wish to eliminate or reduce drawbacks which polymers are characterised by and also to strive for reduction of the price of expensive polymers with particular very precious properties by mixing them with cheaper polymers but without significant deterioration of their properties. In the work some investigation results have been presented for PA6 which is miscible in viscoelastic state with polymer, with ability to create physical bounds with substances of inorganic as well as organic origins. For this purpose, polyvinylpyrrolidone (PVP) has been used with law molecular weight (10 ± 2,5 thousand). The functionalactive material was prepared with sharp tuning sorption ability across physical modification polycapramide mixed from bipolar polyvinylpyrrolidone in batch – free state, which characterises high ability complex. In the paper, some results of chosen properties of PA with the addition of polyvinylpyrrolidone (PVP) have been presented. In chance of mixing PA6 with PVP forms solution PVP in PA6, to which proper are large intermolecular influence, in this case hydrogen bond. It is possible to foresee that under the influences of large tangent stresses and intermolecular interaction colloidal solution PVP in PA forms with sure homogeneity, after cooling of it the inversion of winding phases is not noticeable In the mixtures on the basis of such polymers the intermolecular interactions occur, and they differently influence parameters of the modified materials. Conducted investigations have proved opportunity of physical modification of PA6 during mixing, in viscoelastic state, with polyvinylpyrrolidone. The modified polymer has dielectric properties and a reduced susceptibility to water absorption. It can be used as an insulation material, in all industrial sectors, including the energy sector.

For examinations, the following mixtures were made out: PA 99%/PVP 1%, PA 98%/PVP 2%, PA 90%/PVP 10%. Making mixtures out was begun with weighing elements out on numerical Sortorius AG GO TTINGEN scales and CAS MODEL: SW-1 (PA, PVP). Next elements of mixture were mixed with themselves mechanically. The process of drying was carried out in the ZELMET drier with the thermal kc-100/200 chamber in the temperature 80 °C for 12 h. The process of mixing up was carried out in the arrangement plasticising injections moulding machine of the voluted KRAUSS MAFFEI company KM 65-1600C1 (D screw = 30 mm and the L = 27D, the nozzle about d = 4 mm and the l = 2d) at the following parameters: is the nozzle temperature 230 °C, the speed of turnovers of the screw 210 obr/min. Granulated product of mixtures were get on the rotor grinder. Samples for examinations were made on the computer-operated injection moulding machine of type of KM 65-1600C1 of the KRAUSS MAFFEI company. The conditions which complement the homogeneity of a mixture – these include mixing processes with high shear stresses with the range of temperatures for viscoelastic state for the individual polymers. Such conditions are met by multiple mixing in the injection machine cylinder with extended perpetual screw length (L/D = 25 ÷ 42). Permanent conditions of injecting samples for the research on physical properties were the following: nozzle temperature – 230°C; worm area I temperature – 190°C; worm area II temperature – 210°C; worm area III temperature – 230-245°C, mould temperature 40°C, injection pressure – 60 MPa, clamping time – 5 s, cooling time – 30 s The research on chosen physical properties of getting polymer materials was carried out: hardnesses on hardness testing machine, impact resistance by Charpy’s method, mechanical properties while tension over the endurance machine the INSTON with tension speed of 90 mm/min, softening point by Vicat’s method was determined using testing machine type HAAKE N8, the investigation of DSC method and DMTA method using testing machine type Netzsch, water absorbing power test. The research on the structure was also carried out on the optical microscope type NIKON ECLIPSE E200.

In the paper, for the physical modification of PA 6, the polyvinylpyrrolidone (PVP) – amorphous polymer which is capable of ionisation and creation of complexes with the transition of the charge with many electrophilic compounds and also proton donors have been used. PVP does not change into the viscoelastic state but it is easily soluble in organic and inorganic solvents and the best in water. Its characteristic is high sorption capacity. As a result of ionisation changes PVP preserve the conformation changes. In case of mixing of polar PA6 polymers with PVP, a PVP solution is being created in PA, to whom big intermolecular interactions are proper for, in it hydrogen bonds. Reducing of polarity occurs of both polymers as a result of hydrogen bonds in created macromolecules. Macromolecule so they are interfering easily in fused condition creating the mixture about reliable homogeneity. An effect is applying to mixing with PA6 in case of dissolving PVP in the PA6 stop under the influence of big adjacent tensions in screw extruder what is calling changes of the supermolecular structure and properties of the material after chilling of stop in the form during injecting. The resultant homogeneous mixture is marked by one reflex narrowed in comparison with output PA6 of melting visible on DSC thermogram with moving to the page of higher tmmax temperatures. PA6/PVP mixtures are also providing effects of examinations about the homogeneity with DMTA method which shows results that the mixture is marked by one reflex of mechanical losses on the plot from (T_g) from the maximum at bigger than PA6 T_g (about 10 ÷ 15°C), and it is possible at the same time to reason that the mixture has not very thick frictional network as a result of the exchange of intermolecular bonds what is displayed itself in the increase in T_g intensity. The results of investigations show that PA with PVP additions create more stable material with visible homogeneity (due to strong intermolecular interactions) which is characterised by satisfactory mechanical properties which insignificantly differ from PA6 properties, but which shows higher deformability and sorptive power.

The results of investigations show that PA with PVP additions create more stable material with visible homogeneity (due to strong intermolecular interactions) which is characterised by satisfactory mechanical properties which insignificantly differ from PA6 properties, but which shows higher deformability and sorptive power. The modified polymer has dielectric properties and a reduced susceptibility to water absorption. It can be used as an insulation material, in all industrial sectors, including the energy sector.

The purpose of this paper is to study the effect of treatment using hydrophilic and hydrophobic polymers on mechanical properties and/or water absorption of paper sheets.

Paper sheets produced from paper grade wood pulp were dipped in polyacrylamide (PAA), polymethylmethacrylate (PMM) and polyvinyl alcohol (PVA) polymer solutions, respectively. The effects of using different polymer solutions (PAA, PMM and PVA), as well as the effects of dipping time (1, 5 and 10 min) and concentration of polymer (0.5, 1, 2 and 3 per cent), on the mechanical properties as well as water absorption of paper sheets were investigated.

It was found that the treatment of paper sheets with different polymer solutions improved mechanical properties as well as water absorption of paper sheets when the polymer concentration was below 1 per cent and the dipping time did not exceed 5 min.

Paper sheets resulting from treatment using hydrophilic polymers can be used as printing papers as the printability improves because water absorption improves, while paper sheets resulting from using hydrophobic polymers can be used for packaging because water adsorption is less and breaking length improved.

Improving some mechanical properties and/or water absorption of paper sheets. The improvement of dipped sheets increased by increasing dipping time till 5 min and by increasing polymer concentration till 1 per cent. Utilisation of PAA led to best results especially when it was hydrolysed.

The mechanical and tribological properties of polymers and polymer composites vary with different environmental conditions. This paper aims to review the influence of humidity/water conditions on various polymers and polymer composites' mechanical properties and tribological behaviors.

The influence of humidity and water absorption on mechanical and tribological properties of various polymers, fillers and composites has been discussed in this paper. Tensile strength, modulus, yield strength, impact strength, COF and wear rates of polymer composites are compared for different environmental conditions. The interaction between the water molecules and hydrophobic polymers is also represented.

Pure polymer matrices show somewhat mixed behavior in humid environments. Absorbed moisture generally plasticizes the epoxies and polyamides and lowers the tensile strength, yield strength and modulus. Wear rates of PVC generally decrease in humid environments, while for polyamides, it increases. Fillers like graphite and boron-based compounds exhibit low COF, while MoS2 particulate fillers exhibit higher COF at high humidity and water conditions. The mechanical properties of fiber-reinforced polymer composites tend to decrease as the rate of humidity increases while the wear rates of fiber-reinforced polymer composites show somewhat mixed behavior. Particulate fillers like metals and advanced ceramics reinforced polymer composites exhibit low COF and wear rates as the rate of humidity increases.

The mechanical and tribological properties of polymers and polymer composites vary with the humidity value present in the environment. In dry conditions, wear loss is determined by the hardness of the contacting surfaces, which may not effectively work for high humid environments. The tribological performance of composite constituents, i.e. matrix and fillers in humid environments, defines the overall performance of polymer composite in said environments.

The purpose of this paper is devoted to application of the emulsion polymer of poly(methyl methacrylate-co-butyl acrylate) prepared with in situ nano-silica as a novel tanning agent of hide to partly or totally replace chrome salt and to improve physical, thermal and mechanical properties of the tanned leather and to reduce the environmental impact of chrome tanning effluent.

Polymer/nano-silica hybrid emulsions were prepared via in situ seed emulsion polymerisation. The prepared polymers were characterised for solid content, molecular weight, viscosity, drying time, minimum film-forming temperature (MFFT) and microstructures (via transmission electron microscopy). The mechanical, thermal and surface morphological (by scanning electron microscope) properties of the treated samples were also investigated. The influences of the increase in the content of organic nano-silica on the properties of the tanned leather are discussed.

It was found that the viscosity, the particle size and the solid content of the prepared polymers increased as the content of the nano-silica increased while gloss and drying time of the resulting polymer film decreased. Tanning buffalo hide by Polymer F (containing a high content of nano-silica) gave desirable properties in terms of tensile strength, thermal stability and shrinkage temperature.

This paper discusses the preparation and the characterisation of emulsion polymers with in situ nano-silica and their application in tanning process to enhance and improve the leather quality, as well as reduce the use of chrome tanning materials and consequently chrome tanning waste.

The tanned leather showed an improvement of physico-mechanical properties and enhancement of thermal stability. Furthermore, the tanned leather has uniform colour, softness and firmness of grain. All these promising results provide evidence to support the applicability of the prepared co-polymer/nano-silica emulsions as an efficient tanning agent that also provides lubricating properties for leather.

Since May 2015, REACH Annex XVII restricts Cr(VI) in leather articles or leather parts of articles that come into contact with skin to a concentration of less than 3 mg/kg. Cases of discovery of Cr(VI) in leather papers have been reported by the European rapid alert system on dangerous consumer products (RAPEX). The emulsion poly (methyl methacrylate-co-butyl acrylate) with in situ nano-silica that has been developed via the study reported in this paper is one of the better technologies for the reduction of chromium ratio used in tanning industry.

The issues concerning the prediction of changes in properties of polymer materials as a result of adding reinforcing fibers are currently widely discussed in the field of polymer material processing. This paper aims to present strengths and weaknesses of composites based on polymer materials strengthened with fibers. It touches upon composite cracking at the junction of a matrix and its reinforcement. It also discusses the analysis of changes in properties of chosen materials as a result of adding reinforcing fibers. The paper shows improvement in the strength of polymer materials with fiber addition, which is extremely important, because these types of composites are used in the aerospace, automotive and electrical engineering industries.

Comparing the properties of matrix strength with fiber properties is practically impossible. Thus, fiber tensile strength and composite tensile strength shall be compared (González et al., 2011): tensile (glass fiber GF) = 900 [MPa], elongation ΔL≈ 0; yield point (polyamide 66) = 70−90 [MPa], elongation Δ[%] = 3,5-18; tensile (polyamide 66 + 15% GF) = 80-125 [MPa], elongation Δ[%] ≈ 0; tensile (polyamide 66 + 30% GF) = 190 [MPa], elongation Δ[%] ≈ 0; yield point (polyamide 6) = 45-85 [MPa], elongation Δ[%] = 4-15; tensile (polyamide 6 + 15% GF) = 80-125 [MPa], elongation Δ[%] ≈ 0; tensile (polyamide 6 + 30% GF) = 95-130 [MPa] elongation Δ[%] ≈ 0. Comparison of properties of selected polymers and composites is presented in Tables 1−10 and Figures 1 and 2. The measurement methodology is presented in detail in the paper Kula et al. (2018). The increase in fiber content (to the extent discussed) leads to the increase in yield strength stresses and hardness. The value of yield strength for polyamide with the addition of fiberglass grows gradually with the increase in fiber content. The hardness of the composite of polyamide with glass balls increases together with the increase in reinforcement content. The changes of these values do not occur linearly. The increase in fiber content has a slight impact on density change (the increase of about 1 g/mm³ per 10 per cent).

The use of polymers as a matrix allows to give composites features such as: lightness, corrosion resistance, damping ability, good electrical insulation and thermal and easy shaping. Polymers used as a matrix perform the following functions in composites: give the desired shape to the products, allow transferring loads to fibers, shape thermal, chemical and flammable properties of composites and increase the possibilities of making composites. Fiber-reinforced polymer composites are the effect of searching for new construction materials. Glass fibers show tensile strength, stiffness and brittleness, while the polymer matrix has viscoelastic properties. Glass fibers have a uniform shape and dimensions. Fiber-reinforced composites are therefore used to increase strength and stiffness of materials. Polymers have low tensile strength, exhibit high deformability. Polymers reinforced by glass fiber have a high modulus of elasticity and therefore provide better the mechanical properties of the material. Composites with glass fibers do not exhibit deformations in front of cracking. An increase in the content of glass fiber in composites increases the tensile strength of the material. Polymers reinforced by glass fiber are currently one of the most important construction materials and are widely used in the aerospace, automotive and electro-technical industries.

The paper presents the test results for polyethylene composites with 25 per cent and 50 per cent filler coming from recycled car carpets of various car makes. The tests included using differential scanning calorimetry, testing material hardness, material tensile strength and their dynamic mechanical properties.

The design of polymeric materials for microelectronic applications is based on the recognition that structural features in a polymer chain influence the physical properties of the polymer. Illustrations of structure‐property relationships are drawn from applications in lithography, dielectric interlayers and packaging. Among the properties discussed are resolution, plasma etch resistance, thermal stability, electrical properties, permeability, adhesion, mechanical properties and thermal expansion.

This paper attempted to show the potential relationship between five different interaction coefficients relating solvents and polymers. This review addressed primarily a comparison between the polymer-solvent interaction coefficients obtained from two different types of models. These two primary polymer-solvent interaction coefficients included the Flory-Huggins interaction coefficient developed from thermodynamic colligative properties and the polymer-solvent Sudduth interaction coefficient obtained from the generalized viscosity equation. The other three interaction coefficients included Hildebrand solubility parameter and the interaction coefficients or constants for the Huggins and Kraemers models that are normally generated from viscosity measurements. The paper aims to discuss these issues.

These five different interaction coefficients were compared from theoretical considerations as well as on the basis of available experimental data.

Remarkably the polymer-solvent interaction coefficients for both Flory-Huggins interaction coefficient and the Sudduth interaction coefficient were found to be dimensionless and approximately of the same value. In addition, when both interaction coefficients are negative then both describe solvents. In addition, both interaction coefficients describe a plasticizer when they are in the range of 0 to ½. Finally both interaction coefficients describe a non-solvent or a suspension when both are greater than 1. The Hildebrand solubility parameter was found to be directly related to the Flory-Huggins interaction coefficient. The viscosity constants for the Huggins and Kraemers models were found to be included as subsets of the Sudduth generalized viscosity model.

The strong apparent relationship between these five different interaction coefficients to predict the interaction between polymers and solvents is strongly indicated based on the results from this study. However, approximately half of these interaction coefficients have been derived to be evaluated from colligative properties and half were derived to be evaluated from viscosity measurements.

In general, it is much easier to obtain viscosity measurements compared to the evaluation of the colligative properties. Therefore, if a direct relationship can be shown between these five different interaction coefficients, then it would appear to be much easier to evaluate polymer-solvent interactions from the interaction coefficients obtained from viscosity measurements.

This is the first time that these five interaction coefficients have been compared in such a way that shows their direct relationship even though half of these interaction coefficients have been derived to be evaluated from colligative properties and half were derived to be evaluated from viscosity measurements.

This study aims to highlights the mechanical, thermal and melting behavior compatibility of aluminum (Al)-reinforced polyamide (PA) 6/acrylonitrile butadiene styrene (ABS)-based functional prototypes prepared using fused deposition modeling (FDM) from the friction welding point of view. Previous studies have highlighted the use of metallic/non-metallic fillers in polymer matrix for preparations of mechanically improved FDM feedstock filaments and functional prototypes. But hitherto, very less has been reported on fabrication of functional prototypes which fulfill the compatibility of two polymers for joining/welding-based applications. The compatibility of two dissimilar polymers enables the friction welding for maintenance applications.

The twin screw extrusion process has been used for mechanical mixing of metallic reinforcement in polymer matrix, and final blend of reinforced polymers in the form of extruded feed stock filament has been used on FDM for printing of functional prototypes (for friction welding). The methodology involves melt flow index (MFI) investigations, differential scanning calorimetry (DSC) investigations for thermal properties, tensile and hardness testing for mechanical properties and photo micrographic investigations for metallurgical properties on extruded samples.

It was observed that the reinforced ABS and PA6 polymers have better compatibility in the terms of similar melt flow, thermal properties and can lead to the better joint efficiency with friction welding.

In the present work composite feed stock filament composed of ABS and PA6 with reinforcement of Al powder has been successfully developed for preparation of functional prototype in friction welding applications.

The purpose of this paper is to describe the ageing behaviour of acrylate‐based resins for stereolithography (SL) technology using different test methods and to investigate these effects on polymers.

Controlling the polymer degradation requires an understanding of many different phenomena, including the different chemical mechanisms underlying structural changes in polymer macromolecules, the influences of polymer morphology, the complexities of oxidation chemistry and the complex reaction pathways of polymer additives. Several ageing characterization experiments are given.

The paper covers the ageing process analysis of acrylate‐based polymers. An overview of the ageing behaviour is given, along with the bandwidth of material characteristics for a prolonged lifetime of this material class.

For research and development in the field of rapid prototyping (RP) materials data about ageing behaviour and environmental effects are crucial. The authors show possible methods for measuring these effects and discuss the consequences in material research using a recently developed biocompatible SL resin as an example.

The study of the ageing behaviour of polymers is important for understanding their usability, storage, lifetime and recycling. The presented polymeric formulations are able to meet the growing demand for both soft and stiff manufacturing resin materials in the engineering and medical fields.

The analysis of the ageing behaviour of polymer materials is an important issue for engineering applications, recycling of post‐consumer plastic waste, as well as the use of polymers as biological implants and matrices for drug delivery and the lifetime of an article. The paper gives an overview of details involving ageing behaviour and their meaning for applications of acrylate‐based SL resins and is therefore of high importance to people with interest in long‐term behaviour and ageing of RP materials.

Polymer Structure. A number of articles describe basic research on polymers of interest to the paint industry. Thus Sperling [Journal of Polymer Science, Macromolecular Reviews, 12 (1977) p. 141] describes interpenetrating polymer networks as structures which result when a crosslinked polymer is swelled by a monomer which contains also a crosslinking or polymerising agent. The monomer is thus polymerised in situ, presumably in the voids and intersticies provided by the initial crosslinked polymer. In this way, Sperling describes the morphology and mechanical properties of interpenetrating polymer networks.