Papers by Keyword: Polymer Blends

Abstract: Polymer blends, particularly those containing Polybutylene terephthalate (PBT) and Polycarbonate (PC), are extensively utilized in various industrial applications due to their favorable mechanical and thermal properties. Enhancing the performance of such blends necessitates an understanding of the relationship between their crystalline structure and wear behavior. This study investigates the correlation between wear characteristics and structural aspects of PBT/PC blends having varying PC content. Additionally, techniques such as X-ray diffraction (XRD) and optical microscopy of the worn-out surface are employed. The findings reveal a strong connection between the wear behavior of PBT/PC blends and their crystallographic structure. This study provides useful insights into the wear mechanism and crystallization behavior of PBT/PC blends. Specifically, it is observed that with increasing PC content in the blends, the wear resistance is influenced by the size of crystallites, wherein smaller crystallites demonstrate a greater ability to withstand abrasive action-induced damage. The wear performance of the PBT/PC blend with 70% PC improves by ~37% as a result of the formation of a semi-orderly chain structure with a smaller crystallite size. A mechanism is also explained herein related to the change in the nature of crystallization of PBT/PC blends with increasing PC content. In conclusion, this study underscores the importance of considering crystallographic structure when assessing the wear behavior of polymer blends such as PBT/PC.

Abstract: The removal of particle contamination is key to maximize yield. Some common particle removal techniques are not relevant anymore when complex and fragile structures are present on the surface. This led to the development of new cleaning processes based on innovative concepts to improve particle removal efficiency without any pattern damage. Some of these processes rely on a resist film lift off. One of these particle removal processes is studied in this paper. The process consists in some resist spin-coating followed by a diluted ammonia dispense to remove this film, which results in particle removal. This specific resist film is made of two immiscible organic polymers. A study was conducted to understand how the organization of these two polymers in the film is key for the film lift-off and the cleaning efficiency. This organization was shown to depend on the substrate contact angle and the resist formulation. A surface preparation is required on hydrophobic surface to reduce their water contact angle and ensure the efficiency of the process. As a result, compared to a high velocity aerosol cleaning technique, this resist peeling process requires multiple steps and a significant process time. A Particle Removal Efficiency study was then performed on blanket wafers to determine and understand how the different process parameters impacted on the cleaning efficiency. It led to the optimization of this process efficiency on blanket wafers. A comparison between an optimized process and a high velocity aerosol cleaning technique underlined the potential of such a process. Compared to high velocity aerosol cleaning, it demonstrated higher efficiency on blanket wafers, without causing any pattern damage on patterned wafers. These results lead to promising perspectives for using this process in the cleaning of fragile structure or targeting small particles with high adhesion.

Abstract: In this study, a synthetic scaffold was prepared from polycaprolactone (PCL) and polyurethane (PU) blend, in a ratio of [2:1] [PCL: PU], using electrospinning technique. Electrospun scaffolds from native PCL and PU were also prepared for comparison, using the same polymer concentration 15% weight/ volume w/v. The detailed microstructure and other properties, like mechanical properties, porosity, and contact angle were investigated and compared between the three prepared scaffolds. Then, the survival, adhesion, proliferation and penetration of rat embryonic fibroblast (REF) cells were evaluated on these three prepared scaffolds after being in vitro cultured with these cells for 21 days, using scanning electron microscope (SEM) analysis and histological analysis. The results showed that, all the studied properties, including mechanical properties and contact angle were enhanced by combining PU with PCL in the [PCL: PU] scaffold. The average diameter of fiber and the average size of pore were suitable and proper for cell attachment, cell proliferation, and also the big average pore size in [PCL: PU] scaffold was enough for cell penetration to form a three- dimension 3-D structure, which is the aim of this study.

Abstract: In this work, we have developed a new protocol to prepare conductive polyaniline (PANi) nanofibrous mats via an electrospinning process. The newly developed method started with doping pure polyaniline with concentrated sulphuric acid. The doped PANi is then blended with other spinnable polymers such as Polyacrylonitrile (PAN). The prepared blend is then converted into a solid nanofibrous mat using an electrospinning process. Different parameters, such as solution weight fractions, electrospinning voltage, and feed rate, were optimized and their effect on fibre morphology and conductivity were studied. Several measurement techniques were used to assess the properties of the developed mats. The measurements include Field Emission Scanning Electron Microscopy (FESEM), the intrinsic conductivity of PANi fibres and the conductivity of fibrous mats. Results revealed a direct relationship between the average fibre diameter and the morphology and the conductivities of both the fibres and the mats. Doped polyaniline showed higher conductivity compared with the pure one with an increase in average fibre diameters. Blending polyaniline with PAN improved the mat's morphology and affects their conductivities. In addition, electrospinning process parameters such as feed rate and applied voltage showed a major effect on the fibre’s morphology and conductivity.

Abstract: In this paper, poly(lactic acid) (PLA) was modified with poly(butylene succinate) (PBS) and talc to obtain PLA formulation with good toughness and high crystallization rate. PBS was added as a toughening agent at 40wt% and talc was added as a nucleating agent from 2 to 10wt%. Experimental results showed that both the tensile modulus and strength of PLA significantly decreased with the presence of PBS. Both values were found to notably increase with talc concentration and reached the maximum value at 8wt%. The tensile elongation at break was found to remarkably increase with PBS blending. However, it was linearly dropped with talc addition. Thermal test results also indicated the faster crystallization rate with the decreased crystallization temperature (T_c) and increased degree of crystallinity (X_c), by more than four times, when talc was added at least 4wt%. The isothermal crystallization half-time (t_1/2) was applied to provide the data for injection molding process. The results showed that neat PLA required more than 25 min to obtain its half crystallinity. Minimum t_1/2 of 3.45 min was obtained when talc was added to PLA/PBS at 8wt%. Heat distortion temperature (HDT) was also found to increase from 56.8 (neat PLA) to 97.2°C (8wt% talc). Based on the experimental results, the optimum talc concentration was 8wt% which provided the highest crystallization rate and thermal stability. The practical application of this formulation is for the biodegradable injection molding products.

Abstract: The study of the properties of PEEK blends with different melt flow rate (MFR) and carbon-filled composites based on them was carried out. It was found that with an increase in the relative difference in the MFR of the blended PEEKs, there is an increase in the deviation of the experimental MFR values from the additive ones. Up to a relative difference in the MFR of the components equal to 60%, the blends obey the additivity rule. It is shown that the achievement of a certain MFR value by blending polymers with different viscosities leads to the production of materials with similar properties. Carbon-filled composites based on PEEK blends also demonstrate very similar rheological, mechanical and thermal properties, which indicates the effectiveness of the method of blending PEEKs with different viscosities to achieve the required rheological properties.

Abstract: This present study has been re-established to investigate failure mode and resistance characteristics of the PC/ABS blends and their ABS constituents under impact for a range of rubber contents. This present study has still been experimentally performed under an instrumented-drop weight impact test (DWIT) at a room temperature. It has been finally revealed that with a particular size of rubber particle, content of rubber significantly influenced impact failure modes and impact resistances of the PC/ABS blends and their ABS constituents as well. The test results showed that impact strength of the blends was improved about 23.22% and 155.33% due to increase in content of rubber up to 15 wt% and 20 wt%, respectively. There was also found that an increase in impact toughness of the blends for 57.48% and 239.23% was due to increase in content of rubber up to 15 wt% and 20 wt%, respectively. Whilst, impact strength of the ABS was improved about 392.98% and 190.12% due to increase in content of rubber up to 15 wt% and 20 wt%, respectively. An increase in impact toughness of the ABS for 308.20% and 172.56% was due to increase in content of rubber up to 15 wt% and 20 wt%, respectively.

Abstract: This study presents an experimental study on failure modes and resistances of polycarbonate (PC)/Acrylonitrile Butadiene Styrene (ABS) blends and their ABS constituents under a drop weight impact test (DWIT). Failure modes and impact resistances such as impact strength and impact toughness of such blends are generally influenced by molecular weight of the PC, rubber content and size of rubber particle in ABS system. A preliminary study on ABS materials using a DWIT showed that size of rubber particle not only determined their failure modes but also influencing their resistance characteristics. However, in a previous study performed using the similar DWIT on PC/ABS blends with a 10 wt% rubber content, it was revealed that size of rubber particle did not significantly influence their resistances. Their failure modes were even macroscopically very difficult to be distinguished. This study, hence, is aimed to further explore role of the size of rubber particle on failure mode and impact resistance characteristics of the PC/ABS blends and their ABS constituents with a higher rubber content. The impact test results have revealed that with a 20 wt% rubber content, size of rubber particle only influenced the resistances of the PC/ABS blends. It did not significantly contribute to affect failure mode of the PC/ABS blends. Whilst, it significantly influenced failure modes and resistances of the ABS. The DWIT results also re-confirmed that blending a brittle ABS into PC led to produce a tougher PC/ABS blend.

Abstract: Poly(acrylic acid) (PAA) was grafted onto natural rubber (NR) to improve the compatibility of NR and poly(lactic acid) (PLA). Polymer blend between PLA and NR-g-PAA was prepared by an internal mixer. Fourier-transform infrared spectroscopy (FT-IR), tensile testing, impact testing, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were employed to determine the functional group, mechanical properties and thermal properties of blends, respectively. Results showed that the addition of NR-g-PAA significantly improved the elongation, impact strength and thermal stability of blends. The P70N30 was the optimum composition to obtain improved mechanical properties of PLA.

Abstract: This research prepared poly(lactic acid) (PLA) and PLA/acrylonitrile-butadiene rubber (NBR) blends before and after adding polyethylene-g-maleic anhydride with 3 wt% of maleic anhydride (PE-g-MA3) 3 phr. The effects of NBR and PE-g-MA3 on morphological, mechanical and thermal properties of PLA and PLA blends were discussed. The morphological analysis observed the two-phase morphology of PLA/NBR blends, and it was observed the cavities generated due to NBR phase detachment during sample fracture, and droplets of NBR phase at higher NBR content. The PE-g-MA3 addition could improve adhesion between PLA and NBR phases due to the decrease of cavities in PLA matrix and droplet size of NBR. The mechanical properties showed the impact strength and strain at break of PLA/NBR blends dramatically increased when the amount of NBR increasing. The addition of PE-g-MA3 significantly improved the impact strength of PLA/NBR blends. The thermal properties showed the NBR addition had effect slightly on the melting temperature of PLA/NBR blends. The filling of NBR and PE-g-MA3 greatly decreased the percent crystallinity of PLA more than two times. The thermal degradation of pure PLA and NBR proceeds by one step, while the thermal degradation process of PLA/NBR and PLA/PE-g-MA3 proceeds by two steps. Which the first step showed a large mass loss of PLA degradation and the second step showed a small mass loss of PE-g-MA and NBR degradation.