Tensile properties, biodegradability and bioactivity of thermoplastic starch (TPS)/bioglass composites for bone tissue engineering

Composite fabricated from the combination of biodegradable polymer and bioactive filler is beneficial for bone tissue engineering if the biomaterial can perform similar characteristics of the natural inorganic-organic structures of bone. In this study, we have investigated the thermoplastic starch (TPS)/sol-gel derived bioglass composite as new biomaterial for bone tissue engineering. The composites were produced using selected TPS/bioglass mass ratio of 100/0, 95/5, 90/10, 85/15 and 80/20 by a combination of solvent casting and salt leaching techniques. Tensile test results showed the addition of bioglass increased the tensile strength and Young’s modulus, but reduced the elongation at break of the samples. The modulus of all samples were higher than the requirement for cancellous bone (10-20 MPa). The SEM imaging showed the presence of porous structure on the surface of all samples. XRD results confirmed the formation of hydroxycarbonate apatite (HCA) layer on the surface of bioglass containing samples; indicating the occurrence of surface reactions when the samples were immersed in Simulated Body Fluid (SBF). Furthermore, the presence of P-O stretch band in FTIR spectrum between 1000 and 1150 cm-1 and Si-O-Si stretch band at 1000 cm-1 also proved the bioactivity of TPS/bioglass composite. The in vitro biodegradability analysis shows the biodegradability of TPS/bioglass composite decreases with increasing mass ratio of the bioglass

Thermoplastic Polyurethane (TPU) / Organo- fluoromica Nanocomposites for Biomedical Applications: In Vitro Fatigue Properties

Poly(dimethylsiloxane) (PDMS) / poly(hexamethylene oxide) (PHMO)-based thermoplastic polyurethane (TPU) nanocomposite was investigated for potential use in biomedical application. Studies on the in vitro fatigue behaviour of the TPU and TPU nanocomposite (under physiological saline solution, 37°C conditions) were highlighted in this article. The data were compared with those of commercially available silicone elastomer (Nusil MED 4860). Results indicated that the TPU nanocomposite (2MED-C (2HM)) had greater fatigue properties than the virgin TPU, which provide strong evidence of its greater capacity to withstand cyclic forces than the host TPU when exposed to physiological fluid. This was caused by the presence of well dispersed and impermeable organofluoromica platelets in the TPU matrix resulted in more tortuous path for the physiological fluid diffusion, thereby decreasing the fluid permeability of the polymer. Eventhough the silicone elastomer has lesser hysteresis than the virgin TPU and TPU nanocomposite, its fatigue strength is much lower than those of the TPU nanocomposite. The findings revealed the potential of PDMS/PHMO based TPU nanocomposite to replace silicone elastomer as biomaterial, particularly for implantable biomedical device application

Impact of controlled hydrophobicity of the organically modified silicates on the properties of biomedical thermoplastic polyurethane (TPU) nanocomposites

The impact of nanofiller surface modifications and hydrophobicity on the morphology and mechanical properties of the biomedical TPU nanocomposites was studied. We show that incorporating nanofillers with higher hydrophobicity promotes better dispersion of nanofiller in TPU matrix due to greater interaction between the nanofiller and the hydrophobic PDMS soft segment in this ElastEon TPU system. The nanocomposite with the most hydrophobic surface modification demonstrates the best nanofiller dispersion and intercalation and hence resulted in an overall best mechanical and thermomechanical properties when incorporated in 2 wt%. These findings show that the polarity matching between the TPU and the nanofiller determines the nanofiller-TPU interactions and thus the mechanical properties of the produced nanocomposites

Effect of processing route on the morphology of thermoplastic polyurethane (TPU) nanocomposites incorporating organofluoromica

In the production of polymer nanocomposites, the processing method determines the dispersion of the nanofiller and hence, the final nanocomposite properties. In this work, the potential of high energy milling of the organofluoromica to improve the platelet dispersion and exfoliation in both solvent cast and melt processed thermoplastic polyurethane (TPU)/organofluoromica nanocomposites was investigated. The potential of high energy milling of the organofluoromica to improve the platelet dispersion and exfoliation in both solvent cast and melt processed thermoplastic polyurethane (TPU)/organofluoromica nanocomposites was investigated. The applied high energy milling process has successfully reduced this nanofiller platelet length from 640 nm to 400 nm and 250 nm after 1 hour and 2 hours respectively. These lower aspect ratio milled nanofillers resulted in improved quality of dispersion and delamination when incorporated into the TPU and hence interacted more preferentially with the TPU matrix

Pre-dispersing Process of Montmorillonite by Water and Toluene: Influence on Thermal Properties of Ethylene Vinyl Acetate / Montmorillonite Nanocomposites

Organanically modified montmorillonite (organo-MMT) was incorporated into ethylene vinyl acetate (EVA) copolymer to improve its thermal stability. A processing procedure, the so called ‘predispersing’ process of the organo-MMT was introduced prior to melt compounding process of both constituents in order to facilitate the nanofiller dispersion in the EVA matrix. Water and toluene were used as pre-dispersing medium, while magnetic stirring and ultrasonication were utilized as pre-dispersing method. The effects of pre-dispersing medium and method on thermal behaviour of neat EVA and EVA nanocomposites were analysed. It was anticipated that improvement in organo-MMT dispersion would enhance the matrix-nanofiller interactions, thereby the thermal properties of the resultant EVA/MMT nanocomposite. Based on thermal studies by thermogravimetric analysis (TGA), the organo-MMT nanofiller pre-dispersed by ultrasonication in water medium for 2 minutes (MMT(W)2m–u) resulted in most significant thermal stabilizing effect to the EVA copolymer. This was due to the significant improvement in the organo-MMT dispersion when the above mentioned pre-dispersing parameters were employed. Apparently, the result indicates that the high temperature behaviour of the nanocomposite can be affected by the strength of interphase interactions between the matrix and nanofiller which is also influenced by the dispersion of the organo-MMT

On the Use of Dolomite as a Mineral Filler and Co-Filler in the Field of Polymer Composites: A Review

Polymers are being used in many applications all around the world. However, there are some drawbacks in the properties of polymers that could hamper their usage in certain applications. Therefore, a new material polymer composite was introduced. A polymer composite is a polymer-based material with the addition of a filler. Many researchers have reported the improvement in the properties of a polymer when a filler was introduced. This helps minimize the disadvantages of using a polymer. As a result, polymer composite products can be used in many industries, such as automobile, aerospace, biomedical, and packaging. Fillers derived from natural minerals, such as dolomite, are among the best reinforcement materials for polymeric materials because they are plentiful and low cost, have high rigidity and hardness, and even have tailorable surface chemistry. The use of dolomite as a filler in a polymer composite system has gained increasing attention in recent years after researchers successfully proved that it is capable of improving the mechanical, physical, and thermal properties of various polymeric materials. However, chemical or physical treatment/modification of raw dolomite is needed in order to prepare it as an efficient reinforcing filler. This procedure helps to improve the performance of the resultant polymer composites. This article reviews the usage of dolomite as a filler in a variety of polymeric materials and how it improved the performance of the polymer composite materials. It also highlights several methods that have been used for the purpose dolomite’s treatment/modification. Furthermore, the role of dolomite as a co-filler or a hybrid filler in a polymer composite system is also discussed, revealing the great potential and prospect of this mineral filler in the field of polymer composites for advanced applications

Methyl Methacrylate (MMA) Treatment of Empty Fruit Bunch (EFB) to Improve the Properties of Regenerated Cellulose Biocomposite Films

The empty fruit bunch (EFB) regenerated cellulose (RC) biocomposite films for packaging application were prepared using ionic liquid. The effects of EFB content and methyl methacrylate (MMA) treatment of the EFB on the mechanical and thermal properties of the RC biocomposite were studied. The tensile strength and modulus of elasticity of the MMA treated RC biocomposite film achieved a maximum value when 2 wt% EFB was used for the regeneration process. The treated EFB RC biocomposite films also possess higher crystallinity index. The morphology analysis indicated that the RC biocomposite film containing MMA treated EFB exhibits a smoother and more homogeneous surface compared to the one containing the untreated EFB. The substitution of the –OH group of the EFB cellulose with the ester group of the MMA resulted in greater dissolution of the EFB in the ionic liquid solvent, thus improving the interphase bonding between the filler and matrix phase of the EF RC biocomposite. Due to this factor, thermal stability of the EFB RC biocomposite also successfully improved

Effective Aging Inhibition of the Thermoplastic Corn Starch Films through the Use of Green Hybrid Filler

Recently, hybrid fillers have been widely used to improve the properties of biopolymers. The synergistic effects of the hybrid fillers can have a positive impact on biopolymers, including thermoplastic corn starch film (TPCS). In this communication, we highlight the effectiveness of hybrid fillers in inhibiting the aging process of TPCS. The TPCS, thermoplastic corn starch composite films (TPCS-C), and hybrid thermoplastic corn starch composite film (TPCS-HC) were stored for 3 months to study the effect of hybrid filler on the starch retrogradation. TPCS-C and TPCS-HC were prepared by casting method with 5 wt% of fillers: nanocellulose (NC) and bentonite (BT). The alteration of the mechanical properties, aging behavior, and crystalline structure of the films were analyzed through the tensile test, Fourier transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and water absorption analysis. The obtained data were correlated to each other to analyze the retrogradation of the TPCS, which is the main factor that contributes to the aging process of the biopolymer. Results signify that incorporating the hybrid filler (NC + BT) in the TPCS/4BT1NC films has effectively prevented retrogradation of the starch molecules after being stored for 3 months. On the contrary, the virgin TPCS film showed the highest degree of retrogradation resulting in a significant decrement in the film’s flexibility. These findings proved the capability of the green hybrid filler in inhibiting the aging of the TPCS

Strategies towards Producing Non-Polar Dolomite Nanoparticles as Nanofiller for Copolymer Nanocomposite

Poly (ethylene-co-vinyl acetate) (PEVAc) is a copolymer endowed with high elasticity and resilient properties, potentially utilized in various applications. However, the tensile strength of this copolymer is insufficient for use in certain applications that require enough strength to tolerate high external tension or stress. In this study, dolomite was proposed as a nanofiller to reinforce the PEVAc. Raw dolomite was physically and chemically modified in order to improve its mix ability and interfacial adhesion between the PEVAc and dolomite. Initially, the size of dolomite was reduced by combining the ball-milling and tip-sonication methods. SEM, TEM, and XRD were used to characterize the morphology/structure of the raw dolomite and the size-reduced dolomite. Then, a particle size analysis was performed to confirm the average particle size. Our results show that the particle size of dolomite was reduced from 150 µm to 441.4 nm by the physical modification process (size reduction). Based on the TEM analysis, the Feret diameter (df) of the dolomite particles was also reduced from ~112.78 µm to ~139.58 nm only. This physically modified dolomite is referred as dolomite nanoparticles (DNPs), since one or more of its dimensions is less than 100 nm (e.g., thickness and width). To further improve the dolomite and PEVAc matrix interactions, chemical modification of the DNPs were performed by treating the DNPs with stearic acid, forming non-polar dolomite nanoparticles (NP-DNPs). The presence of stearic acid in dolomite was confirmed through FTIR and contact angle analyses. A PEVAc nanocomposite film with NP-NPDs as a nanofiller appeared more homogeneous and exhibited the highest increment in tensile strength and elongation at break. These findings indicated that the combination of ball milling and tip sonication is an efficient method for producing very fine dolomite particles up to the nano-size range, whereas chemical surface modifications improved the compatibility between the dolomite and the copolymer. The combination of these physical and chemical modifications helped to develop a homogeneous copolymer nanocomposite system with improved tensile properties