Papers by Chanchira Jubsilp
Polymers
Glass fiber post based on the new polymeric material, polybenzoxazine, is prepared and the effect... more Glass fiber post based on the new polymeric material, polybenzoxazine, is prepared and the effects of glass fiber contents on mechanical and thermal properties are evaluated. The mechanical response to externally applied loads of tooth restored with glass fiber-reinforced polybenzoxazine composite posts is also simulated by finite element analysis of a tridimensional model and compared with the response to that of a natural tooth. The reinforcing of glass fiber can help improve the mechanical and thermal properties of the polybenzoxazine influenced by the interfacial adhesion between the glass fiber and polybenzoxazine matrix, except for the relatively high mechanical property of the glass fiber. The mechanical data, i.e., elastic modulus under flexure load or flexural modulus by three-point bending test of the glass fiber-reinforced polybenzoxazine composites are agreed with the elastic modulus of dentin and then used in the finite element model. The restoration using the glass fib...
Polymers
Asbestos-free friction composite based on ultrafine full-vulcanized acrylonitrile butadiene rubbe... more Asbestos-free friction composite based on ultrafine full-vulcanized acrylonitrile butadiene rubber particles (UFNBRPs)-modified polybenzoxazine was successfully developed. The UFNBRPs-modified polybenzoxazine friction composite was characterized for chemical, tribological, and mechanical properties as well as thermal stability. The UFNBRPs not only act as a filler to reduce noise in the friction composites due to their suitable viscoelastic behaviors but also play a key role in friction modifiers to enhance friction coefficient and wear resistance in the polybenzoxazine composites. The chemical bonding formation between UFNBRPs and polybenzoxazine can significantly improve friction, mechanical, and thermal properties of the friction composite. The outstanding tribological performance of the friction composite under 100–350 °C, i.e., friction coefficients and wear rates in a range of 0.36–0.43 and 0.13 × 10−4–0.29 × 10−4 mm3/Nm, respectively, was achieved. The high flexural strength ...
This research aims to modify ultrafine fully vulcanized powdered natural rubber (UFPNR) prepared ... more This research aims to modify ultrafine fully vulcanized powdered natural rubber (UFPNR) prepared by emulsion graft-copolymerization with styrene (St) and acrylonitrile (AN) monomers onto deproteinized natural rubber (DPNR). The effects of monomer content and St/AN weight ratio on grafting efficiency and thermal stability of the developed DPNR-g-(PS-co-PAN) were investigated. The results showed that grafting efficiency was enhanced up to 87% with weight ratio St:AN 80:20. The obtained DPNR-g-(PS-co-PAN) was radiated by an electron beam at various doses, followed by a spray drying process to produce UFPNR. The obtained modified UFPNR particles irradiated at dose up to 300 kGy were relatively spherical with a particle size of approximately 4.4 µm. Furthermore, the degradation temperature of 5wt% loss (Td5) of UFPNR was found in the range of 349–356°C. The results revealed that the modified UFPNR is suitable as a toughening filler for a broader spectrum of polymers.
Chemical Engineering Transactions, 2018
Nanoalumina-filled poly(benzoxazine ester) composite films were prepared by addition of various n... more Nanoalumina-filled poly(benzoxazine ester) composite films were prepared by addition of various nanoalumina contents into poly(benzoxazine-ester) derived from bisphenol-A/3,5 dimethylaniline-based benzoxazine (BA-35x) and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA). Chemical characteristics, thermomechanical properties, thermal stability, and thermal diffusivity of the composite films were investigated. The obtained results, i.e., degradation temperatures, glass transition temperatures, and thermal diffusivity properties of the composite films were enhanced with nanoalumina content. The composite film filled with 15 wt% of nanoalumina showed significant improvement in degradation temperature and solid residue, i.e., 404 o C and 62 %. The glass transition temperature of the composite film was increased with increasing nanoalumina content and exhibited a maximum value of 310 o C at 15 wt% of nanoalumina. IR spectra showed complete curing reaction and all characteristic peaks of the ester linkage and nanoalumina particles were observed in the poly(benzoxazine-ester) composite film. Based on the findings in this work, the poly(benzoxazine-ester) composite films can potentially be used in the case where a high stiffness and high thermal properties are required, i.e., coating film and polymeric matrix for fibre-reinforced composites.
Polymers, 2021
In this paper, the effects of organic based stabilizers (OBS) are investigated and compared with ... more In this paper, the effects of organic based stabilizers (OBS) are investigated and compared with traditional lead (Pb) and calcium zinc (CaZn) heat stabilizers regarding their processability, mechanical property, and thermal degradation behaviors in rigid PVC pipe applications. In addition, the effects of repeated processing cycles on the degree of gelation and the impact strength of the PVC/OBS, PVC/CaZn, and PVC/Pb are also examined. A repeated processing cycle of those three types of the heat stabilizers up to four cycles was found to increase the degree of gelation and proved no significant effect on the impact strength and heat resistance of the resulting PVC samples. The OBS showed a positive effect on preventing the autocatalytic-typed thermal degradation of the PVC samples. This leads to a longer retention time for the initial color change of the PVC/OBS compared to PVC/Pb or PVC/CaZn systems. This characteristic was related to a more uniform fusion behavior of the PVC/OBS, ...
SPE Polymers, 2021
Ultrafine fully vulcanized powdered natural rubber (UFPNR) is a renewable material that is promis... more Ultrafine fully vulcanized powdered natural rubber (UFPNR) is a renewable material that is promising for industrial application as a toughening filler in polymer matrix. In this work, effects of coagent on properties of UFPNR produced by radiation vulcanization and spray‐drying was systematically investigated, in which trimethylol propane trimethaacrylate (TMPTMA) was used as coagent. The crosslinking density of UFPNR could be enhanced by increasing radiation dose from 50 to 350 kGy and it was further enhanced by using TMPTMA as coagent during the production process. UFPNR with the smallest particle size of 3.9 ± 1.8 μm and highest thermal stability (Td5 = 347°C) could be obtained by using TMPTMA with the highest content of 9 phr. The results suggested that polymer chains of natural rubber were more packed into smaller particle as they were more crosslinked by the coagent. Finally, an application of UFPNR as a toughening filler in polybenzoxazine was demonstrated. The highest impact...
Fiber Reinforced Composites, 2021
Abstract Advanced composites such as fiber-reinforced thermosetting polymer composites are curren... more Abstract Advanced composites such as fiber-reinforced thermosetting polymer composites are currently replacing the conventionally used stainless steel, premium alloys, and carbon steels. They have also been finding increased potential for use in many high performance applications that require excellent mechanical properties because of their outstanding specific modulus and strength, light weight, good tribological properties, and flame resistance, with the caveat that the manufacturing costs involved during their development can be high. Important thermosetting polymer composites are often reinforced with glass or carbon fibers and meet certain weight reduction and high specific strength requirements, particularly those found in the aerospace, automotive, marine, ballistic armor, extreme sport, and construction industries. With such context, this chapter provides a contemporary account of glass fiber- and carbon fiber-reinforced thermosetting polymer composites based on outstanding engineering polymers, such as epoxy, phenolic, polyurethane, and polybenzoxazine, and describes the rheological, thermo-mechanical and tribological properties, and morphologies exhibited by these materials as well as their applications.
Polymers, 2021
Graft copolymers, deproteinized natural rubber-graft-polystyrene (DPNR-g-PS) and deproteinized na... more Graft copolymers, deproteinized natural rubber-graft-polystyrene (DPNR-g-PS) and deproteinized natural rubber-graft-polyacrylonitrile (DPNR-g-PAN), were prepared by the grafting of styrene (St) or acrylonitrile (AN) monomers onto DPNR latex via emulsion copolymerization. Then, ultrafine fully vulcanized powdered natural rubbers (UFPNRs) were produced by electron beam irradiation of the graft copolymers in the presence of di-trimethylolpropane tetra-acrylate (DTMPTA) as a crosslinking agent and, subsequently, a fast spray drying process. The effects of St or AN monomer contents and the radiation doses on the chemical structure, thermal stability, and physical properties of the graft copolymers and UFPNRs were investigated. The results showed that solvent resistance and grafting efficiency of DPNR-g-PS and DPNR-g-PAN were enhanced with increasing monomer content. SEM morphology of the UFPNRs showed separated and much less agglomerated particles with an average size about 6 μm. Therefo...
Polymers, 2021
Ultrafine fully vulcanized powdered natural rubber (UFPNR) has a promising application as a renew... more Ultrafine fully vulcanized powdered natural rubber (UFPNR) has a promising application as a renewable toughening modifier in polymer matrices. In this work, the effects of acrylate coagents, which had different amounts of functional groups, on properties of UFPNR produced by radiation vulcanization and spray-drying was systematically investigated for the first time. Dipropylene glycol diacrylate (DPGDA), trimethylol propane trimethaacrylate (TMPTMA), and ditrimethylol propane tetraacrylate (DTMPTA) were used as coagents with two, three, and four acrylate groups, respectively. The radiation in the range of 250 to 400 kGy and coagent contents of up to 11 phr were used in the production process. Physical, chemical, and thermal properties of the UFPNR were characterized by swelling analysis, scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The properties of UFPNR produced by using different type and content of coagen...
Engineering Journal, 2021
The aim of this research is to develop a suture pad simulating human skin for suturing practice. ... more The aim of this research is to develop a suture pad simulating human skin for suturing practice. The suture pad was fabricated with layers of artificial dermis and subcutis which reproduced the mechanical properties of skin. The main focus of this study was to reinforce polydimethylsiloxane with silk fiber to create a realistic dermis. The effects of silk fiber amount and aspect ratio on the mechanical properties of the suture pads were investigated. Results revealed that the tensile strength and modulus of the composite increased in relation to fiber content and aspect ratio. Composites with silk fiber exhibited higher tear resistance to suture thread compared with pure polydimethylsiloxane. Furthermore, the hardness of the composites was improved with the addition of silk fiber. It was found that polydimethylsiloxane composite reinforced with 2 phr of silk fiber with an aspect ratio of 1000 showed a hardness value similar to that of human skin. These results indicate that silk fiber reinforced polydimethylsiloxane composites can realistically simulate human skin and have the potential to be used as suture pads for medical training.
Polymers, 2021
A series of substituted polybenzoxazines was synthesized and studied as binders in non-asbestos f... more A series of substituted polybenzoxazines was synthesized and studied as binders in non-asbestos friction composite materials. The structures of the polybenzoxazines were varied in a systemic fashion by increasing the number and position of pendant alkyl (methyl) groups and was accomplished using the respective aromatic amines during the polymer synthesis step. By investigating the key thermomechanical and tribological characteristics displayed by the composite materials, the underlying structure-properties relationships were deconvoluted. Composite friction materials with higher thermomechanical and wear resistance properties were obtained from polybenzoxazines with relatively high crosslink densities. In contrast, polybenzoxazines with relatively low crosslink densities afforded composite friction materials with an improved coefficient of friction values and specific wear rates.
Polymers, 2020
This study aims to develop a lightweight ballistic helmet based on nanocomposite with matrix of t... more This study aims to develop a lightweight ballistic helmet based on nanocomposite with matrix of the copolymer of benzoxazine with an urethane prepolymer [poly(BA-a-co-PU)], at mass ratio 80/20, reinforced with aramid fabric and multi-walled carbon nanotubes (MWCNTs). This has a protection level II according to the National Institute of Justice (NIJ) 0106.01 standard. The effects of MWCNTs mass content in a range of 0 to 2 wt% on tensile, physical and ballistic impact properties of the nanocomposite were investigated. The results revealed that the introduction of MWCNTs enhanced the tensile strength and energy at break of the nanocomposite; the highest values were obtained at 0.25 wt%. In addition, the nanocomposite laminate with 20 plies of aramid fabric showed the lowest back face deformation of 8 mm which was much lower than that specified by the NIJ standard. According to Military Standard (MIL-STD) 662F, the simulation prediction revealed that the ballistic limit of the ballisti...
Journal of Materials Research and Technology, 2020
Glass fabric reinforced polybenzoxazine-based composites filled with nanosilica (nano-SiO 2) part... more Glass fabric reinforced polybenzoxazine-based composites filled with nanosilica (nano-SiO 2) particles were used to create strike panels for multilayered armor applications. The effect of the added nano-SiO 2 on the mechanical properties and ballistic impact responses of the composites was quantified using a variety of techniques and related to the interfacial interactions between the two materials. Impact response was effectively mitigated by the added nano-SiO 2 as composite panels which contained the additive exhibited smaller damage areas as well as lower penetration depths after being subjected to 5.56 × 45 mm projectiles when compared to composite panels that lacked the additive. Furthermore, a series of numerical simulations predicted that composites of appropriate thickness should protect against the penetration of projectiles with velocities of 930 ± 20 m/s and ballistic limit velocities as high as 1075 m/s. Collectively, these results indicate that the composites may be used as strike panels in ballistic armor applications.
Journal of Applied Polymer Science, 2020
High‐performance room temperature‐cure epoxy structural adhesives utilizing simplified formulatio... more High‐performance room temperature‐cure epoxy structural adhesives utilizing simplified formulation are developed. The developed structural adhesive consists of diglycidyl ether of bisphenol A (DGEBA) and novolac epoxy blend as a base resin, micrometer‐sized silica particles as a reinforcing filler, and triethylenetetramine as a curing agent. The developed ambient temperature‐cure epoxy structural adhesive with optimized formulation exhibits outstanding properties including high glass transition temperature of 95°C, high thermal stability with degradation temperature at 5% weight loss of 364°C, exceptionally high rubbery plateau modulus of 320 MPa, good flame‐retardant characteristics with limiting oxygen index of 40, and high single lap shear strength for single lap steel‐steel bonded joint of 548 MPa at the temperature of 80°C. The silica‐filled DGEBA/novolac epoxy composite adhesive is a potential candidate for applying as a structural adhesive for construction with long‐term dura...
Chemistry – An Asian Journal, 2019
When dealing with smart polymers, in particular with shape memory polymers, the polymer type and ... more When dealing with smart polymers, in particular with shape memory polymers, the polymer type and composition specify the overall material properties and in particular the extent of the shape memory effect. Polybenzoxazines as a polymer with high potential for structural applications represent a promising component for materials with both shape memory effect and structurally interesting material properties. This minireview gives insight into how the shape memory effect, in particular the shape recovery event, is influenced by internal factors such as polymer structure, morphology and external factors such as filler addition.
Engineering Journal, 2014
Significant enhancement on impact property of poly(vinyl chloride)/acrylonitrile styrene acrylate... more Significant enhancement on impact property of poly(vinyl chloride)/acrylonitrile styrene acrylate (PVC/ASA) blends was observed. The effect of ASA content on mechanical characteristics, including impact strength, themomechanical properties, water absorption, and outdoor weathering durability were investigated. The results suggested that the impact strength of the PVC/ASA blends increased drastically at the ASA content of about 30-40 wt% and at the ASA content of 50 wt%, the significant high impact strength of up to 77.6 kJ/m 2 was obtained. The modulus and strength under tensile and flexural loads of PVC/ASA blends were found to increase with the PVC fraction while glass transition temperature of PVC and heat deflection temperature of the blends systematically increased with increasing ASA content. The blends are partially miscible in nature as evidenced from the shift of the two glass transition temperatures towards each other in the dynamic mechanical analysis. In addition, ASA fraction in the blends provides improved resistance to UV radiation for the PVC/ASA blend sample under natural weathering. The obtained PVC/ASA blends clearly showed a potential use as high impact plastic products for outdoor application.
Engineering Journal, 2012
In this research, characteristics of methylcellulose (MC) films modified with two crosslinking me... more In this research, characteristics of methylcellulose (MC) films modified with two crosslinking methods are investigated. The first method is the use of a glutaraldehyde (GA) crosslinker to promote hemi-acetal linkages between MC chains. The second one is gamma irradiation to form insoluble MC gel by intermolecular crosslinking. The effects of the MC concentration on the degree of crosslinking, water absorption, gel content, degree of swelling, and thermomechanical properties were determined. The results indicate that the chemically crosslinked MC films show lower polarity than the radiation crosslinked films. The nature of the crosslinkings was also revealed with FTIR spectra. The waterswelled films of chemically crosslinked MC were found to provide homogeneous gel structure whereas the radiation crosslinked MC films were observed to render less uniform crosslinked films.
Express Polymer Letters, 2012
A series of polymeric alloying films were prepared from bisphenol A/aniline-based bifunctional be... more A series of polymeric alloying films were prepared from bisphenol A/aniline-based bifunctional benzoxazine resin (BA-a) with three isomeric biphenyltetracarboxylic dianhydrides, i.e., 2,3!,3,4!-biphenyltetra carboxylic dianhydride (a-BPDA), 2,2!,3,3!-biphenyltetracarboxylic dianhydride (i-BPDA), and 3,3!,4,4!-biphenyltetracarboxylic dianhydride (s-BPDA) through fully thermal curing. Chemical structure, thermomechanical property and thermal stability of bisphenol A/aniline type polybenzoxazine (PBA-a) copolymers were evaluated. Their chemical structures analyzed via Fourier transform infrared spectroscopy reveal ester carbonyl linkage formation between hydroxyl group of the PBA-a and anhydride group in the isomeric dianhydride. Glass transition temperatures (T g s) of the dianhydride-modified PBA-a increased with PBA-a"<<"i-BPDA"<"a-BPDA"<"s-BPDA. Degradation temperatures (T d) of the PBA-a copolymers recorded to be in the range of 365-402°C were significantly higher than that of the neat PBA-a i.e. 334°C. Finally, char yield of the PBA-a copolymers was found to be about 54-57% which is about twofold increase from that of the parent PBA-a.
Engineering Materials, 2013
ABSTRACT This chapter discusses one engineering application of polybenzoxazines as a highly therm... more ABSTRACT This chapter discusses one engineering application of polybenzoxazines as a highly thermally conductive electronic packaging encapsulant. The combination of various useful properties of benzoxazine resins and their resulting polymers has been demonstrated to render a very high thermally conductive polymer composite. Thermal conductivity value as high as 32.5 W/mK in hexagonal boron nitride-filled polybenzoxazine, up to present, remains the highest reported thermal conductivity value in the literature. Other outstanding properties of the resulting composites as an electronic packaging encapsulant are also discussed in this chapter.
Engineering Materials, 2013
One outstanding property of benzoxazine resins is their very low A-stage viscosity, and therefore... more One outstanding property of benzoxazine resins is their very low A-stage viscosity, and therefore, it provides good filler wetting characteristic and allows large amount of filler or reinforcement to be incorporated in the matrix resin during composite fabrication. The relatively broad processing window with suitable chemorheological properties also renders the resins their ability to fabricate special composite systems of a highly filled kind. In this book chapter, we discuss the above high processability of benzoxazine resins to form various types of highly filled systems. These special kinds of composite materials are of crucial practice and a key success in such applications as dental composites, orthopedic composites, wood-substituted composites, thermally conductive composites, or friction and wear composites.
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Papers by Chanchira Jubsilp