Hiroshi Ito

Yamagata University | YU · Graduate School of Organic Materials Science

Microplastics’ spreading in the ocean is currently causing significant damage to organisms and ecosystems around the world. To address this oceanic issue, there is a current focus on marine degradable plastics. Polycaprolactone (PCL) is a marine degradable plastic that is attracting attention. To further improve the biodegradability of PCL, we sele...

Two biodegradable polyesters, poly(butylene succinate) (PBS) and poly(butylene succinate‐ co ‐adipate) (PBSA), were artificially aged in a UV irradiation test chamber, and their photodegradation behaviors investigated. The attenuated total reflection (ATR) infrared (IR) spectra of the initial and UV‐aged samples revealed conformational changes in t...

The conventional method for the color-matching process involves the compounding of polymers with pigments and then preparing plaques by using injection molding before measuring the color by an offline spectrophotometer. If the color fails to meet the L*, a*, and b* standards, the color-matching process must be repeated. In this study, the aim is to...

The incorporation of thermoplastics with pigments imparts diverse aesthetic qualities and properties to colored thermoplastic products. The selection of pigment type and content, along with specific processing conditions, plays a pivotal role in influencing color properties and overall product performance. This study focuses on optimizing these par...

Bamboo fiber was extracted after alkaline treatment, and the mechanical properties of fibers and polymer composites were measured. The results showed that the strength of bamboo fiber was higher when the diameter was smaller. Smaller diameter bamboo fibers were dense, while larger diameter ones were composed of vascular bundles, which contained ins...

In this study, cellulose nanofibers (CNFs) were treated in an ultrahigh-pressure homogenizer (UHPH) in the thermal imprinting process. After 20 passes, UHPH-treated CNFs with concentrations of 1, 2, and 5 wt% were used to reinforce polyvinyl alcohol (PVA), and PVA/CNF composite films were fabricated by solvent casting. The composite films were subj...

Fused deposition modeling (FDM) 3D printing has printed thermoplastic materials layer-by-layer to form three dimensional products whereby interlayer adhesion must be well controlled to obtain high mechanical performance and product integrity. This research studied the effects of ambient temperatures and crystalline structure on the interlayer adhes...

In the field of metals, especially in magnesium alloys, a new concept has been reported that introducing a kink by applying compression or other deformation to a material with an LPSO structure, in which hard and soft layers are alternately stacked, results in higher strength. Because crystalline polymers are alternately layered with a crystalline...

This research focuses on the mechanical properties of polypropylene (PP) blended with recycled PP (rPP) at various concentrations. The rPP can be added at up to 40 wt% into the PP matrix without significantly affecting the mechanical properties. MFI of blended PP increased with increasing rPP content. Modulus and tensile strength of PP slightly dec...

The effects of oxo-biodegradable additives on the photo-oxidation of four types of polyolefin polymers, namely high-density polyethylene (HDPE), low-density PE (LDPE), linear low-density PE (LLDPE), and isotactic polypropylene (itPP) were investigated. Scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, and wide-...

The effects of annealing conditions and molecular weight on the energies required for cracking and plastic deformation were investigated by the essential work of fracture (EWF) method. We found that the energy required for plastic deformation, βwp, regardless of the molecular weight, decreased upon annealing, and the energy required for cracking, w...

Cellulose nanofibers (CNF) were prepared by nanoisolation using a newly developed ultrahigh-pressure homogenizer (UHPH). The CNF was treated by UHPH with 0, 10, and 20 passes. The effect of UHPH on defibrillation of the CNF and its structure was investigated. The UHPH-treated CNF reinforced poly(vinyl alcohol) (PVA) composite was fabricated by solv...

Commercial filaments of poly(lactic acid) (PLA) composites with particulate filler, carbon fiber, and copper powder with different contents were fabricated by FDM 3D printing in XZ-direction at bed temperatures of 45 °C and 60 °C. The effects of additives and bed temperatures on layer adhesion, fracture behavior, and mechanical performance of the P...

A composite fabricated from 9,9′-bis(aryl)fluorene-modified nanocellulose (FCF) and bamboo fiber was studied to explore its processing conditions and limitations. The FCF acted as a binding agent, and bamboo fibers were used as structural reinforcement. Two types of FCF were fabricated and studied: hydroxy and epoxy functional groups with FCF. The...

Compared with polyolefins that are used as single-use plastics, polylactic acid (PLA) has a lower tear strength in films. The relationship between the tear strength and the higher-order structure of films was investigated using PLA films that absorbed moisture at 30 °C and 95% relative humidity (RH) or that had been annealed under reduced pressure...

An octa-screw extruder (OSE) is equipment for pelletizing, blending, and mixing polymers and composites. In this study, the degree of resin filling, residence time distribution (RTD) of molten resin, and temperature profile in the octa-screw extruder were evaluated both experimentally and numerically. An intermeshing corotating parallel octa-screw...

Highly crystallized polylactic acid (PLA) is suitable for industrial applications due to its stiffness, heat resistance, and dimensional stability. However, crystal lamellae in PLA products might delay PLA decomposition in the environment. This study clarifies how the initial crystal structure influences the hydrolytic degradation of PLA under acce...

This paper reports on an experimental study on the higher-order structural forming of bi-layer film in the process of uni-axial/bi-axial stretching. Bi-layer films produced by co-extrusion of cycloolefin polymer (COP) and linear low-density polyethylene (LLDPE) were stretched using a film stretcher equipped with a high-speed camera to investigate t...

A green composite was fabricated using bamboo fiber and 9,9′-bis(aryl)fluorene-modified cellulose nanofiber (FCNF). Cellulose nanofiber (CNF) and finely crushed bamboo fiber (CBF) were also used as binders. The mechanical properties of the composites were compared. It was found that the FCNF-bamboo fiber composite had the maximum flexural strength...

The diffusion process of water molecules within a polyetherimide (PEI) glassy matrix has been analyzed by combining the experimental analysis of water sorption kinetics performed by FTIR spectroscopy with theoretical information gathered from Molecular Dynamics simulations and with the expression of water chemical potential provided by a non-equili...

The diffusion process of water molecules within a polyetherimide (PEI) glassy matrix has been analyzed by combining the experimental analysis of water sorption kinetics performed by FTIR spectroscopy with theoretical information gathered from Molecular Dynamics simulations and with the expression of water chemical potential provided by a non-equili...

Aluminum (Al) flake filled epoxy resin composites were fabricated, and the effect of flake surface treatment on the mechanical properties of the composites was investigated. The tensile shear test between the Al plate and epoxy resin displayed the highest interfacial shear strength of 12.1 MPa when the Al plate surface was treated with a silane cou...

Ultra-high molecular weight polyethylene (UHMWPE) is one of the well-established bio-materials for artificial prostheses. In order to improve its wear resistance, graphene incorporated UHMWPE nanocomposites are synthesized by octa-screw extrusion process. The exceptional compounding ability of the process is confirmed by uniform graphene dispersion...

Poly(lactic acid) (PLA) filaments have been the most used in fused deposition modeling (FDM) 3D printing. The filaments, based on PLA, are continuing to be developed to overcome brittleness, low heat resistance, and obtain superior mechanical performance in 3D printing. From our previous study, the binary blend composites from PLA and poly(butylene...

Mechanochromic elastomers that exhibit force‐induced cross‐linking reactions in the bulk state are introduced. The synthesis of segmented polyurethanes (SPUs) that contain difluorenylsuccinonitrile (DFSN) moieties in the main chain and methacryloyl groups in the side chains was carried out. DFSN was selected as the mechanophore because it dissociat...

The diffusion process of water molecules within a polyetherimide (PEI) glassy matrix has been analyzed by combining the experimental analysis of water sorption kinetics performed by FTIR spectroscopy with theoretical information gathered from Molecular Dynamics simulations and with the expression of water chemical potential provided by a non-equili...

Mechanofunktionelle Polymere, die einen Farbwechsel, Fluoreszenz und die Fähigkeit zur Selbstverfestigung aufweisen, werden von Hideyuki Otsuka et al. in ihrer Zuschrift (DOI: 10.1002/ange.202015196) vorgestellt. Es ist das erste Beispiel für kraftinduzierte Vernetzungsreaktionen, die nur durch die Dehnung oder Kompression eines Bulk‐Films erreicht...

Mechanofunctional polymers that exhibit color change, fluorescence, and self‐strengthening ability were developed by Hideyuki Otsuka et al. in their Communication (DOI: 10.1002/anie.202015196). It is the first example of force‐induced cross‐linking reactions achieved by only the extension or compression of a bulk film. The cross‐linking reaction ca...

Mechanochromic elastomers that exhibit force‐induced cross‐linking reactions in the bulk state are prepared to demonstrate damage detection ability by color change and fluorescence, and changes in the mechanical properties of bulk elastomers induced by simple compression or extension. Abstract Mechanochromic elastomers that exhibit force‐induced c...

17-4PH stainless steel specimens were fabricated by fused deposition of metals (FDMet) technology, which combines 17-4PH particles with an organic binder. FDMet promises a low-cost additive manufacturing process. The present research aims to clarify the influence of layer directions in the 3D printing process on the mechanical and shrinkage propert...

A ternary composite of poly(lactic acid) (PLA), poly(caprolactone) (PCL), and carbon black (CB) shows the PCL-induced CB self-aggregation and percolation formation when the amount of the PCL phase as the secondary phase is as small as the amount of CB. Furthermore, when the drop size of the PCL phase becomes smaller, the ternary composite forms a p...

A rigid and brittle cross-linking structure was introduced into the flexible poly(n-hexyl methacrylate) (PHMA) network by the mechanochromic cross-linker difluorenylsuccinonitrile-containing methacrylate (DFMA), whose central C-C bond acted as a dynamic covalent bond and could generate pink radicals when fractured. PHMA with DFMA showed a remarkabl...

The influences of the average degree of polymerization (Dp), which is derived from Mn and terminal end group, on optical and thermal properties of various refractive indexed transparent polymers were investigated. In this study, we selected the alicyclic compound, Dinorbornane dimethanol (DNDM) homo polymer, because it has been used as a representa...

We prepared several novel, tough, and transparent poly(methyl methacrylate) (PMMA) blends modified with polyrotaxane (PR) and evaluated their physical properties and morphologies. A styrene/methyl methacrylate/maleic anhydride (SMM) copolymer that was miscible with PMMA was used as a reactive compatibilizer to enhance interfacial adhesion between t...

A difluorenylsuccinonitrile-(DFSN)-based linker, whose central C-C bond is readily cleaved under mechanical stress to generate a relatively stable pink radical species, was introduced into polymer networks. DFSN-based cross-linked polymers exhibit improved mechanical properties as compared to those of the corresponding covalently cross-linked polym...

We developed herein a simple and economical high-resolution wiring process on a plastic substrate. High-resolution conductive patterns on the PEI film was fabricated by utilizing the thermal imprint technology and the capillary flow of the conductive ink. An amorphous thermoplastic polyetherimide (PEI) film was thermally imprinted with a metal mold...

Metal specimens were fabricated via the fused deposition of metals (FDMet) technique with a filament composed of the 316L stainless steel particles and an organic binder. This process was adopted due to its potential as a low-cost additive manufacturing process. The objective of this study is to investigate the influence of the processing condition...

Poly (lactic acid) (PLA) was blended with poly (vinyl alcohol) (PVA) in the composition of 70/30 (L7V3), 60/40 (L6V4), and 50/50 (L5V5) wt.%. L7V3 exhibits a sea–island morphology, while L6V4 and L5V5 show co-continuous phase morphologies. These polymers exhibited a solitary glass transition temperature, which obeyed the Fox equation. Thereafter, t...

Biodegradable poly(lactic acid) (PLA) filaments have been widely used in the fused deposition modeling (FDM) 3D printing technology. However, PLA has low toughness and low thermal resistance that affects printability and restricts its industrial applications. In this study, PLA was compounded with 0 to 40 wt% of poly(butylene adipate-co-terephthala...

Multi-walled carbon nanotube (MWCNT) reinforced polylactide (PLA) nanocomposites were injected molded into a mold with micro needle patterns. In order to alleviate the hesitation effect caused by an increased melt viscositgy of PLA/CNT nanocomposites, the effects of the injection speed and holding pressure on the replication property were investiga...

Three-dimensional (3D) printing is a simple and versatile process for producing parts of complex geometries. Although the process possesses several manufacturing advantages, such as rapid prototyping, customization, and complexity, the optimization of the 3D printing procedure remains a challenge. Here we explore the influences of various processin...

Talc‐containing polypropylene (PP) resin is extensively employed in automobiles. Herein, considering the microstructure transfer process in injection molding, the effect of the talc's dispersibility and particle size on this process and its impact on the gloss level of the product were investigated. Results show that a fine unevenness of about seve...

In this paper, we synthesized MC(BeA-co-MMA) copolymer microcapsules through suspension polymerization. The pendent n-behenyl group of BeA is highly crystalline, and it acts as the side-chain in the structure of BeA-co-MMA copolymer. The highly crystalline n-behenyl side-chain provides BeA-co-MMA copolymer thermal-energy-storage capacity. In order...

In this paper, we synthesized MC(BeA-co-MMA) copolymer microcapsules through suspension polymerization. The pendent n-behenyl group of BeA is highly crystalline, and it acts as the side-chain in the structure of BeA-co-MMA copolymer. The highly crystalline n-behenyl side-chain provides BeA-co-MMA copolymer thermal-energy-storage capacity. In order...

Mesoscale pore one–dimensional (1D) nanostructures, or vertically aligned porous nanostructures (VAPNs), have attracted attention with their excellent hydrophobic properties, ultra−high surface area, and high friction coefficient, compared to conventional vertically aligned nanostructures (VANs). In this study, we investigate the replication of VAP...

One-dimensional (1D) composite nanostructures, or vertically aligned composite nanostructures (VACNs), of polystyrene (PS) and graphene nanoplatelets (GNPs) (1.0-5.0 wt%) were precisely replicated by thermal nanoimprint with an anodic aluminum oxide (AAO) template. In this study, we fabricated VACNs of PS-GNPs (1.0-5.0 wt%) with a diameter of 100 n...

One-dimensional (1D) composite nanostructures, or vertically aligned composite nanostructures (VACNs), of polystyrene (PS) and graphene nanoplatelets (GNPs) (1.0-5.0 wt%) were precisely replicated by thermal nanoimprint with an anodic aluminum oxide (AAO) template. In this study, we fabricated VACNs of PS-GNPs (1.0-5.0 wt%) with a diameter of 100 n...

In our previous paper, we reported that the impact value of polycarbonate (PC) increases with increasing molecular weight and decreases upon annealing [Polymer 2012, 53, 895–896]. To clarify these phenomena, the effects of molecular weight and heat treatment on the fracture of PC are investigated in this study. The results show that the stress for...

Here, the physical properties of maleic-anhydride-modified styrene–ethylene–butylene–styrene copolymer (mSEBS) were controlled by adding paraffin oil; mSEBS formed the interface between polyamide 6 (PA6) and polystyrene (PS). Adding 50 wt% paraffinic oil to mSEBS enabled the reduction of the glass transition temperature (Tg) of the ethylene-butylen...

The influences of degree of polymerization (Dp) and terminal group on thermal and optical properties of polycarbonate are investigated. In this study, Bisphenol-A homo polymer was selected because it has been used as a representative monomer in wide variety optical fields. The end terminating groups were also selected hydroxyl group and phenolic ca...

Ultra-high molecular weight polyethylene (UHMWPE) is a very attractive polymer employed as a high performance material, while filler-reinforced composites have demonstrated its feasibility in various applications. Melt-mixing in an extruder is a key process in the development of polymer nanocomposites. Due to its high melt viscosity, dispersion of...

The influence of talc and rubber contents included in polypropylene (PP) on surface replication properties for microstructure was analyzed. By increasing the talc and rubber contents, surface replication on the injection-molded parts has been reduced. From the surface observation, an uneven microstructure surface was formed for a material containin...

This work reports on an experimental study of the stretching of ultra-high molecular weight polyethylene (UHMWPE) film in various uniaxial/biaxial stretching modes at various temperatures and stretching speeds. We examined the stress-birefringence relationship as a stress-optical rule (SOR) under uniaxial stretching and evaluated the stress-optical...

Co-axial electrospraying is a simple and versatile process, achieving liquid atomization through electrical forces, to produce core-shell-structured nano/microparticles. Despite its advantages in terms of preparing particles with sizes ranging from 300-500 μm down to 50-70 nm, the optimization of the co-axial electrospraying process remains a chall...

Most of the phase change materials (PCMs) have been limited to use as functional additions or sealed in containers, and extra auxiliary equipment or supporting matrix is needed. The emergence of 3D printing technique has dramatically advanced the developments of materials and simplified production processes. This study focuses on a novel strategy t...

Most of the phase change materials (PCMs) have been limited to use as functional additions or sealed in containers, and extra auxiliary equipment or supporting matrix is needed. The emergence of 3D printing technique has dramatically advanced the developments of materials and simplified production processes. This study focuses on a novel strategy t...

In a study of antistatic transparent plastic for optical communication purposes, we previously prepared cyclo olefin polymer (COP)/BN105 composite material and confirmed the improvement of dust resistance as well as good antistatic property on the surface of the molded product. In this study, BN105 composite material using fluorene-based polymer (F...

In the present work, we tried to toughen polyamide 6 (PA6) by blending a small amount of low molecular-weight polyethylene (LMWPE). We obtained the PA6/LMWPE blends with different morphologies using multiple melt-kneading methods such as the uniaxial melt-kneading, the eight-axial screw melt-kneading, and the high shearing method. As a result, it w...

Latent heat storage systems are a highly efficient and environmentally friendly way to use residual heat and store renewable energy. Phase change materials, which can absorb or release the enthalpy of phase changes in certain temperature ranges, are considered one of the most reliable latent heat storage and thermoregulation materials. Phase change...

Ultra-high molecular weight polyethylene (UHMWPE) has been regarded as a representative of bio-materials, especially for artificial prostheses for long term knee/hip joint use. In this work, we have produced micro-nano-composites by using graphite (Gr) as filler to increase the mechanical anti-wear property. The dispersion of graphite in the compos...