The objective of this research is to develop a high tear strength suture pads from a polydimethylsiloxane (PDMS) composite reinforced with degummed silk fibers (DSFs) as artificial hand skin for suturing practice. The influences of fiber diameters, lengths, and contents of DSFs on mechanical properties of the prepared PDMS/DSFs composites were systematically investigated. In composite preparation, PDMS resin and silicone oil were mixed, followed by the gradual addition of DSFs with continuous stirring. The uncured mixture was then cast in molds and cured at room temperature for 4 hours. The results demonstrated that DSFs with a smaller diameter of 170 μm significantly improved tensile strength, elastic modulus, hardness, and, most notably, tear strength—an important property for resisting cuts from medical sutures. The morphology of the composites revealed that the DSFs have uniform dispersion and good adhesion in the PDMS matrix. Additionally, the lengths and contents of DSFs contributed to the enhancement of the mechanical properties of the PDMS/DSFs composites. The developed PDMS/DSFs composites exhibited mechanical properties and texture relatively close to those of real human skin as evaluated by experienced orthopedic surgeons. This indicates that a PDMS/DSFs composite is an effective artificial hand skin model for suture practice.

Developing 4D printing using shape memory polymers (SMPs) with high mechanical and thermal stability is crucial for specific applications, such as deployable structures. In this work, we utilize sustainable chemicals to produce high-performance 4D printing of SMPs by blending biobased eugenol-furfurylamine benzoxazine (E-fa) (0-20 wt%) with a photoreactive acrylic (AC) resin via dual-curing of UV (LCD 3D printer) and thermal methods. Interpenetrating polymer networks (IPNs) were efficiently created in the as-prepared hybrids with enhancements in material properties. DMA analysis revealed the proportional increase in stiffness and crosslinked density with the increase of E-fa resin content. Blending E-fa with AC gradually improved the 4D material properties at an optimum of 15 wt% E-fa, with a 45 % enhancement in flexural strength (101.20 to 146.84 MPa), a 36 % rise in tensile strength (60.33 to 81.80 MPa), and a 16 degrees C increase in 5 % weight loss temperature, in comparison to pure AC resin. The optimum blending of E-fa with AC also exhibited excellent shape memory properties, with a 99.6 % shape fixity ratio, a 97.8 % shape recovery ratio, and stability for up to 15 shape memory cycles. More importantly, 4D spring shapes were produced to illustrate the practical application and efficiency of AC and AC/ E-fa blend 4D materials. Notably, the 4D spring shape from the AC/E-fa blend has a higher recovery force than the 4D spring shape from pure AC. Therefore, the AC/E-fa blend 4D materials show great potential for meeting demanding engineering requirements.

Novel two-way shape memory polymer composites (2WSMPC) consisting of interpenetrating polymer networks (IPNs) of poly(benzoxazine/urethane) reinforced with carbon fiber felt (CFF) were developed in this work. Sequential curing, i.e., moisture curing of urethane followed by thermal curing of benzoxazine (BA-a) was used to synthesize IPNs with molecular phase separation. The thermomechanical properties and two-way shape memory effect (2WSME) of the IPNs were systematically investigated by varying the urethane content. It was found that the glass transition temperature (Tg) and 2WSME of the IPNs based on poly(benzoxazine/urethane) improved by optimizing the urethane content. Moreover, the electro-induced shape memory performance was found to be dependent on the CFF reinforcement. The results showed that the developed IPNs reinforced with CFF triggered by electric current exhibited high two-way shape memory performance, i.e., a fixity at room temperature (RT) of 97–98

The objective of this research is to investigate the effect of aliphatic amine chain lengths on shape memory polymers (SMPs) properties of benzoxazine resin. Bisphenol-A, paraformaldehyde, and different aliphatic amine chain lengths at 1:4:2 mol ratio are reacted at 120 degrees C for an hour. The synthesized samples are represented as BAxMA, where x is the number of C atoms ranging from 6-18. It was found that shape fixity ratio (Rf) increased with short aliphatic chain, conversely to recovery ratio (Rr). Therefore, the self-copolymerization of poly(BAxMA/BA-a)s are developed to improve the fixation ability. Interestingly, the cyclability of the copoly(BA12dda/BA-a) at 60/40 is significantly enhanced reaching 34 cyclability where the Rr remains almost 100 %. Furthermore, the copoly(BA-12dda/BA-a) exhibits multiple-shape memory behavior resulting from a wide range of transition temperatures. The selfcopolymerization of benzoxazine reduces molecular complexity, enhances compatibility, and simplifies preparation steps, making benzoxazine-based SMPs highly promising for advanced shape memory polymer applications.

Novel magnetic-responsive triple shape memory polymers (SMPs) derived from bio-based benzoxazine-urethane (V-fa/PU) polymer alloys containing iron oxide nanoparticles (Fe3O4 NPs) were developed in this work. Shape memory effect and curing behavior of the alloys were investigated at various bio-based PU contents. The polymerization of V-fa/PU polymer alloys with a heterogeneous network generated a broad glass transition temperature, which is a crucial feature for the development of triple SMPs. The influence of Fe3O4 NPs incorporation into the polymer nanocomposites on the SMP performance triggered by magnetic fields was also investigated. It was found that the addition of Fe3O4 NPs can enhance the dynamic mechanical properties and magnetic characteristics of the V-fa/PU polymer alloys thanks to the superparamagnetic property of Fe3O4 NPs. Moreover, the performance of the SMPs based on V-fa/PU polymer nanocomposites filled with Fe3O4 NPs showed high shape fixity of up to 98%, a shape recovery of 98%, and a recovering time of 8 s. Furthermore, bio-based V-fa/PU polymer alloys containing Fe3O4 NPs were developed as magnetic responsive triple SMPs with shape fixity in the range of 95–97% and shape recovery in the range of 85–95%. The results suggested that magnetic responsive triple SMPs from bio-based V-fa/PU polymer alloys filled with Fe3O4 NPs are promising candidate for advanced applications.

A novel dental fiber post from glass fiber-reinforced polybenzoxazine (PBZ) composites was developed in this work. The essential properties, that is, chemical characteristics, thermal and biological properties of the PBZ composites were investigated for various glass fiber loadings (10.5, 23.7, 41.2 and 65.1 vol%). Finite element analysis (FEA) was also utilized to observe mechanical behaviors of the tooth model repaired with PBZ composite posts compared to a natural tooth model. The findings reveal that for the fiber-reinforced PBZ composites not only their thermal properties were significantly improved, but they also showed enhanced cytocompatibility; we found a coefficient of thermal expansion of 12.8 ppm/degrees C and cell viability of 91.55 for the 65.1 vol% glass fiber-reinforced PBZ composite. Moreover, samples reinforced with higher glass fiber loadings effectively resulted in the reduction of stress distribution in dentin observed from FEA suggesting protection againt root fractures. Restoration using the PBZ composite post showed the same stress patterns in the dentin-composite resin-post interface of the repaired tooth as in the natural tooth model. The results revealed that the glass fiber-reinforced PBZ composites possess good thermal properties and mechanical behaviors which renders them suitable candidates for biocompatible dental materials.Highlights The glass fiber/polybenzoxazine (GF/PBZ) composites had nontoxic properties as evidenced through cell viability, growth and morphology studies. The thermal expansion of the GF/PBZ composite was similar to that of dentin, promoting adaptation at the dentin-post interface. Mechanical behaviors evaluated by FEA of tooth model restored with GF/PBZ composite post were similar to those restored with commercial glass fiber post. The biocompatible GF/PBZ composite with good thermal and mechanical properties is a promising new candidate material as dental fiber post. Effect of glass fiber reinforcement on biological and thermal properties, mechanical behaviors and chemical characteristics of the PBZ composites for use as a dental fiber post. image

We report new nanocomposites with poly(benzoxazine-co-epoxy) matrix reinforced with 1 wt% graphene. Curabox 24-111, a benzoxazine resin was copolymerised with Epilok 60-566, a mixture of epoxy resins. Copolymerisation was also carried out in the presence of different graphene powders, namely, Nanene-001 and Nanene-002, used as single fillers and as mixture (relative weight ratio 70:30 or 30:70). DSC results showed the addition of either single filler caused a delay in polymerisation and an increase in the exothermic peak temperature of the curing reaction with a related reduction in ΔH Total. compared to the neat copolymer. Copolymerisation showed a 38% reduction and 24% increase in tensile modulus (E) compared to the neat polybenzoxazine and epoxy polymer, with a respective 18% and 30% reduction in tensile strength (TS). Nanocomposites with 0.7wt% Nanene-002 + 0.3 wt% Nanene-001 showed the highest increase of 35% in TS, a 1.6% reduction in E and 36% increase in elongation at break (EB) compared to the neat copolymer matrix. Samples with 1 wt% Nanene-001 showed the largest reduction of 21% in E, a 27% increase in TS and a 45% increase in EB. Additionally, TGA thermographs showed a 22°C increase in the onset of degradation (300°C–322°C) improving the materials thermal stability.

Biocopolymers based on vanillin/fufurylamine–biobenzoxazine (V-fa) and epoxide castor oil (ECO), a bioepoxy, were prepared for application as dental fiber-reinforced composite post. The mechanical and thermal properties of the V-fa/ECO biocopolymers were assessed with regard to the influence of ECO content. The addition of the ECO at an amount of 20% by weight into the poly(V-fa) preserved the stiffness, glass transition temperature and thermal stability nearly to the poly(V-fa). Differential scanning calorimetry (DSC) was used to examine the curing kinetics of the V-fa/ECO monomer system with different heating rates. To determine the activation energy ( E a ), the experimental data were subjected to the isoconversional methods, namely Flynn–Wall–Ozawa (FWO) and Friedman (FR). The V-fa/ECO monomer mixture showed average E a values of 105 kJ/mol and 94 kJ/mol. The results derived using the curing reaction model and the experimental data were in good agreement, demonstrating the efficacy of the FWO method for determining the curing kinetics parameters. The simulated mechanical response to external applied loads by finite-element analysis of the tooth model restored with glass fiber-reinforced V-fa/ECO biocopolymer post showed a similar stress field to the tooth model restored with a commercial glass fiber post. Therefore, based on the findings in this work, it is evident that the bio-based benzoxazine/epoxy copolymer possesses a great potential to be used for dental fiber post. Graphical Abstract

A novel material based on silicone rubber (SR) modified with natural rubber (NR) was developed. Combinations of sulfur/peroxide curing systems were used as crosslinking agents. The results showed that the incorporation of NR improved the tensile strength, tear strength and elongation at break of the SR/NR blend. It was also found that the blending of SR/NR at 90/10 provided the greatest tensile strength and elongation at break of 1.9 MPa and 1381%, respectively as well as good tear strength. The properties of this SR/NR blend and the corresponding interpenetrating polymer network (IPN) were compared and showed that the IPN provided higher tensile strength. However, the blend exhibited greater elongation at break and hardness, relatively close to human skin which are more important for a birthing model material. It can be concluded that the blending of SR/NR at 90/10 is the most promising material to substitute expensive currently used birthing model.

This work studies the effects of graphene nanoplatelets (GNPs) and hexagonal boron nitride (hBN) on the thermal and mechanical properties of polydimethylsiloxane (PDMS) matrix for use as thermal interface materials (TIMs). Solution mixing of 10 wt% GNPs and 40 wt% hBN with PDMS produced TIMs with through-plane thermal conductivity (TC) of 1.24 W m−1 K−1 showing a 519% increase relative to the neat matrix. A synergistic effect between GNPs and hBN was particularly demonstrated when in samples with 48 wt% total filler content, 8 wt% hBN was replaced by GNPs, and the TC was increased by 33%. The elongation at break of the hBN (40 wt%)/GNP (8 wt%) samples reached 151%, representing a 160% increase when compared to samples with only 40 wt% hBN. Moreover, the shore hardness of samples containing 40 wt% hBN was 68 A, and the introduction of 8 wt% GNPs caused a decrease to 38 A. DSC measurements on samples filled with hBN and GNPs showed a reduction up to 65% in Ultimate Heat of Curing, which was attributed to the presence of graphene flakes interfering with the curing of the matrix. Graphene was found to be an efficient filler in tuning the thermal and mechanical properties of TIMs.

In this work, shape memory polymers (SMPs) were developed from a combination of a bio-based benzoxazine (BZ) monomer and polyurethane prepolymer (PU-prepolymer), both derived from bio-based raw materials. The bio-based BZ monomer (V-fa monomer) was synthesized through a Mannich condensation reaction using vanillin, paraformaldehyde, and furfurylamine. The bio-based PU-prepolymer was obtained by reacting palm oil polyol (MW = 1400 Da) and toluene diisocyanate (TDI). To investigate the curing behavior of poly(V-fa/urethane), with a mass ratio of 50/50, differential scanning calorimetry was employed. The structure of the resulting poly(V-fa/urethane) was confirmed using Fourier transform infrared spectroscopy. Furthermore, the synthesized V-fa/urethane copolymers with weight ratios of 70/30, 60/40, 50/50 and 40/60 were observed to exhibit shape memory behaviors induced by near-infrared irradiation (808 nm). Poly(V-fa/urethane), specifically with a mass ratio of 50/50, demonstrated superior shape memory performance. It exhibited a remarkable capacity to retain the temporary shape up to 90%, achieve 99% shape recovery, and exhibit a recovery time of 25 s. The shape memory properties were further improved with the addition of 3 wt% graphene nanoplatelets (GNPs), exhibiting an improvement in the shape fixity value to 94%, and shape recovery time value to 16 s. Moreover, our findings suggest that 60/40 poly(V-fa/urethane) reinforced with 3 wt% GNPs possesses favorable characteristics for applications as multiple SMPs, with shape fixity values of 97% and 94%, and shape recovery values of 96% and 89% for the first and second shapes, respectively.

In this work, we report the synthesis and study of nanocomposites with a biobased epoxy/amine (Epilok 60-600G/Curamine 30-952) matrix reinforced with reduced graphene oxide (rGO) or functionalised with 3-glycidoxypropyltrimethoxysilane (GLYMO-rGO). These graphene related materials (GRMs) were first dispersed into a Curamine hardener using bath ultrasonication, followed by the addition of epoxy resin. Curing kinetics were studied by DSC under non-isothermal and isothermal conditions. The addition of 1.5 wt% of GLYMO-rGO into the epoxy matrix was found to increase the degree of cure by up to 12% and glass transition temperature by 14 °C. Mechanical testing showed that the addition of 0.05 wt% GLYMO-rGO improves Young's modulus and tensile strength by 60% and 16%, respectively, compared to neat epoxy. Carbon fibre reinforced polymer (CFRP) laminates were prepared via hand lay up, using the nanocomposite system GRM/Epilok/Curamine as matrix, and were cut as CFRP adherents for lap shear joints. GRM/Epilok/Curamine was also used as adhesive to bond CFRP/CFRP and CFRP/aluminium adherents. The addition of 0.1 wt% GLYMO-rGO into the adhesive and CRFP adherents showed improved lap shear strength by 23.6% compared to neat resin, while in the case of CFRP/Aluminium joints the increase was 21.2%.

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. Therefore, it is possible that the developed UFPNRs grafted copolymers with good solvent resistance and rather high thermal stability can be used easily as toughening modifiers for polymers and their composites.

The manufacturing landscape is ever-changing, and one of the most significant driving forces is the emergence of additive manufacturing (AM), which enables cost-effective and small-scale production towards sustainability. To better align AM with manufacturing in suitable applications, this study proposes a business model in terms of the cost pattern and scaling production supported by three key concepts: standardisation, localisation and collaboration. The ambiguity of the cost calculation is one of the key factors slowing down AM progress, and a lack of a cost pattern affects decision-making when applying AM to appropriate applications. The business model in this study is focused on applying the data collected from previous research, the collection-recycling-manufacturing (CRM) model, to discover the implications of AM processes on the road to sustainable manufacturing. The novel business model envisions the nature of AM characteristics and their linkages to cost patterns, so AM applications can be integrated into a cost-effective process. This study contributes qualitative analysis to the cost patterns' integration. Through this integration, the business model mediates the gap between technologies and applications via the formulas of cost patterns, so AM can perform its appropriate role in the industry mainstream. The cost modelling proposed in this study derives generic formulas via the unit cost of tooling, moulding, machine, materials, design, miscellaneous cost and the batch size. The business model applies the "divide-and-conquer" concept, convergence effect and data analysis to support quantitative analysis. The model can calculate the total cost per unit, and its accuracy is close to 100%. Through the novelty of this model, AM and conventional manufacturing (CM) cost benchmarking and decision support functions are enabled to aid in stakeholder decision-making. Eventually, appropriate AM technologies and processes can synchronise with localisation, standardisation and collaboration and, ultimately, the impact of AM towards sustainable manufacturing.

The study describes a homogenisation technique of developing a Polyether ether ketone (PEEK) and calcium hydroxyapatite (cHAp) composite with periodic pattern lattice structures. The continuum depiction of the discrete structures was evaluated to retain the PEEK cellulose composite properties of the lattice cell applied to dental implants. Design approaches were considered, using different software modelling to optimise the orthotropic lattice PEEK material by establishing an optimal variable cell lattice density distribution in the geometric model of a dental implant. A homogenising model was studied based on the lattice optimisation that resulted from the previous stage and considered different volume fractions, pore size, and variable density for different lattice cells for dental implants. Their adequate elastic fatigues were obtained by the unit cell's fast design-based model homogenisation method, and bioactivity cell tests took place in a culture medium. It was evident from the results obtained that the homogenisation increased the stiffness of the bracket by using the same cubic lattice cell, and the fundamental frequency obtained with lattice optimisation to higher results after implants. This result can easily be applied by using these lattice structures and PEEK composite in dental implants for medical industries and institutions as a lightweight and better biocompatible materials compared to metals.

Materials recycling and additive manufacturing (AM) present challenges and great opportunities in plastic industries. The rapid developments in AM are transforming the manufacturing industry. Reducing CO2 emissions, saving cost, and escaping from landfill are the decisive factors in this transformation. In this study, to mitigate any risk caused by production speed and scaling and accelerate shift towards a more localized recycling and manufacturing of plastic parts and components, a collection-recycling-manufacturing (CRM) model is built to envision the evaluation of process flow as well as process integration. The novelty of the CRM model enables optimization between recycling facilities and transportation distance calculation. It further strengthens a seamless integration between recycling and AM processes and envisions the areas that need enhancements. The study reveals that AM creates opportunities such as prototyping, customizing, transportation cost reduction, and creation of jobs in rural areas, which may stop unnecessary immigration; and, most importantly, reducing CO2 emissions and plastic waste despite challenges such as skills requirement and disadvantages in speed and scale production. With a combination of recycling and AM, sustainable manufacturing can be achieved effectively, although several conditions must be met and obstacles must be overcome. A few innovations are further proposed in this study to streamline the transformation and to support the “cradle-to-cradle’’ approach towards “zero waste” for a sustainable future.

Climate change due to greenhouse gas emissions is the most important issue in the world, threatening our lives. Studies reveal that most emissions are caused by transportation (29%), manufacturing (23%), and irregular population distribution across the world. This study suggests the localization of recycling and manufacturing plastic parts and components by additive manufacturing. Localization will decrease transportation, resulting in reduced energy consumption and CO2 emissions. However, the method may not be sufficient because local additive manufacturing means less reliance on supply chains and higher dependence on the workforce in rural areas. Factors such as the workforce in rural areas, multientity authorities, and policy are important to the realization of sustainable manufacturing. In this study, a novel strategic control model is proposed to focus on human-centric approaches. The strategic control model proposes methods to connect strategic planning with demography and the workforce and to apply control metrics to relocate overcrowded populations to rural areas. The strategic control model realizes localization through workforce allocation and home-based manufacturing. It streamlines the integration between recycling, manufacturing, and distribution. As a result, decreased reliance on the supply chain reduces transportation, energy consumption, CO2 emissions, and cost. It also creates job opportunities and mitigates societal issues.

The composite coating can effectively inhibit bacterial proliferation and promote the expression of bone-building genes in-vitro. Therefore, a novel production was used to produce poly-ether-ether-ketone, and reduced graphene oxide (PEEK-rGO) scaffolds with ratios of 1–3%, combining a different lattice for a bone implant. An inexpensive method was developed to prepare the new coatings on the PEEK scaffold with reduced graphene oxide (rGO). Mechanical testing, data analysis and cell culture tests for in-vitro biocompatibility scaffold characterisation for the PEEK composite were conducted. Novel computation microanalysis of four-dimensional (4D) printing of microstructure of PEEK-rGO concerning the grain size and three dimensional (3D) morphology was influenced by furrow segmentation of grains cell growth on the composite, which was reduced from an average of 216–155 grains and increased to 253 grains on the last day. The proposed spherical nanoparticles cell grew with time after dispersed PEEK nanoparticles in calcium hydroxyapatite (cHAp) grains. Also, the mechanical tests were carried out to validate the strength of the new composites and compare them to that of a natural bone. The established 3D-printed PEEK composite scaffolds significantly exhibited the potential of bone implants for biomimetic heterogeneous bone repair.