Rubber Phase Research Articles

Sustainable thermoplastic elastomers based on thermoplastic polyurethane and ground tire rubber

AbstractIn this research, blends are prepared of thermoplastic polyurethane (TPU), ground tire rubber (GTR) and its devulcanized version (dGTR). The primary objective is to produce thermoplastic elastomers wherein TPU is partially substituted by GTR or dGTR obtained from used tires, thereby forming a blend with a favorable cost/value ratio and a smaller environmental footprint. Throughout the experiment, the rubber content of the blends is varied between 0 and 50 wt% and the effect on mechanical properties is investigated. The blends are compounded with a twin‐screw extruder, after which sheet samples are produced by injection molding. With a view to a possible future industrial application, it is important that both the compounding and the injection molding of the specimens are easy to perform, even with a 50 wt% filler content. Increasing the amount of rubber phase reduce the tensile strength and elongation at break of the blends. Unfortunately, devulcanization did not significantly improve the properties of the blends. Overall, even at a (d)GTR content of 50 wt%, an elongation at break of 300% is achieved, which allows the use of the blends as thermoplastic elastomers. In addition, dynamic tests show that the rubber phase increases the damping capacity of the samples.

PPR/EPDM/POE-g-MA/OMMT nanocomposites with superior low-temperature toughness based on embedded OMMT within compound rubber dispersion phase

A new approach to produce polypropylene random copolymer/ethylene propylene diene monomer/polyolefin elastomers modified with maleic anhydride/organic modified nanomontmorillonite (PPR/EPDM/POE-g-MA/OMMT) nanocomposites with superior low-temperature toughness was conducted. The brittle-ductile transition temperature (Tbd) of PPR/EPDM/POE-g-MA/OMMT nanocomposites reduced from −20 °C to −40 °C. The incorporation of POE-g-MA results in the distribution of OMMT changing from the interfacial distribution into dispersed inside rubber phase and a compound rubber dispersed phase in PPR/EPDM/POE-g-MA/OMMT nanocomposites was comprised of EPDM, POE-g-MA and embedded OMMT. The synergistic effect of POE-g-MA and OMMT was considered to result from the special compound rubber dispersed phase consisting of EPDM and POE-g-MA as well embedded OMMT, which led to the reduction in space between rubber domains and the increase in internal friction and ultimately brought about the remarkable enhancement in mechanical properties.

Water Absorption Effect on Tensile Properties of Linear Low-Density Polyethylene (LLDPE) Blend with Recycle Acrylonitrile Butadiene Rubber Gloves (NBRr) in Saline Water

Nowadays, waste acrylonitrile butadiene rubber glove (NBRr) has been studied for use in building materials. The primary limitation of using rubber in construction was its low water absorption capacity. The goal of this research is to investigate the effect of Linear Low-Density Polyethylene (LLDPE) on water absorption and the temperature differential (20 and 30 oC) of NBRr blender composite in distilled water (DW) and saline water (SW). The rubber glove has been blended with heated two-rolled mills at 120 °C. The substance had been compressed using a hot press. Five samples had already been created. The sample was formed like a dumbbell. The five samples were immersed in DS and SW for 30 days at temperatures of 25°C and 35°C, respectively. The result shown the tensile strength, elongation at break Eb and Young’s modulus of LLDPE/NBRr blend decrease. The tensile properties of saline water lower compare to distilled water due to corrosion and degradation. Saline water contains dissolved salts, which can contribute to corrosion and degradation of the materials. The presence of salts can accelerate chemical reactions, leading to the degradation of the polymer matrix and the rubber phase. This degradation can weaken the material and reduce its tensile strength. Moreover, as the temperature increases, the thermal energy also increases, causing the polymer chains to gain more kinetic energy. This increased energy disrupts the intermolecular forces and reduces the overall molecular interactions within the material. Weaker intermolecular interactions lead to a decrease in tensile strength. As conclusion, hydrothermal effect tensile properties when temperature increase tensile properties decrease. distilled water has better diffusion than saltwater. LLDPE/NBRr blend was discovered that both distilled and salt-water absorption resulted in a decrease in tensile properties.

Control of the rubber particle size and phase structure for the design of transparent methacrylate-acrylonitrile-butadiene-styrene resin with excellent performance

Control of the rubber particle size and phase structure for the design of transparent methacrylate-acrylonitrile-butadiene-styrene resin with excellent performance

Nanoindentation Response of Structural Self-Healing Epoxy Resin: A Hybrid Experimental-Simulation Approach.

In recent years, self-healing polymers have emerged as a topic of considerable interest owing to their capability to partially restore material properties and thereby extend the product's lifespan. The main purpose of this study is to investigate the nanoindentation response in terms of hardness, reduced modulus, contact depth, and coefficient of friction of a self-healing resin developed for use in aeronautical and aerospace contexts. To achieve this, the bifunctional epoxy precursor underwent tailored functionalization to improve its toughness, facilitating effective compatibilization with a rubber phase dispersed within the host epoxy resin. This approach aimed to highlight the significant impact of the quantity and distribution of rubber domains within the resin on enhancing its mechanical properties. The main results are that pure resin (EP sample) exhibits a higher hardness (about 36.7% more) and reduced modulus (about 7% more), consequently leading to a lower contact depth and coefficient of friction (11.4% less) compared to other formulations that, conversely, are well-suited for preserving damage from mechanical stresses due to their capabilities in absorbing mechanical energy. Furthermore, finite element method (FEM) simulations of the nanoindentation process were conducted. The numerical results were meticulously compared with experimental data, demonstrating good agreement. The simulation study confirms that the EP sample with higher hardness and reduced modulus shows less penetration depth under the same applied load with respect to the other analyzed samples. Values of 877 nm (close to the experimental result of 876.1 nm) and 1010 nm (close to the experimental result of 1008.8 nm) were calculated for EP and the toughened self-healing sample (EP-R-160-T), respectively. The numerical results of the hardness provide a value of 0.42 GPa and 0.32 GPa for EP and EP-R-160-T, respectively, which match the experimental data of 0.41 GPa and 0.30 GPa. This validation of the FEM model underscores its efficacy in predicting the mechanical behavior of nanocomposite materials under nanoindentation. The proposed investigation aims to contribute knowledge and optimization tips about self-healing resins.

Modeling of the temperature‐dependent tensile strength of polymer considering the effect of the two‐phase transition of glass and rubber phases

AbstractThis study explores the contribution of glass phase and rubber phase to polymer failure, and establishes a theoretical model of temperature‐dependent tensile strength (TDTS) considering the effect of two‐phase transition based on the Force‐heat Equivalence Energy Density Principle (FHEEDP). The model achieves good verification by comparison with the TDTS experimental data of various polymer materials, including epoxy‐based shape memory polymer (SMP), PEEK‐based SMP and CdS/PMMA. The results demonstrate that the model can perform an accurate prediction for the tensile strength of polymer at different temperatures by easily obtainable material parameters. In conclusion, the proposed theoretical model deepens the understanding on the two‐phase transition and their effect on the TDTS, as well as supplies a practical predicted method on the TDTS of polymer, which is crucial for polymer applied in extreme condition.

Thermo-Mechanical Behavior and Strain Rate Sensitivity of 3D-Printed Polylactic Acid (PLA) below Glass Transition Temperature (Tg).

This study investigated the thermomechanical behavior of 4D-printed polylactic acid (PLA), focusing on its response to varying temperatures and strain rates in a wide range below the glass transition temperature (Tg). The material was characterized using tension, compression, and dynamic mechanical thermal analysis (DMTA), confirming PLA's strong dependency on strain rate and temperature. The glass transition temperature of 4D-printed PLA was determined to be 65 °C using a thermal analysis (DMTA). The elastic modulus changed from 1045.7 MPa in the glassy phase to 1.2 MPa in the rubber phase, showing the great shape memory potential of 4D-printed PLA. The filament tension tests revealed that the material's yield stress strongly depended on the strain rate at room temperature, with values ranging from 56 MPa to 43 MPA as the strain rate decreased. Using a commercial FDM Ultimaker printer, cylindrical compression samples were 3D-printed and then characterized under thermo-mechanical conditions. Thermo-mechanical compression tests were conducted at strain rates ranging from 0.0001 s-1 to 0.1 s-1 and at temperatures below the glass transition temperature (Tg) at 25, 37, and 50 °C. The conducted experimental tests showed that the material had distinct yield stress, strain softening, and strain hardening at very large deformations. Clear strain rate dependence was observed, particularly at quasi-static rates, with the temperature and strain rate significantly influencing PLA's mechanical properties, including yield stress. Yield stress values varied from 110 MPa at room temperature with a strain rate of 0.1 s-1 to 42 MPa at 50 °C with a strain rate of 0.0001 s-1. This study also included thermo-mechanical adiabatic tests, which revealed that higher strain rates of 0.01 s-1 and 0.1 s-1 led to self-heating due to non-dissipated generated heat. This internal heating caused additional softening at higher strain rates and lower stress values. Thermal imaging revealed temperature increases of 15 °C and 18 °C for strain rates of 0.01 s-1 and 0.1 s-1, respectively.

Dynamic response of ultra-high performance engineered cementitious composites (UHP-ECC) under low-velocity impact: Effect of waste rubber incorporation and low temperatures

This study aims to explore the dynamic response of ultra-high performance engineered cementitious composites (UHP-ECC) incorporating waste crumb rubber (CR) at various temperatures, focusing on its potential to enhance the resilience and sustainability of civil infrastructures against low-velocity impacts. To date, the impact behaviour of UHP-ECC under low temperatures has rarely been explored. Firstly, natural river sand and waste tyre CR was utilized to prepare the UHP-ECC. Then, a series of mechanical tests, including compression test, flexural test and uniaxial tensile test were carried out to investigate the static mechanical properties of rubberised UHP-ECCs. In addition, the effects of different waste CR incorporations (0%, 5%, 10%, and 15%) and various temperatures (25 °C, −5 °C, −30 °C, −50 °C, −100 °C and −196 °C) were comprehensively investigated by low-velocity impact tests with constant impact energy. Lastly, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) model was introduced to evaluate the overall performance of UHP-ECC. It was found that the use of river sand and CR significantly enhanced the tensile ductility and impact toughness of UHP-ECC. Impact energy primarily dissipates through damage such as matrix crack initiation, propagation, and fibre pull-out/rupture within the specimen. Adding CR notably decreased stress fluctuations during impact at room temperature, facilitating steady state energy absorption. Moreover, the time to reach peak impact force decreased with decreasing temperature across all UHP-ECC groups. At room temperature during impact process, fibre failure mode is dominated by pull-out failure, while lower temperatures lead to increased fibre rupture at the cracking surface. In low-temperature conditions, the impact response of rubberised UHP-ECC necessitates a comprehensive consideration of the synergistic effects, including material contraction, fibre bridging capacity, rubber phase transition, and water freezing.

Largely Improved Creep Resistance and Thermal-Aging Stability of Eco-Friendly Polypropylene High-Voltage Insulation by Long-Chain Branch-Induced Interfacial Constraints.

Polypropylene (PP)-based composites have attracted numerous attention as a replacement of prevailing cross-linked polyethylene (XLPE) for high-voltage insulation due to their ease of processing, recyclability, and excellent electrical performance. However, the poor resistances against high-temperature creep and thermal aging are obstacles to practical applications of PP-based thermoplastic high-voltage insulation. To address these problems, in this Letter, we synthesized an impact polypropylene copolymer (IPC) containing multifold long-chain branched (LCB) structures in phases, especially the interfaces between the PP matrix and the rubber phase. The results indicated that the structural stability of LCBIPC was significantly enhanced under extreme conditions. In comparison to IPC (without LCB structures), 24.1% less creep strain and 75.2% less unrecoverable deformation are achieved in LCBIPC at 90 °C. In addition, the thermal aging experiments were performed at 135 °C for 48 and 88 days for IPC and LCBIPC, respectively. The results show that the resistance against thermal aging was also enhanced in LCBIPC, which showed a 133% longer thermal aging life compared to IPC. Further results revealed that the interfacial layer between the PP matrix and the rubber phase was constructed in LCBIPC. The two phases are tightly linked by chemical bonds in LCB structures, leading to enforced constraints of the rubber phase at the micro level and better resistance performance against creep and thermal aging at the macro level. Evidently, the reported eco-friendly LCBIPC thermoplastic insulation shows great potential for applications in high-voltage cable insulation.

Morphology evaluation and mechanical properties of oil-resistant thermoplastic vulcanizates comprising carboxylated nitrile butadiene rubber and thermoplastic polyurethane and their comparison with commercial grades

The morphology, the mechanical properties, and the oil-resistance of thermoplastic vulcanizates (TPVs) of carboxylated nitrile butadiene rubber (XNBR) and thermoplastic polyurethane (TPU) were studied & compared with the commercial ethylene-propylene-diene monomer (EPDM)/polypropylene (PP) TPVs from two suppliers. The rubber phase in these new generations of TPVs was cured with an addition-type curative, and no oil & compatibilizer were required to make these TPVs processable. Three XNBR/TPU TPVs were made with different rubber/plastic ratios (15/85, 30/70, and 45/55). The AFM analysis showed that the morphology shifted from a continuous plastic phase to a co-continuous phase with increased rubber content. The rubber domains in these TPVs were not as discrete as reported in the literature for the EPDM/PP TPVs. Still, because of using an addition-type curative, unlike peroxide and resole phenolic resin curatives for the latter, the former TPVs had a significantly better balance of rubber and plastic properties. The oil resistance of these TPVs was 3.5–5 times better than the commercial EPDM/PP TPVs. These promising results show advancement in the TPV world and make these TPVs appealing for hydraulic oil applications.

Influence of cement type, excess removal, and polishing on the cement joint.

To compare marginal gap width and depth with different cementation systems, excess removal, and after polishing. In total, 80 composite crowns were milled, divided into ten groups, and cemented on identical artificial teeth. Eight crowns per group were fixed with (i) zinc phosphate cement (ZnOPh), (ii) glass-ionomer cement (GIC), (iii) resin-reinforced glass-ionomer cement (GIC mod), (iv) dual-curing adhesive composite (Comp dual), or (v) dual-curing self-adhesive composite (Comp SE dual). Excess removal was performed with a scaler after brief light-cure (tack-cure), final light-cure, during rubber or gel phase or by wiping with foam pellet. Curing was completed in chemical, dark cure, or light-curing modus. The specimens were polished and stored in water (37°C). The margins were digitized using a 3D laser-scanning microscope (VK-X100 series, Keyence). The width and the depth of the marginal gap were measured at 10 points between the crown margin and the preparation margin. The width after excess removal varied between 65.1 ± 15.7 µm (Comp dual, wipe, with polishing) and 208.6 ± 266.7 µm (Comp SE dual, dark cure, without polishing). The depth varied between 29.8 ± 22.2 µm (Comp dual, wipe, with polishing) and 89.5 ± 45.2 µm (Comp SE dual, dark cure, without polishing). The impact on gap width and depth was detected for fixation material, excess removal, and polishing. The gap depth and width depend on the luting material and the mode of access removal. Polishing can improve the gap quality, especially for GIC and resin-based systems.

Insights into the tiger stripe phenomenon of polypropylene and its blend in injection molding with a rapid heat exchange mold

AbstractTo examine the formation of tiger stripes (TS) phenomenon on the surface of the injection molding parts, a home‐made injection mold with a rapid heat exchange system and in situ measurement of pressure and temperature was designed and manufactured. Based on this special mold, the TS diagrams as a function of mold temperature and injection pressure for isotactic polypropylene (iPP) and its blend with a type of polyolefin elastomer (iPP/POE) were explored for the first time. It is found that there exists a critical mold temperature and a critical injection pressure for the TS appearance or disappearance in both systems. The critical temperatures of TS disappearance for iPP and iPP/POE are ~50 and ~ 120°C, respectively. As evidenced by the correlation between melt pressure drop and TS appearance, the wall slip mechanism is regarded as the main cause of TS formation. Compared with the critical shear stress of wall slip (σw) in totally molten PP, the lower σw value in this study further indicates that the wall slip could be facilitated by the crystallization of iPP during injection. Combined with white light interferometer, micro‐area x‐ray diffraction nanoindentation and scanning electron microscopy, it is demonstrated that the cloudy and glossy region of TS in pure iPP system could be distinguished by surface crystallinity. In the blend system, however, the rubber phase orientation as a dominant factor contributes to the glossiness of TS.

Total revalorization of high impact polystyrene (HIPS): enhancing styrene recovery and upcycling of the rubber phase

The styrene recovery from high impact polystyrene waste can be enhanced by pre-fractionation with ethyl acetate followed by pyrolysis of the isolated polystyrene phase and ethenolysis of the polybutadiene phase.

Fabricating super-tough polypropylene nanocomposites incorporating silane cross-linked in-situ nano-fibrillated ethylene-1-butene copolymer

In this study, we propose a novel approach to toughening polypropylene (PP) by integrating in-situ fibrillation technology with the silane crosslinking mechanism. Specifically, we graft vinyl trimethoxy silane (VTMS) onto the backbone of ethylene-butene-rubber (EBR) chains using reactive extrusion. Subsequently, we perform the in-situ fibrillation process using a spunbond machine, resulting in PP composites with in-situ nano-fibrillated EBR-g-VTMS. The next step involves crosslinking the fibrillated EBR-g-VTMS using moisture in order to preserve the fibrillar morphology. The unique fibrillar morphology and the substantial interfacial area of the rubber phase significantly enhance the mechanical, rheological, and crystallization behavior of the PP composites. Rheological data reveal that the in-situ nano-fibrillated rubber phase forms an interconnected network at around 3 wt% loading. Scanning Electron Microscopy (SEM) images show that the average EBR-g-VTMS fiber size is approximately 70–80 nm at 10 wt% rubber loading. Notably, the presence of fibrillar EBR-g-VTMS leads to a substantial increase in β phase content up to ∼65 %. Moreover, the matrix-spanning network of cross-linked EBR fibers exhibits toughening mechanisms superior to those found in classical sea-island blends, resulting in a dramatic enhancement of PP toughness across various test conditions (such as 50 % in the elongation at break in room temperature, 300 % in sub-zero tensile testing, and 200 % in Izod impact test) while showing only marginal reduction around 10 % in its strength and stiffness. Finally, this innovative and practical approach enables the leveraging of in-situ fibrillation for a wide range of polymer/rubber systems, optimizing rubber performance as a toughening agent.

Prediction and evolution of core-shell morphology and their effect on mechanical properties of PP blends

The prediction of phase morphology is highly valuable in designing and regulating the properties of multiphase composites, particularly polymer blends. In this study, we prepared two types of ternary blends, PP/HDPE/EPR and PP/HDPE/EPDM composites and compared and analyzed the predicted and observed phase morphology of blends with different elastomers. Using Palierne and Bousmina equations, we calculated the interfacial tensions between two components in PP blends and then predicted the relationship between the spreading coefficient, interfacial tension, and phase morphology according to the spreading coefficient theory. Based on our findings, it was observed that the core-shell structure of EPR and EPDM rubber phase encapsulated HDPE core tends to form in PP ternary blends, which aligns with our experimental results. Additionally, SEM morphology observation results revealed a less number of dispersed phases in PP/HDPE/EPR composites with the same composition ratio. It was observed that the shell had a greater thickness due to the difficulty in dispersing EPR with higher viscosity. Mechanical tests indicated that composites with thin-shell and small-core dispersed phases had better toughness. These composites also displayed less yield strength loss under the same impact conditions compared to those with single rubber phases.

Maintaining modulus of polypropylene composites with ultra-high low temperature toughness by synergistic branched polyethylene and nucleating agents

In this work, the synergistic effect of highly branched polyethylene (HBPEs, s = 1, 2) elastomers featuring dendritic structure and α-type nucleating agents (NA1, NA2) on the toughness and stiffness of block polypropylene (PP–B) was investigated. Blends of PP-B/HBPE/nucleating agent ternary systems were prepared, yielding materials with exceptionally high low-temperature toughness and minimal stiffness loss. The results indicate that HBPE enhances the low-temperature impact strength of the system but leads to a reduction in modulus. After the addition of the nucleating agent, both the low-temperature toughness and stiffness of the blend are improved simultaneously. The PP-B/HBPE2/NA2 (90/10/0.2) blend achieves the optimal balance between low-temperature toughness and stiffness, with its low-temperature impact strength increasing by a factor of 7 compared to PP-B, reaching 56.9 kJ/m2, and a bending modulus of 1110 MPa, nearly identical to PP-B. Dynamic mechanical properties and phase morphology results indicate that HBPE reduces the glass transition temperature of the rubber phase in the blended system and exhibits good compatibility with PP-B. Analysis of the crystallization behavior reveals that the significant increase in the crystallization temperature of PP-B and the substantial reduction in the size of spherical particles observed in PP-B/HBPE/NA blends are facilitated by NA1 and NA2. Additionally, NA1 and NA2 promote the transformation of the PP-B matrix into α-type crystals and enhance the crystallinity of PP-B.

Toward partially bio‐based thermoplastic vulcanizates based on poly (lactic acid) and chloroprene rubber

AbstractPolylactic acid (PLA)‐based thermoplastic vulcanizates (TPVs) were fabricated using dynamic and static vulcanization in the presence of untreated and surface‐treated zinc oxide (ZnO). Initially, the effect of chloroprene rubber (CR) as the elastomeric phase in the PLA‐based thermoplastic elastomer (TPE) was tailored. The CR content varied from 20 to 40 wt%, leading to 46%–70% and 19%–76% decrement in tensile strength and modulus, respectively, while elongation at break increased up to 9–13 times, highlighting the soft rubber phase's impact on ductility. Impact resistance testing showed improved toughness with CR addition, peaking at 20 wt% CR. Scanning electron microscopy (SEM) revealed matrix‐dispersed morphology with increasing CR droplet size, and co‐continuous morphology at 40 wt% rubber in BP6R4. In the next step, the optimized TPE was selected, and the focus shifted to investigate the effect of dynamic/static vulcanization on mechanical properties. It is revealed that adding modified ZnO (ZnO60) increased melt torque, but it decreased after 1.5 min. All vulcanized samples exhibited lower tensile strength and elongation at break but higher elastic modulus due to metallic particle reinforcement. ZnO particle agglomerates and rubber aggregations led to lower mechanical properties. These findings offer quantitative insights into vulcanization's influence on PLA‐based TPVs, informing partially biobased TPEs development and addressing vulcanization limitations.Highlights Fabrication of biobased thermoplastic elastomer (TPE) and thermoplastic vulcanizate (TPV) based on polylactic acid/chloroprene rubber (PLA/CR) shows the sustainable material prospect. The effects of dynamic/static vulcanization on TPE's behavior are investigated. Micro‐morphology analysis showed dispersed CR phase in TPEs when PLA content is <40 wt%. The addition of modified ZnO through static vulcanization minimized degradation. ZnO Agglomeration and CR aggregations caused subpar TPV mechanical properties.

Bismaleimide resin co‐modified by allyl ether of resveratrol and allyl ether of eugenol‐grafted polysiloxane with enhanced toughness, heat resistance, and flame retardancy

AbstractModifying bismaleimide (BMI) resin to improve its toughness and flame retardancy without sacrificing the glass transition temperature (Tg) and thermal decomposition stability is still a challenge. In this study, we employed the allyl ether of resveratrol (AER) and eugenol allyl ether grafted polysiloxane (PMES‐Allyl) to co‐modify BMI resin. For the BMI/AER/PMES‐Allyl (BAPA) resin, the content of PMES‐Allyl was 15 wt%, and the molar ratio of maleimide and allyl groups was controlled as 1:0.8. Compared to commercial 2,2′‐diallyl bisphenol A modified BMI (BD) resin, the BAPA resin exhibited superior thermal properties after curing, due to the role of AER in improving the crosslinking density and chain rigidity of the network. The cured BAPA resin had a Tg more than 380°C, and its initial thermal decomposition temperature (Td5%) and char yield (Y800°C) reached 424.8°C and 46.4%, respectively. Meanwhile, PMES‐Allyl as a rubber phase could effectively improve the toughness of the cured resin. The impact strength of the cured BAPA resin was 15.2 kJ/m2. Moreover, the two modifiers both helped to improve the flame retardancy of the material. Compared with the cured BD resin, the cured BAPA resin showed a decrease of peak heat release rate (PHRR), total heat release (THR), and maximum average rate of heat emission (MARHE) by 25.5%, 35.5%, and 31.5%, respectively. Its total smoke production (TSP) was only 35.6% of that of the cured BD resin. In addition, the cured BAPA resin also displayed a lowered water absorption and improved thermal aging resistance. Therefore, it is suggested to be a promising and high‐performance thermosetting resin for cutting‐edge applications.

The effect of dynamic vulcanization on the morphology and biodegradability of super toughened poly(lactic acid)/unsaturated poly(ether-ester) blends

Preparing a super-tough polylactic acid (PLA) material while maintaining its biodegradability is a significant challenge. This study synthesized a biodegradable unsaturated poly(butylene succinate-co-fumarate)-poly(ethylene glycol) multiblock copolymer (PBSFG) and dynamically vulcanized it with PLA to obtain super-tough blends. The PBSFG self-vulcanized and formed a crosslinked “hard-soft” core-shell rubber phase in the blending process, where the PBSF segment acted as the core and PEG as the shell. As a result, the elongation at break and notched Izod impact strength of PLA increased significantly from 3 % to 66 % and from 3.2 to 58.0 kJ/m2, respectively. Furthermore, adding a small amount of dicumyl peroxide (DCP) promoted dynamic vulcanization and improved the compatibility between PLA and PBSFG. With the addition of 0.03 % DCP, the elongation at break and notched Izod impact strength of PLA/PBSFG were further increased to 218 % and 88.9 kJ/m2, respectively. Meanwhile, the crystallization rate of PLA was enhanced by the addition of PBSFG and DCP. The PLA/PBSFG blends also degraded in a proteinase K Tris-HCl buffered buffer solution. Finally, fully biodegradable and super-tough PLA blends were achieved.

Numerical explorations of solvent borne adhesives: a lattice-based approach to morphology formation

The internal structure of adhesive tapes determines the effective mechanical properties. This holds true especially for blended systems, here consisting of acrylate and rubber phases. In this note, we propose a lattice-based model to study numerically the formation of internal morphologies within a four-component mixture (of discrete particles) where the solvent components evaporate. Mimicking numerically the interaction between rubber, acrylate, and two different types of solvents, relevant for the technology of adhesive tapes, we aim to obtain realistic distributions of rubber ball-shaped morphologies—they play a key role in the overall functionality of those special adhesives. Our model incorporates the evaporation of both solvents and allows for tuning the strength of two essentially different solvent–solute interactions and of the temperature of the system.