Reinforcement Filler Research Articles

Use of Inorganic Wastes as Fillers in Production of Polyester Composites and Evaluation of Properties of Obtained Composite

The use of industrial factory wastes as a filler in polymer composite materials is becoming more and more common. In this way, these wastes that cause environmental pollution are eliminated and new composite materials are developed. Polymer composites with low cost and high thermal stability are preferred in many sectors. In this research, some physical and chemical properties of inorganic waste reinforced polyester composites have been evaluated. The use of industrial inorganic wastes as fillers in polyester composites develops some thermophysical properties of composites. In particular, such industrial wastes are dried before being used in the composite, the particle size is reduced, and it is ensured to have a homogeneous structure. This type of waste, which is used as filler, is used in the polyester composite in optimum proportions. The use of high inorganic fillers in polyester both weakens the mechanical strength of the composites and negatively affects the matrix structure. Besides, inorganic waste reinforcement raises the surface hardness of polyester composites. Such fillers are improved both the thermal stability and non-flammability of the polyester composite. High-density inorganic fillers are used to obtain a high-density and economical polyester composite. Low-density inorganic industrial wastes also reduce the density of composites. However, the reinforcement of inorganic fillers into polyester at a high rate adversely affects both the surface morphology and the workability of the produced composites.

Evolution of the Viscoelastic Properties of Filler Reinforced Rubber under Physical Aging at Room Temperature.

Filler reinforced rubber is widely used for engineering applications; therefore, a sound characterization of the effects of physical aging is crucial for accurately predicting its viscoelastic properties within its operational temperature range. Here, the torsion pendulum is used to monitor the evolution of the storage and loss modulus of carbon black filled samples for four days after a temperature drop to 30 °C. The storage modulus presents a continuous increase, while the loss modulus generally displays a steady decrease throughout the four days that each test was conducted. The relationship of the recovery rates with the carbon black properties is also studied, analysing its dependency on the particle size and aggregate structure. The evolution of the recovery rate seems to depend linearly on the surface area while the carbon black structure appears to have a much weaker influence on the physical aging behavior for the set of compounds tested. The obtained results corroborate the presence of physical aging at room temperature for filler rubber materials and the ability of the torsion pendulum to monitor the storage and loss modulus change, providing pivotal data on the influence of physical aging on the viscoelastic properties of the material.

Effects of Fiber Loading on Mechanical Properties of Kenaf Nanocellulose Reinforced Nanohybrid Dental Composite Made of Rice Husk Silica

The innovation of nanocellulose as reinforcement filler in composites has been a topic of interest in the development of new biomaterials. The objective of this study was to investigate the mechanical properties of a nanohybrid dental composite made of rice husk silica and loaded with different percentages of kenaf nanocellulose. Kenaf cellulose nanocrystals (CNC) were isolated and characterized using a transmission electron microscope (TEM) (Libra 120, Carl Zeiss, Germany). The experimental composite was fabricated with fiber loadings of 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 6 wt% silane-treated kenaf CNC, and subjected to a flexural and compressive strength test (n = 7) using an Instron Universal Testing Machine (Shimadzu, Kyoto, Japan), followed by a scanning electron microscopic assessment of the flexural specimen's fracture surface using a scanning electron microscope (SEM) (FEI Quanta FEG 450, Hillsborough, OR, USA). Commercial composites Filtek Z350XT (3M ESPE, St. Paul, MN, USA), Neofil (Kerr Corporation, Orange, CA, USA) and Ever-X Posterior (GC Corporation, Tokyo, Japan) were used as a comparison. The average diameter of kenaf CNC under TEM was 6 nm. For flexural and compressive strength tests, one-way ANOVA showed a statistically significant difference (p < 0.05) between all groups. Compared to the control group (0 wt%), the incorporation of kenaf CNC (1 wt%) into rice husk silica nanohybrid dental composite showed a slight improvement in mechanical properties and modes of reinforcement, which was reflected in SEM images of the fracture surface. The optimum dental composite reinforcement made of rice husk was 1 wt% kenaf CNC. Excessive fiber loading results in a decline in mechanical properties. CNC derived from natural sources may be a viable alternative as a reinforcement co-filler at low concentrations.

High-Performance Self-Healing Polymers

ConspectusSelf-healing ability is one of the most attractive features of biological tissues, as it helps living creatures to recover physiological functions and prolongs their lifespans after unexpected injuries. Inspired by this feature, self-healing artificial polymers have been developed based on extrinsic and intrinsic designs since the 1950s. In particular, the intrinsic self-healing polymers have received enormous attention since 2001 because of their unlimited self-healing times and easy preparation. Therefore, many excellent works are reported, and our understanding of the self-healing polymer goes deeper and deeper. Self-healing is the process of the rejoining of the dynamic bonds/interactions. Therefore, the healing process involves two critical factors. One is the dynamic nature of dynamic bonds/interactions. The other is the high mobility of the polymer chains. However, the dynamic bonds/interactions are vulnerable to external forces and environmental stimuli because their bond energy is lower than that of the covalent bonds, which leads to several innate drawbacks of intrinsic self-healing polymers, such as poor mechanical properties (low fracture strength, low fracture strain, low modulus, and low fracture toughness) and poor resistance against the external environment (vulnerable to acid, alkali, or moisture). Also, since high chain mobility is also a prerequisite for intrinsic self-healing, most polymers cannot be healed in the glassy state where the polymer chains are frozen. Therefore, it is challenging to develop high-performance self-healing polymers, which not only possess high mechanical strength, toughness, and stability under ambient conditions or severe environments but also manifest high self-healing efficiency in the rubbery state or even in the glassy state. Therefore, how to overcome this challenge has become a hot topic in the field of self-healing polymers.To address the above problem, many high-performance self-healing polymers with high mechanical properties, high self-healing ability, or high environmental stability are published by using different strategies. These strategies are effective at enhancing the mechanical properties or increasing its environmental stability and are worth learning about. Our group has carried out some work in this field. In this Account, we highlight our works toward fabricating high-performance self-healing polymers. We summarize the high-performance self-healing polymers from three aspects: self-healing polymers with high mechanical properties (such as high toughness, tensile strength, stretchability, and modulus), glassy polymers capable of self-healing in the glassy state, and environmentally stable self-healing polymers. In particular, strategies based on tailoring molecular-level structure, condensed structure, and filler reinforcement are discussed in detail to construct self-healing polymers with high mechanical properties. Finally, the future development of intrinsic self-healing polymers is examined from the perspective of practical application and fundamental research.

Potato thermoplastic starch nanocomposite films reinforced with nanocellulose

Abstract Potato is a widely available feedstock with biocompatibility and biodegradability properties, making it a strong candidate for producing thermoplastic starch. The application of thermoplastic starch to replace petroleum-based plastic as a sustainable and environmentally friendly approach led to its further improvement through various techniques such as modification and filler reinforcement. Numerous studies have been done addressing the properties enhancement of potato thermoplastic starch through filler reinforcement including nanocellulose. This review focus on the recent and future potential of potato-based starch as one of the feedstocks for producing potato thermoplastic starch composites reinforced with nanocellulose.

Thermoreversibly crosslinked silica-rubber composite prepared via melt processing

This paper addresses the industrially viable and environmentally sustainable preparation of thermoreversibly crosslinked composite rubbers. A maleimide-functionalized silica (Sil-M) is prepared and used as a reinforcement filler and crosslinking agent via Diels-Alders (DA) reaction onto furan-grafted ethylene-propylene rubber (EPRgF). The preparation of composite rubbers is carried out by reactive melt blending to guarantee for industrial scalability and avoiding use of organic solvent. Mechanical properties of EPRgF/Sil-M is compared to unfunctionalized EPRgF/Sil to demonstrate the role of DA crosslinking on mechanical properties. Furthermore, the combination between Sil-M and bismaleimide as a conventional DA crosslinker was investigated, to optimize crosslinking degree and materials performances. Overall, results reported in this paper demonstrate the possibility to develop a new class of recyclable composite rubbers for the substitution of conventional rubbers, that are currently causing major problems in the management of rubber products at their end-of life.

Mechanically robust 3D printed elastomeric lattices inspired by strong and tough hierarchical structures

Lattice structures have been proven capable of a wide range of engineering applications due to their complex design arrangements, such as periodicity, topology, and morphologies. Yet, developing a hybrid design is challenging due to limitations of node boundaries, material, and fabrication constraints for improving mechanical performance. To overcome these challenges, hybrid designs were developed here using the vat photopolymerization technique by grading the bend- and stretch-dominant strut morphology in parallel and perpendicular directions. Firstly, numerical simulations predicted the unit cell performances, and then the structural behavior of periodically arranged 3D-printed elastomeric lattices was also investigated. As a result, hybrid design provided a better performance strategy under high load conditions, including a significant amount of mechanical performance (7 times) than the uniform lattice topology. In addition, a vat photopolymerization-based 3D printing technique was investigated by introducing a high-loaded silica filler in the polymer, as a filler reinforcement exhibiting the advantages of enhanced stiffness (12 times) and reduced buckling to the lattices. Finally, the performance of hybrid-graded design was examined via filler-coated surfaces, which could provide insight into their ability to adapt to lightweight devices and engineering applications.

Natural Rubber Composites Using Hydrothermally Carbonized Hardwood Waste Biomass as a Partial Reinforcing Filler- Part I: Structure, Morphology, and Rheological Effects during Vulcanization.

A new generation biomass-based filler for natural rubber, 'hydrochar' (HC), was obtained by hydrothermal carbonization of hardwood waste (sawdust). It was intended as a potential partial replacement for the traditional carbon black (CB) filler. The HC particles were found (TEM) to be much larger (and less regular) than CB: 0.5-3 µm vs. 30-60 nm, but the specific surface areas were relatively close to each other (HC: 21.4 m2/g vs. CB: 77.8 m2/g), indicating a considerable porosity of HC. The carbon content of HC was 71%, up from 46% in sawdust feed. FTIR and 13C-NMR analyses indicated that HC preserved its organic character, but it strongly differs from both lignin and cellulose. Experimental rubber nanocomposites were prepared, in which the content of the combined fillers was set at 50 phr (31 wt.%), while the HC/CB ratios were varied between 40/10 and 0/50. Morphology investigations proved a fairly even distribution of HC and CB, as well as the disappearance of bubbles after vulcanization. Vulcanization rheology tests demonstrated that the HC filler does not hinder the process, but it significantly influences vulcanization chemistry, canceling scorch time on one hand and slowing down the reaction on the other. Generally, the results suggest that rubber composites in which 10-20 phr of CB are replaced by HC might be promising materials. The use of HC in the rubber industry would represent a high-tonnage application for hardwood waste.

Effect of bio-fibers and inorganic fillers reinforcement on mechanical and thermal characteristics on carbon-kevlar-basalt-innegra fiber bio/ synthetic epoxy hybrid composites

The hybridization of plant cellulose fillers in polymeric laminates is applied in different applications because of several benefits. The present investigation deals with the fabrication of four other eight-layer laminates by reinforcing bio fillers (coir, sisal, and hemp), Titanium carbide (TiC) nanoparticles, and ranging the stacking sequence of synthetic fabrics (carbon, Kevlar, Basalt, and Innegra) with bio/synthetic epoxy from wet layup technique. The fabricated laminate's characteristics were appraised by examining density, porosity, water absorption, flexural, impact strength, shore hardness, and thermal stability. It was observed from the experimental outcomes that the 3F8LTSE (Sisal, hemp, coir fillers, 2 layers of Carbon, Kevlar, Basalt, Innegra fabrics, and Titanium carbide reinforced synthetic epoxy) composite exhibited higher mechanical characteristics with a higher flexural strength (312.58 MPa), impact strength (35.13 kJ/m2), and shore D hardness (84.95), and decreased water absorption capacity by justifying its adequate for lightweight structures. The scanning electron microscope displayed the fiber pull out, debonding, and dispersion of fillers within the matrix of the composite. The current study also evaluates the prediction and performance of the artificial neural network (ANN) to model the physical, mechanical and thermal characteristics of bio/synthetic epoxy hybrid composites. However, the ANN model was more precise and proved that it is a primary method to optimize the properties of the fabricated bio/synthetic epoxy laminate.

Waste marble dust-filled sustainable polymer composite selection using a multi-criteria decision-making technique

This research works with the optimal design of marble dust-filled polymer composites using a multi-criteria decision-making (MCDM) technique. Polylactic acid (PLA) and recycled polyethylene terephthalate (rPET)-based composites containing 0, 5, 10, and 20 wt% of marble dust were developed and evaluated for various physicomechanical and wear properties. The results showed that the incorporation of marble dust improved the modulus and hardness of both PLA and rPET. Moreover, a marginal improvement in flexural strength was noted while the tensile and impact strength of the matrices were deteriorating due to marble dust addition. The outcomes of wear analysis demonstrated an improvement in wear resistance up until 10 wt% filler reinforcement, after which the incidence of dust particles peeling off from the matrix was observed, thereby reducing its efficiency. The best tensile modulus of 3.23 GPa, flexural modulus of 4.39 GPa, and hardness of 83.95 Shore D were obtained for 20 wt% marble dust-filled PLA composites. The lowest density of 1.24 g/cc and the highest tensile strength of 57.94 MPa were recorded for neat PLA, while the highest impact strength of 30.94 kJ/m2 was recorded for neat rPET. The lowest wear of 0.01 g was obtained for the rPET containing 5 wt% marble dust content. The experimental results revealed that for the examined criteria, the order of composite preference is not the same. Therefore, the optimal composite was identified by adopting a preference selection index-based MCDM technique. The findings demonstrated that the 10 wt% marble dust-filled PLA composite appears to be the best solution with favorable physical, mechanical, and wear properties.

Hydroxyl terminated polybutadiene-based shape memory polyurethane nanocomposites containing nano metal-oxide fillers for microfluidic valve actuator applications

We report here a novel and unique thermo-responsive Shape Memory Polyurethane Nanocomposites (SMPUNCs) derived from Hydroxyl Terminated Polybutadiene (HTPB) and Poly Tetra Methylene Glycol (PTMG) blend encapsulated with nano metal oxides fillers such as CuO, NiO, Fe2O3, CuFe2O4, and Fe2NiO4 for possible use in polymer-based microvalve actuator systems. The synthesis methods adopted and the various characterization techniques employed are presented. The corresponding SMPUs are named PU−CuO, PU−Fe2O3, PU-NiO, PU−CuFe2O4, and PU-Fe2NiO4 respectively. HTPB and PTMG are used as the base polyols for reacting with isocyanates to form the polyurethane base matrix, named as PU-Neat for comparison. Different fillers were used to study the effect of these fillers on the enhancement of the shape memory properties of polyurethane. Morphological, thermal, mechanical, and shape-memory properties of the prepared SMPUs are fully characterized. Morphological studies confirm that all the nano-metal oxide fillers are uniformly dispersed within the SMPU matrix. The shape memory transition temperature (Ttrans), which plays an important role in the shape memory effect (SME), is obtained from DSC analysis. The results show that Ttrans is enhanced with the reinforcement of the nano-metal oxide fillers (resulting in about 10% enhancement in the shape recovery time). The metal oxide filler integrated samples show higher thermal stability as well as shape fixing and recovery performances than PU-Neat. The tensile test confirmed that the PU−Fe2O3 matrix possesses a high tensile modulus and is rigid when compared to other SMPUs. We also demonstrated a microvalve actuator system using PU−Fe2O3, as it possesses the optimum shape recovery and better shape fixing properties, compared to other prepared Shape Memory Polyurethane Nanocomposites. An improvement of 10% efficiency in the closing and opening of the valve for PU composite film was observed in the demonstrated actuator setup.

The Effects of Hybrid Nano addition on Maxillofacial Silicone Elastomer VST50F Mechanical Properties

Purpose: To investigate the effects of hybrid nano (Tio2 – Al2o3) addition on maxillofacial silicone elastomer mechanical properties. Methods: A total of 70 samples were prepared and divided into 7 groups; control, 1% Tio2 (nano-titanium oxides), 2% Tio2, 1% Al2o3 (nano-alumina oxides), 2% Al2o3, 0.5% Tio2-0.5% Al2o3, and 1% Tio2-1% Al2o3. which was added to silicone elastomer. Samples were exposed to artificial weathering for 250 hours, then tested for tear strength and roughness tests. The data were analyzed using a one-way ANOVA to determine the differences between groups. Results: After artificial weathering, a high increase in the mean value for tear strengths with an acceptable increase in the mean value for roughness was observed in samples containing 2% Tio2, followed by the samples with a hybrid of 1% Tio2-1% Al2o3, compared to the control and other groups. Conclusions: The addition of Tio2, Al2o3, and hybrid nanoparticles addition to maxillofacial silicone improved its mechanical properties. Hybrid nanoparticle filler reinforcement is encouraging for enhancing tear strength and roughness properties values for the longevity of maxillofacial silicone.

Preparation and Characterization of Acrylonitrile Butadiene Rubber Reinforced with Bio-Hydroxyapatite from Fish Scale.

This work aims to enhance the mechanical properties, oil resistance, and thermal properties of acrylonitrile butadiene rubber (NBR) by using the Nile tilapia fish scales as a filler and using bis(triethoxysilylpropyl)tetrasulfide (TESPT) as a coupling agent (CA). The prepared fish scale particles (FSp) are B-type hydroxyapatite and the particle shape is rod-like. The filled NBR with FSp at 10 phr increased tensile strength up to 180% (4.56 ± 0.48 MPa), reduced oil absorption up to 155%, and increased the decomposition temperature up to 4 °C, relative to the unfilled NBR. The addition of CA into filled NBR with FSp at 10 phr increased tensile strength up to 123% (5.62 ± 0.42 MPa) and percentage of elongation at break up to 122% relative to the filled NBR with FSp at 10 phr. This work demonstrated that the prepared FSp from the Nile tilapia fish scales can be used as a reinforcement filler to enhance the NBR properties for use in many high-performance applications.

Investigate the effect of ground tyre rubber as a reinforcement filler in natural rubber hybrid composites

ABSTRACT This paper investigates the effect of various proportions of Ground Tyre Rubber (GTR) blends with Natural Rubber (NR)/Ethylene Propylene Diene Monomer (EPDM) or NR/Chloroprene Rubber (CR) composites. The NR (95 phr) composites were developed with 5 phr of EPDM or 5 phr of CR along with different ratios of GTR (0, 10, 20, 30, and 40 phr) by a two-roll mill and hydraulic press. The interfacial adhesion of NR/EPDM and NR/CR composites was improved with the addition of nylon 6 at 5 phr. Hence, the silica (20 phr) and carbon black (10 phr) were used as conventional fillers in these composites. The mechanical and curing properties of the developed NR-based hybrid composites were evaluated and compared with control samples. It was noted that the maximum tensile strength, tear strength, hardness, and Young’s modulus were increased by 8%, 9.39%, 6.35%, and 18.31% in NR/EPDM/GTR (95/5/10), while for NR/CR/GTR (95/5/10), 17.1%, 10.71%, 6%, and 31.72% over the control sample. The elongation at break was reduced by 29.11% in NR/EPDM/GTR (95/5/10), but for NR/CR/GTR (95/5/10) was 21.65% over the control sample. The cure properties like scorch time (tS2) and cure time (tC90) were decreased, while minimum torque (ML) and maximum torque (MH) were enhanced with the incorporation of GTR 10 phr in both the composites when compared with the control sample. The addition of GTR increased the sulfur in the cured composites, which was confirmed in EDS analysis. Based on the microstructure and thermogravimetric analysis, GTR particles were uniformly distributed, and the thermal stability was increased by 19.6% and 21.5% in NR/EPDM/GTR (95/5/10) and NR/CR/GTR (95/5/10) composites, respectively, over the control sample. The absorption peaks of NR, EPDM, CR, and GTR elements in the developed composite were identified using Fourier Transform Infrared spectroscopy (FTIR). In the NR/EPDM composite, the glass transition temperature (Tg) was increased from −60.7°C to −58.17°C, but for the NR/CR composite, it was −61.43°C to −58.96°C. Finally, the inclusion of 10 phr of GTR was recommended to be suitable for NR with EPDM or CR composites.

In-plane shear strengthening of traditional unreinforced masonry walls with near surface mounted GFRP bars

In this study, the effectiveness of Near Surface Mounted (NSM) method, for in-plane shear strengthening of traditional and historical Unreinforced Masonry (URM) walls, is investigated through a comprehensive experimental study. For this purpose, square solid clay brick masonry wallettes (42 samples) with three different types of traditional mortars including gypsum mortar, lime-cement-sand mortar and lime-sand mortar are prepared and retrofitted with NSM Glass Fiber Reinforced Polymer (GFRP) bars. Then, diagonal shear tests are conducted to evaluate the in-plane shear behavior of the masonry wallettes. The effects of some key variables such as wall thickness, the retrofitted face of the wall, reinforcement ratio, and the type of paste for mounting the reinforcing bars, on the effectiveness of the retrofitting method are investigated. The results of the tests are presented in terms of the failure modes and the lateral shear stress-drift curves of the test specimens. Accordingly, the retrofitting method can enhance the in-plane shear strength, and the ultimate lateral drift capacity of the URM wallettes. According to the test results, the type of filler paste and reinforcement ratio influence the strength enhancement of the test specimens. Furthermore, in specimens retrofitted with the one-side retrofitting scheme, due to the asymmetry of walls under in-plane loads, an unexpected out-of-plane deformation is induced in the walls under in-plane load which adversely affects its global behavior.

Mechanical Properties of a Bone-like Bioceramic-Epoxy-Based Composite Material with Nanocellulose Fibers.

Several composite materials are being investigated as reinforcement fillers for surgery simulations. This study presents an artificial composite material with properties similar to those of the human bone, which may be used in surgery simulations. Moreover, considering the potential toxicity of debris generated during sawing, a safe epoxy-based composite material was synthesized using cellulose nanocrystals (CNCs) and bioceramics (i.e., hydroxyapatite, Yttria stabilized zirconia oxide, Zirconia oxide), which were used to mimic the stiffness of human bone. To examine the change in mechanical properties according to the composition, 1, 3, and 5 wt% of CNCs were mixed with 5 wt% of the bioceramics. When CNCs were added at 1 wt%, there was a confirmed change in the non-linear stiffness and ductility. The CNC-added specimen fractured when forming a nano-network around the local CNCs during curing. In contrast, the specimen without CNCs was more densely structured, and combined to form a network of all specimens such that a plastic region could exist. Thus, this study successfully manufactured a material that could mimic longitudinal and transverse characteristics similar to those of real human bone, as well as exhibit mechanical properties such as strength and stiffness. Bioceramics are harmless to the human body, and can be used by controlling the added quantity of CNCs. We expect that this material will be suitable for use in surgery simulations.

In Situ Formation of Soft–Rigid Hybrid Fibers Decorated by Sparse Lamellae of PLLA: Achieving Ductile and Heat-Resistant Materials with High Strength

Constructing an oriented crystalline structure with high crystallinity in poly(l-lactide) (PLLA) is one efficient way to improve its mechanical strength, but flexibility is sacrificed because orderly arrangement restricts molecular mobility seriously. In this work, a unique hierarchical structure of soft–rigid hybrid fibers decorated by sparse lamellae of PLLA is in situ constructed successfully to improve mechanical strength and flexibility simultaneously. Through interfacial stereocomplexation between the PLLA matrix and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)–poly(d-lactide) (PHBV-PDLA) copolymers, followed by a strong flow field during the multistage stretching extrusion (MSE), soft–rigid hybrid fibers of PHBV/interfacial stereocomplex crystallites (i-SCs) are formed to not only act as a reinforcement filler but also favor energy-dissipating deformation mechanisms. Moreover, under the coupling effect of hybrid fibers and intense flow field, the sparse PLLA lamella with a stiff shish is obtained. Consequently, nanofibrillar PLLA/PHBV-PDLA composites with a highly oriented structure exhibit high strength (94.1 MPa), considerable ductility (65.7%), and excellent heat resistance (E′140 °C > 310 MPa), compared to sea–island structured PLLA/PHBV-PDLA composites with an isotropic structure (59.3 MPa, 11.7%, and E′140 °C > 60 MPa). Furthermore, nanofibrillar PLLA/PHBV-PDLA composites can maintain ductility (57.7%) and strength (98.3 MPa) for 886 days at ambient temperature. The strengthening and toughening mechanisms based on the unique structure are proposed by investigating the microstructural changes before and after a tensile test. This work provides significant guidance for strong, ductile, and heat-resistant PLLA-based materials for durable applications.

The Effect of Powder and Emulsion Binders on the Tribological Properties of Particulate Filled Glass Fiber Reinforced Polymer Composites.

Investigations into polymer composites are mainly focused on properties dependent on glass fiber reinforcement and particulate fillers. In the present study, the effect of the binder was examined. The specimens were produced with two types of epoxy resin, with similar numbers of glass mat layers and similar proportions of quartz powder added. However, one group was fabricated with an emulsion binder in the glass mats and another group with a powder binder. Attention was concentrated on the tribological properties of the as-prepared composites, though their strength was examined as well. The hardness of the Sikafloor matrix was found to be much more sensitive to the applied binder than that of the MC-DUR matrix. No direct correlation between the microhardness and the specific wear rate was observed and increasing the particulate filler proportion did not cause a direct increase of the specific wear rate. In particular, the highest specific wear rate, around 350 J/g, was reached for both matrices with a 1% quartz addition when the emulsion binder was applied, while in the case of the powder binder it was with 6% quartz with the MC-DUR matrix, and there was no quartz addition with the Sikafloor matrix. The highest microhardness, HV0.5 = 25, in turn, was reached for the mats with the emulsion binder in the Sikafloor matrix with an addition of 10% quartz powder, while the highest friction coefficient was exhibited in the composite with the MC-DUR matrix, when 1% of the quartz powder and the emulsion binder were applied.

Bioinspired Sustainable Polymer with Stereochemistry-Controllable Thermomechanical Properties

The regulation of polymer properties based on stereochemistry is essential but rarely studied. Inspired by the isomerization of unsaturated phospholipids in cell membranes, we report a novel method of preparing stereocontrolled polymer using sustainable Eucommia ulmoides gum (EUG) as a raw material. Under the catalysis of thiyl radical, EUG with 100% trans-1,4-polyisoprene structure isomerized to cis-configuration partly in a controllable way, thus achieving the rational modulate of thermomechanical properties. The isomerization mechanism was verified by density functional theoretical calculation. The isomerized EUG (IEUG) with low cis content (≤8.7%) can serve as plastics or shape memory materials, while high cis content (≥10.7%) IEUG transferred into elastomer materials. Especially for IEUG-10.7%, its vulcanizates without filler reinforcement shows high tensile strength (15.5 MPa) and elasticity (97%) comparable to natural rubber due to its strain-induced crystallization ability, which has the potential to be the second natural rubber. This paper provides a new strategy for stereocontrol of polymer properties, and the prepared materials have broad application prospects in the intelligent sensing and rubber industry.

Experimental investigations on the tribological behaviour of thermoplastic composites with partial sand replacements

The present study investigates the effect of filler reinforcement on the tribological performances of polymer-based composite materials. The composites were developed by using waste plastic of low-density polyethylene as matrix and natural sand as fillers. The evaluation of sliding wear rate and three-body abrasive wear were carried out. The structural analysis of the developed composite surfaces verified the homogeneity of the mixture. The density and hardened were found in the ranges of 0.8404–1.5304 (g/cm3), and 4.6 – 15.8 HV respectively. The wear performance improves with the incorporation of fillers. The minimum value for the sliding wear rate and three-body abrasive wear were found to be 0.885 × 10−8 kg/meter and 0.07495 cm3 respectively for the specimen LDPE50. Whereas, the maximum values of sliding wear rate and abrasive wear were 5.311 × 10−8 kg/meter and 0.09822 cm3 respectively, for the specimen LDPE100. The study showed an irregular behaviour for wear with replacement of low-density polyethylene. Moreover, the interactions of several encountering forces makes the wear response a complex process. The structural analysis revealed that the fillers are completely encapsulated with matrix, resulting in optimum strength at 50 wt% replacement of low-density polyethylene. The study successfully provides a sustainable composite to replace the conventional composite materials and the results and discussions pave the way for future research.