Low Impact Strength Research Articles

Impact response of gradient CNT-reinforced epoxy encapsulating materials with a printed circuit board

The encapsulation process is an effective method to protect electronic components from the threat of the external environment. However, traditional encapsulating materials are brittle and easily crack due to their low impact strength. Therefore, it is necessary to toughen encapsulating materials. The gradient structure can effectively improve the performance of materials but is not yet used in the field of encapsulation. This study prepared several homogeneous and gradient materials for experimentation, including epoxy plates with different carbon nanotube (CNT) distributions, such as “EP” (no CNT), “X” (a high CNT content in the top and bottom and a low CNT content in the middle), “V” (a CNT content that gradually decreases from top to bottom), and “Λ” (contrary to “V”), and epoxy plates encapsulating a printed circuit board (PCB), such as “V-P” (an “V” epoxy gradient with a PCB). The quasistatic tensile tests and dynamic impact tests show that the tensile and impact strengths of the homogeneous composites with 0.7 wt% CNT are the highest. The drop-weight tests show that regardless of the inclusion of a PCB, gradient materials have better impact strength and energy absorption than pure epoxy materials. In particular, among the gradient plates without a PCB, the impact strength and critical failure energy of the “Λ-5” plate (“Λ” with five layers) are the highest, 125% and 8 times higher than those of the pure epoxy (“EP”) plate. Among the plates encapsulating PCBs, the impact strength and critical failure energy of the “V-5-P” plate are the highest, with values 40% and 15.8% higher than those of the “EP-P” plate. The more continuous the CNT distribution is, the higher the impact strength of the material. These results provide feasibility for the application of gradient materials in the field of encapsulation and provide a reference for encapsulation design.

Supertoughened Polylactide via the Addition of Low Content Poly(ε-caprolactone) and Tensile Deformation above the Glass Transition Temperature

Polylactide (PLA) is considered as an ideal alternative of petroleum-based plastics due to its high tensile strength and biodegradability. However, the low impact strength limits its extensive application in the engineering field. In this work, a supertough binary PLA blend was fabricated through pre-stretching above the glass transition temperature to a certain pre-strain. The biodegradable and biocompatible poly(ε-caprolactone) (PCL) was used as a toughening modifier for the PLA/PCL 95/5 (wt/wt) blend. It was found that the impact strength increased with the increase in pre-strain. The highest notched Izod impact strength reached 251 kJ/m2 at the pre-strain of 400%, nearly 132 times of that for neat PLA (1.9 kJ/m2). To our knowledge, such fabulous impact toughness has not been referred in literature. Even at the pre-strain of 150%, the blend exhibited a sufficiently high notched Izod impact strength of 149 kJ/m2. Small-angle X-ray scattering demonstrated a typical structural feature of combination of PLA shish-kebabs and oriented PCL lamellar stacks due to strain-induced crystallization. The wide-angle X-ray diffraction indicated that PLA crystals had high orientation at the pre-strain of 200% and above. The crystallinity of the PLA matrix increased with the increase in pre-strain, which was consistent with the increasing trend of impact strength. The high orientation of shish-kebabs and increased crystallinity of PLA matrix were the key factors for drastically toughening PLA. This work provides a feasible and effective method to manufacture competitive PLA materials, which can be extended to improve impact toughness of other brittle glassy polymers.

Epoxidized linseed oil as a plasticizer for All-Cellulose Composites based on cellulose acetate butyrate and micronized pulp fibers

All-Cellulose Composites (ACCs) with cellulose derivatives have been neglected in the composite industry due to their high brittleness, low impact strength, and flowability. Epoxidized vegetable oils are well-known plasticizers for several polymers and composites but have never been exploited on the production of ACCs. The present work investigates the potential of an epoxidized linseed oil (ELO) as a cost-effective additive to enhance the properties and processability of ACCs made with cellulose acetate butyrate (CAB) and micronized Eucalyptus pulp fibers. The thermo-mechanical characterization of the composites, obtained by melt-mixing, revealed that ELO significantly decreases the glass transition temperature (Tg) of the obtained composites without compromising their thermal stability. Moreover, an 84-fold improvement was achieved on the melt flow rate (MFR) with 30 wt% ELO, and growing amounts of this additive caused an augment on the elongation and flexural strains at break. High loads of ELO resulted also on a substantial improvement of the impact strength, with values raising from 5.3 ± 0.9 kJ.m−2 up to 29.5 ± 1.7 kJ.m−2. Furthermore, this eco-friendly plasticizer also led to higher water uptake values, as well as higher biodegradation rates than the non-plasticized ACCs. Therefore, these results evince a remarkable improvement on the ACCs processability, performance, and biodegradation upon addition of a bio-based and cost-effective plasticizer.

A Comparative Evaluation of Flexural and Impact Strength of Polymethyl Methacrylate (PMMA) Reinforced With Graphene and Multi-Walled Carbon Nanotubes: An In Vitro Study.

Background and objective Low flexuralstrength (FS) and impact strength (IS) are major drawbacksin removable prostheses made from polymethyl methacrylate (PMMA). Attempts to enhance the strength and longevity of theseprostheses have been of keen interest among researchers. Nanofillers are new and advanced reinforcements that can chemically modify PMMA. Graphene and multi-walled carbon nanotubes (MWCNTs) were used in this study to evaluate FS and IS when added to polymer and monomer individually. Method Four groups were created based on the addition of nanofillers: no nanofillers - control; 0.5% by weight of graphene; 0.5% by weight of MWCNT; and 0.25% by weight of both. These groups were further subdivided into two according to the nanofiller being added to polymer and monomer each. The samples were then subjected to a 3-point bending test to assess FS, and an Izod impact tester was used to test IS. Results Decreased FS and FS were seen in all groups with the addition of nanofillers in the polymer (p<0.001). With the addition of nanofillers in monomer, increased FS and IS were seen in groups with MWCNTs whereas a decrease was seen with the addition of graphene (p<0.001). Conclusion Nanofillers should be added to the monomer of heat-cure PMMA instead of polymer; 0.5% by weight of MWCNT has shown the highest FS and IS when added to the monomer.

Mechanical properties of sinter hardened sintered steels prepared by hybrid alloying

For PM steel precision parts, high mechanical loading is very common in service. In particular for automotive applications, fatigue up to very high loading cycle numbers may be encountered. Advanced alloying concepts for sintered steels are required, involving also alloy elements with high oxygen affinity. In the present study, hybrid alloyed sintered steels based on prealloyed steel powder Fe-1.8%Cr were prepared by the press-and-sinter route. Mn and Ni, respectively, were admixed as well as a masteralloy containing Mn and Si, the alloy element content being varied, and the combination hardness vs. impact energy was assessed. From the most promising variants, fatigue test specimens were prepared, sinter hardened and characterized, fatigue testing being done by ultrasonic resonance up to Nmax = 10E10 cycles. Ni alloying proved to be positive both for the impact energy and the gigacycle fatigue strength while Mn resulted in high hardenability but low impact and fatigue strength, in part because of intergranular embrittlement. The grade with Mn-Si masteralloy was slightly less ductile than the Ni alloyed variant, but in particular at N > 10E8 the fatigue endurance strength was similar to that of the Ni alloyed type, however with significantly lower scatter.

Toughening of linear low-density polyethylene/brominated polystyrene blend by styrene-ethylene/butylene-styrene elastomer

Brominated polystyrene (BPS) is blended with linear low-density polyethylene (LLDPE) to improve its fire retardancy for various applications such as wire and cable covering. To improve compatibility and mechanical properties, styrene-ethylene/butylene-styrene (SEBS) copolymer was added as a compatibilizer. The influence of processing temperature and SEBS elastomer on morphology, interfacial and mechanical properties has been investigated. It was found that melt blending at 230 °C with addition of SEBS elastomer can significantly reduce the BPS particle size to less than 0.5 μm by forming a core-shell structure that enhances the interfacial strength between BPS and LLDPE phases. Addition of 8 phr SEBS elastomer can increase the Izod impact strength at −37 °C by a factor of nearly three, compared to the non-compatibilized LLDPE/BPS system. Double-notch four-point bending (DN-4PB) test reveals that crazing and shear banding are two primary toughening mechanisms for the observed increase in the low temperature impact strength.

Влияние компонентов гибридной матрицы на изменение ударной вязкости углепластиков в условиях экстремально низких температур Арктики

The results of tests to determine the impact strength of carbon fiber reinforced plastics based on an epoxy matrix and components that form an independent liquid phase in the composite structure (anaerobic polymer material (Loctite 638), silicone elastomer (Unisil-9628), synthetic wax) are presented. The tests were carried out after holding the samples at temperatures of 20±2 °C, –30 °C and –50 °C according to the Charpy method with the direction of an impact perpendicular to the plane. The use of an anaerobic polymer material as a component of the liquid phase of the hybrid matrix makes possible to obtain the highest impact strength among the compared types of carbon plastics and to ensure the stability of this characteristic after exposure at a temperature of –50°C. Synthetic wax in the structure of the composite matrix ensures the stability of impact strength after storage at a temperature of –30°C. Samples of carbon fiber reinforced plastics with silicone elastomer as part of the hybrid matrix have the lowest impact strength after holding under different temperature conditions.

A Review of Cellulosic Natural Fibers’ Properties and Their Suitability as Reinforcing Materials for Composite Panels and Applications

There has been much effort to provide eco-friendly and biodegradable materials for the next generation of composite products owing to global environmental concerns and increased awareness of renewable green resources. Increased use of natural materials in composites has led to a reduction in greenhouse gas emissions and the carbon footprint of composites. In addition to the benefits obtained from green materials, there are some challenges in working with them, such as poor compatibility between the reinforcing natural fiber and matrix and the relatively high moisture absorption of natural fibers. Green composites can be a suitable alternative for petroleum-based materials. However, before this can be accomplished, a number of issues need to be addressed, including poor interfacial adhesion between the matrix and natural fibers, moisture absorption, poor fire resistance, low impact strength, and less durability. Several researchers have studied the properties of natural fiber composites. These investigations have resulted in developing several procedures for modifying natural fibers and resins. To address the increasing demand to use eco-friendly materials in different applications, an up-to-date review of natural fiber and resin types and sources, modification, and processing techniques, physical and mechanical behaviors, applications, life-cycle assessment, and other properties of green composites is required to provide a better understanding of the behavior of green composites.

The Influence of Nano-CaCO3 on the Mechanical and Dynamic Thermo-Mechanical Properties of Core–Shell Structured Wood Plastic Composites

Using bamboo residue and high-density polyethylene (HDPE) as the main raw materials, core–shell structured wood plastic composites (WPCs) with nano-CaCO3 filling shell were prepared by coextruded technology. The effect of nano-CaCO3 contents on the flexural properties, impact strength and dynamic thermo-mechanical properties of the core–shell structured WPCs were investigated. And the value of core–shell interface interaction parameter was calculated by dynamic thermodynamic parameters. The results showed that the flexural strength increased by 48.1% and 40.3% when it was loaded with 10%–15% nano-CaCO3, compared to the HDPE shell composites, respectively. While nano-CaCO3-filled HDPE shell had lower impact strength in comparison with HDPE shell, the field emission scanning electron microscope revealed proper interfacial adhesion between the core and shell layers. The storage modulus of core–shell structured WPCs increased as nano-CaCO3 contents increased, but the values were lower than that of the HDPE shell. Addition of nano-CaCO3 caused an increase in the glass transition temperature (Tg) of the core–shell structured WPCs, loss factor (tanδ) of the core–shell structured WPCs decreased. The value of the core–shell interface interaction parameter of the core–shell structured WPCs increased significantly after the nano-CaCO3 loading reached 15%, which was consistent with the bending test results. These findings demonstrate that the core–shell structured WPCs have excellent properties filling with nano-CaCO3 in the shell layer, and bamboo residue is added to the core layer.

Sustainable green poly(lactic acid) (PLA)/eggshell powder (ESP) biocomposites

Poly(lactic acid), which is most commonly referred to by its acronym PLA, is a polymer that may be recycled and naturally deteriorated. It is also inherently fragile and has a low impact strength. PLA, when mixed with eggshells powder, can produce a PLA/ESP composites. The purpose of this study was to investigate the physical characteristics of PLA composites that contained ESP or calcium carbonate (CaCO3). Extrusion melt mixing in a twin-screw extruder was used in conjunction with PLA with different ESP concentrations to develop this eco-friendly and sustainable nanocomposite material. The blended compounds were allowed to reach room temperature before being formed into thin films with dimensions of 20 mm in width, 100 mm in length, and 5 mm in thickness. These films were put through a series of tests to determine their mechanical, thermal, and chemical properties. Tests including stress–strain properties, FTIR, thermogravimetric analysis (TGA), and scanning electron microscopy were performed on the films (SEM).

Influence of steel slag and steel fibers on mechanical properties of normal concrete

Cement, water, and both fine and coarse aggregate make up the composite material known as concrete. It is more versatile than the other building materials and has a variety of uses. However, it is brittle in nature and weak in tensile strength. Concrete also has low impact strength and poor energy absorption. Steel slag and steel fibres are added to the concrete to strengthen the weak spots and create a sustainable mix, and green concrete is created. In this study, concrete is mixed with hook-end steel fibres at concentrations of 0.25%, 0.50%, 0.75%, and 1% by volume, and its mechanical properties are assessed and compared with conventional concrete having 20 % replacement with slag. It was observed that adding hooked-end steel fibres to concrete enhanced its mechanical properties. The required number of cubes were cast, and the M40-grade concrete was then put through compressive, split tensile, and shear tests. The mechanical characteristics of concrete that have changed as a result of the addition of steel fibres were then compared.

Investigation of cold cracking resistance of HSLA 950A steel by taguchi optimization technique

Cold cracking is one of the major issues during welding High Strength Low Alloy (HSLA) 950A steel. The aim of the present research work is to optimize preheating temperature, the addition of oxide particles, and heat input using the Taguchi design of experiments for bead on plate, especially on the improved impact strength of weld metal. The experiments are carried out at three levels of mentioned parameters and Charpy impact strength is considered as a response. L27 orthogonal array is selected for experimentation in the present investigation using three parameters. An addition of vanadium oxide (V2O5) has acted as a nucleation site for acicular ferrite and enhanced the cold cracking resistance of investigated steel. The experimental results suggested that the impact strength of weldment is strongly influenced by pre-heating temperature (74.5%) and less influenced by oxide particle concentration (12.7%), and heat input (12.2%). Microstructure at HAZ revealed the presence of a small proportion of acicular ferrite of Widmanstatten morphology and upper bainite near weldment causes the reason for enhancement in cold cracking resistance. Fractographic examination revealed the presence of both ductile and brittle fracture modes, which attributed to higher and lower impact strength of weld joint respectively.

Comparative evaluation of impact strength of mechanically modified heat polymerized polymethyl methacrylate (PMMA) resin with addition of 0.5, 1, 2 wt% of silver nanoparticles (AgNPs): An in-vitro study.

Polymethyl methacrylate (PMMA) is one of the most widely used denture base material because of favorable esthetics and desirable characteristics such as easy handling. Acrylic resins, although, have some inherent disadvantages such as relatively poor physical and mechanical properties. The objective of the present study was to evaluate and compare the impact strength of unmodified and modified heat cure PMMA-based denture base material with addition of different concentrations of silver nanoparticles (AgNPs) (0.5, 1, 2 wt%). The present in-vitro study comprised of a total of 60 samples allocated to four groups with Group A samples consisting of heat cure acrylic resin without any modification (used as control); Group B samples consisting of heat cure acrylic resin modified with 0.5 wt% of AgNPs; and subsequently, Group C and Group D samples consisting of heat cure acrylic resin modified with 1 wt% and 2 wt% of AgNPs, respectively. The impact strength of the prepared acrylic samples was evaluated using Izod/Charpy Impact Tester, while the values obtained were tabulated and subjected to statistical analysis. Statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 17.0 (SPSS Inc., Chicago, IL, USA), while one-way analysis of variance and Tukey's multiple post-hoc procedures were used for statistical analysis. P < .05 was considered statistically significant. The highest impact strength was found in Group C samples consisting of heat cure acrylic resin modified with 1 wt% of AgNPs to be closely followed by Group B samples consisting of heat cure acrylic resin modified with 0.5 wt% of AgNPs. Group D samples consisting of heat cure acrylic resin modified with 2 wt% of AgNPs, although, revealed relatively lower impact strength compared to Group B and Group C samples. Within the limitations of the present study, it was concluded that the impact strength of mechanically modified heat polymerized PMMA resin was significantly enhanced with addition of varying concentrations of AgNPs, although, it was observed that with an increase in the concentration of AgNPs, a subsequent decrease in the tensile strength of the final polymer material was observed.

Using mixture design method for developing and optimizing eco-friendly ultra-high performance concrete characteristics

Due to its high cement content, ultra-high performance concrete (UHPC) is not an eco-friendly material. Utilizing alternative materials as a replacement of cement could improve UHPC's sustainability and reduce environmental impact. This study intends to examine the impact of using different alternative filler materials such as quartz powder (QP), limestone powder (LP), granite powder (GP) and basalt powder (BP) along with silica fume (SF) as a cement replacement on mechanical characteristics and durability of UHPC. The total powder content composed of 60% cement, 20% SF, and 20% filler materials (QP, LP, GP, and BP). Mixture design method in Minitab program was used to design concrete mixtures. Flowability, compressive strength, water permeability, rapid chloride permeability, sulfate resistance and concrete microstructure were the tests performed on the concrete mixtures. Utilizing QP, LP, BP, and GP as a partial replacement of cement in the production of UHPC resulted in significant negative impact on concrete flowability. UHPC with low environmental impact and compressive strength more than 120 MPa with higher durability could be produced using QP, LP, BP, and GP as a replacement of cement. Mixture composed of 711 kg/m3 cement, 237 kg/m3 SF, 118.5 kg/m3 QP, 118.5 kg/m3 BP, 1017 kg/m3 sand, 142.2 kg/m3 water, 31.3 kg/m3 super plasticizer, and 156 kg/m3 steel fibers achieved the highest compressive strength at age 7, 90, 180 days, the strength were 85 MPa, 123 MPa, and 126.1 MPa respectively. The findings demonstrated the development of a strong relationship between responses and constituent materials in predicting and optimizing compressive strength of UHPC, enabling construction implementers to obtain mixture design proportion to obtain UHPC with certain desirable properties using the proposed models without resorting to making experimental mixtures using a trial-and-error method, which consume time and effort.

Study of impact strength of C-Mn-Si composition metal after wire-arc additive manufacturing (WAAM)

The results of study of impact strength of C-Mn-Si composition metal after wire-arc additive manufacturing (WAAM) are presented. It was established that destruction of the samples of such composition at the temperatures below tough-brittle transition occurs both via tough and brittle mechanisms. The samples manufactured in the direction along built-up welding are characterized by essentially lower impact strength comparing with those manufactured in vertical direction of samples cutting. Impact strength of the samples made of 09G2SA standard steel is substantially lower than for C-Mn-Si composition metal which was obtained via additive technology. Fractographic analysis of fractures for C-Mn-Si compositions manufactured via additive technology using carbon dioxide and gas mixture displays tough pit destruction type. The samples with high impact strength are characterized by forming of cleavage facets after tough crack propagation to the sample middle, what is accompanied by significant widening opposite to a notch and narrowing under a notch. The samples with low impact strength are characterized by forming of brittle fracture directly under a notch without essential sample plastic deformation. It is shown that built-up welding with partial or complete recrystallization of rolls is required for forming of cold-resistant metal structure. In this case, order of rolls location, heat input and parameters of welding conditions make the direct effect on shape, geometrical dimensions, fusion penetration and number of rolls, as well as on size and morphology of the structural components, percent relation between cast and recrystallized microstructure of seam metal. The complex of these factors finally determines structural state and cold resistance of seam metal. The materials for this publication were prepared using&nbsp;the results of investigations, which were conducted within&nbsp;the framework of the program of activity of "Baikal" interregional&nbsp;educational center of global level, according to the&nbsp;priority direction "Processing of industrial wastes", with use&nbsp;of equipment of the Shared knowledge center of isotope and&nbsp;geochemical researches of the Institute of Geochemistry of&nbsp;RAS Siberian branch.

Synthesis of a Novel Hyperbranched Polyimide for Reinforcing Toughness and Insulating Properties of Bismaleimide Resin.

Bismaleimide (BMI) resin has great potential in aerospace, electronic, and machinery fields due to its extraordinary thermal stability. Owing to BMI’s lower impact strength, various modified BMI resins have been prepared using CTBN, PEEK, fillers, and hyperbranched polymer to achieve higher impact strength. However, enhancement of toughness causes deterioration of other performance, such as Tg, thermal stability, and brittleness. In this work, BMI resin modified by hyperbranched polyimide (HBPI) was obtained. HBPI designed with flexible segments, unsaturated bonds, and a low degree of branching was synthesized. FT-IR and 13C-NMR were applied to confirm the successful fabrication of HBPI. The mechanical strength and dielectric properties of cured BMI resin containing various levels of HBPI were analyzed systematically. The impact and bending strength were improved significantly with increased HBPI content. When the content of HBPI is 40 wt.%, the impact strength and bending strength reach the maximum value of 32 kJ/mm and 88 MPa. In addition, the BMI cured with HBPI exhibits enhanced bending modulus to the value of 5.9 GPa. Furthermore, the dielectric strength of cured resin was improved to 28.3 kV/mm. The improved mechanical strength and enhanced dielectric properties are attributed to the increasing free volume induced by HBPI. These results indicate the promise of BMI resin modified by HBPI applied in insulating coatings and low dielectric laminates used in high frequency.

Excellent toughness of rigid polyvinylchloride at low temperature improved by polycarbonate‐polydimethylsiloxane block copolymer

AbstractRigid polyvinylchloride (PVC) is widely used in various fields, but its low impact strength at low temperature limits its deep application in some cold regions. This work utilizes polycarbonate‐polydimethylsiloxane block copolymer (PC‐b‐PDMS) to toughen PVC. PDMS segment has extremely low glass transition temperature (−126°C) and PC segment has a good compatibility with PVC, which proved by the Fourier transform infrared and dynamic mechanical thermal results. For verifying toughening effect of PC‐b‐PDMS, the impact behavior at 23°C, 0°C and −30°C of PVC/PC‐b‐PDMS blends is investigated. The impact strength of modified PVC increases from 2.09 to 95.00 kJ·m−2 at 23°C, and the significant brittle‐ductile transition occurs at 10 phr PC‐b‐PDMS. At −30°C, 25 phr PC‐b‐PDMS makes brittle‐ductile transition appear and impact strength increased by 17 times. According to impact‐fractured morphology, PDMS acts as stress concentrator in PVC/PC‐b‐PDMS and produces a lot of cavities, crazes, and shear bands to consume impact energy, exhibiting good toughening effect. Overall, the PC‐b‐PDMS with excellent toughening effect is a promising alternative to traditional toughening agents, showing great promising application prospects in low‐temperature toughening of the rigid PVC products.

Investigating the Microstructural and Mechanical Properties of Novel Ternary Reinforced AA7075 Hybrid Metal Matrix Composite.

This study investigates the comparison of the microstructural and mechanical properties of a novel ternary reinforced AA7075 hybrid metal matrix composite. Four samples, including AA7075 (base alloy), AA7075-5wt %SiC (MMC), AA7075-5wt %SiC-3wt %RHA (s-HMMC), and AA7075-5wt %SiC-3wt %RHA-1wt %CES (n-HMMC) were developed using the stir casting liquid metallurgy route, followed by the heat treatment. The experimental densities corresponded with the theoretical values, confirming the successful fabrication of the samples. A minimum density of 2714 kg/m3 was recorded for the n-HMMC. In addition, the highest porosity of 3.11% was found for n-HMMC. Furthermore, an increase of 24.4% in ultimate tensile strength and 32.8% in hardness of the n-HMMC was recorded compared to the base alloy. However, its ductility and impact strength was compromised with the lower values of 5.98% and 1.5 J, respectively. This was confirmed by microstructural analysis, which reveals that n-HMMC has mixing issues and forms agglomerates in the matrix, which served as the potential sites of stress concentration leading to low impact strength and ductility. Nevertheless, the hybrid composites showed superior mechanical properties over the MMC and its base alloy.

Low-Density Particleboards Modified with Blowing Agents—Characteristic and Properties

Although lightweight particleboards have been commercially available for years, they still have a number of disadvantages, including difficulty to process, brittleness, low impact strength, and other mechanical resistance. The aim of the paper was to determine the possibility of producing particleboards of reduced density (dedicated for furniture industry) as a result of using blowing agents from the group of hydrazides, dicarboxamides, or tetrazoles, which were modifiers of the adhesive resin used for bonding the particles of the core layer of three-layer particleboards. The concept presents the possibility of producing low-density particleboards in a standard technological process by modifying the adhesive resin, which has not been practiced by others until now. Analysis of the results of testing the particleboards properties with various types of modifiers (blowing agents), glue content (high 10%/12% and low 8%/10%), differing in glue dosing method, and different particle sizes allowed concluding that the most satisfactory effect was found in particleboards made of the variant modified with p-toluenesulfonyl hydrazide. This variant was characterised by the highest mechanical properties (bending strength, modulus elasticity, and internal bond strength) with high dimensional stability. The presented technology proposal can be applied in the industry.

Effects of different polyolefin copolymers on properties of melt mixed polypropylene blends

AbstractPolypropylene (PP) is an affordable plastic commodity but lacks massive use in engineering applications given its limited mechanical properties including significantly low impact strength. In this work, three polyolefin‐based copolymers including ethylene‐octene random block (Engage, E), ethylene‐octene multi‐block (Infuse, I), and ethylene‐propylene copolymer (Versify, V) were blended with PP. It was found that the V copolymer was miscible while the rests were immiscible in the PP matrix. Mechanical testings indicated that the addition of the 20% E and 20% I copolymers significantly enhanced the impact toughness of PP up to 83% and 108% at −20°C, respectively. At a higher temperature such as 25°C, the impact toughness of the PP/E20 and PP/I20 were 400 and 571%, respectively. The enhancement of the PP impact toughness was governed by the particle size of the added immiscible copolymers. Experimental results also revealed that the good compatibility between PP and copolymers has an insignificant influence on the mechanical properties of PP while the essence of added copolymer plays a key role instead. The findings from this work provide significant insights into the design of PP‐based products with desirable properties to satisfy requirements demanded by engineering applications.