Nucleation Effect Research Articles

Study on the Influence of SAP on Properties of White Fair-Faced Concrete with Limestone Powder

Introducing SAP internal curing material and limestone powder into white fair-faced concrete in order to greatly improve the durability of white fair-faced concrete, alleviate the influence of mechanical property deterioration caused by SAP, and facilitate the popularization and application of SAP and limestone powder in white fair-faced concrete. Therefore, this paper studies the effect of the content of SAP and limestone powder on the properties of white fair-faced concrete, conducts slump, electric flux, standard cube compressive strength, and splitting tensile strength tests, and examines SAP and limestone powder from a macroscopic perspective. The effect of the dosage on the properties of white, fair-faced concrete was explained by a scanning electron microscope (SEM) from a microscopic point of view. The results show that SAP can increase the slump of white fair-faced concrete, and the slump of SAP white fair-faced concrete increases with the addition of limestone powder content. Adding SAP can greatly reduce the electric flux of white fair-faced concrete. The addition of limestone powder can further reduce the electric flux and improve the durability and adding SAP will deteriorate the mechanical properties of white fair-faced concrete. Adding limestone powder is beneficial to the improvement of the mechanical properties of SAP mixed with white fair-faced concrete. Adding 30% limestone powder can give full play to the optimal performance of SAP white fair-faced concrete. SAP can refine the internal structure of white fair-faced concrete, and the filling and nucleation effects of limestone powder can improve the situation where SAP deteriorates the mechanical properties of white fair-faced concrete, further optimizing concrete internal structure.

A facile green and cost-effective manufacturing process from coal gangue-reinforced composites

Utilization of high-filler coal gangue (CG) to produce cost-effective composites is a promising strategy. To clarify the impact of high-filled CG on composite preparation and performance, in this research, the composite was prepared from CG and polyethylene (PE) through physical mixing and then hot-pressing. The role of CG in the properties of the composites and the influence of the interface formation mechanism are obtained by establishing the relationship between CG content and the composites' feature. The results show that: high-filler CG is helpful to the increment of the composite's mechanical and thermostable properties. When the CG addition is up to 80%, the density and hardness from 0.93 g/cm3 and 50.5 HD increased to 1.60 g/cm3 and 66.5HD, which was increased by 72.0% and 31.6%, respectively. Meanwhile, the bending strength and modulus reach 17.5 MPa and 3400.6 MPa, which is respectively exceeded by 56.3% and 628.6% than composite from pure PE (11.2 MP and 466.7 MPa). In addition, high-filler CG is beneficial for the enhancement of entanglement between CG and PE during the composite preparation, and has the effect of heterogeneous nucleation, which facilitated the crystallization and thermal stability of the composite. The properties of the composites prepared by this simple technique meet national standards and are more economical and environmentally sustainable than composites prepared with other fillers. This new material holds great promise for the development and realisation of carbon-neutral decorative materials such as assembly buildings, vehicles and coloured panels.

Influence on Rheology and Microstructure of Nanosilica and Modified Polycarboxylate in Water‐Glass‐Activated Fly Ash/Ground Granulated Blast Furnace Slag Geopolymers

AbstractThis study establishes the effect of nano silica (NS) in the alkali activator on the behaviour of rheology and microstructure of Alkali activated material. The rheological behaviour of the Fly ash (FA)‐Ground granulated blast furnace slag (GGBS) (4 : 1) activated using water glass of Ms 1.1 (SiO2/Na2O), with nano silica (NS), Modified Poly carboxylate (MPC) was studied and the link between the composition and fundamental behaviour are reported. A total of 12 mortar mixtures were cast by varying the dose of NS from 0–3 %, and MPC 0–2.5 % and their fresh properties were obtained from the slump, setting time and flow value. The compressive strengths of mortars showed an increasing trend from 40 to 55 MPa with NS addition from 0–2.5 wt% at an optimal dose of 1 % MPC. The suspensions with and without NS fit well with Herschel‐Bulkley model, in the hysteresis cycle. The incorporation of NS at a threshold value below 2 % leads to a drastic change in viscosity with increasing time at a constant shear rate, implying. a thixotropy with yield‐type behaviour that are associated with the rebuilding of the flocculated structure with time. The nucleating effect of NS progressively improved the strength of the mix, due to the formation of compact gel microstructure which was confirmed by SEM micrograph with fewer pores. NS improves CSH gel and gelatinous silica phase in the matrix as is evident from the formation of the SiQ4 structural unit as it is absent in control. The poly (Sialate) structural unit in geopolymer ascertained from 29Si, 27Al MAS NMR chemical shift corresponds to Alq3(3Si) with the absence of remnant Al(IV) peak of Fly ash in NS (2.%) activated samples.

Preparation of cellulose nanocrystal (CNCs) reinforced polylactic acid (PLA) bionanocomposites filaments using biobased additives for 3D printing applications.

This work presents the experimental steps taken towards the preparation of 3D printable bionanocomposites using polylactic acid (PLA) biopolymer containing 0.1, 0.5 and 1 wt% CNCs. Optimized amounts of bio-based additives were added to improve the processability and flexibility of the bionanocomposites. The 3D printable bionanocomposite filaments were drawn using a single screw extruder. The bionanocomposites filament was used to 3D print prototypes and test specimens for dynamic mechanical analysis (DMA). Characterization of the CNCs and bionanocomposites was performed using Fourier Transform Infrared Spectroscopy (FTIR) analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The nucleating effect of CNCs enhanced the crystallization behaviour of bionanocomposites by 5%, 15% and 11%, for the different CNCs loadings. The TGA analysis revealed a ∼20 °C improvement in the thermal stability of the bionanocomposites. Meanwhile, the tensile analysis showed a ≥48% increase in the tensile strength of the bionanocomposites filaments which was attributed to the reinforcing effects of CNC. The addition of CNCs significantly increased the melt viscosity, storage and loss modulus of PLA. In summary, the bionanocomposite filaments produced in this study exhibited excellent processibility and superior mechanical and thermal properties.

Effects of Nucleation and Crystal Growth Rates on Crystal Size Distribution for Seeded Batch Potash Alum Crystallization Process

The driving force of the cooling crystallization process is supersaturation, where the supersaturation level during the crystallization process is crucial to grow the crystal sufficiently. Nucleation and crystal growth rates are two concurrent phenomena occurring during crystallization. Both are supersaturation functions that determine the growth of seed crystals and the formation of fine crystals. Trade-offs between nucleation and crystal growth are essential for achieving the large size of seed crystals with the minimum number of fine crystals. Thus, the objective of this study is to analyze the effects of nucleation and crystal growth rates on final product quality, which is crystal size distribution (CSD). Modeling of the crystallization process using a potash alum case study is highlighted and simulated using Matlab software. Then, the effects of nucleation rate, crystal growth rate, and both nucleation and crystal growth rates on CSD are evaluated using local sensitivity analysis based on the one-factor-at-a-time (OFAT) method. Based on simulation results for all strategies, a low combined rate delivers the best performance of the final CSD compared to others. Its primary peak has a mean crystal size of 455 µm with 0.0078 m3/m volume distribution. This means that the grown seed crystals are large with high volume distribution compared to the nominal strategy, which is at the mean crystal size of 415 µm and 0.00434 m3/m. Meanwhile, the secondary peak has the mean crystal size of 65 µm, 0.00028 m3/m in volume distribution. This corroborates the least number of fine crystals at the considerably small size compared to nominal’s (0.00151 m3/m, 35 µm). Overall, the low nucleation and crystal growth rates strategy provides useful insights into designing temperature profiles during the linear cooling crystallization process, whereby achievable supersaturation levels in obtaining large crystals with fewer crystal fines are provided via simulation.

Recycling of waste crab shells into reinforced poly (lactic acid) biocomposites for 3D printing

To promote natural waste resource utilization, a novel biocomposite, composed of waste crab shells and poly (lactic acid) matrix, was developed by combining chemical treatment and 3D printing. A crab shell powder (ISCSP) with an abundant porous structure and a high specific surface area was obtained by treatment with hydrochloric acid and sodium hydroxide. Importantly, under the optimal printing parameters determined by the finite element analysis, test samples, and porous bones were successfully printed using CSP/PLA composites by a commercial fused deposition modeling (FDM) 3D printer. The morphology, mechanical and thermal properties, antibacterial properties, and biocompatibility of the CSP/PLA composites were then assessed. Our results revealed that the tensile strength and flexural strength of the ISCSP/PLA composites reached 58.71 and 90.11 MPa, which were 28.6 % and 28.8 % higher than that of pure PLA, respectively. The glass transition and melting temperatures of the composites remained similar to those of pure PLA. Interestingly, the addition of CSP increased PLA crystallinity, which could be attributed to the nucleation effect of CSP in the system. The antibacterial activity of the PLA-1.5ESCSP composite samples against Escherichia coli (E. coli) was greater than 99 %. More importantly, the live/dead assay showed that the CSP/PLA composites possessed excellent biocompatibility. Therefore, the developed CSP/PLA biocomposites are potential feedstocks for 3D printing in bone tissue engineering and may be used as graft substitutes in reparative and reconstructive surgery. They are especially beneficial due to their superior mechanical and thermal properties, excellent antibacterial activities, and significant biocompatibility.

Bio-nanocomposite foams of starch reinforced with bacterial nanocellulose fibers

In this study, the bio-nanocomposite foams of cassava starch incorporated with nanocellulose fibers (NCF) produced by bacteria were prepared by microwave processing. The effect of NCF adding content of 0.25–2.0 wt% on the morphology, structure, mechanical properties as well as water resistant properties of the starch/NCF nanocomposite foams was examined. The cellular structure of starch-based foams essentially changed by the addition of NCF, owing to its nucleating effect. The number of cells in the foam structures was found to increase dramatically with the cell size decreased (but more uniform) and the cell wall thickness increased (as confirmed by SEM). From the flexural tests, the strength and modulus of these nanocomposite foams were markedly improved (2 to 3-fold increase). At the optimum NCF loading content of 1.0 wt%, the flexural strength and modulus of this nanocomposite foam were raised to 7.71 MPa and 448 MPa, respectively. The water resistance of the current starch/NCF nanocomposite foams were also noticeably improved. The results in this study demonstrate another promising greener technology to produce a sustainable foam material for our planet with enhanced performance.

Investigation on Roles of Packing Density and Water Film Thickness in Synergistic Effects of Slag and Silica Fume.

The ternary blended cement with finer slag and silica fume (SF) could improve the packing density (PD) through the filling effect. The excess water (water more than needed for filling into voids between the cement particles) can be released to improve the fresh properties and densify the microstructure which is beneficial for improving the hardened properties. To verify the hypothesis and reveal how and why (cement + slag + SF) the ternary blends could bring such advantages, the binder pastes incorporating slag and SF with various water-to-binder ratios were produced to determine the PD experimentally. To evaluate the optimum water demand (OWD) for maximum wet density, the influence of the dispersion state of the binder on PD was investigated using the wet packing density approach. The effect of PD of various binary and ternary binder systems on water film thickness (WFT), fluidity, setting time, and compressive strength development of cement paste was also investigated. The results show that the ternary blends could improve the PD and decrease the water film thickness (WFT). The enhanced PD and altered WFT are able to increase fluidity and compressive strength. The ternary blends could improve the compressive strengths by increasing PD and exerting nucleation and pozzolanic effects.

Melt processing behaviour and structure development in recycled PP blends with recycled PET

Commercially available recycled polypropylene (R-PP) and recycled bottle grade polyethylene terephthalate (R-PET) were melt compounded in different proportions of R-PET in twin screw extruder at temperatures used typically for PP processing. The melt flow behaviour was investigated for these blends using capillary rheometer at different temperatures viz. 230, 250, 260°C. The crystallization and structure development was studied using DSC and XRD. The melt viscosity (η) of these blends followed the usual non-Newtonian behaviour with decrease of η with high shear rate (γ′) and saturation at low shear rate. Most noteworthy finding was that the low shear viscosity at melt temperatures of 230 and 250 showed a peak with increase of R-PET content while at 260°C there was uniform decrease in the viscosity with addition of R-PET. The high shear viscosity also showed similar trend but with less pronounced changes. This was attributed to the cross over of domain shape from spherical to ellipsoidal and finally fibrous shape according to Utracki model. At the melt compounding/processing temperature of 230°C, the R-PET phase was in semi solid state and hence it formed fibrous morphology in the PP melt which was confirmed by SEM analysis. The most interesting finding was that crystallization of both the component polymers was affected due to the presence of the other. R-PP showed nucleation effect in presence of R-PET with the shift in Tc from 118°C to higher temperature side (123°C). Even R-PET exhibited shift in the Tc from 178°C to 201°C in presence of R-PP. These results are discussed in terms of nucleation and slow heat dissipation for PET domain in PP melt together with shear induced crystallization. These structural modifications in the R-PP/R-PET blends led to improvement in properties at certain compositions processed under certain conditions.

Effect of multilayer graphene oxide on the hydration and early mechanical strength of cement mortar in low temperature

The mechanical strength of cement mortar is normally decreased in a low-temperature environment, which is mainly due to the slow cement hydration reaction rate and an increase in the total pore volume, especially the harmful pore volume. With the modification of nano-materials, the early mechanical strength of cement-based materials can be effectively compensated. In this study, the effect of multilayer graphene oxide (MGO) on the early mechanical properties and microstructure of cement mortar at low temperatures of 0 °C, 5 °C, and 10 °C is studied by measuring the fluidity, setting time, mechanical property, scanning electron microscope (SEM), thermogravimetric (TG), and nitrogen adsorption/desorption test. Compared with the mechanical strength of control mortar with curing temperature of 20 °C, the mortars with the addition of MGO curing at low temperature present higher mechanical strength and denser microstructure. And the mechanism of the interaction between cement particles and MGO nano particles at low temperatures (0 °C, 5 °C, and 10 °C) is further discussed. The initial hydration reaction of MGO mortar is accelerated, which is mainly due to the nucleation effect of MGO and chemical reactions between –COOH on the edge of MGO nanosheets and the Ca2+ of Ca(OH)2. The promotion of the initial hydration refined the pore diameter of samples by reducing the pore size and total porosity, thus making the microstructure of samples denser and enhancing the strength of specimens.

Filler effects of CaCO3 polymorphs derived from limestone and seashell on hydration and carbonation of reactive magnesium oxide (MgO) cement (RMC)

This study investigated the influence of CaCO3 polymorphs from limestone and seashell on the hydration and carbonation kinetics of reactive MgO cement (RMC). Replacement levels at 5 and 10 wt% were adopted, and the samples were exposed to ambient curing before carbonation under 20 % CO2. The superior filler effects imparted by the limestone powder were demonstrated with an enhancement to the normalized heat flow at an early stage of hydration, leading to an increase in the compressive strength under air curing. Its nucleation effect did not lead to more brucite but involved the formation of amorphous phases, which encapsulated and passivated the MgO substrate, consequently restricting its hydration. Under carbonation, nucleation induced by both the CaCO3 forms improved the composite strengths by producing carbonation products of larger morphologies, resulting in pore filling and matrix densification. Amorphous phases of a hydromagnesite-like and fused structure were observed.

Durability effect of nano-SiO2/Al2O3 on cement mortar subjected to sulfate attack under different environments

Ambient humidity and air pressure have significant effects on the durability of cement-based materials subjected to sulfate attack. This paper investigated the durability performance of cement paste and cement mortar containing nano-SiO2 (NS) and nano-Al2O3 (NA) attacked by Na2SO4 solution under low air pressure (60 kPa, LP) and normal air pressure (101 kPa, NP) environments. The results showed that supersaturated Na2SO4 solution could crystallize in the pores of mortar and deposit on the surface of mortar, accompaning by the transformation from Na2SO4∙10H2O with fibrous to Na2SO4 with powder. The presence of low air pressure environment exacerbated the capillary transport rate and the water evaporation rate, resulting in a severer salt efflorescence. However, the incorporation of NS/NA could reduce the adsorption height of the salt solution on the surface of the mortar and thus alleviate the Na2SO4-induced damage. Moreover, the flexural/compressive strength of nano-modified mortar subjected to Na2SO4 attack under NP and LP environments were enhanced due to the nucleation effect and chemical activity of NS and NA. Furthermore, the addition of nanomaterials decreased the porosity and the amount of harmful pores above 50 nm in the samples and increased the consumption the erodible Ca(OH)2, reducing the generation of Na2SO4-induced corrosion products. Among them, the system containing NA at 0.5 wt% performed better, which is of great significance for the protection of concrete components exposed to sulfate attack in the practical engineering.

Characteristics of CSH under carbonation and its effects on the hydration and microstructure of cement paste

This paper investigated the characteristics of synthesized calcium silicate hydrate (CSH) during the carbonation process and the effects of CSH and carbonated C-S-H (CCSH) seeds on the performance of cement pastes. The result showed that the CCSH is composed by 68.4% calcite and 31.6 % silica gel with Ca/Si of 0.09 and can absorb 301 g CO2 per kg C-S-H, which had a high potential for CO2 capture. please modifed to The result showed that the CCSH is composed by 68.4% calcite and 31.6 % silica gel and can absorb 301 g CO2 per kg C-S-H, which had a high potential for CO2 capture. The addition of CCSH showed more significant improvement on the cement hydration due to the higher surface area and the generated calcite and silica gel after carbonation treatment in comparison to CSH. A new hydration product of calcium aluminate mono-carbonate was generated in CCSH sample with the reaction between calcium carbonate and aluminate. Different from the only additional nucleation sites provided by CSH seeds, the generated calcite after carbonation provided nucleation effect, chemical effect and finer effect, and the silica gel had a high pozzolanic reaction degree, which significantly accelerated the hydration and led to a denser pore structure. Therefore, the CCSH seeds significantly accelerated the early hydration and increase the early compressive strength without an obvious decrease of the later compressive strength due to the coupling effect of calcite and silica gel.

The synergistic effect of nanocellulose and nanocapsules into poly(butylene adipate-co-butylene terephthalate) films for active packaging

The pandemic scenario has impacted the consumption pattern, increasing the use of single-use materials. This work presents the development of active films for application in food packaging products. Poly(butylene adipate-co-butylene terephthalate) (PBAT) films, reinforced with nanocellulose (2 % by weight) and chitosan nanocapsules containing essential oils (EO), were developed using two different EO and different capsules content (1 %, 3 %, and 5 % by weight). The films were investigated by thermal analysis (TGA), mechanical properties, X-Ray diffraction (XRD), water vapor permeability (WVP), contact angle, oil release, and antimicrobial tests. The films presented excellent thermal stability and showed increased mechanical properties compared with pristine films. The film's crystallinity corroborated these results, indicating that the fibers and capsules promoted a nucleating effect during film formation. The WVP and contact angle results indicated that EO's hydrophobicity impacted the film's surface properties. The antimicrobial activity of the films was evaluated against Escherichia coli (E. coli), and it was observed inhibition of bacterial growth for all films containing EO. These results show a promising application for extending food products' shelf life in new formulations and using environmentally friendly materials.

Effect of twin nucleation and twin on the recrystallization of a nickel-based superalloy during hot compression

The nucleation mechanism of deformation twin (DT) and annealing twin (AT), and the effect of twins on recrystallization were studied comprehensively for Nickel-based superalloys during dynamic recrystallization (DRX). The aim is to improve the understanding of microstructure evolution during hot deformation. Hot compression tests were carried out at the temperature of 900-1150 °C with the strain rate of 0.01-1 s -1 for a Nickel-base superalloy. The results show that the DT and the Ʃ3 boundary exist simultaneously in the DRX stage. DTs are nucleated by the rotation of Franck partial dislocations and the decomposition of perfect dislocations. The DTs hinder the movement of dislocations in deformed grains and promote the nucleation of DRX grains. Ʃ3 boundaries associated with stacking faults are formed at recrystallized grain boundaries. In the condition of continuous DRX (CDRX), the Ʃ3 boundary changes the grain orientation and restrain the CDRX nucleation. While for the discontinuous DRX (DDRX), the Ʃ3 boundary provides an additional nucleation site and increase the nucleation rate. In addition, the comprehensive effect of DTs and ATs can promote the DRX nucleation, for which increase at first and then decrease with nucleation mechanical transform from CDRX to DDRX. • Deformation twins are nucleated by the rotation of Franck partial dislocations and the decomposition of perfect dislocations. • The quantity of deformation twins decreasing with the increase of DRX volume fraction. • Deformation twins hinder the movement of dislocations and promote the nucleation of CDRX. • The Ʃ3 boundaries hinder the CDRX nucleation and accumulate the DDRX nucleation process.

Effect of Recycling on the Mechanical, Thermal and Rheological Properties of Polypropylene/Carbon Nanotube Composites

In this research the effect of physical recycling on the mechanical, thermal, and rheological properties of polypropylene (PP)/multiwalled carbon nanotube (MWCNT) was investigated. After melt homogenization by extrusion, specimens were injection moulded with 0.1 and 0.5 wt% MWCNT content. The recycling process was simulated by multiple grinding and re-moulding, then we compared the behavior of original and recycled PP/MWCNT composites. Differential scanning calorimetry (DSC) measurements proved that MWCNT had double the effect on the morphology of the PP matrix: on the one hand nucleating effect can be detected because 0.5 wt% MWCNT increased the onset temperature of crystallization by 10 °C, compared to the basic PP material; on the other hand, the crystalline fraction of the recycled composite materials decreased compared to the original PP material with the same MWCNT content. This resulted in a slight decrease in strength and stiffness but an increase in elongation at break. However, compared to the original unreinforced PP reference, even the recycled materials have better properties. The mechanical test results showed that recycled PP/MWCNT 0.5 wt% increased the elastic modulus (~15%) and decreased the tensile strain at yield (~10%). However, in the values of tensile stress at yield, relevant difference was not found. It was also shown by oscillatory rheometry that MWCNT had a significant effect on the rheological properties (storage and loss modulus, complex viscosity) of PP compounds in a wide temperature range (190-230 °C).

The synergistic effect of heterogeneous nucleation and stress-induced crystallization on supramolecular structure and performances of poly(lactic acid) melt-spun fibers

As a kind of bio-based polymer, poly (lactic acid) has potential application in fibers fields. Due to the weak nucleation ability, PLA crystallizes slowly and forms large spherulites during the forming process, which deteriorates the properties of PLA fibers. In this work, melt-spun method is employed for the fabrication of PLA/T composite fibers using succinate diphenyl dihydrazide (TMC-306) as the nucleating agent, and then the hot-drawing and heat setting is performed to the as-spun fibers. Compared with pure PLA fibers, PLA/T fibers show faster crystallization rate and improved performance due to the synergistic effect of heterogeneous nucleation and stress-induced crystallization. The characterization of non-isothermal crystallization behavior indicates that the peak crystallization temperature as well as crystallinity of PLA composites is increased to 121.5 °C and 36.78 % respectively by blending 0.3 wt% TMC-306. Meanwhile, the obtained PLA/0.3T composite fibers are highly crystallized and oriented at hot-drawing ratio of 2.4 folds and heat setting temperature of 100 °C, and the conformational stability is noticeably enhanced. Further, the tensile strength and storage modulus of PLA/0.3T composite fiber are 3.46 cN/dtex and 46,953 MPa respectively, which are increased by 42 % and 41 % compared with neat PLA fibers.

Preparation of lightweight and high‐strength polypropylene‐based ternary conductive polymer foams by in situ microfiber reinforcement

AbstractConductive polymer composites (CPCs) have demonstrated significant potential in the aerospace, electronics, and communications industries. In this study, polypropylene (PP)/multiwalled carbon nanotubes (MWCNTs) binary composites and in situ fiber reinforced multicomposites made from PP/MWCNTs were fabricated by microcellular injection molding. In addition to crystallization behavior, foam morphology, mechanical properties, dielectric properties, and electromagnetic shielding properties of the composites were analyzed. According to the results, microporous structures can facilitate the distribution of conductive fillers, thereby enhancing the electromagnetic shielding performance and mechanical properties of the composite. In situ microfiber networks display a heterogeneous nucleation effect, resulting in an increase in foam density, which improves composite performance. In situ fiber‐reinforced microporous multicomposites are capable of exhibiting higher elongation at break and electromagnetic shielding properties than binary systems, and the multicomposites can achieve greater electromagnetic shielding effectiveness (SE) with fewer conductive fillers. Ultimately, fiber‐reinforced microporous composites with an elongation at break of 194.40%, an electromagnetic shielding effect of >20 dB, and an absorption mechanism are produced. A feasible method is presented in this study for preparing CPCs that produce light weight, excellent mechanical properties, and high electromagnetic SE at low filler levels.

Dynamic Compression of a SiC Foam

Silicon carbide foam is a material that can be used as reinforcement of interpenetrated composites. This paper presents an analysis of such a foam subjected to low and fast compression. The analysis is performed using the peridynamics (PD) method. This approach allows for an evaluation of failure modes and such effects of microcracks nucleation, their growth, and, finally, fragmentation. Furthermore, the material appears to behave qualitatively and quantitatively differently while subjected to low- and high-speed steel piston movement. Under slow compression case, damage appears in the entire specimen, but the shape of the structure is not changing significantly, whereas during the fast compression the sample is dynamically fragmented.

Effect of short-chain architecture on the resulting thermal properties of polypropylene

Polypropylene (PP) is a versatile commodity polymer with a plethora of potential applications, in this work, short-chain branches of anhydride, amine, and various acrylate monomers with varying molecular weights were grafted onto PP using reactive extrusion. It was envisioned that such graft co-polymers can enhance the performance of PP making it a viable material such as water heating applications. The main interest herewith is to evaluate the occurrence of the grafting reaction and its effect on the thermal properties of the resulting graft co-polymers. Fourier Transform Infrared (FTIR), Differential Scanning Calorimeter (DSC), Polarized Optical Microscopy (POM), Thermogravimetric Analysis (TGA), gel content, and rheology tests were conducted to evaluate the effect of grafting on the performance of PP. DSC results showed a novel increase in crystallinity and crystallization temperature indicating a nucleating effect by the grafted chains. This is correlated with TGA and rheology results, where an increase in the temperature of maximum degradation and a reduction in the viscosity proved to be converging confirmations of grafting. The results clearly indicated successful grafting of PP which resulted in improved thermal stability that is essential for use in energy applications.