Good Processing Properties Research Articles

Analysis of the mechanical composite properties of ii-chamber variations in the closed injection pultrusion process

Pultrusion is an established and efficient process for producing continuous fiber-reinforced composites. The resin systems that are currently most frequently used are unsaturated polyesters and vinylesters. These have a long pot life, are well known, and have good processing properties. Highly reactive resins such as polyurethane (PU) and amine hardening epoxy have been in use for a few years. These resin classes are remarkable for their extended range of properties. This opens up new application fields for pultrusion technology but poses challenges for the processing technology. Short pot lives of just a few minutes require a modified process: closed injection pultrusion (CIP). Various approaches about the design and layout of the internal geometry of the injection and impregnation chambers (ii-chamber) are the subject of ongoing research. Numerous parameters influence the impregnation process in the ii-chamber and the quality of the resulting composite. In this study, two innovative, highly reactive resins for use in the pultrusion process were analyzed, both resins based on aliphatic polyurethanes. In phase 1 of the experiments, a commercial aliphatic polyurethane-system for pultrusion applications was used. In Phase 2, the recently developed bio-based aliphatic polyurethane-system for pultrusion applications was used for the study's main experiments. The aim of the study was to analyze the material and processing properties with various modifications of the impregnation setup. Therefore, a newly developed ii-chamber and die were tested. The ii-chamber was designed to enable easy adjustment of some of the main influencing parameters during the pultrusion process. A test strategy was developed to evaluate the properties of the composites. An assessment of the influence of the process- and die-based parameters should enable an evaluation of the optimal processing settings by analysis of the material characteristics. The most significant effect of variations in the pultrusion process was found in the interlaminar shear strength (ILSS). ILSS was analyzed for all process variations for both resin systems.

Comparative Studies on Crystallinity, Thermal and Mechanical Properties of Polyketone Grown on Plasma Treated CVD Graphene.

In this work, we report a facile way to control crystalline structures of polyketone (PK) films by combining plasma surface treatment with chemical vapor deposition (CVD) technique. The crystalline structure of PKs grown on plasma-treated graphene and the resulting thermal and mechanical properties were systematically discussed. Every graphene sheet used in this work was produced by CVD method and the production of PKs having different crystallinity were performed on the O2- and N2-doped graphene sheets. It was evident that the CVD-grown graphene sheets acted as the nucleating agents for promoting the crystallization of β-form PK, while suppressing the growth of α-form PK crystals. Regardless of the increase in surface roughness of graphene, surface functionality of the CVD-grown graphene was found to be an important factor in determining the crystalline structure of PK. N2 plasma treatment of the CVD-grown graphene promoted growth of the β-form PK, whereas the O2 plasma treatment of CVD graphene led to transformation of the unoriented β-form PK into the oriented α-form PK. Thus, the resulting thermal and mechanical properties of the PKs were highly dependent on the surface functionality of the CVD graphene. The method of controlling crystalline structure of the PKs suggested in this study, is expected to be very effective in realizing the PK with good processability, heat resistance and mechanical properties.

Advances in waterborne polymer/carbon material composites for electromagnetic interference shielding

Electromagnetic interference (EMI) shielding materials are of great importance for modern daily life, military actions and precise instrument protection because of the complex electromagnetic pollution caused by explosive growth of telecommunications and electronics devices. The conductive polymer composites (CPCs) have been proved to be one of the most promising EMI shielding materials both in fundamental research and practical application due to it set of intriguing lightweight, good processability, low density, chemical stability and excellent mechanical properties. Carbon materials (e.g. graphene, carbon nanotubes, carbon fiber, carbon black) based composites have occupied a prominent position in CPCs for EMI shielding. Not only the electromagnetic pollution should be eliminated or solved, but also the pollution coming from the preparation or processing of polymers. In this regard, waterborne polymer/carbon material composites for EMI shielding can meet the demand. Waterborne polymer will affect the EMI SE performance remarkably by improving the interfacial interaction between carbon materials and polymer and further structure designing of the composite. The composite structure forms including homogeneous structures, multilayer structures, segregated structures and porous structures are mainly discussed in details in this review which may inspire the design for more environment-friendly EMI shielding materials.

Evaluation of the nutritional value of processed plant-based foods

This paper presents the data on nutritional value of food products obtained from plant-based feedstock. Purées made from apples, cranberries, red beets, and horseradish roots were used as study objects. The pre-made purées were found to be a valuable source of dietary fiber as the contents of pectic substances and fibers in them are rather high. The hydropectin/protopectin ratio in the study objects was evaluated. The protopectin content was the highest in the purée made from horseradish roots, while the lowest protopectin content was observed in cranberry purée. The degree of pectin methylation was determined experimentally. The cranberry and apple purées contain high-methoxy pectin, while the beet purée and the purée made from horseradish roots contain low-methoxy pectin. Information about the degree of pectin methylation is needed to understand the processing features of the ingredients. The data on antioxidant capacity of the samples are reported. Cranberry purée has pronounced antioxidant properties. The mineral composition of the samples was determined. Beet purée is rich in Na, K and Fe; the purée made from horseradish roots is rich in K, Ca and Fe; apple purée contains a sufficiently high amount of Fe. The analyzed plant-based purées can be used to design functional food products characterized by good processing properties, longer shelf life, and high nutritional value.

3D printed bone tissue regenerative PLA/HA scaffolds with comprehensive performance optimizations

Polylactic acid/Hydroxyapatite (PLA/HA) composite was widely studied and applied in the field of biomaterials for its good processability, bioactivity, and mechanical properties. In addition to traditional preparation methods, additive manufacturing has also been adopted to prepare PLA/HA composites with customized geometries. This work combined the comprehensive optimized PLLA (L-polylactic acid)/nano-HA (nHA) composite with the low-cost and stable Fused deposition modeling (FDM) technology to successfully prepare PLLA/nHA porous bone repair scaffolds. The results showed that PLLA/nHA composite ink satisfied the smoothness of printing, and the accuracy also met the requirements of personalized bone repair application. The high loaded nHA scaffold had suitable compressive strength was significantly higher than those of pure HA ceramic scaffold and cancellous bone. Besides, in vitro bone-like apatite formation on the surface in the degradation process and in vivo evaluations further verified its good osteogenic property. Compared with other complex and cutting-edge 3D printing technologies, this study provides a low-cost, stable, simple and fast way to realize personalized printing of bone repair scaffolds, which is undoubtedly conductive to the improvement and rapid deployment of personalized biomaterials in clinical applications.

Mechanical Properties of High Mg-Content Al-Mg-Sc-Zr Alloy Fabricated by Selective Laser Melting

The effects of process parameters and aging treatment on the microstructure and mechanical properties of selective laser melting (SLM) fabricated high Mg-content Al-Mg-Sc-Zr aluminum alloy were systematically studied. Our experiment results show that the samples exhibit good processability with porosity less than 1%. The increase of Mg content in Al-Mg-Sc-Zr is beneficial to reduce the texture of the alloy. The laser scanning speed has a large influence on the Vickers hardness of as-fabricated samples. The maximum microhardness of as-fabricated sample reaches 148 ± 2 HV with a compression yield strength of 342 ± 7 MPa. After aging treatment, the distinction in microhardness of the samples obtained under different laser scanning speed is obviously reduced, and the mechanical properties of the samples are further improved with a maximum microhardness of 175 ± 5 HV and a maximum compressive yield strength of 476 ± 10 MPa, which are superior to the known Al-Mg-Sc-Zr alloy with same Sc and Zr content fabricated by SLM. In this study, a novel high Mg-content Al-Mg-Sc-Zr aluminum alloy specifically for SLM with good processability and mechanical properties was reported.

New thermoplastic elastomer triblock copolymer of PLLA for cardiovascular tissue engineering: Annealing as efficient tool to tailor the solid-state properties

A new high molecular weight aliphatic copolyester of PLLA characterized by a ABA triblock architecture was successfully synthesized by ring opening polymerization, using as initiator a low molecular weight hydroxyl terminated random copolymer of PBS, poly(butylene/triethylene succinate). To increase the final polymer molecular weight, thus ensuring both good processability and mechanical properties, chain extension reaction has been performed with hexamethylene diisocyanate (HDI) as chain extender. All the synthetic steps have been carried out in solvent-free conditions. Specifically, the A block consists of LLA sequences, whereas the B one is an aliphatic biodegradable and biocompatible random copolyester of poly(butylene succinate) containing “PEG-like” moiety. The so-obtained material was first characterized by the molecular point of view and then, prior to further characterization, subjected to two different annealing treatments. Annealing revealed to be an efficient tool to control the kind and amount of crystalline phase developed by the material, as confirmed by WAXS structural analysis, and to tailor the mechanical properties, typical of thermoplastic elastomers. Thermal treatment was found to affect also the mechanism of polymer degradation under physiological conditions. Last, but not least, in order to explore the possible use of such new PLLA-based copolymer in vascular tissue engineering, preliminary biocompatibility tests, using endothelial cells, were carried out.

Reactive compatibilization and properties of low-cost and high-performance PBAT/thermoplastic starch blends

Poly(butylene adipate-co-terephthalate) (PBAT) is widely used for production of biodegradable films due to its high elongation, excellent flexibility and good processability properties. However, PBAT is costly with prices approximately double or even triple the prices of traditional plastics like polyethylene. Fully biodegradable PBAT/TPS blends are prepared through melt extrusion of PBAT and thermoplastic starch (TPS) to significantly reduced PBAT cost. Effects of reactive epoxy compatibilizer (REC) and preparation methods on morphology and properties of PBAT/TPS blends were determined using scanning electron microscopy (SEM), mechanical analysis, rheological measurement, gel permeation chromatography (GPC), differential canning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results indicated that REC effectively improves compatibility of PBAT/TPS blends and extends polymer chains of PBAT. Blends obtained through two-step extrusion showed a bicontinuous phase structure without phase separation or starch particles, which were observed in blends prepared through one-step extrusion. Excellent mechanical properties were obtained even with high contents of TPS through two-step extrusion in the presence of REC.

Application of poly(L, L-lactide-co-ε-caprolactone) copolymer medical implants to the treatment of massive rotator cuff tears in orthopedic shoulder surgery

Massive rotator cuff tears (MRCTs) remain a challenge in orthopedic shoulder surgery. The medical implant is a feasible and effective treatment option for MRCTs. However, the complications of implant migration usually occurred in clinical trials. To address this problem, biodegradable implants from poly(L, L-lactide-co-ε-caprolactone) (PLCL) copolymers were applied to treat MRCTs and presented major clinical effects in this study. The medical implants were designed in a dented shape to clad the head of the humerus, which could prevent the migration of implants and effectively improve shoulder function in a human specimen test. The structure was tested through finite element analysis and human specimen experimentation. The appropriate ratio of PLCL constituents was confirmed by examining the degradation of PLCL implants and measuring their mechanical, physical, chemical, and biological features. Samples were characterized using a scanning electron microscope, gel permeation chromatography, mechanical test, and transmission electron microscope. It was found that PLCL5050 (segment ratio PLA:PCL = 50:50) copolymer implants possess good processability and mechanical properties, as well as an appropriate degradation time of 177 days, which could satisfy the treatment requirements of MRCTs.

Thermoplastic Blends Based on Poly(Butylene Succinate-co-Adipate) and Different Collagen Hydrolysates from Tanning Industry: I\u2014Processing and Thermo-mechanical Properties

In this study, blends of a biodegradable thermoplastic polyester, poly (butylene succinate-co-adipate) (PBSA) with two different raw hydrolyzed collagens (HCs), derived from the tannery industry, were investigated in terms of processability, rheological, thermal and mechanical properties. HCs, obtained by alkaline (HCa) and enzymatic (HCe) hydrolysis of the solid wastes generated during the shaving of the tanned leather, were used in PBSA/HC blends, up to 20 wt% of HC, produced by melting extrusion and processed by injection molding. All the blends up to 20 wt% HCs resulted suitable for the injection molding obtaining flexible molded specimens with good tensile properties. The different secondary structure of the two HCs influenced the rheology, morphology and mechanical properties of the produced blends. In particular, HCa, due its higher content of oligopeptides and free amino-acids, showed a good compatibility with the polymeric matrix acting as a plasticizer with consequent reduction of melt viscosity with increasing its loading. The molded dog-bones specimens containing 20 wt% HCa showed a value of elongation at break of 810%. While, HCe, due its higher presence of b-sheet structures, behaved as organic filler, showing a poor interfacial interaction with PBSA with consequent decrease of the tensile properties with increasing its loading. The good processability and satisfactory mechanical properties obtained encourage the use of both investigated collagen hydrolysates in the production of thermoplastic blends and relative molded products for applications in agriculture and plant nurseries, such as pots or small containers with fertilizing properties, due the presence of HCs.

Magnesium hydroxide nanoparticles grafted by DOPO and its flame retardancy in ethylene‐vinyl acetate copolymers

AbstractMagnesium hydroxide (MH) nanoparticles have been considered as an excellent nonhalogen flame‐retardant. However, the drawbacks of easy aggregation and relatively low flame retardancy limit their applications in polymer materials. In this research, MH nanoparticles were successfully grafted by 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) through the bridge of vinyl silane coupling agents (WD70). The grafted MH nanoparticles (MH‐WD70‐DOPO) were characterized by Fourier transform infrared spectra, 31P nuclear magnetic resonance spectra, thermogravimetric analysis, transmission electron microscopy, and X‐ray photoelectron spectroscopy spectra. MH‐WD70‐DOPO nanoparticles were incorporated into ethylene‐vinyl acetate copolymer (EVA) matrix by melt blending method. The results indicated that MH‐WD70‐DOPO nanoparticles were much homogenously dispersed in EVA matrix than unmodified MH particles. EVA/MH‐WD70‐DOPO nanocomposites with 51.32 wt% loading showed higher flame retardancy, better mechanical and processing properties compared with EVA/MH‐WD70 sample. These findings could provide a novel method to enhance the flame‐retardant efficiency of inorganic hydroxide flame retardants, while keeping good mechanical and processing properties of polymer materials.

Transparent films based on functionalized Poly(ionic liquids) coordinating to photoactive Lanthanide(Eu3+,Tb3+) and Poly(methyl methacrylate): Luminescence and chemical sensing

Two kinds of hybrid luminescence films ([C8VIM][Eu (nta)4]@PMMA and [C8VIM][Tb (acac)4]@PMMA) have been synthesized by the copolymerization of MMA with lanthanide functionalized ionic liquid [C8VIM][Eu (nta)4]. The structure and composition of the as-synthesized films have been characterized by 1HNMR, XPS, FTIR, UV–vis, XRD, TGA and SEM. In addition, the photophysical properties of as-synthesized films have been investigated in detail by luminescence spectroscopy. It was found that the transparent and thermal stability of as-synthesized films are improved by the long chains of PMMA. More significantly, [C8VIM][Eu (nta)4] @PMMA exhibits the improvement of photo physical properties (ƞ = 52.6%) and is selected as the representative sample to examine the potential fluorescence sensing of metal ions and anions. It has been showed highly selective and sensitive fluorescence sensing for Cu2+ and CrO42−. Meanwhile, [C8VIM][Eu (nta)4]@PMMA exhibits a good stability in the aqueous solution, which is further used as fluorescence probe for detecting CO32−. The good stability, sensitive fluorescence response and good mechanical processing properties of [C8VIM][Eu (nta)4]@PMMA show a great potential to establish a fast response anion and cationic of aqueous solution fluorescence colorimetric sensor devices.

One-step synthesis of novel renewable multi-functional linseed oil-based acrylate prepolymers and its application in UV-curable coatings

The use of renewable resources and their derivatives provides a "green" approach to synthesizing UV-curable raw materials, and it possesses many advantages, such as environmental protection and energy conservation. Linseed oil has become a research hotspot because of its high content of double bonds and biodegradability. In this study, boron trifluoride diethyl ether was used as a catalyst to successfully introduce acrylic acid into the double bond of linseed oil long chain. Therefore, the UV-curable acrylated linseed oil prepolymers (ALO) were prepared in one step. The characterizations of 1H NMR and FT-IR were employed to verify the successful preparation of ALO. The viscosity of ALO was measured via rheological test, and it was turned out to be 803 mPa·s, indicating the prepolymers had a good processing property. The synthesis mechanism of ALO catalyzed by boron trifluoride diethyl ether was also proposed. Furthermore, different kinds of UV-curable films were prepared by mixing ALO with polyurethane acrylate resin (PUA-2665), trimethylolpropane triacrylate (TMPTA), and photoinitiator (PI-1173). As for the cured films, their thermal stability was investigated by thermogravimetric analysis (TGA), the dynamical mechanical properties were probed via dynamic mechanical analysis (DMA), and the mechanical properties were measured by tensile test. It was found that increasing TMPTA content promoted crosslinking density, leading to the improvement in thermal stability, storage modulus, and tensile strength of the cured films. Besides, they also exhibited excellent hardness, strong adhesion, and outstanding water (solvents) resistance on wood surface. Therefore, this study provides a novel one-step approach for the synthesis of UV-curable materials from vegetable oils, and the as-prepared high-performance films have potential for broad applications.

Using recycled material to produce gas-atomized metal powders for additive manufacturing processes

Additive manufacturing refers to the technologies used to directly produce parts from a three-dimensional model. Recycled AISI 316L and standard AISI 316L materials were used to produce powders via gas atomization process, and two additive manufacturing technologies, i.e., selective laser melting and laser metal deposition, were investigated. This study aims to determine the feasibility of using recycled material to produce powders for additive manufacturing. For each technology, the effect of process parameters on the solidification of the recycled powders was evaluated. Then, tensile tests were conducted on the specimens produced using the optimized process parameters. Specimens from both the technologies exhibited higher ultimate tensile strength values than standard AISI 316L. Recycled powders made from selective laser melting and laser metal deposition exhibited tensile strength values of 653 ± 1.79 MPa and 675 ± 2 MPa, respectively, whereas the standard powders exhibited a tensile strength of 594 ± 0.89 and 585 ± 3.1 MPa, respectively. We conclude that recycled AISI 316L can be used to produce powders for AM applications, resulting in good processability and high mechanical properties.

Copper Filled Poly(Acrylonitrile-co-Butadiene-co-Styrene) Composites for Laser-Assisted Selective Metallization.

Selective metallization of polymeric materials using the technique known as laser direct structuring (LDS) is intensively developed. In this technique, metallized products can be manufactured by injection molding or by 3D printing process if rapid prototyping is need. Special additives present in the polymer matrix enable direct electroless metallization only on the surface which was laser activated. This paper presents the results of using copper microparticles introduced into the poly(acrylonitrile-butadiene-styrene) (ABS) matrix at various amounts (up to about 5 vol %). ABS was selected due to its good processing and mechanical properties and as one of the most common thermoplastics used in 3D printing. The influence of copper on structural, mechanical, and processing properties as well as on the effects of laser surface activation were determined. Two types of infrared lasers were tested for surface activation: Nd:YAG fiber laser (λ = 1064 nm) and CO2 laser (λ = 10.6 µm). Various irradiation parameters (power, scanning speed, and frequency) were applied to find suitable conditions for laser surface activation and electroless metallization. It was found that the composites tested can be effectively metallized using the Nd:YAG laser, but only in a narrow range of radiation parameters. Activation with CO2 laser failed, regardless of applied irradiation conditions. It resulted from the fact that ablation rate and thickness of modified surface layer for CO2 were lower than for Nd:YAG laser using the same irradiation parameters (power, speed, and frequency of laser beams), thus the laser wavelength was crucial for successful surface activation.

Dendritic poly(silylene arylacetylene) resins based on 1,3,5-triethynylbenzene

Dendritic poly(silylene arylacetylene) resins based on 1,3,5-triethynylbenzene were synthesized through Grignard reaction. The influences of the content of 1,3,5-triethynylbenzene on the properties of the resin including processability, mechanical properties, heat resistance and thermal stability are studied. Results show that dendritic poly(silylene arylacetylene) resins possess good processability and high mechanical properties while maintaining excellent heat-resistance and thermal stability. The viscosity of dendritic poly(silylene arylacetylene) resins at 90 °C are below 200 mPa·s, and the flexural modulus of the cured DPSA-43H resin is up to 12.65 GPa. The degradation temperatures at 5% weight loss and the residue yield at 800 °C of the cured resins in nitrogen are all above 700 °C and 93%, respectively.

Effect of cold rolling on microstructure and mechanical properties of a Cu–Zn–Sn–Ni–Co–Si alloy for interconnecting devices

A Cu–Zn–Sn–Ni–Co–Si alloy has been developed to meet the requirements of high thermal stability and good processing properties for interconnecting devices. The effects of cold rolling on the microstructure and mechanical properties are investigated. The tensile properties, thermal stability, and microstructure are characterized, complemented by electron back-scatter diffraction analysis and transmission electron microscopy. The precipitated phase of the orthorhombic (Ni, Co)2Si has been found in the rolled alloy, which is incoherent to the Cu matrix. With the increasing rolling strain, the alloy exhibits higher tensile strength and thermal stability while the electrical conductivity and strain rate sensitivity remain constant. The increasing rolling strain has a combined effect on the matrix and precipitates, leading to higher densities of dislocation and twin as well as more and finer precipitates. After cold rolling to 50% stain, the tensile strength, electrical conductivity and softening temperature of the Cu–Zn–Sn–Ni–Co–Si alloy are 650 MPa, and 33% IACS, and 325 °C, respectively.

Preparation and Characterization of Micro-Graphite Filled Poly(Lactic Acid) Composites: Part 1 - Rheological and Thermal Properties

Conductive polymer composites (CPCs) have attracted great attention of researchers due to their enhanced properties such as an adjustable electrical conductivity, good processability, good mechanical and thermal properties, etc. CPCs had many potencies for wider application in electronic devices. Poly (lactic acid) or PLA is one of the interesting polymers used in the developing of these new important materials. PLA properties are comparable to the synthetic petroleum-based polymers such as polyethylene terephthalate (PET), polypropylene (PP), etc. This research focuses on studying the rheological and thermal properties of PLA/micro-graphite as a conductive polymer composite which adjustable its electrical conductivity. In this study, the PLA/micro-graphite was prepared through solvent blending method using chloroform. The micro-graphite composition was varied from 0%, 5%, and 10 % (w/w) with different stirring time (30 and 60 minutes) and then, poured in glass mould. In the melt rheology study, the frequency sweep test showed that the complex viscosity (|η*|) of the bio-composite increased with the micro-graphite loading. The same tendency was also found in thermal property and stability. The melting temperature and thermal degradation were slightly increasing. The crystallinity of PLA was influenced by the presence of micro-graphite. In this solvent blending method, the homogeneous distribution of micro-graphite in the bio-composite required at least 60 minutes (stirred at 650 rpm and 60 °C).

Thermo-Mechanical Behavior and Hydrolytic Degradation of Linear Low Density Polyethylene/Poly(3-hydroxybutyrate) Blends

In this work, a commercial linear low density polyethylene (LLDPE) utilized for packaging applications was melt compounded with different amounts (from 10 wt% up to 50 wt%) of poly(3-hydroxybutyrate) (P(3HB)), with the aim to evaluate the possibility to partially replace LLDPE with a biodegradable matrix obtained from renewable resources. The processability, microstructural and thermo-mechanical behaviour of the resulting blends was investigated. Melt flow index (MFI) values of the LLDPE matrix were not much affected until a P(3HB) content of 20 wt%, while for higher P(3HB) concentrations an evident decrease of the viscosity was detected. Scanning electron microscope (SEM) observations on the blends highlighted that at limited P(3HB) concentrations the secondary phase was homogeneously dispersed in form of isolated domains, while at a P(3HB) content of 50 wt% a continuous layered morphology could be detected. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) did not evidence any chemical or physical interaction between the two polymer phases. Quasi-static tensile tests and dynamical mechanical analysis showed that the introduction of P(3HB) led to a pronounced stiffening effect, while the progressive drop of the yield and ultimate mechanical properties could be attributed to the weak interfacial adhesion and poor compatibility between the two matrices. The resistance to hydrolytic degradation of the LLDPE/P(3HB) blends was evaluated over a period of 100 days of immersion in water at 50 °C. It was observed that the weight variation and the decrease of the tensile properties due to the hydrolytic process on the biodegradable phase were evident only for a P3HB content of 50 wt%. In conclusion, this work showed that the partial replacement of LLDPE with a biobased P(3HB) could lead to the development of an innovative blend with good processability and mechanical properties, until a P(3HB) amount of 20 wt%.

Optimized synthesis of isocyanate microcapsules for self-healing application in epoxy composites

Microcapsules containing isophorone diisocyanate were fabricated in oil-in-water emulsion. The emulsification effect of different emulsifiers during the capsule synthesis was systematically investigated by optical microscope. Three kinds of shell materials were discussed to obtain the high core content, smooth-surfaced, and robust capsule by scanning electronic microscope and Fourier transform infrared spectroscopy. Self-healing performance of corresponding self-healing epoxy composites was fully evaluated by accelerated corrosion test and mechanical test. The results demonstrated that high core content and smooth-surfaced capsules with dense composite shell could be synthesized in polyvinyl alcohol emulsion, and the core content of the optimized capsules was determined as 71.3–84.6 wt% at the capsule size from 35 µm to 154 µm. In addition, the optimized capsules had good processing properties and the corresponding self-healing epoxy composites exhibited excellent core release and self-healing performance.