In this study, the effect of carbon fiber (CF) surface chemistry and grafting of nano-SiO2 on CF surface with respect to the interfacial adhesion of CF-reinforced nylon 6 composites was investigated. ...CFs were oxidized and reacted with poly(oxypropylene) diamines to modify the surface chemistry. The oxidized CFs were modified with 3-aminopropyltriethoxysilane and then grafted with SiO2 nanoparticles. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microcopy (SEM), and atomic force microscopy (AFM) were used to characterize the chemistry and topographies of the CF surface. The transverse fiber bundle strength of CF oxidized and grafted nano-SiO2 increased to 31.92 MPa and 39.35 MPa, respectively, from 12.57 MPa for untreated CF. The results indicated that the reaction between the carboxyl group and nylon 6 led to chemical bonding at the interface and it meanwhile was strengthened and toughened by uniformly distributed SiO2 nanoparticles on the CF surface.
Highly porous, bendable laterally compressed graphene foam (cGF)/acrylonitrile butadiene styrene (ABS) composites are developed by dip coating of ABS on dense cellular-structured, freestanding cGFs. ...Electrical conductivities of the cGF/ABS composites are enhanced to 6.5 S/cm, higher than that of GF/ABS composites. An electromagnetic interference shielding effectiveness (SE) of 42.4 dB and a specific SE (SSE) of 300.7 dB·cm3/g are delivered, shielding 99.99% incident electromagnetic radiations. Compared with isotropic and fragile graphene foam (GF)/ABS composites, the cGF/ABS composites with 75% compression degree of GFs exhibit a distinctive two-layer structure which endows them with strong and bendable performances to a maximum wrapping angle of 50°. Synergistic effects of the unique two layer morphology, the balance between the thicknesses of two layers, the bending direction, and the compressively strong porous structure contributed to the highly bendable properties of 75%-cGF/ABS composites.
Interface thickness and modulus of carbon fiber (CF) reinforced polyamide 6 (PA 6) composites with different thermal histories are characterized as 331–394nm and 0.24–0.30 times to fiber modulus, ...respectively. Transverse fiber bundle (TFB) test is firstly employed for evaluating semi-crystalline PA 6 interfacial adhesion. TFB Failure mechanisms are schematically given. Besides enhanced molecular entangling on fiber surface, increased matrix toughness is also found to have a great effect on improved TFB results. Droplet micro-debonding results show that decreasing cooling rate and increasing annealing temperature both decrease interfacial shear strength (IFSS) though residual PA 6 on carbon fiber surface increases. In the end, the above data are normalized together with some previous measured parameters. It shows that quenching of the CF/PA 6 composites and subsequent annealing are shown to give similar results as slow cooling. Relationships between each other are also discussed.
Using fiber-reinforced polymer composite to replace metal in window frames has become a trend in aircraft manufacturing to achieve structural weight reduction. This study proposes an innovative ...winding compression molding process for continuous production of aircraft window frames using continuous carbon fiber-reinforced polyamide 6 thermoplastic composite filaments (CF/PA6). Through process parameter optimization, the production cycle of CF/PA6 composite window frames was controlled within 5 min, with an ultra-low porosity of 0.69%, meeting aviation application standards. Combining mechanical property experimental tests and finite element analysis, the mechanical performance of window frames made from three different materials was compared and evaluated. In the hoop direction, the mechanical performance of the continuous CF/PA6 thermoplastic window frames were significantly higher than that of chopped CF/epoxy compression molding window frames and aluminum alloy window frames. In the radial direction, the maximum strain occurred at the corner with the highest curvature of the frame due to the absence of fiber reinforcement, resulting in weak pure interlayer shear. Nevertheless, the thermoplastic CF/PA6 winding compression molded window frame still exhibited a high resistance to crack propagation and damage, as evidenced by the absence of any detectable sound of microdamage during testing with a 9000 N load. It is believed that achieving a further-balanced design of hoop-radial performance by appropriately introducing radial ply reinforcement can lead to a significant weight reduction goal in the window frame. The findings in this study provide an innovative process reference that can be universally applicable to high-speed and near-net-shape manufacturing without material waste of continuous fiber-reinforced thermoplastic composite products.
Polyvinyl chloride (PVC) foam, valued for its mechanical and thermal properties along with cost-effectiveness, is extensively utilized across diverse industries. However, its high volatile organic ...compound (VOC) emissions hinder its adoption in eco-friendly synthetic leather. This study proposes a solution by optimizing the formulation design and foaming processes and achieving mechanical property enhancement via carbon-fiber-reinforced PVC composite foam (CF/PVC). The aim is to reduce PVC usage via enhancing its intrinsic properties. Systematic investigations were carried out on the impact of foaming raw materials, foaming processes, fiber content, and fiber length on the foaming performance, mechanical properties, and VOC emissions. The material formulation and process parameters were successfully optimized. Further assessment of various indicators such as the density, mechanical properties, and tear resistance of synthetic leather samples confirmed that the innovative CF/PVC foam developed in this study meets the requirements for automotive interior applications. Notably, the tensile strength and tear resistance of CF/PVC composite synthetic leather increased by 50% and 29%, respectively, compared to pure PVC, while VOC emissions decreased by 28%. It is anticipated that a more pronounced reduction in VOC emissions will be achieved in practical automotive interior leather applications when further considering the reinforcing effect of fibers, which leads to a reduction in PVC usage. The findings present a technical reference for innovative applications, aiming to enhance PVC foam performance and minimize emissions.
Juvenile amyotrophic lateral sclerosis (JALS) is an uncommon form of amyotrophic lateral sclerosis whose age at onset (AAO) is defined as prior to 25 years. FUS mutations are the most common cause of ...JALS. SPTLC1 was recently identified as a disease-causative gene for JALS, which has rarely been reported in Asian populations. Little is known regarding the difference in clinical features between JALS patients carrying FUS and SPTLC1 mutations. This study aimed to screen mutations in JALS patients and to compare the clinical features between JALS patients with FUS and SPTLC1 mutations.
Sixteen JALS patients were enrolled, including three newly recruited patients between July 2015 and August 2018 from the Second Affiliated Hospital, Zhejiang University School of Medicine. Mutations were screened by whole-exome sequencing. In addition, clinical features such as AAO, onset site and disease duration were extracted and compared between JALS patients carrying FUS and SPTLC1 mutations through a literature review.
A novel and de novo SPTLC1 mutation (c.58G>A, p.A20T) was identified in a sporadic patient. Among 16 JALS patients, 7/16 carried FUS mutations and 5/16 carried respective SPTLC1 , SETX , NEFH , DCTN1 , and TARDBP mutations. Compared with FUS mutation patients, those with SPTLC1 mutations had an earlier AAO (7.9 ± 4.6 years vs. 18.1 ± 3.9 years, P < 0.01), much longer disease duration (512.0 416.7-607.3 months vs. 33.4 21.6-45.1 months, P < 0.01), and no onset of bulbar.
Our findings expand the genetic and phenotypic spectrum of JALS and help to better understand the genotype-phenotype correlation of JALS.
The inherent π-π interfacial interaction between carbon nanotubes (CNTs) and polystyrene (PS) makes the CNT/PS composite a representative thermoplastic nanocomposite. However, the strong van der ...Waals force among CNTs poses challenges to achieving effective dispersion. This review provides an overview of various CNT functionalization methods for CNT/PS composites, encompassing covalent grafting with PS-related polymers and non-covalent modification. A focus in this section involves the pre-introduction surface modification of CNTs with PS or PS-related polymers, substantially enhancing both CNT dispersibility and interfacial compatibility within the PS matrix. Furthermore, a comprehensive summary of the mechanical, electrical, thermal, and electromagnetic shielding properties of CNT/PS nanocomposites is provided, offering an overall understanding of this material. The surface modification methods of CNTs reviewed in this paper can be extended to carbon material/aromatic polymer composites, assisting researchers in customizing the optimal surface modification methods for CNTs, maximizing their dispersibility, and fully unleashing the various properties of CNTs/polymer composites. Additionally, high-performance CNTs/PS composites prepared using appropriate CNT modification methods have potential applications in areas such as electronic devices, sensors, and energy storage and conversion.
This study addresses the challenge of achieving foam with a high expansion ratio and poor mechanical properties, caused by the low melt viscosity of semi-crystalline polypropylene (PP). We ...systematically employ a modification approach involving blending PP with polyolefin elastomers (POE), irradiation crosslinking, and fiber reinforcement to prepare fiber-reinforced crosslinked PP/POE composite foam. Through optimization and characterization of material composition and processing conditions, the obtained fiber-reinforced crosslinked PP/POE composite foam exhibits both low density and high performance. Specifically, at a crosslinking degree of 12%, the expansion ratio reaches 16 times its original value, and a foam density of 0.057 g/cm
is reduced by 36% compared to the non-crosslinked PP/POE system with a density of 0.089 g/cm
. The density of the short-carbon-fiber-reinforced crosslinked sCF/PP/POE composite foam is comparable to that of the crosslinked PP/POE system, but the tensile strength reaches 0.69 MPa, representing a 200% increase over the crosslinked PP/POE system and a 41% increase over the non-crosslinked PP/POE system. Simultaneously, it exhibits excellent impact strength, tear resistance, and low heat shrinkage. Irradiation crosslinking is beneficial for enhancing the melt strength and resistance to high temperature thermal shrinkage of PP/POE foam, while fiber reinforcement contributes significantly to improving mechanical properties. These achieve a good complementary effect in low-density and high-performance PP foam modification.
Perinatal asphyxia induces neuronal cell death and brain injury, and is often associated with irreversible neurological deficits in children. There is an urgent need to elucidate the neuronal death ...mechanisms occurring after neonatal hypoxia-ischemia (HI). We here investigated the selective neuronal deletion of the Atg7 (autophagy related 7) gene on neuronal cell death and brain injury in a mouse model of severe neonatal hypoxia-ischemia. Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death. Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells. These findings reveal that selective neuronal deletion of Atg7 is strongly protective against neuronal death and overall brain injury occurring after HI and suggest that inhibition of HI-enhanced autophagy should be considered as a potential therapeutic target for the treatment of human newborns developing severe hypoxic-ischemic encephalopathy.
Epoxy resin-based composites have an important and extensive application value in both military and civilian, but their poor fire safety hinders their further development. Therefore, it is very ...important to improve the flame retardant properties of epoxy resin matrix composites, and a large number of literature reports have appeared in recent years. Biogenic epoxy resin flame retardants have emerged as the times require due to the problems of large amount of addition, difficult dispersion and low interfacial strength of epoxy resin flame retardants, as well as the continuous improvement of people's awareness of green chemistry and sustainable development. In this review, scholars will realize the necessity of flame retardant epoxy resin, understand the burning process, type of flame retardants and flame retardant mechanism of epoxy resin. Mastering the preparation method of epoxy resin flame retardants related to the two most popular biogenic materials, phytic acid (PA) and chitosan (CS), and the influence on the performance of epoxy resin matrix and the flame retardant mechanism. Discovering the advantages, challenges and prospects of biogenic materials PA and CS in the research of flame retardant properties of epoxy resins.
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