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Dynamic cross-linked networks (DCNs) endow thermoset rubber with self-healability and recyclability to extend its lifetime and alleviate environmental pollution. However, the contradiction between high self-healing and mechanical properties in DCNs rubber is always difficult to be resolved. Herein, we used boronic ester (BO) and Diels-Alder dynamic covalent bonds (DA) to synthesize polybutadiene-based dual networks rubber (PB-BO-DA) via thiol-ene reaction. This approach achieved a tensile strength of 16.46 MPa and 99% self-healing efficiency, facilitated by extensive intermolecular interactions (π-π packing and N-B coordination) and fully dynamic cross-linking. In addition, multiple dynamic cross-linked networks (MDCNs) polybutadiene-based rubber also show excellent shape memory ability and recyclability. This strategy might open a helpful pathway to fabricate intelligent multifunctional polymers with high strength and high self-healing efficiency.

In order to improve the impact toughness of polyamide 1012 (PA1012) by reducing the amount of hydrogen bonding resulting from PA1012 itself, 3-pentadecylphenol (PDP) was considered to be added into PA1012 using melting extrusion. The hydrogen bonding interaction between PA1012 and PDP was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The effects of PDP on the crystallization, melting process, and mechanical behavior of PA1012 were tested in detail. The results show that the PDP can reduce the temperature of PA1012 crystallization and melting but it can significantly improve elongation at break and impact toughness. The notched impact strength of the PA1012/PDP composites containing 20 wt% PDP reached to 70.6 kJ·m–2, which is about seven times that of the neat PA1012. The effects of PDP on PA1012 properties is ascribed to hydrogen bonding interaction between hydrogen bonding between phenol hydroxyl groups and amino groups on PA1012 chains. The deduction was also verified by adding acetylated 3-pentadecylphenol (APDP) to modify PA1012. It is believed the research will open up new prospects for the wide application of PA1012 toughening.

In order to improve the inherent flammability of polylactic acid (PLA) and make this new biodegradable material more widely used, B-modified ZSM-5 (B/Z5) was designed as synergistic agent of intumescent flame retardant (IFR), composed of ammonium polyphosphate (APP) and pentaerythritol (PER), and introduced into PLA/IFR (PLAs) to fabricate PLAs/B/Z5 composites by melt extrusion. The flame retardancy, surface morphology, and thermal stability of the composites were investigated by TG, LOI, UL-94, CCT, and SEM. The addition of B/Z5 makes the decomposition temperature of T5% as well as T10% of PLAs reduction in nitrogen atmosphere and carbon layer form in advance. UL-94 test shows the composites reach V-0 rating. LOI value also steadily increases, and the maximum value is 36.0% with B actual loading of 5.26% (recoded as 14B/Z5) in B/Z5. The PHRR decreases by 75% from 417.77 kW/m2 for pure PLA to 103.19 kW/m2 for PLAs/14B/Z5, and THR reduces from 92.78 to 19.26 MJ/m2, which decreases by about 80% and the char yield reaches 50%. This study provides a simple and green method for the preparation of high flame-retardant PLA, which has a broad practical application prospect.

In the current work, the polypropylene composites filled with a M-T-ZnOw@Ag filler with antibacterial and antistatic properties was firstly synthesized. The composites and the fabricated nanocomposites were characterized using SEM, TEM, XRD, FTIR and XPS techniques. With the addition of M-T-ZnOw@Ag, the antibacterial and antistatic properties of composite materials are greatly improved by the synergistic effect of AgNPs and T-ZnOw. When the filler content is 10 wt%, the antibacterial activity of the composite material against Gram negative (Escherichia coli) and Gram positive (Staphylococcus aureus) bacterial were 100%. And the surface resistivity was reduced to 5.5 × 1010 Ω, fell by nearly 7 orders of magnitude compare with the neat PP. Furthermore, the composites showed better mechanical properties. The maximum impact strength of the composites is 56.3% higher than the neat PP. We believe the composite material with antibacterial and antistatic properties could greatly expand the application range of polypropylene materials.

Different crystal planes of nanocrystalline often displayed diverse physical and chemical properties. In this paper, the effects of nano-ZnO with two kinds of crystal planes on crystallization, thermal stability and mechanical properties of PLLA were investigated. The results show that the (1010) planes with no-polar and low surface energy increased the chain mobility of PLLA chain, showed a plasticizing effect; the glass transition temperature, melt and cold crystallization temperature decreased by 12 °C, 10 °C and 12 °C, respectively. The size of spherulites increased and the number of spherulites decreased, the crystal form changed from mixed crystal form α, α′ to unique α crystal form. However, the (0002) planes with polar and high surface energy has highly nucleating effective for PLLA, the crystallization temperature increased to 106.41 °C, the cold crystallization peak disappear. The size of spherulites decreased and the number of spherulites increased. Moreover, the (0002) planes increases the elongation at break of PLLA to 20.34% but the (1010) planes reduces to 7.49%. Their thermo-gravimetric analysis results showed the similar trend. Our results indicate that the interface wettability and compatibility between crystal planes and PLLA, which was caused by the polarity and surface energy of (1010) or (0002) planes played key role in improving the performance of polymers.

In this study, we synthesized a type of microcrystalline H-ZnOc with columnar structure by controlling the solubility of the reaction solution. Poly(ethylene 2,6-naphthalate) (PEN) and hexagonal zinc oxide column (H-ZnOc) composite materials were prepared by a twin screw extruder and the properties of the composites were characterized. The results showed that H-ZnOc has a remarkable nucleation effect on PEN, especially when the loading amount of H-ZnOc is 1.5 wt%; the nucleation efficiency is as high as 52.28%, and the crystallization temperature increased by nearly 23 °C. The crystal morphology changed, with the disappearance of the cold crystallization peak after the addition of H-ZnOc, the size of spherulites decreased and the number of spherulites increased. During the isothermal crystallization process, H-ZnOc significantly reduced the crystallization time of PEN. The impact strength of PEN increased from 1.86 kJ m-2 to 2.73 kJ m-2. Our results showed that H-ZnOc can be used as an effective nucleating agent for PEN, effectively improving the crystallization ability and mechanical properties, and its performance is comparable to the proprietary polymer nucleating agents NX8000, HPN68L, and TMB-5, etc. [ABSTRACT FROM AUTHOR]

The blends of poly (butylene terephthalate) (PBT) and 4,4'-dihydroxyphenyl (DHP) were prepared by melt blending, and the effects of DHP on the crystallization and melting behaviors of PBT were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized optical microscopy (POM). The results showed that crystallization temperature and crystallinity of PBT apparently decreased with the addition of DHP. A remarkably decline in crystallization rate of PBT was achieved, and the blends had higher σe and q values than that of pure PBT as analyzed based on the Avrami equation and Lauritzen-Hoffman equation. The crystal structure of PBT did not change by the addition of DHP, while the spherulite size of PBT decreased. [ABSTRACT FROM AUTHOR]

Amorphous poly(vinyl phenol) (PVPh) is introduced into poly(butylene succinate-cobutylene adipate)/poly(L-lactic acid) (PBSA/PLLA) blends via solution casting. Fourier transform infrared spectroscopy (FTIR) analysis verifies that intermolecular hydrogen bonding formed in PBSA/PVPh/PLLA blends. The miscibility between PBSA and PLLA is improved with PVPh incorporation as evidenced by approaching Tgs of the two components. When PVPh content reaches up to 50 wt %, the blend sample exhibits only one Tg, meaning complete miscibility between PBSA and PLLA. The improved miscibility of PBSA/PLLA blends is further confirmed by scanning electron microscope (SEM). Typical "see-island" phase separation structure for PBSA/PLLA blend transforms into homogenous phase structure for blend samples with 5 wt % PVPh and above. Non-isothermal crystallization analysis shows that the crystallization temperature and crystallization enthalpy of PBSA decrease with PVPh addition, and those of PLLA also show a decreasing trend. Isothermal crystallization rate of PBSA in blend samples distinctly decreases with PVPh incorporation, whereas that of PLLA in blend samples increases slightly with PVPh addition. Wide angle X-ray diffraction (WAXD) analysis indicated that PLLA in blend samples remained partly crystallized, while PBSA turned into amorphous state with increasing PVPh contents. [ABSTRACT FROM AUTHOR]

Maleated poly(propylene carbonate)/calcium stearate (MAPPC/CaSt2) composite was prepared through melt‐extruding poly(propylene carbonate) (PPC) with maleic anhydride and CaSt2. The processability, thermal stability, interaction between two components as well as the morphology of the composites were systematically characterized. The flow instability of biodegradable PPC was greatly alleviated due to the incorporation of stearate additive in polymer matrix. It was found that the MAPPC and MAPPC/CaSt2composites were more thermostable than pristine PPC under melt‐processing conditions. The melt fluidity of the composites was noticeably superior to that of MAPPC, arising from the lubricating effect of CaSt2on the polymer/barrel wall interface as well as from the improvement of resistance to thermal degradation of the composite. The coordination interaction between MAPPC and calcium ion also contributes to the enhanced thermal stability and high melt stability of composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]