Abstracts:Raw kaolinite (kaol) was experimentally transformed to P-type hydrated silica aluminate (HSA-P). After treated by LaCl3·7H2O solution, the final product of La-loaded for P-type hydrated silica aluminate (HSA-P-La) was obtained. The middle and final products were characterized using fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM). Kaol, HSA-P, HSA-P-La was introduced into PP with intumescent flame retardants (IFR), respectively. And their effect on the flame retardant and thermal properties of PP composites was studied by limiting oxygen index (LOI), vertical burning test, cone calorimeter test (CCT) and thermogravimetric analysis (TGA). The LOI increases from 18.0% of neat PP to 31.2 in composite of 75 wt% PP/25 wt % IFR, further increases to 32.5, 35.1, 37.5 in 75 wt% PP/23.5 wt % IFR/1.5 wt% Kaol, HSA-P or HSA-P-La, respectively. CCT results show heat release content and rate is best controlled in PP/IFR/HSA-P-La composite. Morphology observation indicates the char layer of PP/IFR/HSA-P-La composite is most compact and thick, which guarantees excellent fire resistance. At same time the effect of HSA-P/HSA-P-La was also compared with generally used A-type hydrated silica aluminate (HSA-A)/HSA-A-La. Anyway HSA-P/HSA-P-La exhibited higher efficiency than HSA-A/HSA-A-La in both flame retardancy and thermostability.

Abstracts:New generation agricultural films combine multilayer technologies, with the latest developments in chemicals resistant UV stabilisers and possibly the incorporation of barrier layers against agrochemicals. The photo-degradation behaviour of a series of experimental multilayer (ML) films exposed to accelerated ageing in combination with agrochemicals, was analysed. It has been shown that the presence of a barrier layer (EVOH or PA) adversely affects the mechanical behaviour of ML films, because of the low ductility of these barrier layers, whose failure is propagating to the other layers leading to premature failure of ML film structures. ML films with barrier layer have shorter lifespan due to the rapid photo-degradation of the barrier layer. It was confirmed that these layers absorb the main part of the agrochemicals load, acting as effective barriers. Agrochemicals were shown to accelerate the detrimental effect of the UVA radiation on PA and EVOH layers causing premature failure of the barrier layers, compromising evenmore the mechanical strength and durability of the entire film. The presence of barrier layers such as PA (mainly) and EVOH in agricultural ML films is not recommended, as both their mechanical properties and photodegradation behaviour are adversely affected by the presence of low ductility barrier layers, deteriorated by the combination of UVA radiation and agrochemicals.

Abstracts:Blends/composites of poly(lactic acid) (PLA) with poly(butylene succinate-co-lactate) (PBSL) and hydroxyapatite (HAp) were successfully prepared by a conventional melt-mixing process. The thermal properties, phase morphology, crystal structure, and in vitro hydro-degradability of the prepared samples were characterized and compared. Thermogravimetric analysis confirmed that adding HAp increased the thermal stability of PLA/PBSL blends in both air and nitrogen environments. The activation energy for PLA thermal degradation increased with increasing HAp content in the samples. Scanning electron microscopy results showed that HAp was uniformly distributed within the composites. HAp also played a compatibilizer role for the PLA/PBSL blends, leading to evidently reduced size of dispersed PBSL domains. The Avrami crystallization analysis revealed that the n values of PLA in different samples ranged within 2.1–3.9, and the presence of HAp caused athermal nucleation process of PLA crystallization. The activation energy for non-isothermal crystallization of PLA decreased from 136 kJ/mol in neat state to 86 kJ/mol in PLA(70)/PBSL(30)/HAp(20 phr) composite. Melting behavior study revealed that the presence of HAp increased the original crystals stability of PLA in the composites. X-ray diffraction results confirmed that the crystal structures of PLA and PBSL remained in the blends and composites. Finally, in vitro hydrolytic degradation tests showed that the HAp addition facilitated the degradation of the prepared samples.

Abstracts:Tubular one-dimensional poly (cyclotriphosphazene-melamine) (PHMA) sub-microtubes were conveniently synthesized from co-polymerization of hexachloro -cyclotriphosphazene and melamine. The SEM and TEM results showed PHMA sub-microtubes were opened at one end with diameters of 100–300 nm and lengths of 1–10 μm. The inner diameters of closed and open end were 10–30 nm and 50–100 nm, respectively. The PHMA sub-microtubes were melt blended with PET (PET/PHMA) to be used as an effective flame retardant. The flame-retardant and anti-dripping properties of PET/PHMA composites were evaluated by TGA, LOI, vertical burning, MCC and rheological test. The results confirmed the efficiency of PHMA in enhancing the self-extinguishing ability and inhibiting melt-dripping of PET. The morphological characteristics and graphitic structure of the charred residues were evaluated by SEM, Raman spectroscopy. Results demonstrated the formation of a compact protective carbon layer and a carbonaceous micro-structures, which acted as insulator against oxygen and heat.

Abstracts:Polyetherimide (PEI)/Polycarbonate (PC) blends were prepared and their thermal behaviour was evaluated in the perspective of an improved processability, thus favouring the use as feeding material for a Fusion Deposition Modelling (FDM) 3D printing machine. PEI/PC blends obtained with a batch mixer were characterized by the means of Thermogravimetric (TG) and Differential Thermogravimetric (DTG) analysis and Differential Scanning Calorimetry (DSC). The parameters associated with the physical properties of the various blends were evaluated and compared with those obtained for the pristine polymers. Both thermal and spectroscopic analyses showed the formation of an immiscible blend, with some possible regions of partial miscibility, furthermore the glass transition temperature (T g) values demonstrated that the presence of PC in the blend allowed an important lowering of the viscosity, thus meaning an improved processability. Finally, the TGA and DSC results were compared with those obtained for Ultem 9085 that is the standard PEI grade for FDM printing in advanced applications developed by Stratasys, Ltd.

Abstracts:Easily oxidized group of traditional phenolic resin (PF) results in poor oxidation resistance at high temperature, which is unable to satisfy the requirements of advanced aerospace vehicles for high-performance application, especially ablation resistance. In order to improve the oxidation resistance of PF, a SiO2/RGO binary hybrid nanomaterial assisted anti-oxidation for PF was designed. Here, we reported a simple sol-gel process and high temperature reduction for synthesis of dispersed SiO2 nanoparticles on graphene (G-S). The designed structure of G-S was confirmed by FTIR, XRD, SEM and TEM. Introduction of G-S into PF (P-G-S) was beneficial to enhancement of oxidation resistance in whole temperature range (0–1000 °C). P-G-S-3 (3 wt.% of G-S) exhibits both lower thermal oxidative decomposition rate and higher termination temperature of thermal oxidative decomposition (increase from about 750 °C up to 900 °C) than those of neat PF in air. In addition, P-G-S-3 decomposed by thermal oxidation in air (at 557 °C, weight loss> 30 wt.%) later than neat PF (at 519 °C, weight loss> 20 wt.%). What's more, compared to the collapse of skeleton structure and few residual fragments of neat PF, P-G-S-3 showed greater oxidation resistance which resulted in the retention of a large number of aromatic C-C, methylene and different kinds of ether bond at temperature from 550 °C to 700 °C by FTIR and XPS. The section of P-G-S-3 expresses skin lamination that can act as a barrier to slow down the diffusion of oxygen into resin matrix. And SiO2 on the surface protected the matrix continually as indicated from the SEM analysis.

Abstracts:The influence of mesoporous SBA-15 on the thermal stability of nanocomposites with isotactic polypropylene has been evaluated in detail, both under inert and air conditions, by performing dynamic weight loss measurements and by tracking the evolution of degradation species in materials prepared by melt extrusion. A superior thermal stability has been found in the composites, both under nitrogen and air, compared with that observed in the pristine PP. An almost identical effect has been found under those two atmospheres, in spite that the mechanisms involved in both of them are completely different. The rheological characteristics of these materials turn out the driving aspect in the observed thermal behaviour, prevailing on other specific detrimental parameters.

Abstracts:We are proposing in this work a new model of ultraviolet (UV) damage for polymers and Polymer Matrix Composites (PMCs). Flat and sinusoidal polymer surfaces were numerically simulated for their UV damage as a function of UV intensity, surface topography, and exposure time. Experimentally determined UV degradation rates for a unidirectional glass/epoxy composite were used to predict numerically the local rates of material degradation on sinusoidal epoxy surfaces subjected to UV. This allowed us to show that UV damage on uneven polymer surfaces reduces their surface roughness making them planar and that the degradation rates are the largest at the tips of the local heights of the surfaces. This was subsequently verified experimentally by exposing neat epoxy specimens to UV in air at 80 °C for 1000 h and by precisely monitoring their surface topography as a function of time. It was found that the surface roughness of the epoxy was reduced by about 12.5% and that UV affected the local peaks on the surfaces of the specimens more than the valleys.

Abstracts:This work explores the process of water ageing of high-temperature high-pressure polymerized urethane dimethacrylate (UDMA) networks. UDMA samples polymerized under several pressures (0.1–300 MPa) and differing by the conversion degree of polymerization were aged in water at 37, 50 and 70 °C and followed by gravimetry. Diffusion was observed to obey Fick's law. The diffusion coefficient and water maximal uptake were observed to be almost independent of polymerization pressure, consistently with analysis of Dynamic Vapor Sorption data suggesting that external polymerization pressure has no effect on polymer affinity with water. This was ascribed to the fact that all materials have the same cohesive energy, as confirmed by ultrasonic measurements of elastic moduli. Polymerization pressure (used to improve conversion degree and mechanical properties) would thus have a minor influence on water ageing that is mainly triggered by polymer chemistry. When elevating the polymerization pressure, there is hence no compromise between the optimization of thermo-mechanical properties and the resistance to water ageing.

Abstracts:Aspergillus fumigatus strain 76T-3 formed clear zones on agar plates containing emulsified polyhydroxybutyrate (PHB), polyethylene succinate (PES), polybutylene succinate (PBS), polycaprolactone (PCL), or polylactide (PLA). The strain grew well at 40 °C in Sabouraud Dextrose Broth. Solution-casted PHB films were almost completely degraded after incubation with 76T-3 at 45 °C for 17 h. An extracellular polyester-degrading enzyme was purified from the supernatant of 76T-3 cultures in basal medium containing PHB as the sole carbon source. Zymography results portrayed that the purified enzyme degraded PHB, PES, and PBS but not PCL or PLA. The amino acid sequence obtained from LC-MS/MS identified this enzyme to be a PHB depolymerase with a molecular mass of 57 kDa. The optimal reaction condition for the enzyme was pH 6.4 at 55 °C. The recombinant PHB depolymerase (rPhaZ) expressed in E. coli showed the enzyme can act on PHB only and not on PES or PBS.