Effect of Polyborosiloxane on the Flame Retardancy and Thermal Degradation of Intumescent Flame Retardant Polypropylene

A novel synergistic flame retardant agent containing boron and silicon, namely polyborosiloxane (PBSil), was prepared via the condensation reaction of boric acid (BA), tetraethoxysilane (TEOS), and octamethyl cyclotetrasiloxane (OMCTS). The obtained PBSil was then combined with an intumescent flame retardant (IFR) to flame retard polypropylene (PP), and the effects of PBSil on the flame retardancy and thermal degradation of the PP/IFR composite were investigated. It was found that PBSil could improve the compatibility between the IFR and the PP matrix, thereby improving the mechanical properties of the composite. Compared with zinc borate, zeolite, and nano-silica, PBSil showed much better flame retardancy and smoke suppression in the PP/IFR composite. When the content of PBSil was 3.0 wt%, the limiting oxygen index (LOI) value of the flame retardant PP was increased from 29.0% to 35.0%, and the UL-94 rating was improved from V-1 to V-0 rating. Simultaneously, the heat release rate (HRR) and smoke production rate (SPR) of the composite were decreased dramatically. The thermogravimetric (TG) analysis, Fourier transform infrared (FTIR), and thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) results showed that, PBSil could enhance the thermostability of the IFR, and promote the char formation. Furthermore, the compactness and thermostability of the intumescent char were significantly improved, contributing to the improvement of the flame retardancy of the composite.     

Synergistic Effect of Organic Vermiculite on the Flame Retardancy and Thermal Stability of Intumescent Polypropylene Composites

Organic vermiculite (OVMT) prepared from vermiculite (VMT), with high aspect ratio and orderly arranged platelets intercalated by octadecyl trimethyl ammonum bromide (OTAB), was used as a synergistic agent on the flame retardancy of a polypropylene/intumescent flame retardant (PP/IFR) system. The flammability and thermal stability of PP/IFR/OVMT composites were investigated by limiting oxygen index (LOI), UL-94 testing, cone calorimetry tests, and thermogravometric analysis. The results of LOI and UL-94 testing showed that low loading of OVMT improved the flame retardancy and retarded dripping for PP/IFR composites. OVMT, with 1% loading, increased the char residue of PP/IFR composites and could act as an effective additive for improvement in flame retardancy, which was confirmed by the cone data. The char layer morphological structures observed by scanning electron microscopy (SEM) showed that OVMT with 1% loading can promote formation of a continuous and compact intumescent char layer. Raman spectroscopy results indicated that the OVMT or its pyrolytic products led to a decrease in size of the carbonaceous micro-domain during combustion, resulting in formation of more compact charred layers. Thus, OVMT with 1% loading showed a synergistic effect with IFR in the combustion of the PP/IFR composites.     

Effect of Modified Intumescent Flame Retardant via Surfactant/Polyacrylate Latex on Properties of Intumescent Flame Retardant ABS Composites

In order to prepare intumescent flame retardant acrylonitrile-butadiene-styrene (ABS) composites with only a small decrease in their mechanical properties, we investigated the effect of adding an elastomeric polyacrylate latex and the surfactant TX-10 phosphate to modify the ammonium polyphosphate, melamine, and calcium 3-hydroxy-2, 2-bis(hydroxymethyl) propyl phosphate normally used, which resulted in an intumescent flame retardant composite (IFRC) powder with the aim of improving compatibility. These ABS/IFRC composites were compared with standard material containing unmodified intumescent flame retardant (NIFR) by investigating their thermal properties, melt characteristics, mechanical properties, and microstructure. The data showed that the glass transition temperature of the ABS/IFRC composites decreased slightly in all cases, the complex viscosity of the ABS/IFRC composites was remarkably reduced, and the mechanical properties improved in comparison with the material containing NIFR. A slight increase in impact strength retention, as well as a remarkable increase in tensile and flexural strength retention of ABS/IFRC, was achieved due to superior compatibility between ABS and IFRC in comparison with ABS/NIFR.     

Synthesis of a Novel Flame Retardant and Its Synergistic Effect With a Phosphapheanthrene Flame Retardant in Polypropylene/Polyethylene Vinyl Acetate Blends

A novel flame retardant (NSiB) containing nitrogen, silicon and boron was synthesized through reacting of N-(β-aminoethyl)-γ-aminopropyl trimethoxy-silane (KH-792) and boric acid. The structure of NSiB was characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS). The effects of NSiB on the flame retardancy and thermal behaviors of polypropylene (PP)/polyethylene vinyl acetate (EVA) blends were investigated by limiting oxygen index value (LOI), vertical burning tests (UL-94) and thermal gravimetric analysis tests (TGA). The results showed that the flame retardancy and thermal stability of PP/EVA blends were improved with the addition of NSiB. When 7.5 wt% DOPO (phosphaphenanthrene) and 0.5 wt% NSiB were incorporated, the LOI value of the PP/EVA blends was 26.9%, and the class V-0 of UL-94 test was passed, as compared to the LOI value of 22.4% and class V-2 of UL-94 test for 8.0 wt% DOPO only and 16.7% and fail, respectively, for the PP/EVA blends alone. The char structure observed by SEM indicated that the surface of the char for the PP/EVA/7.5 wt% DOPO/0.5 wt% NSiB blends had a denser and continuous char structure when compared with that of the PP/EVA blends and PP/EVA/8.0 wt% DOPO blends. These results indicated that there was a good synergistic effect for NSiB and DOPO.     

Mechanical and Flame Retardant Properties and Microstructure of Expandable Graphite/Silicone Rubber Composites

Flame-retardant expandable graphite (EG)/silicone rubber (SR) composites were prepared using nano-CaCO₃ particles as reinforcement filler. In addition to mechanical measurements, limited oxygen index (LOI), UL-94 and cone calorimeter tests (CCT), the thermal properties were tested by thermogravimetric analysis (TGA). The results showed that the content and particle size of the EG both had large effects on the flammability and mechanical properties of the EG/SR blends. The composites that contained 25 phr EG (50–80 mu) had excellent LOI values, 47–48, and achieved the UL-94 V-0 level while the pure SR sample had the LOI value of 25 and achieved the UL-94 V-2 level. The data obtained from the CCT indicated that the addition of EG decreased remarkably the heat release rate, smoke emission, and mass loss rate of the composites. SEM microphotographs of the EG/SR composites before and after combustion demonstrated that EG underwent a large volume expansion, and the multiporous char structure blocked heat transfer and protected the substrate from fire.     

Effect of Ultrafine Full-Vulcanized Powdered Rubber on the Properties of the Intumescent Fire Retardant Polypropylene

Ultrafine full-vulcanized powdered rubber (UFPR) was added into intumescent fire retardant polypropylene (IFR-PP) composites, and fire retardance, morphology, and properties of the composite were analyzed. Ammonium polyphosphate and pentaerythritol were used as the intumescent fire retardants (IFR). The mechanical properties (elongation at break increased from 70% to 110%) and the melt flowability of IFR-PP improved by adding a small quantity of UFPR (less than 0.5 phr) but decreased when the UFPR was more than 0.5 phr. At the same time, the fire retardance, as measured by the limiting oxygen index and the UL94 vertical test rating, and other mechanical properties decreased appreciably with adding UFPR. The reasons were analyzed by using SEM micrographs, and a model was proposed to explain the reasons.     

Synergistic Effect Between Organically Modified Montmorillonite and Ammonium Polyphosphate on Thermal and Flame-Retardant Properties of Poly(Butyl Acrylate/Vinyl Acetate) Copolymer Latex

Hexadecyl trimethyl ammonium bromide modified montmorillonite (1631-MMT) was successfully synthesized via an ion exchange reaction and characterized through Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Various poly(butyl acrylate/vinyl acetate) P(BA-VAc) copolymer P(BA-VAc)/1631-MMT emulsions were prepared via in-situ polymerization method using potassium persulphate (K₂S₂O₈, KPS) as an initiator. Ammonium polyphosphate (APP) was introduced for obtaining P(BA-VAc)/APP/1631-MMT flame-retardant latex. The flame retardancy and thermal behavior of the latex films were investigated through limiting oxygen index (LOI) and vertical burning test (UL-94) and thermo-gravimetric analysis (TGA/DTA [differential thermal analysis]) analysis. Compared with the P(BA-VAc)/APP composite, the LOI value of P(BA-VAc)/APP/1631-MMT sample was increased from 27.7 to 30.3 with a concentration of 1631-MMT 0.5 wt% in composition, and its UL-94 was raised to V-0 from no rating. TG date showed that the amount of residues increased significantly when 1631-MMT was added. The morphology and microstructure of the residues generated during LOI testing were investigated by scanning electron microscopy (SEM). The outer surface of the P(BA-VAc)/APP/1631-MMT charred layer was more continuous and compact than that of P(BA-VAc)/APP.     

Preparation and Combustion Behavior of Polyamide 6/Polypropylene/Clay Nanocomposites

Polyamide 6(PA 6)/Polypropylene (PP) blends as well as PA 6/PP/clay composites were prepared by melt compounding. The distribution of clay was characterized by transmission electron microscopy. The combustion surface morphology as well as product composition after burning were studied by scanning electron microscopy along with electro-probe microanalysis. Moreover, the flame retardance and thermal stability were evaluated by a cone calorimeter together with thermogravimetric analysis. The results showed that the clay was selectively located in the PA6 phase. It is proposed that, in the presence of clay, the combustion surface changed from a branch-shaped structure to a compact carbonaceous–silicate structure. When the clay content was 3 phr, the layered silicates became enriched on part of the surface and formed an island-like structure; the islands displayed a loose cinders structure with much higher silicon content, in contrast to a branch-shaped surface with low silicon content of the surrounding polymer substrate. As the clay content continued to increase, the char covered most of the combustion surface and more clay accumulated on the burning surface. In addition, the clay particles promoted the formation of the carbonaceous–silicate structure. The peak of the heat release rate of the PA6/PP blend decreased with increasing addition of clay and the thermal stability of the PA6/PP blend also improved.     

The role of mosaic block structure on onset of deformation and fatigue of bulk crystallized polyethylene

The influence of the mosaic block structure of bulk-crystallized high-density polyethylene upon deformation within the elastic limit and upon fatigue phenomenon has been extensively studied in the temperature range of the α relaxation mechanism. The magnitude of elastic limit, estimated from two models involving a tilt sliding mechanism and a simple tension mechanism, was compared with experimental results obtained using a tensile tester and a dynamic viscoelastometer at various temperatures of measurement. The two models for onset of deformation are applied on the assumption that the intermosaic block region is selectively affected by strain without any structural change occurring in the mosaic block crystalline core. Also, dynamic mechanical properties were obtained on specimens subject to an increasing number of fatigue cycles. The variation of E'1, max, attributed to deformation processes of the intermosaic block region, is strongly affected by slight elongation and by fatigue cycling of the sample. A direct observation of the mosaic block structure is made with the electron microscope using a detachment replica of the surface of the bulk crystallized material, that has been elongated by 15% at 55°C in biaxial directions.     

Preparation and Flammability of a Flame-Retardant Poly(Butyl Acrylate-Vinyl Acetate) System Based on Gemin-Surfactant Modified Montmorillonite and Ammonium Polyphosphate

Gemin-surfactant modified montmorillonite (G-MMT) was successfully prepared by an ion exchange reaction and characterized via Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The P(BA-VAc)/G-MMT emulsion was prepared via an in-situ polymerization method using potassium persulfate (K₂S₂O₈, KPS) as an initiator. Ammonium polyphosphate (APP) was introduced for obtaining P(BA-VAc)/APP/G-MMT flame-retardant latex with a constant total content of 15 wt% of APP and G-MMT in P(BA-VAc). The flame retardancy and thermal behavior of the latex films were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and thermal gravimetric analysis (TG/DTA). Compared with the P(BA-VAc)/APP composite, the LOI value of P(BA-VAc)/APP/G-MMT containing 0.5 wt% G-MMT at the same total additive loading increased to 29.1 from 20.0 and its UL-94 increased from no rating to V-0. Thermal gravimetric (TG) data showed that the amount of residues increased significantly with the loading of G-MMT. In addition, the LOI values increased with the increase in char residues. The morphology and microstructure of the residues generated during LOI testing were investigated by scanning electron microscopy (SEM). The outer surfaces of P(BA-VAc)/APP/G-MMT charred layers were more continuous and compact than those of P(BA-VAc)/APP.     

31P NMR在阻燃剂DOPO合成中的应用

9,10-二氢-9氧杂-10-膦杂菲-10-氧化物（DOPO）的合成涉及酯化、酰基化、水解和脱水环化反应.通过核磁共振磷谱（³¹P NMR）对各步反应得到的产物进行表征,分析各反应产物的组成,由此得出各步反应规律,并找出了影响DOPO的产率和纯度的一些关键因素.     

Preparation of Zinc Hydroxystannate Coated Dendritic-Fibrillar Barium Carbonate and its Flame Retardant Effect on Soft Poly (Vinyl Chloride)

Abstract

Zinc hydroxystannate (ZHS) coated dendritic-fibrillar barium carbonate (ZHS/BaCO_3-F) was obtained by a simple ultrasonic assisted method at room temperature without any guide reagent; the flame retardant soft poly (vinyl chloride) (S-PVC) treated with ZHS/BaCO_3-F was prepared by melt blending and studied by the limiting oxygen index (LOI), univeral tensile testing machine, thermogravimetric analyzer-Fourier transform infrared spectroscopy (TGA/FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that ZHS/BaCO_3-F had a good dispersion in the PVC matrix, increased the LOI value and reinforced the S-PVC. The ZHS/BaCO_3-F played its role during the first degradation stage of S-PVC; the integrated effects of the earlier dehydrochlorination of ZHS on PVC, the reaction of ZHS/BaCO_3-F and HCl, and the thermal degradation of ZHS resulted in the production of H₂O, CO₂, olefins, aryl compounds, carboxylic compounds and alcohols, and the decrease of HCl production.     

Synergistic Effects of Polyethylene Glycol and Polyhedral Oligomeric Silsesquioxanes on Crystallization Behavior of Poly(L-lactide)

The synergistic effects of poly(ethylene glycol) (PEG) and polyhedral oligomeric silsesquioxanes (POSS) on the crystallization behavior of semicrystalline poly(L-lactide) (PLLA) were systemically investigated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Initially, the influences of PEG and POSS, individually, on PLLA crystallization were studied. The results indicated that PEG, as an efficient plasticizer, enhanced the mobility of the PLLA chains, resulting in decreasing of the glass transition temperature. The enhanced crystallization capacity of PLLA was strongly dependent on the molecular weight and content of the PEG, increasing with decreasing of the molecular weight and increasing of the PEG content. The experimental results also indicated that POSS was a heterogeneous nucleating agent, promoting the crystallization of PLLA. The synergistic effects of PEG and POSS on PLLA crystallization were then analyzed. The results showed that in the presence of PEG and POSS the crystallinity of PLLA was further enhanced due to their synergistic effects.     

Phase Structure,Thermal, and Mechanical Properties of Polypropylene/Hollow Glass Microsphere Composites Modified with Maleated Poly(ethylene-octene)

Maleated poly(ethylene-octene) (POE-g-MAH), as a compatilizer and toughener, was incorporated in polypropylene/hollow glass microspheres (PP/HGM) binary composites, and the phase structure and thermal and mechanical properties of these composites were investigated. Scanning electron microscopy analysis indicated that the phase structure of ternary composites could be controlled by POE-g-MAH and the surface treatment of HGM. Fourier transform infrared spectroscopy revealed that there was an amidation reaction between the treated HGM and POE-g-MAH during melt compounding. Differential scanning calorimetry suggested that the crystallization and melting behaviors of ternary composites were influenced by phase structure. Evaluation of mechanical properties showed that the amide linkage between the treated HGM and POE-g-MAH was favorable for improving the properties of ternary composites.     

利用1H NMR探究混合离子型/非离子型表面活性剂临界胶束浓度降低的实质

利用¹H NMR技术研究了离子/非离子表面活性剂形成的二元混合体系,结果显示表面活性剂的混合导致各组分的临界胶束浓度（CMC）均比各自纯溶液有所降低,用吸附平衡理论清楚地解释了这个现象.通过定量分析,发现不同的表面活性剂混合使得其组分CMC降低的程度各异,可以理解为它们吸附于界面单分子吸附层上的分子之间相互作用的不同（相吸或相斥）引起的.由此揭示了"协同效应"的实质,可以为选择适当的表面活性剂类型和混合比例以达到预期的性能提供有力的参考.     

光泵浦双反射带半导体激光器的热效应有限元分析

给出了808 nm/980 nm双反射带布拉格反射镜的反射谱线,建立了光泵浦双反射带半导体激光器件的热学模型及其内部热载荷分布形式,运用有限元分析方法,详细分析了双反射带光泵浦半导体激光器件的热学特性。结果表明,对于激射光反射率为99.96%的单反射带和双反射带布拉格反射镜结构的垂直外腔面发射半导体激光器件,前者的散热性能较好,而后者的最大温升明显低于前者。本文的分析结果可为半导体激光器件的结构优化和实验研究提供理论参考。     

Calibration Curve with Improved Limit of Detection for Cadmium in Soil: An Approach to Minimize the Matrix Effect in Laser-Induced Breakdown Spectroscopic Analysis

The present article describes a working or combined calibration curve in laser-induced breakdown spectroscopic analysis, which is the cumulative result of the calibration curves obtained from neutral and singly ionized atomic emission spectral lines. This working calibration curve reduces the effect of change in matrix between different zone soils and certified soil samples because it includes both the species' (neutral and singly ionized) concentration of the element of interest. The limit of detection using a working calibration curve is found better as compared to its constituent calibration curves (i.e., individual calibration curves). The quantitative results obtained using the working calibration curve is in better agreement with the result of inductively coupled plasma–atomic emission spectroscopy as compared to the result obtained using its constituent calibration curves.