苯乙烯/聚氯乙烯接枝膜的热稳定性研究

用自由基悬浮聚合法合成了苯乙烯 /聚氯乙烯接枝膜 ,并对产物热处理 ,然后进行紫外 -可见光谱 ,红外光谱 ,热失重分析。结果表明接枝苯乙烯后的聚氯乙烯膜热稳定性得到了提高。同时 ,讨论了热稳定性机理。     

PVC硬脂酸轻稀土热稳定剂的复配与应用研究

为了进一步研发性价比高且"无铅化"的稀土复合热稳定剂,研究了系列硬脂酸轻稀土盐(镧/铈/镨/钕/钐/铕/混合)与其他常用PVC热稳定(助)剂的复配效果。通过刚果红试纸法、红外光谱分析(FT-IR)、转矩流变仪等探究了复合热稳定剂对PVC性能的影响。结果表明:复合热稳定剂配方为硬脂酸轻稀土盐0.7~1.0份、硬脂酸锌0.8~0.9份、β-二酮0.3~0.6份和季戊四醇0.8~0.9份。将3份复合热稳定剂添加到100份PVC树脂中,静态及动态热稳定时间延长至100和35 min左右;动态热稳定性能和力学性能优于市售钙锌热稳定剂,与市售铅盐较接近。红外光谱分析表明复合热稳定剂可在加热初期减缓PVC氧化降解,较好地抑制初期着色,对PVC性能影响顺序为:镧组钕组混合组铈组镨组钐组铕组。     

Al(OH)3和Mg(OH)2对PVC热解特性的影响研究

利用热重分析仪并借助电导率测定法探讨了Al(OH)3和Mg(OH)2对PVC热解特性的影响,简要分析了其机理。结果表明:加入Al(OH)3和Mg(OH)2后均能增加PVC体系在第一阶段的最大热解速率和残炭量,最大热解速率增加约1倍,残炭量增加约4倍。并且分解产生的结晶水吸收大量的热量,惰性金属氧化物也有利于成核、炭层生长和凝聚,有着明显的阻燃和抑烟作用。HCl毒性气体的释放主要集中在体系的第一阶段,Al(OH)3能促使HCl提前释放,HCl的释放总量增加,Mg(OH)2也能促使HCl提前释放,但HCl的释放总量却是减少的。     

Thermal,Mechanical and Morphological Behavior of Poly(propylene)/Wood Flour Composites

The comparative studies on the thermal, mechanical and morphological behavior of compression molded poly(propylene) (PP)/wood flour (WF) composites were performed using wood flours (WFs) of different origins. The comparison has been made on the basis of results obtained from thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile testing. It has been demonstrated that an addition of 5 wt.-% of maleic anhydride grafted polypropylene (PP-g-MA) has a significant effect on the morphological and thermomechanical behavior of the composites. Although, microscopic examinations revealed no significant differences in the morphology of the compatibilized composites, a remarkable improvement of thermal degradation behavior was observed. From the view point of mechanical properties, the composites with high amount of filler (60 wt.-%) showed similar behavior irrespective of the origin of wood flour.     

Structure of reactively extruded rigid PVC/PMMA blends

A novel route for producing polymer blends by reactive extrusion is described, starting from poly (vinyl chloride)/methyl methacrylate (PVC/MMA) dry blend and successive polymerization of MMA in an extruder. Small angle X‐ray scattering (SAXS) measurements were applied to study the monomer's mode of penetration into the PVC particles and to characterize the supermolecular structure of the reactive poly(vinyl chloride)/poly(methyl methacrylate) (PVC/PMMA) blends obtained, as compared to the corresponding physical blends of similar composition. These measurements indicate that the monomer molecules can easily penetrate into the PVC sub‐primary particles, separating the PVC chains. Moreover, the increased mobility of the PVC chains enables formation of an ordered lamellar structure, with an average d‐spacing of 4.1 nm. The same characteristic lamellar structure is further detected upon compression molding or extrusion of PVC and PVC/PMMA blends. In this case the mobility of the PVC chains is enabled through thermal energy. Dynamic mechanical thermal analysis (DMTA) and SAXS measurements of reactive and physical PVC/PMMA blends indicate that miscibility occurs between the PVC and PMMA chains. The studied reactive PVC/PMMA blends are found to be miscible, while the physical PVC/PMMA blends are only partially miscible. It can be suggested that the miscible PMMA chains weaken dipole–dipole interactions between the PVC chains, leading to high mobility and resulting in an increased PVC crystallinity degree and decreased PVC glass transition temperature (T_g). These phenomena are shown in the physical PVC/PMMA blends and further emphasized in the reactive PVC/PMMA blends. Copyright © 2005 John Wiley & Sons, Ltd.     

Development and characterization of reactive extruded PVC/polyacrylate blends

This paper describes a method to obtain polymer blends by the absorption of a liquid solution of monomer, initiator, and a crosslinking agent in suspension type porous poly(vinyl chloride) (PVC) particles, forming a dry blend. These PVC/monomer dry blends are reactively polymerized in a twin‐screw extruder to obtain the in situ polymerization in a melt state of various blends: PVC/poly(methyl methacrylate) (PVC/PMMA), PVC/poly(vinyl acetate) (PVC/PVAc), PVC/poly(butyl acrylate) (PVC/PBA) and PVC/poly(ethylhexyl acrylate) (PVC/PEHA). Physical PVC/PMMA blends were produced, and the properties of those blends are compared to reactive blends of similar compositions. Owing to the high polymerization temperature (180°C), the polymers formed in this reactive polymerization process have low molecular weight. These short polymer chains plasticize the PVC phase reducing the melt viscosity, glass transition and the static modulus. Reactive blends of PVC/PMMA and PVC/PVAc are more compatible than the reactive PVC/PBA and PVC/PEHA blends. Reactive PVC/PMMA and PVC/PVAc blends are transparent, form single phase morphology, have single glass transition temperature (T_g), and show mechanical properties that are not inferior than that of neat PVC. Reactive PVC/PBA and PVC/PEHA blends are incompatible and two discrete phases are observed in each blend. However, those blends exhibit single glass transition owing to low content of the dispersed phase particles, which is probably too low to be detected by dynamic mechanical thermal analysis (DMTA) as a separate T_g value. The reactive PVC/PEHA show exceptional high elongation at break (～90%) owing to energy absorption optimized at this dispersed particle size (0.2–0.8 µm). Copyright © 2005 John Wiley & Sons, Ltd.     

Hydroxylbenzylthioethers as novel organic thermal stabilizers for rigid PVC

An investigation was carried out on the performances of hydroxylbenzylthioethers employed as organic thermal stabilizers for rigid poly(vinyl chloride). The efficiency of these compounds as thermal stabilizers was evaluated by using Haake polydrive mixer and TGA. The stabilizing efficiency was compared with Ca-Zn soap and methyltin stabilizer. Hydroxylbenzylthioethers exhibit greater efficiency than both of these stabilizers. This is attributed to the ability of these compounds to prevent the formation of polyene sequences. The hydroxylbenzylthioethers-stabilized PVC showed a slightly lower glass transition temperature (T_g) in comparison with the original PVC. Hydroxylbenzylthioethers and epoxidized soybean oil (ESBO) exhibit synergistic effect on the stabilizing effect, when the mass ratios of ESBO to hydroxylbenzylthioethers are less than 0.5.     

Allylated PVC

Active chlorines in poly(vinyl chloride) (PVC) were quantitatively replaced by pendant allyl groups ( CH₂CHCH₂) with allyltrimethylsilane in the presence of Friedel–Crafts acids (e.g., Et₂AlCl and TiCl₄). The thermal stability of the allylated PVCs was significantly superior to that of the starting material. Our allylation method is essentially quantitative; indeed, it was used for the determination of the active chlorine content in the PVCs. Furthermore, the pendant allyl groups were quantitatively oxidized by m‐chloroperbenzoic acid to epoxides; thus, PVCs carrying propylene oxide substituents [ CH₂CH CH₂(O)] were prepared. The structures of the products were characterized by high‐resolution NMR spectroscopy, and their thermal characteristics were characterized by TGA and color formation. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 307–312, 2001     

Antimicrobial,mechanical, optical and thermal properties of PVC/ZnO‐EDTA nanocomposite films

Covalent surface functionalization of synthesized ZnO nanoparticles (NP)s with ethylenediaminetetraacetic acid (EDTA) was successfully carried out. Modified ZnO‐EDTA NPs as a viable and inexpensive filler were incorporated into poly(vinyl chloride) PVC matrix after their chemical modification to investigate the agglomeration behavior. All prepared materials including modified NPs and PVC/ZnO‐EDTA nanocomposites (NC)s were analyzed by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, X‐ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. Fabricated PVC/ZnO‐EDTA NCs were reported to have high transparency and improved mechanical properties compared with PVC. Modified ZnO and the fabricated NCs were shown to exhibit excellent antibacterial activity against two bacteria species: Escherichia coli and Staphylococcus aureus. The obtained NCs could be considered as self‐extinguishing materials on the basis of the LOI values. Copyright © 2016 John Wiley & Sons, Ltd.     

PVC/MBS共混物的紫外光交联及光氧化反应

PVC及其共混物应用广泛,MBS作为PVC制品的透明抗冲改性剂,在提高PVC抗冲性能的同时,必然影响PVC在紫外光照下发生的光化学反应过程,我们用紫外可见光研究了MBS对PVC紫外光解脱HCl动力学,发现MBS对PVC光解脱HCl有抑制作用,本文利用FTIR光谱研究PVC／MBS共混体系中,MBS对PVC光氧化、光交联及光降解过程的影响。     

Development of PVC/Silica Hybrids Using PVC Plastisols

A novel method for producing a plasticised PVC with increased porosity has been developed, by the use of an organic-inorganic hybrid. Silica was produced in situ from tetraethoxysilane via a hydrolytic sol-gel processing route. Tetrahydrofuran was used as co-solvent, and γ-glycidyloxypropyl-trimethoxysilane as coupling agent. The films produced were transparent, with moderate mechanical properties. A film containing 20% silica showed a 45% increase in water vapour permeability.     

Structural aspects of suspension poly(vinyl chloride): The thermal aspects of rigid suspension PVC

The thermal aspects of a series of suspension PVC samples, polymerized at different temperatures, have been investigated using DSC, WAXS, and dielectric measurements. The observed thermal behavior, extending over a wide temperature range, is in line with the presence of ordered entities, having a wide distribution of size and perfection. The importance of small variations of the syndiotacticity on the crystallizability is demonstrated by cooling experiments. © 1994 John Wiley & Sons, Inc.     

Overview of the recent literature on flame retardancy and smoke suppression in PVC

This paper presents an overview of the recent literature on flame retardancy of poly(vinyl chloride) (PVC). A short overview of mechanisms of thermal decomposition of PVC, especially those which lead to char formation, is also presented because this gives insight into the mechanisms of flame retardant action. New developments in the area are mostly focused on combinations of various flame retardants and smoke suppressants in the search for synergistic effects. Because different additives show different mechanisms of action, synergistic combinations are very probable. New developments in phosphate ester plasticizers are reported in the literature. Copyright © 2005 John Wiley & Sons, Ltd.     

Physico-Mechanical Characteristics of Some EPDM/Plasticized PVC Blends

Summary: In this study were prepared blends based on ethylene propylene terpolymer rubber (EPDM) and plasticized poly (vinyl chloride) (PVC). These blends are immiscible and need to be compatibilized. The following compatibilization methods were used: (1) addition of a compatibilization agent; there were used: maleinized EPDM, maleinized polyethylene (PE), chlorinated polyethylene (CPE) and maleinized polypropylene (PP); chlorinated polyethylene has proved to be the most efficient; the amount of the added CPE giving the best physico-mechanical characteristics was of 7,5 parts to 100 polymer parts; (2) reactive compatibilization, using crosslinked copolymer formation strategy; three different crosslinking systems were used: (a) common method with sulphur and accelerators, (b) crosslinking with benzoyl peroxide and trimethylpropane trimethacrylate (TMPT DL 75), (c) vulcanization with phenol resin and tin chloride. The best physico-mechanical characteristics were obtained with the EPDM/plasticized PVC blends crosslinked with 8 phr phenol resin. Such types of polymer blends can be processed by methods specific for plastics, removing thus vulcanization operation required in case of elastomers. These blends can be used in the manufacture of hoses, gaskets, footwear constituents etc.     

Patterning of cells on a PVC film surface functionalized by ion irradiation

Micropatterns of cells on a poly(vinyl chloride) (PVC) film surface were created by using ion irradiation. A PVC film was irradiated with H⁺ ions through a pattern mask in order to create patterns of the hydrophilic/hydrophobic regions on the PVC surface. The effect of ion irradiation on the surface properties of the PVC film was characterized by using Fourier transform‐infrared spectroscopy (FT‐IR), water contact angle measurement, and X‐ray photoelectron spectroscopy (XPS). The results revealed that the chemical environment of the PVC film surface was effectively changed by ion irradiation due to dehydrochlorination and oxidation. The in vitro cell culture on the patterned PVC film surface showed selective adhesion and proliferation of the cells on the ion‐irradiated regions. Well‐defined 50 µm patterns of the cells were obtained on the PVC film surface irradiated to 1 × 10¹⁵ ions/cm². Copyright © 2009 John Wiley & Sons, Ltd.     

Transition from crazing to shear deformation in ABS/PVC blends

ABS/PVC blends were prepared over a range of compositions by mixing PVC, SAN, and PB‐g‐SAN. All samples were designed to have a constant rubber level of 12 wt % and the ratio of total‐SAN to PVC in the matrix of the blends varied from 70.5/17.5 to 18/80. Transmission electron microscope and scanning electron microscope have been used to study deformation mechanisms in the ABS/PVC blends. Several different types of microscopic deformation mechanisms, depending on the composition of blends, were observed for the ABS/PVC blends. When the blend is a SAN‐rich system, the main deformation mechanisms were crazing of the matrix. When the blend is a PVC‐rich system, crazing could no longer be detected, while shear yielding of the matrix and cavitation of the rubber particles were the main mechanisms of deformation. When the composition of blend is in the intermediate state, both crazing and shear yielding of matrix were observed. This suggests that there is a transition of deformation mechanism in ABS/PVC blends with the change in composition, which is from crazing to shear deformation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 687–695, 2006     

Kinetics of thermal decomposition of PVC/fly ash composites

In this study, the kinetics and mechanisms of thermal degradation of Poly Vinyl Chloride (PVC) composites reinforced with class-F fly ash are studied experimentally and numerically using Flynn–Wall model. The addition of fly ash to the polymer matrix results in a decrease in the primary degradation temperature and an increase in the secondary degradation temperature. The metal oxides in the fly ash act as acid absorbers, which results in the destabilization of PVC during its dehydrochlorination process. However, they also react with the chlorine free radicals, which prevents the formation of HCl during degradation. In addition, it is observed that calcium and iron oxides, present in fly ash, are more reactive to the chlorine radicals rather than the silicon and aluminum oxides. The effect of fly ash chemical composition on the degradation of PVC composites was studied by comparing the thermal properties of composites containing two different classes of fly ashes, class-F and class-C, at similar levels. Thermal stability of the composites is found to be dependent on the chemical composition of fly ash. Higher dehydrochlorination rate is observed in the case of composites filled with class-F fly ash than those reinforced with class-C fly ash.     

Preparation and characterization of PVC/PANI conductive composite with extremely low percolation threshold

Aniline was polymerized in the presence of poly(vinyl chloride) (PVC) powders in hydrochloric acid to in situ prepare poly(vinyl chloride)/polyaniline (PVC/PANI) composite particles. UV‐vis spectra and FT‐IR spectra indicate PANI in PVC/PANI composite particles possessed a higher oxidation state with decreased aniline content in reactants. Both conductivity and impact strength of the dodecylbenzenesulfonic acid (DBSA) doped PANI composites (PVC/PANI‐DBSA), which were compression molded from the in situ prepared PVC/PANI particles, increase with the pressing temperature and decrease with the increase of DBSA doped PANI (PANI‐DBSA) loading. An excellent electric conductivity of 5.06 × 10^?2 S/cm and impact strength of 0.518 KJ/m² could be achieved for the in situ synthesized and subsequently compression molded composite. Copyright © 2004 John Wiley & Sons, Ltd.     

Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

Radiation effects on the formation of conjugated double bonds in the thermal degradation of poly(vinyl chloride) (PVC) and poly(vinyl alcohol) (PVA) were investigated. Thin films of PVC and PVA were either irradiated with γ-rays at ambient temperature (pre-irradiation) and then subjected to thermal treatment, or irradiated at elevated temperatures (in situ irradiation). An extensive enhancement of the thermal degradation was observed for the pre-irradiation of the PVC films, which was more effective than the effect of the in situ irradiation at the same absorption dose. For the PVA degradation, however, the effect of the in situ irradiation was larger than that of the pre-irradiation. The results were explained and related mechanisms were discussed based on radiation-induced chemical reactions and their individual contributions to the thermal degradation behaviors of the two polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3089–3095, 1998