Surface Modification of Poly Vinyl Chloride (PVC) Using Low Pressure Argon and Oxygen Plasma

In this study, commercial poly vinyl chloride （PVC） films were treated by oxygen and argon plasmas in a cylindrical glass tube which was surrounded by a DC variable magnetic field, with different sample positions in the plasma reactor and also different exposure durations. Effects of the plasma treatment on the hydrophilic properties of the films were studied by mea- suring the water drop contact angle on the surface of the samples. The surface topography of the untreated and plasma treated films was analyzed and compared by atomic force microscopy （AFM）. The optical characteristic changes in treated samples were investigated using reflective spectrophotometry. Also, the chemical changes which appeared on the surface of the samples were investigated using Fourier transform infrared spectroscopy （FTIR）. The results show that the plasma treated PVC becomes more hydrophilic with an enhanced wettability. A sharp de- crease in the water contact angle may also be a consequence of the surface texturization. The aging effect on wettability of the samples was also investigated. The results show that the effect of oxygen plasma on the surface properties of the samples is more pronounced compared with that of argon plasma.

十二烷基硫酸钠表面改性水滑石对PVC热稳定性能的影响

采用十二烷基硫酸钠(SDS)对镁铝镧碳酸根型水滑石(LDHs)表面进行湿法改性,讨论了不同改性条件对聚氯乙烯(PVC)静态热稳定性能的影响,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和红外光谱仪(FTIR)进行表征。采用刚果红试纸法、烘箱变色法、转矩流变法、热重分析法等测定了SDS改性前后PVC/LDHs样品的热稳定性能。结果表明,恒定pH=7,SDS为LDHs质量的10%,水浴80℃下搅拌3 h,改性效果最佳;SDS并未破坏LDHs的晶体结构,仅吸附在表面,增强了与PVC的相容性;改性后的PVC/LDHs样品静态及动态热稳定时间达65、28.5 min,改善了后期着色,更易塑化成型;最大质量损失速率对应温度为346℃,较未添加前增加55℃,能较好地抑制PVC的热降解。

N⁃苯基马来酰亚胺共聚物的合成及对PVC树脂耐热改性效果研究

通过种子乳液聚合结合半连续加料方式,成功聚合出分子结构一致且与聚氯乙烯(PVC)树脂具有良好相容性的聚(N‐苯基马来酰亚胺‐苯乙烯‐丙烯腈)(PNSA)共聚物胶乳,将其与PVC树脂直接复合制备PNSA/PVC复合材料,并对PNAS耐热改性的效果进行评价。结果表明,PNSA纳米胶乳颗粒粒径在155.3~251.5 nm之间,粒径分布均一;PNSA共聚物分子组成呈无规结构,分子结构一致,差示扫描量热曲线呈现单一的玻璃化转变温度(T_(g)),且与PVC树脂具有极佳的相容性;PNSA含量由0升高至50%(质量比,下同)时,复合材料的T_(g)由84.8℃提高到107.2℃,提高了22.4℃,维卡软化温度由71.2℃提高到91.9℃,提高了20.7℃;除耐热性改善以外,复合材料的力学性能也有一定程度的提高,本文的研究有利于PVC应用领域的进一步拓展。

Rare Earth Stearates as Thermal Stabilizers for Rigid Poly(vinyl chloride)

A series of stearates with different rare-earth ion were investigated as thermal stabilizers for rigid PVC at 180 ℃ in air. Their stabilizing efficiency was based on measuring the rate of dehydrochlorination. The resulted revealed the higher stabilizing efficiency of the investigated rare-earth stearates as thermal stabilizers for rigid PVC compared with the thermal stabilizers for industry: calcium stearate, zinc stearate, butyl stannum mercaptide, phosphite esters, β-diketone and epoxidized sunflower oil. This was well illustrated by longer incubation period (T_S) values and lower rate of dehydrochlorination. The stable efficiency was affected by the nature of rare-earth element's individual electronic shell. The mechanism for the stabilizing effect of rare-earth stearates was proposed. The result was experimentally proved based on IR spectrum.

Creep Behaviour of Wood Flour/Poly(vinyl chloride) Composites

The experimental creep data were focused on wood-flour （WF）/poly vinyl chloride （PVC） composites with the variations in additive concentrations of wood flour, silane coupling agent, organomodified montmorillonite （OMMT） and nano-cacium carbonate （nano-CaCO3）. Their effects were analyzed using the Four-element Burger Model incorporating microscopic mechanisms. Total creep strain was low with increasing WF while elastic strain was high and plastic flow strain was low in modeling. Modification of WF with silane was beneficial to creep resistance, so did adding low ratio of OMMT （1.5 wt%） and nano-CaCO3 in composites. Thus, it was effective in reducing creep either by stiffening the PVC matrix using rigid nano-particles or by improving their adhesion with resin. However, superfluous quantity of any additament did not benefit the improvement owing to either earlier destruction of their agglomerates or stress-concentrated cracks in the over-incrassated interface.

Antiplasticizing Effect of MOCA on Poly(vinyl chloride)

An obvious antiplasticizing effect has been observed in PVC with small amount of MOCA, 3,3’-dichloro-4,4’-diamino-diphenylmethane. PVC-MOCA interaction and crystallization behavior of PVC/MOCA blends were investigated in detail to explain the mechanism of antiplasticization on the basis of a series of techniques including DMA, FTIR, and DSC. The results of mechanical properties tests show that the tensile strength of PVC with 5 phr of MOCA reaches a maximum value, 69.5 Mpa, which is about 23 % higher than that of pure PVC. The rise in tensile strength was attributed to an antiplasticizing effect of MOCA on PVC as confirmed by DMA measurements. The evidences from FTIR reveal that a strong hydrogen-bonding interaction takes place between the nitrogen atom of –NH2 groups in MOCA and the methine proton of PVC repeat units. The results of DSC analysis indicate that crystallization behavior of MOCA is suppressed completely and the crystallinity of PVC decreases with the increase of MOCA amount.

Influence of Annealing and Additives on the Crystallization Behavior and Properties of Poly(vinyl chloride)

Acetanilide （AC）, adipic acid （AA） and potassium hydrogen phthalate （PHP） were chosen as additives to accelerate PVC crystallization and improve its mechanical properties. The influences of the additives and annealing on the crystallization behavior, micromorphology and the tensile properties were investigated by the thermal analysis, scanning electron microscopy （SEM） and the tensile test. Based on the analysis results, it was concluded that the melting peaks ranging from 110 to 200 ℃ and 200 to 240 ℃ were caused by the fusion of the fringed micelle crystals and chain-folded crystals respectively. AC advanced the fringed micelle crystal to develop, while AA and PHP promoted obviously the chain-folded crystal to grow. The addition of the foreign additives did not change the growth pattern ofPVC crystallites, the growth of the micelle crystal was favorable at 110 ℃, and the chain-folded crystal was developed at higher temperature. For PVC/ AA and PVC/PHP, when annealed at 110 ℃, a regular nest like network was formed, the crystallinity and the crystallite size were increased as well, and as a result, the tensile strength, Young＇s modulus and the elongation at break point were improved simultaneously and greatly.

Structures of LDHs Intercalated with Ammonia and the Thermal Stability for Poly(vinyl chloride)

MgAl-NH3 LDHs (layered double hydroxides), ZnAl-LDHs and ZnAl-NH3 LDHs with different molar ratio of Al/ammonia were synthesized by co-precipitation method. The synthetic LDHs samples were characterized by XRD, FT-IR, TGA-DTG and SEM techniques and tested by Congo red method. In addition, after PVC (Poly vinyl chloride) and DOP (Dioctylphthalate) were added to LDHs, the thermal stability for PVC was characterized by TGA-DTG. The results indicated that LDHs intercalated with ammonia improved thermal stability for PVC significantly, MgAl-NH3 LDHs (Mg2+:Al3+: NH3·H2O = 3:1:0.5) and ZnAl-NH3 LDHs (Zn2+:Al3+:NH3·H2O=2:1:1.5) showed the best thermal stability for PVC, interlayered space of LDHs became larger by intercalating ammonia.

UV enhanced gas–solid synthesis of chlorinated poly vinyl chloride characterized by a UV–Vis online analysis method

Dynamic characteristics of UV enhanced gas–solid PVC chlorination process were revealed by a UV–Vis spectral online analysis method. Experimental results showed an instantaneous increase of the chlorination rate as soon as UV light was affiliated, which demonstrated the intensified effect of UV radiation on PVC chlorination directly.Different affiliation methods of UV light were then studied, proving that continuous UV radiation could enhance the chlorination process significantly while intermittent UV radiation was able to initiate the chlorination reaction once it was conducted. Besides, experiments were carried out to study the influences of parameters on the chlorination process such as UV wavelength, chlorination temperature, partial pressure of chlorine gas and PVC raw materials. Among all the parameters, chlorination temperature and partial pressure of chlorine gas were testified as two key factors to determine the chlorination performance. Thermal analysis of CPVC products showed that their corresponding properties such as the glass transition temperature(Tg) and the homogeneity of chlorine distribution in polymer phase were improved with the increase of chlorine content.

Synthesis of CaZnAl-CO3 ternary layered double hydroxides and its application on thermal stability of poly(vinyl chloride)resin

In this work,hydrothermal method was used to prepare the CaZnAl-CO3 ternary layered double hydroxides(CaZnAl-CO3-LDHs)with various Ca/Zn/Al molar ratios,which were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscope(FT-IR)and scanning electron microscopy(SEM)techniques.The obtained results demonstrate that the samples were well-crystallized and flake-structured.The CaZnAl-CO3-LDHs used alone for thermal stability of poly(vinyl chloride)(PVC)resin,with different Ca/Zn/Al molar ratios and varying additive amounts,were investigated through the tests such as static thermal aging,mass loss and congo red,respectively.The optimum Ca/Zn/Al molar ratio and additive amount were 3.6:0.4:2 and 5 phr(parts per hundred PVC resin),respectively.In addition,the synergistic effects of Ca3.6Zn0.4Al2-CO3-LDHs and CaSt2 were discussed in detail,showing better thermal stability compared with Ca3.6Zn0.4Al2-CO3-LDHs used alone,and the optimum additive amounts of Ca3.6Zn0.4Al2-LDHs and CaSt2 were 6 and 1.0 phr,respectively.

Synthesis of Bio-Plasticizer from Soybean Oil and Its Application in Poly(Vinyl Chloride) Films

Herein,epoxidized soybean oil methyl ester(ESOM)plasticizer was synthesized for the preparation of plasticized poly(vinyl chloride)(PVC)films by the alcoholysis and epoxidation.The chemical structure of ESOM was investigated by infrared spectrum and 1 H nuclear magnetic resonance.The effect of content of ESOM and petroleum based plasticizer di-2-ethylhexyl phthalate(DEHP)on the performance of plasticized PVC films was studied.The result showed that substituting DEHP with ESOM can improve the thermal stability of plasticized PVC films.When the weight ratio of ESOM and PVC is fixed at 1:2,plasticized PVC film presents higher elongation at break(350.8%vs.345.1%)and lower tensile strength(14.21 MPa vs.15.8 MPa)compared with PVC plasticized with DEHP.ESOM showed less weight loss than DEHP in all solvents.The excellent migration resistance of ESOM is helpful to improve stability of plasticized PVC films.In all,the obtained bio-based plasticizer will be potential to replace petroleum based plasticizer DEHP in flexible PVC materials.

Effect of phosphite and epoxy soybean oil on heat stability of poly （vinylchloride） composite stabilizers

The influences ofphosphite and epoxy soybean oil in combination with liquid calcium/zinc isocaprylates on the thermal stability of flexible poly （vinyl chloride） were studied. The stabilizing effect of poly （vinyl chloride） was evaluated by Congo red method, thermoaging test and Thermogravimetric-differential Scanning Calorimetry （TG-DSC）. The results showed that the addition of the phosphite or epoxy soybean oil improved the thermal stability of PVC with the calcium/zinc isocaprylates stabilizing system, especially epoxidied soybean oil exhibited a remarkable effect, and the synergism on PVC thermal stability for 3：2 phenyl dioctyl phosphite to epoxidized soybean oil weight ratio was acquired. Accordingly, the rapid mass loss in TG curve occured between 258.9 ℃ and 334.4 ℃, which corresponded to the enthalpy of the pyrogenation of 609.2 J/g. It was also found that the stabilized PVC of the best ratio gave better mechanical and processing properties.

Preparation of MgAl LDHs Intercalated with Amines and Effect on Thermal Behavior for Poly(vinyl chloride)

MgAl LDHs intercalated with CO(NH2)2, NH4Cl and NH3·H2O were prepared by co-precipitation and XRD, FT-IR, TGA-DTA and SEM techniques were employed for characterization. The results indicated that the layer-layer spacing of LDHs was enlarged by 0.169, 0.285 and 0.227 Åwith the intercalation of CO(NH2)2, NH+4 and NH3, separately. The effects on thermal stability and degradation behavior of synthesized LDHs where mole ratios of Mg/Al/urea = 3:1:1, Mg/Al/NH4Cl = 3:1:1.5 and Mg/Al/NH3·H2O = 3:1:0.5 were investigated by Congo Red Method and thermogravimetric analysis (TGA) from 25°C - 800°C under N2. The TGA and DTA results showed, by incorporating 5% MgAl-CO(NH2)2 LDH, the dehydrochlorination temperature of PVC composites is 12°C higher than MgAl-NH+4 and MgAl-NH3 LDHs. MgAl-NH3 LDH enhances the ending temperature of the first degradation stage of PVC composites by 8°C compared with MgAl LDH. The LDH intercalated with CO(NH2)2 is proved to be an effective thermal stabilizer for PVC processing.

PHASE EQUILIBRIUM FOR THE TERNARY SYSTEM VINYL CHLORIDE-CHLORINATED POLYETHYLENE-POLY(VINYL CHLORIDE)

Swelling capacity of vinyl chloride (VC) in chlorinated polyethylene (CPE) with 25—40 wt% Cl at temperature 30—57℃ was studied and their relationships were correlated with Langmuir and Freundlich adsorption equations. A ternary phase diagram for VC-CPE-PVC was also established. In-situ polymerization conditions of CPE-g-VC were proposed and CPE content control was analyzed for the manufacturing process of CPE-g-VC graft product based on results of phase equilibrium study.

PVC树脂产品质量提升总结

针对PVC树脂“鱼眼”数超标问题,进行了系统排查分析。通过采取增大注水速率,调整助剂配方和用量等措施,减少了PVC树脂中的“鱼眼”,提高了产品的优等品率。

Microstructure and Mechanical Properties of Poly (Vinyl Chloride) Modified by Silica Fume /Acrylic Core-Shell Impact Modifier Blends

This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processed by dry blending and twin-screw extrusion. Severe silica fume agglomeration was observed by scanning electron microscope （SEM） in the PVC matrix when 8 phr pure silica fume was used and processed by screw speed of 20 rpm. Its tensile strength was thereby reduced by 38% comparing to unmodified PVC. The silica fume was successfully dispersed while the screw speed was slowed down to 10 rpm to give a stronger screw torque and a longer melt residential time in the extruder. The tensile strength was ’recovered’ to a level comparable to unmodified PVC. Impact test were performed on all formulations extruded at 10 rpm screw speed and synergetic toughening effect was found with 50% substitution and it had the impact strength that was comparable to 8 phr pure AIM toughened PVC.

Development of a Poly(vinyl chloride)-based Nitrate Ion-selective Electrode

The authors developed a nitrate ion-selective electrode（ISE） based on poly（vinyl chloride）（PVC） membrane with methyltrioctylammonium nitrate as a carrier and 1-decanol as a plasticizer.The performance of the nitrate-sensitive membranes was optimized by tuning the composition of components.The electrode exhibits a linear response with a Nernstian slope of（52±1.0） mV per decade for the nitrate ion concentration ranging from 5.8×10-5 mol/L to 1.0 mol/L.The electrode can be used to detect a low concentration of nitrate ions down to 3×10-5 mol/L in a pH range of 2.1―11.5 without any compensation.The advantage of the electrode includes simple preparation,short response time and good repeatability.The detection performance of the novel electrode on nitrate ions has been tested for water samples.

PVC/TPU共混材料静动态力学性能及本构模型研究

利用万能材料试验机和高速拉伸试验机对2种成型方式和6种共混比的聚氯乙烯/热塑性聚氨酯(PVC/TPU)共混材料开展静动态拉伸力学性能测试,并基于断裂伸长率和邵氏硬度进行成型方式和共混比优选。进一步获取了共混材料在较宽应变率范围(0.001~700 s-1)的应力⁃应变数据,并进行了拉伸断面的微观表征。结果表明,模压成型材料断裂伸长率更高,共混比为90/10时材料具有最高的断裂伸长率,邵氏硬度符合试验假人软组织材料的硬度范围(邵尔40~70 A)。共混比为90/10(PVC/TPU)材料在静动态载荷下均具有显著的应变率效应。选取朱⁃王⁃唐(ZWT)方程和Sherwood⁃Frost方程构建了材料的本构模型,对比发现Sherwood⁃Frost方程拟合效果更好。形貌分析发现,静动态加载下,材料均为典型的脆性断裂,未出现明显的相分离现象。随着应变率的增加,断面逐渐变粗糙,并产生空穴及微小裂纹。

Kinetics of Vinyl Chloride Polymerization with Mixture of Initiators

Kinetic models for the rate constants of vinyl chloride polymerization in the presence of initiator mixtures were proposed. They may be used to design the initiator recipes for the vinyl chloride polymerization with uniform rate at different temperatures at which various grades of poly(vinyl chloride) will be prepared.