Generalization of the temperature-strain characteristics for polyvinyl chloride under tension

A universal temperature-time characteristic of the stress-strain relation has been derived for polyvinyl chloride under uniaxial tension.Notation P true stress - strain - l ₀ initial length of specimen - l length of specimen at any instant of time - total elongation factor - _p=max elongation factor at maximum stress on P () curve - v elongation rate - strain rate - t time - T absolute temperature - E_t relaxation modulus - H relaxation spectrum - relaxation time - T_S reference temperature, °K - a _T reference temperature coefficient Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 22, No. 6, pp. 1031–1035, June, 1972.     

Effect of increased compacting pressures on the physicomechanical characteristics of metal-filled polyvinyl chloride

Based on the principles of linear thermodynamics, molecular physics, and spatial organization of amorphous polymers, the energy of formation of microdefects and the increments in their volumes as functions of the compacting pressure and the content of the filler of polyvinyl chloride systems are calculated. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 807–812, July–August, 2000.     

Fracture of slightly plasticized polyvinyl chloride

Impact tests and fracture toughness tests using compact tension specimens were carried out on a number of slightly plasticized PVC compositions. These measurements, together with calculations from the craze thickness profile were used to determine the fracture mechanisms operating in the various tests. The marked decrease in the impact strength of PVC on addition of small amounts of a conventional plasticizer was found to be due to the plasticizer decreasing the stress intensity necessary to nucleate a craze at the notch tip of the impact specimen. The fracture toughness of the compact tension specimens which failed by a crazing mechanism increased with increasing plasticizer content. It is thought that the fracture of these specimens is controlled by the stress intensity necessary to propagate the pre-existing crack/craze system through the material.     

聚乙烯醇/原花青素共混物薄膜的制备及其性能研究

采用天然植物中提取的原花青素(OPC)作为自由基捕获剂,通过溶液浇铸法将OPC与聚乙烯醇(PVA)共混制膜。利用差示扫描量热仪(DSC)、热重分析仪(TGA)、全反射傅里叶红外光谱仪(FTIR)、双束紫外可见分光光度计(UV-Vis)、小角X射线散射仪(SAXS)等仪器研究共混物薄膜的热力学稳定性、紫外屏蔽性能、透光率以及结晶性能等。结果表明,1.0%～2.0%原花青素的加入可有效提高PVA的热稳定性,拓宽熔融加工窗口,且PVA/OPC薄膜能保持优异的力学性能、透光率以及紫外屏蔽性能。小角X射线散射的结果进一步证明OPC的加入抑制PVA的结晶。     

High temperature creep of polyvinyl chloride

The creep behaviour of polyvinyl chloride (PVC) has been studied in the temperature range 280 to 340° F under constant stress varying from 3.4 to 22.7 p.s.i. It is shown that the steady-state creep rate is an exponential function of stress as suggested by Norton but the exponent decreases with temperature. The activation energy for creep is determined using an activated-state rate process and it is found to be a decreasing function of stress with a higher value at temperatures 320° F and above. It is shown that the time dependent strain can be represented by $$\gamma = \gamma _0 + \dot \gamma _s t + \gamma _T \left[ {1 - \exp \left( { - K\dot \gamma _s t} \right)} \right]$$ where γ ₀ is the instantaneous strain on stressing, \(\dot \gamma _s\) the secondary creep rate, γ _T transient strain, and K is a constant. Scanning electron micrograph studies of the fracture surface and the change in activation energy apparently support the probability of two different deformation mechanisms i.e., domain flow and chain segmental or molecular flow at temperatures below and above 320° F, respectively.     

Elastic behaviour of polyvinyl chloride melts

A study has been made of the elastic behaviour of Polyvinylchloride commercial samples at high shear stresses, under similar conditions to those used in the processing industry, by means of an extrusion capillary rheometer.The influence in the die swell of variables as molecular weight, temperature and shear rate has been studied. Results are in agreement with general literature data.Smooth extrudates are obtained only in the zone of intermediate shear rates. In this zone it is observed that the die swell increases with shear rate.     

Structural-mechanical and thermophysical properties of modified polyvinyl chloride

On the basis of a systematic investigation of the viscoelastic properties of polyvinyl chloride filled with waste from mineral fertilizer and phosphoric acid production in the form of highly dispersed phospho-gypsum, the specific heat is calculated and the energy of interaction of the structural elements of the system matrix is determined, together with the effective thermal conductivity coefficient, with allowance for energy dissipation by the elements of the structure.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 60, No. 6, pp. 987–994, June, 1991.     

聚氯乙烯掺混树脂的合成与应用

采用不同体系分散剂、不同调粒剂用量合成了系列聚氯乙烯掺混树脂 .观察了掺混树脂在糊树脂加工中的作用 .结果表明 ,采用明胶体系及适量的调粒剂可获得颗粒均匀、光滑致密的聚氯乙烯掺混树脂 ;该种树脂可以改善糊树脂的加工性能和制品质量     

Stabilization of high-impact polystyrene/ polyethylene blends

Commercial poly(styrene-b-butadiene) copolymers (SBS) can act as effective compatibilizers in blends between high-impact polystyrene (HIPS) and polyethylene (PE), allowing a fine dispersion of PE in the polystyrene matrix, with a good balance of stiffness and impact strength. However, when processed under more severe conditions (e.g. in multiple extrusions, which simulate customer's product scrap recovery), the above blends show rather poor stability and their useful properties are rapidly lost. That undesirable effect is mainly due to cross-linking of SBS, which thus looses its compatibilizing activity. A correlation has been found between the time-to-cross-linking of SBS rubber in a Brabender mixer and the rapid decay of mechanical properties. The analysis of the mixing process and the morphology examinations of the final blend sample by TEM seem to support the above hypothesis. A significant reduction of block copolymer degradation has been achieved by means of a suitable stabilization.     

Performance properties of pigmented polyvinyl chloride nanocomposites

This work highlighted the role of blue CoO·MgO·Al₂O₃ pigments in changing some properties of PVC composites such as electrical, mechanical and thermal properties. The pigments were prepared by doping different ratios of magnesium in cobalt aluminate crystals using solid–solid interaction. The prepared pigments were characterized by different instrumental analysis (e.g. XRD, SEM and TEM). The influences of different concentrations of nanosized CoO·MgO·Al₂O₃ pigment on PVC prepared by solution blending were studied. The obtained data revealed that PVC nanocomposites containing 1CoO·1MgO·Al₂O₃ pigments show the most promising results. The composites containing 5 wt% of the three compositions of pigments exhibit the optimum electrical, mechanical as well as thermal properties.     

磺化聚苯乙烯/聚乙烯醇交联膜的制备与性能

以磺化度为75%的磺化聚苯乙烯(SPS)和聚乙烯醇(PVA)为原料,按一定的配比共混后浇铸成膜,在程序升温的过程中进行热交联,通过控制不同交联时间得到不同交联密度的交联膜.考察了交联膜的离子交换容量(IEC)、吸水率、溶胀性和尺寸稳定性;利用原子力显微镜和交流阻抗仪对交联膜的表面形貌及电导率进行了表征.结果表明:交联膜的IEC值略有降低;吸水率和溶胀度得到了很好的控制,具有较好的尺寸稳定性;膜表面出现了明显的亲水相和憎水相相分离,且亲水相微区的聚集尺寸和连续性随交联时间的长短而变化;随交联时间的延长,交联膜的电导率值略有下降,但交联后膜的室温电导率仍高于0.01 S/cm.     

Fatigue propagation behaviour of polystyrene/polyethylene blends

Fatigue crack propagation (FCP) of injection-moulded polystyrene (PS) and 95/5, 85/15 and 70/30 PS/high-density polyethylene (HDPE) blends at loading frequencies of 2 and 20 Hz was studied. The FCP results showed that increasing the HDPE content caused a progressive reduction of the fatigue crack growth rates, especially when a styrene/ethylene– butylene/styrene (SEBS) terpolymer was added as a compatibilizer. Increasing the loading frequency also led to a fatigue crack growth rate reduction. Moreover, the fatigue crack growth rates were lower at a given cyclic stress intensity factor range, K, when the crack propagated normal, instead of parallel, to the melt-flow direction during injection moulding. Fractographic observations indicated that discontinuous growth bands (DGBs), associated with the fracture of crazes in the plastic zone, were present through most or all of the fracture surfaces of the PS/HDPE specimens. In the presence of sufficient HDPE, these DGBs were formed by the initiation, growth and coalescence of large dimples initiated at HDPE particles ahead of the microscopic crack front, similar to a multiple crazing effect. The loading frequency effect on the FCP behaviour of these blends is attributed to a time-dependent deformation process. It is concluded that the FCP behaviour of these blends is strongly affected by the loading direction with respect to the matrix and minor phase orientation, by the presence of a compatibilizer, by the composition of the blend and by the testing conditions. © Chapman & Hall.     

Migration of lead from unplasticized polyvinyl chloride pipes

The effect of water quality parameters, such as water pH, temperature, and total dissolved solids (TDS), and direct exposure to UV-radiation on the migration of lead, tin and other metal stabilizers, such as calcium, cadmium, and barium from unplasticized polyvinyl chloride (uPVC) pipes were investigated using locally manufactured pipes. Specimens of 1m were used to investigate the effect of water quality parameters using the circulatory method. To investigate the effect of UV-radiation, specimens of 33cm long were used throughout the research. The investigation was carried out, using the static method at different times of exposure to the UV-radiation. The concentrations of lead, tin, and other metal stabilizers in the water were evaluated using the inductively coupled argon plasma (ICAP) technique. The results on the effect of water quality parameters showed that water pH, temperature, TDS, and time of water circulation were all having an effect on the migration of lead, tin, and other metal stabilizers. On the other hand, exposure to UV-radiation was seen to promote the migration of lead, tin, and other metal stabilizers. A lead concentration of about 0.8mg/l (ppm) was detected after 14 days of exposure to the UV-radiation.     

谈聚氯乙烯膜的功能特点及其应用领域

PVC材料的使用非常有利于环境保护,其自身的安全性是非常理想的。PVC与添加荆混合、塑化后,利用三辊或四辊压延机制成规定厚度的透明或着色薄膜,用这种方法加工薄膜,成为压延薄膜。也可以通过剪裁,热合加工包装袋、雨衣、桌布、窗帘、充气玩具等而应用广泛。针对聚氯乙烯膜的功能特点及其用途,介绍了聚氯乙烯膜的应用种类,研究了聚氯乙烯薄膜配方设计要点,分析了聚氯乙烯吹塑薄膜增塑剂系统的选择,提出了聚氯乙烯薄膜的制作工艺。     

Surface modification of polyvinyl chloride towards blood compatibility

The surface modification of medical grade polyvinylchloride (pvc) from various sources with the ionic bonding of polyelectrolyte is investigated by exposing thepvc sheets to 1% zephiran chloride for 10 min and then to 50 mg% solution of polyelectrolyte for 10 min. Surface energy and platelet adhesion studies were carried out to demonstrate the suitability of our improved surface towards blood compatibility. Relative changes due toγ-irradiation are also discussed.     

Behavior and products of mechano-chemical dechlorination of polyvinyl chloride and poly (vinylidene chloride)

The mechano-chemical (MC) dechlorination of polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) was performed by mechanical milling PVC/PVDC powder with zinc powder in a planetary ball mill, and the products of dechlorination were characterized by Infrared spectra (IR), X-ray diffraction (XRD), Raman spectroscopy, gas chromatography-mass spectrometry (GC-MS), and 13C solid-state nuclear magnetic resonance (NMR). The experimental results show that PVC/PVDC can be easily dechlorinated by milling with zinc powder, and formed various kinds of inorganic and organic products. Inorganic compounds included Zn2OCl(2).2H2O, Zn5(OH)8Cl2.H2O etc., and organic products involved diamond-like carbon, carbyne fragment, polyacetylene etc. Organic products formed following the paths of dechlorination, dehydrochlorination, crosslink, and oxidation. The mechano-chemical dechlorination process of PVC/PVDC may be an effective approach for carbyne synthesizing in the appropriate condition.     

Comparison of the fatigue propagation behaviour of polystyrene and 95/5 polystyrene/polyethylene blends

The fatigue crack propagation (FCP) behaviour of polystyrene (PS) and 95/5 PS/high density polyethylene (HDPE) was studied at cycling frequencies (f) of 0.2, 2 and 20 Hz. At the latter two frequencies, the fatigue crack growth rates (FCGRs) in the blends were lower than in PS, especially when a styrene/ethylene–butylene/styrene (SEBS) triblock copolymer was added as a compatibilizer. The fractographic features observed were analysed in detail. Discontinuous growth bands (DGBs), associated with the fracture of crazes, formed at low FCGRs in PS and at low and high FCGRs in the blends. Large dimple-like features formed at intermediate FCGRs and fatigue striations at high FCGRs were observed in PS. The observations indicated that the reduction in FCGR when HDPE was added to PS was associated with the presence of stretched HDPE particles which fractured behind the crack front, with increased particle–matrix adhesion favoured by the compatibilizer. An increase in cycling frequency decreased the FCGRs, with the fractographic observations indicating that this effect was associated with a decrease in the time-dependent deformation in the fracture process zone slightly ahead of the crack tip.