Damping properties of chlorinated polyethylene‐based hybrids: Effect of organic additives

In this article, the damping properties of organic hybrids consisting of chlorinated polyethylene (CPE), N,N‐dicyclohexyl‐2‐benzothia‐zolylsufenamide (DZ), and 4,4′‐thio‐bis(3‐methyl‐6‐tert‐butylphenol) (BPSR) have been investigated by dynamic mechanical analysis (DMA). It is found that DZ and BPSR seem to have a synergistic effect on the damping improvement of CPE/DZ/BPSR hybrids. For CPE/DZ/BPSR three‐component hybrids, when BPSR content is below 20 wt %, the values of damping peak maximum are just the same, while the damping peak position shifts to a higher temperature at a higher BPSR concentration. When BPSR content is fixed at 10 wt %, the damping peak maximum increases with increasing DZ/CPE ratio, while there is little shift in the peak position within the ratio range of 0.75–1.25. The decrease in damping peak maximum against annealing can be attributed to the phase separation resulting from the crystallization of hybrids components. Such a crystalline phase, which has been formed during annealing, contains not only pure DZ crystallites but also some CPE–DZ or CPE–DZ–BPSR eutectic crystals. Furthermore, the damping stability of the hybrids can be improved excellently by adding a small amount of BPSR or changing hot‐pressing temperature. These may imply that a series of high‐performance damping materials possessing both high damping peak maximum and controllable damping peak position can be achieved. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3307–3311, 2006     

Degradation of polyethylene–starch blends in soil

Binary polymer films containing different percentages of corn starch and low-density polyethylene (LDPE) were exposed to soils over a period of 8 months and monitored for starch removal and chemical changes of the matrix using FTIR spectroscopy. A standard curve using the area of the C? O stretch band and an empirical second-degree polynomial to fit the data made it possible to calculate starch concentration over a wide range (0–46% by mass). Starch removal was found to proceed rapidly during the first 40 days and to nearcompletion in very high starch blends (52% and 67% by weight). Starch removal was slower, consisting of mostly surface removal in 29% starch blends. Weight loss data supported spectroscopic data showing similar gross features. Weight loss and spectroscopic data were consistent with percolation theory and suggested that starch removal continues past 240 days. Degradation rates in different soils containing different amounts of organic matter were approximately the same after a period of a few weeks. IR analysis did not show significant chemical changes in the polyethylene matrix after 240 days. However, the matrix did show evidence of swelling, an increase in surface area, and removal of low molecular weight components.     

助剂对软质聚氯乙烯脱氯化氢反应的影响

采用刚果红法研究了防老剂、有机过氧化物、填料、金属氧化物、增韧改性剂、加工助剂和润滑剂等助剂的品种、用量对软质聚氯乙烯(PVC)脱氯化氢反应的影响。实验结果表明:防老剂、二氧化硅和粉末丁腈橡胶增韧剂(P-83)对软质PVC的脱氯化氢反应有明显的抑制作用,其中防老剂D的抑制作用最明显;有机过氧化物、云母和增韧剂氯化聚乙烯(CPE135A和CPE135B)对软质PVC的脱氯化氢反应有一定的促进作用,其中软质PVC的刚果红试纸初始变色时间、完全变色时间和脱氯化氢温度等均随着有机过氧化物DCP用量的增加而明显降低;滑石粉、陶土、加工助剂和润滑剂对软质PVC的脱氯化氢反应影响较小。     

Polymer reprocessing: Properties of polyethylene—polyvinyl chloride mixtures

The increasing tendency to consider waste polymers as suitable stocks for reconversion calls for guidelines as to the processing and end-product behavior of mixtures involving commodity polymers. In the present case, flow and some mechanical properties of mixtures involving low density polyethylene (PE) and filled polyvinyl chloride (PVC) were determined and used as a base-line of comparison with similar properties of multi-component mixtures involving potential compatibilizers for the incompatible matrix pair. Chlorinated polyethylene (CPE) ethylene-vinyl acetate (EVA) copolymer and ELvaloy polymeric plasticizer were the property modifiers selected. Blends were produced by roll-mill, Brabender or Banbury mixing. Flow properties were measured by capillary viscometry and solid-state properties were characterized by stress-strain data and tensile impact performance. Melt viscosities were non-linear functions of blend composition and varied significantly with the choice of compatibiliser, EVA and CPE producing greater benefits of melt strength than did Elvaloy. Elastic moduli, ultimate tensiles and tensile impact data also responded to the presence of compatibiliser, the EVA and CPE again being more effective in upgrading the properties of the incompatible matrix pair than was Elvaloy. Results, while preliminary, suggest guidelines for the composition of PE/PVC stocks with upgraded performance balance.     

Environmental stress relaxation studies of polymers: Effect of temperature on polyethylene–xylene and polyethylene–toluene systems

The method of stress relaxation has been used to study the effect of temperature on the stress decay behavior in the systems of polyethylene–xylene and polyethylene–toluene. The behavior of stress decay in the polyethylene under xylene or toluene at various temperatures was observed and the activation energies of polyethylene–xylene and polyethylene–toluene were obtained.     

Effect of amphiphilic compatibilizers on the filler dispersion and properties of polyethylene—thermally reduced graphene nanocomposites

Compatibilizers of different chemical structures and specifications were used to enhance the filler exfoliation in nanocomposites of polyethylene and thermally reduced graphene prepared by melt mixing route. The mechanical performance of the compatibilized nanocomposites was observed to be better than PE/G nanocomposites due to enhanced extent of filler exfoliation and distribution. Highest increase of 45% in tensile modulus and 13% in peak stress was observed in the composites. Overall, from the mechanical, rheological, thermal, and calorimetric properties, the compatibilizers with best performance were ethylene acrylic acid (EAA) copolymer and chlorinated polyethylene (CPE25). Furthermore, the extent of filler exfoliation was observed to increase with increasing EAA content thus confirming positive interactions between EAA and thermally reduced graphene, though no specific chemical interactions could be detected. The composite properties were observed to reach maximum around 7.5 wt % EAA content, followed by reduced performance due to extensive matrix plasticization. The observed behaviors were a result of interplay of opposing factors like filler exfoliation due to compatibilizer addition and matrix plasticization due to its lower molecular weight, thus the observed optimum comaptibilizer amount was specific to the compatibilizer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42484.     

氯化石蜡-70脱氯制备石蜡烯及性能表征

通过氯化石蜡?70（CP-70）在NaOH乙醇溶液中的脱氯反应制得了石蜡烯,并对产品的氯含量、双键值和结构分别采用离子色谱、碘量法和红外光谱法进行了分析和表征。研究发现,NaOH浓度增加、温度上升和反应时间延长有助于提高脱氯反应的程度;碘量法和红外光谱的分析结果表明,在较高温度下制得的石蜡烯含有更多的共轭双键和三键。     

Photosensitized dehydrochlorination of poly(vinyl chloride). I. Effect of commercial additives

A commercial formulation of thermal antioxidant has been shown to photosensitize the dehydrochlorination of poly(vinyl chloride). The species responsible was shown to be a p-alkyl-substituted phenol, and this was confirmed using p-cresol as a model compound.     

Degradation of poly(vinyl chloride). III. Kinetics of thermal dehydrochlorination catalyzed by slow-diffusing HCl

The dehydrochlorination reaction of poly(vinyl chloride) was investigated by subjecting molded polymer discs to thermal treatments at comparatively low temperatures and for low degradation extents, such as to maintain practically unchanged the sample's composition and physical state. The HCl evolution-versus-time curves exhibited accelerating behaviors to be ascribed to the catalytic action of HCl accumulating in the samples owing to a hindered diffusion. By assuming a catalyzed dehydrochlorination reaction occurring independently from the uncatalyzed one and being first order with respect to HCl, a kinetic equation describing satisfactorily the experimental evidence was deduced.     

Relationship between surface energy and adhesion strength in polyethylene—paper composites

This work reports adhesion behaviour of polyethylene on paper, and deals with the surface energy of the materials involved in the manufacture of these composites, and its influence on the adhesion strength, at constant roughness, for the paper substrates. The surface energy of different papers treated with various sizing agents was determined by measuring contact angles according to the Owens-Wendt method. The peeling energy was shown to follow a linear relationship versus the reversible energy of adhesion. This result is explained by the fact that rupture takes place at the interface and that the size of the defect at the interface depends on the spreading coefficient. Corona treatment, applied to strongly sized papers before making the composites, restored the adhesion strength to its original range of values, again demonstrating the thermodynamic character of adhesion in thermoplastic-paper composites.     

有机锡热稳定剂对CPE脱氯化氢热降解性的影响

采用刚果红法研究有机锡热稳定剂对氯化聚乙烯(CPE)脱氯化氢热降解性的影响。结果表明，硫醇锡复合热稳定剂T-137和T-395A抑制CPE脱氯化氢的效果优于非硫醇锡热稳定剂二月桂酸二丁基锡；环氧大豆油能协同二月桂酸二丁基锡减慢CPE脱氯化氢速度；热稳定剂用量小于3份时，二月桂酸二丁基锡／二盐基亚磷酸铅和二月桂酸二丁基锡／硬脂酸钡并用体系(并用比1：1)抑制CPE脱氯化氢的效果较二月桂酸二丁基锡差，热稳定剂用量为3份时则较好。     

硬脂酸盐热稳定剂对CPE脱氯化氢热降解性的影响

采用刚果红法研究硬脂酸盐热稳定剂对氯化聚乙烯(CPE)脱氯化氢热降解性的影响。结果表明，随着硬脂酸盐用量增大，CPE的脱氯化氢温度呈升高趋势，脱氯化氢初始时间呈延长趋势；采用硬脂酸铅和硬脂酸钡的CPE脱氯化氛温度较高，脱氯化氢初始时间较长；硬脂酸铅／硬脂酸钡、硬脂酸铅／硬脂酸钙和硬脂酸钙／硬脂酸钡并用比分别为1：1，2：1和1：3时，CPE的脱氯化氢温度较高，并用比分别为3：1，2：1和1：1时，CPE的脱氯化氢初始时间较长。     

Aluminium‐filled low‐density polyethylene—structural,morphological, and mechanical properties

Low‐density polyethylene (LDPE) was filled with aluminium (Al) powder having concentrations of 1, 4, and 6% w/w. The samples in the form of disc containing the above concentration of Al powder were obtained using hot press molder. The structural properties have been investigated using density measurement and WAXD techniques. The morphology of pure LDPE and Al‐filled LDPE samples has been studied from scanning electron micrographs. The modulus of elasticity of the samples has been determined using Instron tensile tester. Results indicate that the crystallinity of LDPE component increases with the concentration of aluminium filler. Morphological changes also have been observed. The Young's modulus (Y) generally increases and becomes maximum for 4% Al‐filled LDPE sample. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Environmental stress relaxation studies of polymers: Effect of temperature on polyethylene–alcohol system

The method of stress relaxation has been used to study the plasticizing effect of sorbed alcohols on polyethylene as it changes with temperature. From the observation of the stress relaxation in polyethylene under alcohols at various temperatures, the activation energy of penetrant-enhanced relaxation of polyethylene caused by alcohols was obtained.     

Crystallization of low‐density polyethylene‐ and linear low‐density polyethylene‐rich blends

The crystallization of a series of low‐density polyethylene (LDPE)‐ and linear low‐density polyethylene (LLDPE)‐rich blends was examined using differential scanning calorimetry (DSC). DSC analysis after continuous slow cooling showed a broadening of the LLDPE melt peak and subsequent increase in the area of a second lower‐temperature peak with increasing concentration of LDPE. Melt endotherms following stepwise crystallization (thermal fractionation) detailed the effect of the addition of LDPE to LLDPE, showing a nonlinear broadening in the melting distribution of lamellae, across the temperature range 80–140°C, with increasing concentration of LDPE. An increase in the population of crystallites melting in the region between 110 and 120°C, a region where as a pure component LDPE does not melt, was observed. A decrease in the crystallite population over the temperature range where LDPE exhibits its primary melting peaks (90–110°C) was noted, indicating that a proportion of the lamellae in this temperature range (attributed to either LDPE or LLDPE) were shifted to a higher melt temperature. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1009–1016, 2000     

Rotomolded polyethylene‐agave fiber composites: Effect of fiber surface treatment on the mechanical properties

In this work, a comparison between different agave fiber surface treatments has been presented to improve the mechanical properties of rotomolded natural fiber composites (NFC). The fiber treatments were carried out with sodium hydroxide, 2‐chlorobenzaldehyde, maleic anhydride grafted polyethylene, acrylic acid, methyl methacrylate, and triethoxy vinyl silane. In particular, a simple dry‐blending technique was used to introduce agave fibers in the polymer matrix (linear medium density polyethylene). The samples were produced at 15 wt% fiber content and characterized in terms of morphology, density, hardness, and mechanical properties (tension, flexural, and impact). The results showed that surface treatments improved the homogeneity (uniform morphology) of NFC and the best mechanical improvements (77% for strength and 30% for stiffness) were obtained with maleic anhydride grafted polyethylene. POLYM. ENG. SCI., 56:856–865, 2016. © 2016 Society of Plastics Engineers     

Effect of polymer additives on hydrodynamics and oxygen transfer in a bubble column bioreactor

The influence of polymer additives (polyethylene oxide and polyacrylamide) on the hydrodynamics and oxygen transfer in a bubble column bioreactor was examined. The addition of small amounts of these polymers has been known to cause significant drag reduction in turbulent flow circumstances. The gas hold-up was slightly decreased and the liquid-phase mixing was somewhat enhanced due to the addition of the polymers. The addition of polymer additives brought about a reduction of the volumetric oxygen transfer coefficient by about 40%. In dilute polymer solutions, large bubbles formed by bubble coalescence moved with high rise velocities in the presence of many small bubbles and the bubble size distributions were less uniform compared with those in water. The complicated changes in bubble hydrodynamic characteristics were examined to give possible explanations for oxygen transfer reduction.     

Grafting of vinyl acetate onto low density polyethylene—starch biodegradable films for printing and packaging applications

Starch‐based biodegradable low‐density polyethylene (LDPE) films were used for graft copolymerization of vinyl acetate with ceric ammonium nitrate (CAN) in aqueous acidic medium as redox initiator with nitric acid. The extent of grafting was examined by Fourier‐transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR) spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The objective behind the grafting of vinyl acetate onto the LDPE–starch biodegradable films is to make these suitable for printing and packaging applications without affecting the biodegradability of the original films. Copyright © 2004 Society of Chemical Industry     

Effect of exfoliation and dispersion on the yield behavior of melt‐compounded polyethylene–montmorillonite nanocomposites

The yield behavior of melt‐mixed nanocomposites containing 5 wt % organically modified montmorillonite in matrices of a linear low‐density polyethylene (LLDPE) or a modified polyethylene was studied as a function of the temperature and strain rate. In the melt‐mixed LLDPE nanocomposite, the montmorillonite showed a slight increase in the clay spacing, which suggested that the clay was at best intercalated. Transmission electron microscopy (TEM) images showed that the dispersion in this nanocomposite was poor. The use of the modified polyethylene promoted exfoliation of the clay tactoids in the nanocomposite, as assessed by X‐ray diffraction and TEM. In both nanocomposites, the yield mechanisms were insensitive to the addition of the organoclay, even though modest increases in the modulus were produced. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3044–3049, 2006     

Thermal dehydrochlorination of poly(vinyl chloride). I. Effect of iron oxide on the rate of dehydrochlorination

The thermal degradation of poly(vinyl chloride) (PVC) was studied by following the rates of dehydrochlorination at temperatures between 180°C in pure nitrogen and air flow. Iron oxide accelerates the elimination of hydrogen chloride from PVC. The accelerating effect depends on the concentration of the oxide, and it has a maximum. This work tried to explain these behaviors. A mechanism of dehydrochlorination is suggested for polymer containing iron oxide.