The grafting of maleic anhydride on high density polyethylene in an extruder

The grafting of maleic anhydride (MAH) on high density polyethylene in a counter-rotating twin screw extruder has been studied. As the reaction kinetics appear to be affected by mass transfer, good micro mixing in the extruder is important. Due to the competing mechanisms of increasing mixing and decreasing residence times at increasing screw speed, and due to the complicated reaction scheme, various non-linearities exist that are prohibitive for simple optimization rules. The interaction diagram presented in this paper for a twin screw extruder as a MAH grafting reactor can be used for better understanding of the influence of the extruder parameters on the reaction process.     

Solvothermal preparation and characterization of maleic anhydride grafting high density polyethylene copolymer

In this article, the grafting copolymerization of maleic anhydride (MAH) onto high density polyethylene (HDPE) was carried out through solvothermal process. Infrared spectra (IR) revealed that MAH had been successfully grafted onto the HDPE backbone. The influences of the reaction parameters on the grafting copolymerization, e.g., the concentration of the initiator, MAH and HDPE content, reaction time, reaction temperature, comonomer, and different solvents were also studied. Further studies found that MAH could be grafted onto HDPE in both good solvents and poor solvents, which was much different from the traditional solution grafting method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

马来酸酐接枝PS相容剂的研究

研究了马来酸酐(MAH)在螺杆挤出机中与聚苯乙烯的接枝反应，确定了挤出接枝反应的最佳工艺条件，初步探索了温度、螺杆转速、引发剂浓度以及MAH浓度对接枝反应的影响。     

Esterification effect of maleic anhydride on swelling properties of natural fiber/high density polyethylene composites

The natural fibers (banana, hemp, and sisal) and high density polyethylene were taken for the preparation of natural fiber/polymer composites in different ratios of 40 : 60 and 45 : 55 (w/w). These fibers were esterified with maleic anhydride (MA) and the effect of esterification of MA was studied on swelling properties in terms of absorption of water, at ambient temperature, and steam. It was found that the steam penetrates more within lesserperiod of time than water at ambient temperature. Untreated fiber composites show more absorption of steam and water in comparison to MA‐treated fiber composites. The more absorption of water was found in hemp fiber composites and less in sisal fiber composites. Steam absorption in MA‐treated and untreated fiber composites are higher than the water absorption in respective fiber composites. The natural fiber/polymer composites containing low amount of fibers show less absorption of steam and water at ambient temperature than the composites containing more amount of fibers in respective fiber composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Compatibilization effects of block copolymers in high density polyethylene/syndiotactic polystyrene blends

Three triblock copolymers of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) of different molecular weights and one diblock copolymer of poly[styrene-b-(ethylene-co-butylene)] (SEB) were used to compatibilize high density polyethylene/syndiotactic polystyrene (HDPE/sPS, 80/20) blend. Morphology observation showed that phase size of the dispersed sPS particles was significantly reduced on addition of all the four copolymers and the interfacial adhesion between the two phases was dramatically enhanced. Tensile strength of the blends increased at lower copolymer content but decreased with increasing copolymer content. The elongation at break of the blends improved and sharply increased with increments of the copolymers. Drop in modulus of the blend was observed on addition of the rubbery copolymers. The mechanical performance of the modified blends is strikingly dependent not only on the interfacial activity of the copolymers but also on the mechanical properties of the copolymers, particularly at the high copolymer concentration. Addition of compatibilizers to HDPE/sPS blend resulted in a significant reduction in crystallinity of both HDPE and sPS. Measurements of Vicat softening temperature of the HDPE/sPS blends show that heat resistance of HDPE is greatly improved upon incorporation of 20 wt% sPS.     

Mechanical properties of polystyrene/low density polyethylene blends

Some mechanical properties of blends of polystyrene and low density polyethylene have been derived from stress-strain and impact measurements. The strength and impact properties are improved by adding a graft copolymer of polystyrene and low density polyethylene to the blends. It is assumed that the copolymer acts as an adhesive at the interface of the homopolymers thus decreasing the stress concentrations around the dispersed polymer particles at yield. The impact strength and modulus of polystyrene-graft copolymer blends could be made comparable to those of commercial rubber-modified impact polystyrenes by adjusting the fraction of copolymer in the blend.     

PP-g-MAH对玻璃纤维增强PP的影响

研究了聚丙烯接枝马来酸酐(PP-g-MAH)和剪切场强度等对玻璃纤维增强聚丙烯(GFRPP)性能的影响。加入PP-g-MAH后,GFRPP的拉伸强度持续增加,最大达82.5 MPa;弯曲性能大幅度提高;缺口冲击强度明显增大,最大达160.3 J/m;热变形温度基本维持不变。PP-g-MAH的加入可改善玻璃纤维与聚丙烯间的界面作用,从而有利于提高GFRPP的性能。在极高剪切场强度的条件下,GFRPP的力学性能和热性能有所下降。     

Work of fracture of polystyrene/high density polyethylene blends compatibilized by triblock copolymer

The fracture toughening behavior of polystyrene/high density polyethylene blends compatibilized by 10 wt % of a styrene‐ethylene‐butylene‐styrene triblock copolymer (SEBS) was assessed using single‐edge notched tension (SENT) and double‐edge notched tension (DENT) specimens of various gauge lengths over a wide range of tensile rates. The fracture of DENT and SENT specimens was completely ductile under the plane‐stress condition. A linear relationship was observed between the specific total work of fracture and the ligament length (L) for a given L range. The results showed that the essential work (w_e) was independent of the tensile rate (R) range of 1–30 mm/min, and it then decreased considerably when R was increased to 50 mm/min and above. However, the nonessential work exhibited a rate independent trend behavior. In addition, w_e and the specific nonessential work of fracture (βw_P) were basically independent of the gauge length (G), provided that G was greater than the width of the sample. Finally, it was also shown that the w_e and βw_P values for SENT specimens are obviously greater than those for DENT specimens. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2074–2081, 2000     

Influence of high density polyethylene‐g‐maleic anhydride on compatibility and properties of poly(butylene terephthalate)/high density polyethylene blends

Poly(butylene terephthalate)/high density polyethylene (PBT/HDPE) blends and PBT/HDPE‐grafted maleic anhydride (PBT/HDPE‐g‐MAH) blends were prepared by the reactive extrusion approach, and the effect of blend compositions on the morphologies and properties of PBT/HDPE blends and PBT/HDPE‐g‐MAH blends was studied in detail. The results showed that flexural strength, tensile strength, and notched impact strength of PBT/HDPE blends decreased with the addition of HDPE, and flexural strength and tensile strength of PBT/HDPE‐g‐MAH blends decreased, while the notched impact strength of PBT/HDPE‐g‐MAH increased with the addition of HDPE‐g‐MAH. Compared with PBT/HDPE blends, the dimension of the dispersed phase particles in PBT/HDPE‐g‐MAH blends was decreased and the interfacial adhesion was increased. On the other hand, the effects of HDPE and HDPE‐g‐MAH contents on the crystalline and the rheological properties of the blends were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6081–6087, 2006     

Melt rheology of compatibilized polystyrene/low density polyethylene blends

Investigations have been made on the melt rheological behaviors of compatibilized blends composed of polystyrene, low density polyethylene and hydrogenated (styrene‐butadiene‐styrene) triblock copolymer used as a compatibilizer. The experiments were carried out on a capillary rheometer. The effects of shear stress, temperature and blending ratio on the activation energy for viscous flow and melt viscosity of the blends are described. The study shows that the viscosity of the blends exhibits a maximum or minimum value at a certain blending ratio. The activation energy for viscous flow decreases with increasing LDPE content. Furthermore, the concept of equal‐viscosity temperature is presented and its role in the processing of the blend is discussed. In addition, the morphology of the extrudate sample of the blends was observed by scanning electron microscopy and the correlation between the morphology and the rheological properties is explored. © 1999 Society of Chemical Industry     

Dynamic mechanical properties of polystyrene/low density polyethylene blends

The dynamic mechanical properties of polystyrene/low density polyethylene blends and of polystyrene/polyethylene/di-block polystyrene-polyethylene copolymer blends have been investigated in the temperature range −160°C to +100°C. It is shown that anomalies in the low temperature shear modulus data of polystyrene-polyethylene blends are a consequence of non-adhesion between the components. From similar data of blends containing a partial di-block PS-PE copolymer it appears that only very small amounts of copolymer are needed to ensure adhesion between the polystyrene and polyethylene phase. Further it is shown that for modulus considerations of the blends, LDPE together with partial PS-PE copolymer can be treated as a single phase. In some cases the presence of copolymer causes formation of a continuous network throughout the polystyrene matrix, as reflected by a low value for the shear modulus of these blends. Phase reversal of polystyrene-polyethylene blends results in an increase of the loss modulus at 40°C which is ascribed to an increased friction caused by phase entanglements. This increase is more pronounced if an excess of polyethylene is present which is again a consequence of non-adhesion between the components.     

Interfacial modification of high density polyethylene/glass fiber reinforced and non reinforced polyamide 66 blends

High density polyethylene (HDPE) and polyamide (PA66) are well known to be incompatible. An ionomer (Surlyn) was added as a compatibilizer to HDPE and glass fiber reinforced (HDPE/GFRPA66) and non‐reinforced (HDPE/PA66) blends. Two compositions were considered: 25/75 wt % and 75/25 wt %, with an emphasis on the former formulation. The influence of the compatibilizer on the rheology, thermal properties, and the morphology, as well as mechanical properties of the blends, was investigated using melt flow index measurements, DSC, scanning electron microscopy (SEM), and impact strength. The ionomer was found to be more effective as a compatibilizer with HDPE as a minor phase compared to the case when HDPE becomes the major phase. The results indicated that the interfacial properties of the blends were improved, with a maximum appearing at a critical concentration of the ionomer (7.5 vol %). At this level of compatibilization, SEM analysis revealed better interfacial adhesion and a finer dispersion. MFI results revealed a probable reaction between the amine groups of PA66 and the acid functions of the ionomer. The mechanical properties support the above results and showed that the addition of 25 wt % HDPE did not affect the properties of PA66 much and the presence of glass fiber did not hinder the effect of the compatibilizer. Only 20% decrease in notched Izod impact strength of the blends is observed at 7.5 vol % ionomer content, suggesting that the addition of 25 wt % of HDPE to PA66 is not detrimental at this level of compatibilization. The emulsification curve was established and revealed that, in terms of impact properties, the finer the particle size, the higher the impact strength corresponding to 7.5 vol % ionomer content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1748–1760, 2005     

熔融法聚乙烯蜡接枝马来酸酐的研究

研究了熔融法聚乙烯蜡接枝马来酸酐的工艺过程和影响反应的主要因素。以丙酮为溶剂，将MAH和聚合引发剂配成溶液滴加反应，引发剂和MAH的质量分数各为12％，反应温度165℃左右，接枝率可达15．6％。经红外谱图分析证明聚乙烯蜡与马来酸酐发生了接枝反应。在热熔胶的制备中，发现使用接枝聚乙烯蜡比使用未接枝聚乙烯蜡的粘接强度(PVC／木材)提高了约90％。     

Hydrophilic polystyrene/maleic anhydride ultrafine fibrous membranes

Polystyrene/maleic anhydride (PSMA) was synthesized to reach a viscosity‐average molecular weight of 700 kDa and fabricated into ultrafine fibrous membranes consisting of fibers with an average diameter of 300 nm. These ultrafine PSMA fibers were rendered insoluble in organic solvents by reactions with hydrazine and ethylenediamine (ED). The highly efficient incorporation of diamines into the fibrous membranes was easily achieved by brief immersions in either dilute (0.5 wt %) hydrazine for 1 min or ED ether solution for 2 min. Heating at 150°C for 5 min produced crosslinked PSMA with very little or no solubility in acetone with the retention of the fibrous membrane structure. The ED‐crosslinked membranes were particularly stable to both bases and acids as well as hydrophilic solvents, had a 46° water contact angle, and absorbed 22 times the amount of water as the as‐spun fibrous membrane. This post‐fiber‐formation crosslinking approach was robust, highly efficient, and fast and required very little crosslinking reagent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ultraviolet preirradiation of high‐density polyethylene for the grafting of maleic anhydride during reactive extrusion

High‐density polyethylene was irradiated with ultraviolet light for various exposure times, as a prestep for hydroperoxide production, before a bulk grafting reaction with maleic anhydride in the melt phase by reactive extrusion. This method was compared with a traditional grafting procedure using peroxides optimized by an evaluation of the grafting level versus the screw speed; the highest speed showed the greatest grafting value. The reaction was followed by Fourier transform infrared, the gel percentage, and the grafting degree, which was evaluated by titration. The effect of grafting for both methods under the established processing conditions on the thermal properties was observed with differential scanning calorimetry via their heating and cooling thermograms; there were notorious changes in the fusion peak temperatures, indicating differences in the crystallization process after the grafting reaction. The latter was confirmed by NMR spectroscopy, which showed succinic anhydride rings attached to the polyethylene chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2882–2888, 2006     

Peroxide‐initiated comonomer grafting of styrene and maleic anhydride onto polyethylene: Effect of polyethylene microstructure

Maleic anhydride has been grafted onto various polyethylenes (PEs) using 2,5‐dimethyl‐2,5‐(di‐t‐butylperoxy)hexane as a free radical initiator in the presence of styrene as a comonomer. Three polyethylenes, differing systematically in their levels of terminal unsaturation and branching, were selected to investigate the effect of these microstructural characteristics on the course of both grafting and crosslinking. It was observed that when polyethylenes containing high levels of terminal unsaturation were reacted in the presence of peroxide or peroxide–maleic anhydride, crosslinking events were enhanced. When styrene was added as comonomer to the reaction medium to eliminate these undesirable side reactions, crosslinking was still observed with those polyethylenes that contained a high concentration of terminal unsaturation. This is attributed to a low reactivity between styrene and the allylic radical generated on the polyethylene backbone, which is believed to be responsible for the increased crosslinking. However, in the presence of high concentrations of styrene, crosslinking was eliminated for PEs containing high degrees of branching. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 96–107, 2001     

Compatibilization of polyethylene/polyaniline blends with polyethylene‐graft‐maleic anhydride

The use of compatibilizers as interfacial agents in composites can offer a convenient way to improve the mechanical properties of immiscible polymer blends. The aim of this article is to illustrate the compatibilization effect of polyethylene‐graft‐maleic anhydride (PEgMA) in blends of low‐density polyethylene (LDPE) and n‐dodecylbenzene sulfonate doped polyaniline (PANIDBSA) prepared by extrusion. Films with different compositions of the coupling agent were evaluated with optical spectroscopy and thermomechanical, electrical, mechanical, and morphological techniques. The incorporation of PEgMA into the LDPE/PANIDBSA composites resulted in an improvement of their electrical conductivity and changes in the mechanical and morphological properties of the films. When 5 wt % of the coupling agent was added to a 30 wt % of the polyaniline‐containing film, the conductivity increased by more than three orders of magnitude, and the ductility also improved qualitatively. The morphology analysis also indicated that the addition of PEgMA produced a strengthening of the filler–matrix interfacial region. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Functionalization of high density polyethylene with maleic anhydride in the melt state through ultrasonic initiation

Grafting of maleic anhydride (MAH) onto high density polyethylene (HDPE) performed in the melt state through ultrasonic initiation by a laboratory‐scale ultrasonic extrusion reactor was studied in this paper. The effect of sonic intesity on the amount of grafted MAH, viscosity‐average molecular weight and melt flow index of the grafted product was investigated. The results show that the ultrasonic waves can obviously decrease the molecular weight of the grafted product and cause the increase of the amount of grated MAH, implying that the grafting reaction consists of the chain scission and the grafting reaction of the produced macroradicals with MAH. The percentage of grafting of the product amounts to 0.6%; its melt‐flow index is between 0.5 and 2.0 g/10 min, depending upon ultrasonic intensity, MAH content and grafting temperature. Compared with the method of peroxide initiation, in this method the crosslinking reaction can be prevented easily through the allocation of ultrasonic intensity. The mechanical properties of the improved HDPE/GF composite produced by ultrasonic initiatives are higher than in those produced by peroxide initiatives.     

SEBS-g-MA对PS/PA6的相形态及非等温结晶行为的影响

采用熔融共混的方法制备共混物PS/PA6(质量比为50/50)和PS/PA6/SEBS-g-MA(质量比50/50/5).SEM观察发现PS/PA6呈现双连续的相态,加入质量分数为5%的SEBS-g-MA到PS/PA6中,PS和PA6的相畴尺寸均减小,但仍然保持双连续的相态.采用差示扫描量热法分析了PS/PA6和PS/PA6/SEBS-g-MA的非等温结晶行为,加入SEBS-g-MA提高了PS/PA6中PA6的结晶起始温度To、结晶峰温度Tp,减小了结晶过程总时间At和半结晶时间t1/2.Jeziorny法和Mo法都适用于PS/PA6和PS/PA6/SEBS-g-MA的非等温结晶动力学过程,通过Jefiomy法分析第一阶段非等温结晶过程得到PS/PA6的Avrami常数n为4.40～4.91,PS/PA6/SEBS-g-MA的Avrami常数n为2.47～3.25,PS/PA6/SEBS-g-MA的Z.也大于PS/PA6的Z.通过Mo法得到在相同的相对结晶度X,下,PS/PA6/SEBS-g-MA的leF(T)小于PS/PA6的IgF(T)值.这些都说明SEBS-g-MA对PS/PA6中的PA6有诱导结晶作用.而Ozawa 法不适合于PS/PA6和PS/PA6/SEBS-g-MA的非等温结晶动力学过程.     

Crystallization and dynamic mechanical properties of polypropylene/polystyrene blends modified with maleic anhydride and styrene

Polypropylene (PP)/polystyrene (PS) blends modified with reactive monomers, such as maleic anhydride (MAH) and styrene (St), and in situ formed PP/PS blends were prepared by melting extrusion. The crystallization and melting behavior and the dynamic mechanical properties of the PP/PS blends, including the structure of the grafted copolymer, were investigated with differential scanning calorimetry, dynamic mechanical analysis, and Fourier transform infrared. The results indicated that the addition of MAH hardly influenced the crystallization temperature of PP in the blends, but the addition of MAH and St increased the crystallization temperature of PP in its blends. The blends showed no remarkable variety for the melting temperature, but the shapes of the melting peaks were influenced by the addition of the reactive monomers. In addition, a significant increase in the storage and loss moduli of all the modified PP/PS blends was observed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2038–2045, 2005