GRAFT COPOLYMERIZATION OF POLYPROPYLENE COPOLYMER WITH MALEIC ANHYDRIDE: EFFECT OF GRAFTING ON THERMAL,MECHANICAL PROPERTIES,AND PAINTABILITY

Graft copolymerization of polypropylene copolymer (PCP) with maleic anhydride (MA) was studied in melt in Brabender Plasticorder, Twin Screw Extruder by using peroxide initiators, such as benzoyl peroxide (BPO), lauryl peroxide (LPO), luperox-101 (LPU), and dicumyl peroxide (DCP). The variation of MA and initiator concentrations on percent grafting (G), melt flow index (MFI), torque, and gel formation was investigated. Graft copolymers (PgMA and PgMAT) were characterized by FT-IR, DSC, and TGA. Melt flow index increased and torque values decreased with an increase in initiator concentration. The increase in MFI values are in the order: DCP>LUP>BP0>LPO. Maximum chain scission was observed by using DCP and LUP as indicated by their MFI values. The incorporation of MA in PgMA and PgMAT was confirmed by the presence of carbonyl groups at 1712 cm^?1 and a shift in crystallization peak temperature from 113 to 123°C due to nucleating effect of the poly(maleic anhydride). The thermal stability was increased by the presence of PgMA. Addition of PgMAT as an additive to PCP, PCP/PP, and amines improves mechanical properties and paintability. Primary amines are more reactive towards PgMAT compared to tertiary amines.     

Investigation of styrene‐assisted free‐radical grafting of glycidyl methacrylate onto high‐density polyethylene using response surface method

In this study, the free‐radical grafting of glycidyl methacrylate (GMA) onto high‐density polyethylene (HDPE) in the presence of styrene, as a comonomer, is investigated using a Brabender internal mixer. To optimize grafting level of GMA onto HDPE, response surface method (RSM) was exploited. Using RSM method of experimental design, it was possible to investigate the individual effects of various variables including dicumyl peroxide (DCP) concentration, GMA content, as well as reaction time, and their interactions on grafting efficiency. The fitted quadratic model obtained from statistical analysis is expressed by an approximating function to investigate the final torque as a responding variable over the experimental range of the independent variables. The grafting yield of GMA onto HDPE for the prepared samples was determined using titration/back‐titration technique and Fourier transform infrared spectroscopy (FTIR). According to the torque–time diagrams, increasing the DCP content led to an increase in GMA grafting yield. Also, it was found that the reaction time imparts minor effect on the final processing torque, and there exists an interaction between DCP and GMA content. The results of melt flow index (MFI) test showed that increasing the reaction time at constant DCP and GMA content enhances the MFI values of the samples, due to the more probability of chain scission phenomenon. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of grafting formulations and extrusion conditions on properties of silane‐grafted polypropylenes

The melt grafting of unsaturated silanes onto powdered polypropylene (PP) in a Haake TW100 twin‐screw extruder and curing in hot water were studied. The influence of grafting formulations and extrusion conditions on the melt flow rates of grafted PP and the gel percentages of crosslinked PP was investigated. The gel percentages of methacryloylpropyltrimethoxysilane (VMMS)‐grafted PP were markedly higher than those of vinyltriethoxysilane (VTES)‐ and vinyltrimethoxysilane (VTMS)‐grafted PP, while significantly less degradation of PP during grafting was observed for VMMS‐grafted PP. When benzoyl peroxide (BPO) was used as an initiator, no degradation of PP during grafting was observed, and the melt flow rates of grafted PP decreased with increasing BPO concentration. In contrast, use of dicumyl peroxide (DCP) as an initiator resulted in severe degradation of PP, and the melt flow rates of grafted PP increased gradually with increasing DCP concentration. BPO resulted in higher gel percentages than those of DCP at a fixed initiator concentration. Introduction of styrene into the grafting system greatly improved the gel percentage of crosslinked PP and reduced the degradation of PP during grafting. The optimum molar ratio of styrene to monomer is at about 1.5:1. Relatively low processing temperatures and high screw speeds are favorable. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1233–1238, 2000     

PP/LDPE blends produced by reactive processing. I. Grafting efficiency and rheological and high‐elastic properties of [PP/LDPE]‐g‐IA melts

Itaconic acid (IA) was grafted onto polypropylene/low‐density polyethylene (PP/LDPE) blends. The ratio of polymeric components was varied from 100 : 0 to 0 : 100. The effect of the variation in the ratios of the components on grafting efficiency and concomitant side processes was studied. Grafting of IA (1 wt %) was initiated by 2,5‐dimethyl‐2,5‐di(tert‐butyl peroxy)‐hexane (0.3 wt %) and was carried out in an extruder reactor equipped with a dynamic mixer. An increase in the PP content of the blend led to a lower yield of the grafted product. With low concentrations of LDPE in the blend (up to 25 wt %), grafting efficiency was observed to increase, and this increase was greater in comparison with the additive rule. Between 25 and 99 wt % of LDPE in the blend, grafting efficiency rose monotonically with LDPE concentration. At or below an LDPE content of 25 wt %, the melt flow index (MFI) of [PP/LDPE]‐g‐IA would increase unlike with PP‐g‐IA systems. But a small quantity of PP (below 25 wt %) in the [PP/LDPE]‐g‐IA blends would result in a decreased MFI unlike with LDPE‐g‐IA. The dependence of swell index and melt strength on the ratio of polymeric components in [PP/LDPE]‐g‐IA blends also was investigated. ©2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5095–5104, 2006     

苯乙烯存在下马来酸酐熔融接枝聚丙烯的研究

分别在哈克流变仪（Haake）和双螺杆挤出机（TSE）中,研究了苯乙烯（St）存在下马来酸酐（MAH）熔融接枝聚丙烯（PP）的过程。讨论了过氧化二异丙苯（DCP）用量、St用量、MAH用量、反应时间、反应温度、螺杆转速以及反应器型式对接枝反应的影响．实验发现：随DCP用量的增加,MAH的接枝率先增加后减小,熔体流动速率（MFR）一直增加;保持MAH用量不变增加St用量时,MAH的接枝率在MAH与St的摩尔比为1：1时达到最大,MFR却一直减小;保持St用量不变增加MAH用量,MAH的接枝率先增加后略有减小,MFR却存在极大值;随反应时间的增加,MAH的接枝率与MFR都先增加后减小;温度过高,MAH的接枝率降低,PP热降解较严重;螺杆转速较低时,MAH的接枝率较低,螺杆转速较高时,PP降解增加;在TSE中的MAH接枝率比Haake中的低,但降解比Haake中的小得多。     

Rheology and morphology of polypropylene in situ grafted and blended with methyl methacrylate/n‐buthylacrylate copolymer

The rheology and morphology of polypropylene (PP) modified by grafting and blending with vinyl monomers were studied in this work. The PP powder was impregnated by mixture of methyl methacrylate (MMA)/n‐buthylacrylate (n‐BA) and copolymerized with azobisisobutyronitrile (AIBN) initiator. The simultaneous grafting and blending of PP with MMA‐co‐n‐BA copolymers were performed in a corotating, 40 L/D, twin‐screw extruder in the presence of dicumyl peroxide. The Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were used to verify the grafting level and dispersion state of MMA/n‐BA copolymer on PP matrix, respectively, and their rheological properties were studied. It is observed that MMA/n‐BA copolymer is finely dispersed in the PP matrix. In this way, PP can be grafted, blended, and simultaneously compatibilized with polar copolymers, as is seen in SEM images. The results showed that by increasing acrylate monomers grafting on to PP increased. The same trend was observed for AIBN initiator. The gel content of samples with 25% monomers showed an increased from 0.7% to 3.5% by increasing AIBN from 0.2% to 0.4%. The grafting reaction took place with chain scission of PP molecules and also cross‐linking reactions. The optimum grafting of 7.3% with lowest chain scission and cross‐linking were obtained for samples containing 15 wt% monomer and 0.3% AIBN initiator. J. VINYL ADDIT. TECHNOL., 21:290–298, 2015. © 2014 Society of Plastics Engineers     

Preparation of polypropylene/acrylonitrile–styrene copolymer alloys by one‐step reactive blending

The compatibilization of polypropylene/acrylonitrile–styrene (PP/AS) blends through the addition of peroxide (DCP) was investigated in this study. The grafting reaction between PP and AS with the addition of peroxide occurred during the reactive‐blending process. The in situ‐formed grafting copolymers of PP‐g‐AS and AS‐g‐PP were then characterized by FTIR. The optimum concentration of the initiator, DCP, was 0.2 wt %, and the reaction temperature should be above 195°C. It was found that, when AS was the major component of the blends, the grafting of AS onto PP was the main process; conversely, when PP was the major component, PP was grafted onto AS. These results can be explained by the main‐chain scission of PP during the reactive‐blending process. With increase of the AS component, the total degree of grafting increased at first and then decreased after the composition of the blends reached 50/50. The maximum degree of grafting was found to be 6 wt % for the 50/50 PP/AS/DCP blend. PP was more degradable than was AS in the presence of peroxide at high temperatures. The MFR values of the PP/AS/DCP blends were slightly greater than were those of the simple PP/AS blends, which means that blending is an effective way to protect PP from degradation. SEM micrographs of the cross section of PP/AS/DCP showed a fine dispersion and a smaller domain size of the dispersed‐phase particles, implying that the in situ‐formed grafting copolymers act as a compatibilizer to reduce the interfacial tension between the PP and AS phases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1284–1290, 2001     

羟甲基丙烯酰胺熔融接枝聚丙烯亲水性的研究

分别以羟甲基丙烯酰胺（NHA）、苯乙烯（St）为接枝单体,过氧化二异丙苯（DCP）为引发剂,用双螺杆挤出机制备了聚丙烯（PP）的接枝共聚物PP-g-NHA和PP-g-NHA/St。红外分析表明,NHA和St接枝到PP链上形成接枝共聚物。探讨了NHA用量、St用量、DCP用量及加工温度、螺杆转速对接枝率及接触角的影响。结果表明,NHA的最佳用量是3 %,此时接枝率达到最大值为1.6 %,接触角最小为83 °;随着DCP用量的增加,接枝率先增大后下降;加工温度不能太高,螺杆转速一定要大于40 r/min。     

Studies on effect of improved d‐spacing of montomorillonite on properties of poly(vinyl chloride) nanocomposites

Surface modification of montomorillonite for improvement in d‐spacing was done by column chromatography with quaternary long chain ammonium salt having cation exchange capacity of 110 meq/100 g. Organically modified montomorillonite (OMMT)/poly(vinyl chloride) (PVC) nanocomposites were prepared through direct melt compounding on a conventional twin screw extruder. Because of improved d‐spacing of OMMT, the polymer chains get exfoliated in between the plates of clay and dispersed uniformly. The mechanical properties of the nanocomposites were found to be appreciable at 12 wt % loading of OMMT. Moreover, rheological data, such as torque, fusion time, viscosity, and shear rate were also recorded on Brabender Plasticorder. The improvement in mechanical properties with increase in amount of OMMT loading is evidenced from reduction in shear viscosity and torque. Also nanoclay is acting as a lubricating agent with packing effect, which reduces the torque with decrease in viscosity along with increment in elongation at break. Because of soft nature of OMMT and improvement in d‐spacing the processing of PVC becomes easier, and hence, OMMT is playing a dual role as a (i) good processing aid and (ii) filler. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical,flow, and morphological properties of talc‐ and kaolin‐filled polypropylene hybrid composites

Polypropylene (PP) hybrid composites have been produced by compounding two types of mineral fillers, viz., talc and kaolin with PP copolymer using a twin screw extruder. The PP hybrid composite was injection‐molded into dumbbell specimen for tensile, flexural, and impact properties characterizations. MFI and SEM studies were used to characterize the flow and morphological properties of the PP hybrid composites. The result shows that most of the hybrid composites showed a significant decrease in flow, tensile, flexural, and impact properties compared with the single filler‐filled PP composites. However, a hybridization effect was seen for the PPT20K10 hybrid composites, through the synergistic coalescence of positive characteristics from 20 wt % of talc and 10 wt % of kaolin. This hybrid formulation have given an economically advantageous material with the mechanical properties (tensile, flexural, and impact) comparable to those of the talc‐filled PP composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 434–441, 2007     

多功能单体对反应共混PP／PS合金的影响

研究了在聚现烯／聚苯乙烯／过氧化二异丙苯（ＰＰ／ＰＳ／ＤＣＰ）反应挤出共混过程中,不同分子结构的多功能单体添加剂对共混物降解的抑制及增容作用的影响。研究发现,多功能单体所含的双键越是靠近分子末端,分子链越长,结构越简单,增容效果越好;若多功能单体分子中含有一定含量的碳－碳双键,则能很好地抑制降解。     

Melt grafting of n‐butyl methacrylate onto poly(vinyl chloride): Synthesis and characterization*

The graft copolymerization of n‐butyl methacrylate monomer onto compounded poly(vinyl chloride) was carried out by melt‐mixing process in a Brabender plasticorder (BPCR) using a free‐radical initiator. The reaction conditions such as initiator and monomer concentration, shear rate (rpm), residence time, and temperature were optimized in the mixing head of BPCR attached to a torque rheometer. The graft copolymers were Soxhlet extracted with cyclohexane and were characterized by intrinsic viscosity, FTIR, and ¹³C‐NMR spectroscopy. A maximum of 14% grafting was obtained. The graft copolymer showed significant improvement in processibility and both thermal and mechanical properties. Scale‐up studies of the optimized recipe were carried out in a single‐screw extruder for commercial trials/evaluation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2442–2449, 2004     

Morphology and mechanical properties of blends of linear low density polyethylene and poly(ethene‐propene‐1‐butene)

Blends of linear low density polyethylene (LLDPE) and ethene‐propene‐1‐butene copolymer (t‐PP) were obtained through mechanical mixing using a single‐screw extruder with different compositions: 20, 40, 50, 60, and 80 wt % of t‐PP. For this, two types of polyethylene were used: 1‐hexene comonomer and 1‐octene comonomer based. The same blends were prepared in a batch mixer and the torque and temperature were analyzed. The torque showed a decrease with increasing t‐PP content, indicating better processability of the mixture in comparison with LLDPE. The morphology of the blends was analyzed by SEM and showed a composition dependence. The mechanical properties of the blends were evaluated by tensile tests. The results revealed that the best properties were obtained in a 20% t‐PP blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1255–1261, 2006     

Effect of processing parameters on fusion and mechanical properties of a twin‐screw extruded rigid PVC pipe

The effect of varying mass temperature and screw speed on the fusion level and mechanical properties of a rigid PVC pipe produced by a twin‐screw extruder has been investigated. Differential Scanning Calorimetry (DSC) and capillary rheometry have been used to determine pipe fusion levels. While yield stress was shown to be completely insensitive to fusion level, a very distinct maximum of falling weight and notched Charpy impact strengths and elongation at break was observed at moderate fusion level. Short‐term burst strength values increased with degree of fusion while hydrostatic internal pressure tests revealed optimum resistance for pipes of varying fusion level. The effect of processing temperature on fusion in the Brabender Plasticorder was also examined.     

EPDM与马来酸酐的反应挤出接枝

用同向双螺杆挤出机,对三元乙丙共聚物（EPDM）进行熔融接枝马来酸酐（MAH）,考察了单体、引发剂（DCP）用量和加工条件对接枝率的影响。结果表明,在EPDM接枝MAH的反应中,随着DCP用量的增加,接枝率增大,随着MAH用量的增加,接枝率趋于一个平衡值,较佳的实验配方为EPDM：MAH：DCP=100：1：0.03。     

N-羟甲基丙烯酰胺熔融接枝聚丙烯的制备

利用双螺杆挤出机,制备了聚丙烯(PP)熔融接枝N-羟甲基丙烯酰胺,探讨了过氧化二异丙苯(DCP)和N-羟甲基丙烯酰胺用量、反应温度、螺杆转速等因素对接枝率的影响。分析表征了PP熔融接枝N-羟甲基丙烯酰胺的结构、流变性能及阻燃性能。     

Study of multi‐monomer melt‐grafting onto polypropylene in an extruder

Free‐radical melt‐grafting of the dual‐monomer systems glycidyl methacrylate–styrene (GMA‐St) and hydroxyethyl methacrylate–styrene (HEMA‐St) onto polypropylene (PP) has been studied using a single‐screw extruder. For single monomer grafting systems, degradation of PP was unavoidable and deterioration of the mechanical properties of the grafted PP subsequently occurred because of β‐scission of PP chains during the free‐radical melt‐grafting process. However, for the dual‐monomer systems, it is shown that the addition of styrene as a comonomer can significantly enhance the GMA or HEMA grafting levels on PP and reduce the extent of β‐scission of PP backbone. It has been found that the grafting degree of dual‐monomer melt‐grafted PP, such as PP‐g‐(GMA‐co‐St) or PP‐g‐(HEMA‐co‐St), is about quadruple that of single‐monomer grafted PP for the same monomer and dicumyl peroxide concentrations. Moreover, the melt flow rate of the dual‐monomer grafted PP is smaller than that of the unmodified PP. Hence, PP not only was endowed with higher polarity, but also kept its good mechanical properties. © 2000 Society of Chemical Industry     

Maleic anhydride grafting of polypropylene: peroxide and solvent effects

Abstract

The grafting of polyolefins with maleic anhydride (MA) has been incorporated into industrial practice to generate copolymers that can act as coupling agents between the non-polar polyolefins and different polar fillers and reinforcements. In the present study, two different peroxides were used to initiate the MA grafting onto polypropylene (PP), namely dicumyl peroxide (DCP) and 1,3-bis (terbutylisopropyl peroxi)benzene (DIBP). The use of DIBP allowed similar grafting yields to DCP to be obtained, but with less chain scission of the polyolefin. Moreover, the utilisation of a coagent, toluene (Tol), leads to a reduction in the chain scission of PP. A monotonous decrease in the melt flow index (MFI) of the polymer was observed with increasing molar ratio of Tol/MA, in the range of ratios considered (0–2·5). In addition, the free radical grafting of MA onto PP remained high and optimum grafting was obtained for a molar ratio Tol/MA of ～0·5. It was observed that the addition of toluene was effective, independent of the reaction process utilised, namely batch mixing or extrusion.     

Compatibilization of polyethylene/poly(propylene)/polystyrene blends

The compatibilization of mixtures of polyolefins or of polyolefins with polystyrene using either liquid polybutadiene (l-PB)/organic peroxide or styrene-butadiene-styrene (SBS) block copolymers was investigated. Tensile impact strength was chosen as a measure of compatibility. Binary blends LDPE/high-impact polystyrene (HIPS) and LDPE/poly(propylene) (PP) as well as LDPE/HDPE/PP/HIPS blends were prepared by blending in the chamber of a Brabender Plasticorder. Composition of the blends corresponds to real commingled plastic waste. It was found that l-PB-based compatibilizer enhanced the impact strength of LDPE/HIPS blends with LDPE contents higher than 60 wt.-% only. Also SBS copolymer enhanced the impact strength of LDPE/PP blends with LDPE contents higher than 40 wt.-%. Both the compatibilizers substantially increased the toughness of LDPE/HDPE/PP/HIPS blends with composition similar to the municipal plastic waste.     

丙烯酸改性水滑石接枝PP的制备工艺

采用单一变量法研究了化学参数(接枝单体用量、引发剂用量)和加工参数(螺杆转速、螺杆温度)对丙烯酸改性水滑石(AA-LDH)和聚丙烯(PP)接枝反应的影响。结果表明,通过FTIR谱图证实了丙烯酸接枝到PP上。随着AA-LDH含量的增加,接枝物的接枝率呈现先增大后减小的趋势,在AA-LDH用量为5.0 g时,接枝率有最大值,为1.45%;接枝物的拉伸强度和弯曲强度随着AA-LDH用量的增加逐渐减小,而冲击强度却随着AA-LDH用量的增加而逐渐增大。改变引发剂过氧化二异丙苯(DCP)用量、螺杆温度和螺杆转速,接枝物的力学性能的变化规律和接枝率的变化规律相似,都是呈现先增大后减小的趋势。综合分析得到制备AA-LDH接枝PP的最佳工艺条件为:PP用量为100 g时,AA-LDH用量为5.0 g,DCP用量为0.2 g,螺杆温度为190℃,螺杆转速为300 r/min。