High‐density polyethylene modified by polydimethylsiloxane

High‐density polyethylene (HDPE) was modified by the grafting of polydimethylsiloxane (PDMS) through a free‐radical process, in a melt‐mixer chamber, using dicumyl peroxide (DCP) as an initiator. The influence of PDMS (0.2–0.8 mol %) and peroxide (0.03–0.08 mol %) concentrations on the grafting, final torque, and melt flow rate (MFR) of copolymers were investigated using factorial planning. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), MFR, and rheometry were used to characterize the copolymers obtained. Surface plots showed that higher degrees of grafted PDMS and higher final torques were obtained with increase in the PDMS amount at low DCP levels and with increase in the DCP amount at low PDMS levels. The peaks of fusion and crystallization of the copolymers showed no significant changes with respect to HDPE. Data of MFR and GPC suggested that crosslinking reactions and/or chain extension occurred concomitant with the grafting reactions. Copolymers with high grafting degrees showed high MFR and low dynamic shear viscosities in comparison with low grafting degree copolymers, which is probably due to the migration of the PDMS‐containing copolymers on the surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3460–3467, 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。     

E/VAC与马来酸酐反应挤出接枝的研究

用同向双螺杆挤出机进行Ｅ／ＶＡＣ熔融接枝ＭＡＨ的反应。考察了单体、引发剂用量和加工条件对接枝率及熔体流动速率的影响。结果表明,在Ｅ／ＶＡＣ接枝ＭＡＨ的反应中,接枝率随着ＤＣＰ用量、ＭＡＨ用量以及螺杆转速的增加出现峰值,较佳的实验配方为Ｅ／ＶＡＣ：ＭＡＨ：ＤＣＰ＝１００：２：０．２。接枝反应对Ｅ／ＶＡＣ的流动性有很大影响,接枝物的熔体流动速率随ＤＣＰ用量的增加而下降。     

相容剂马来酸酐-苯乙烯接枝聚丙烯的制备及性能研究

研究单体用量、引发剂用量、反应温度、反应时间对熔融接枝法制备的马来酸酐-苯乙烯接枝聚丙烯(PP-g-(MAH-co-St))的接枝率(GMAH)、熔体流动速率(MFR)和拉伸强度的影响,并通过红外光谱图对PP-g-(MAH-co-St)进行表征。结果表明:当PP:MAH:St:DCP质量分数比为100:6:6:0.4,反应温度为180℃,反应时间为3 min时,接枝物的GMAH达1.51%,MFR达55.28 g/10min,拉伸强度为26.72 MPa;红外分析表明:MAH和St与已接枝到PP上。     

Comparison of maleic anhydride grafting onto powder and granular polypropylene in the melt by reactive extrusion

The grafting of powder and granular polypropylene (PP) with maleic anhydride (MA) was investigated in a reactive extrusion process with dicumyl peroxide (DCP) as an initiator. The effects of the MA and DCP contents in the feed on grafting were investigated. Under the experimental conditions applied in this study, the grafted monomer unit content was varied from 0.023 to 0.5%. The MA grafting efficiency of powder PP was higher than that obtained for the granular form of PP. In general, the grafting degree first increased with the MA or DCP content in the feed, then reached a maximum value, and finally decreased because of several possible alternative reactions during the grafting. The grafting of powder PP was more successful because of better initial mixing and less diffusional resistance during the grafting. An increase in the MA content in the feed caused significant reductions in the melt‐flow index of the graft copolymers. The results obtained with Fourier transform infrared, differential scanning calorimetry, and X‐ray powder diffraction analyses indicated that the structure, macrotacticity, crystallinity, crystallization, and thermal behavior of PP changed with grafting and depended on the grafting degree. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3675–3684, 2004     

Assessment of the utilization of different peroxide dispersion media on the controlled degradation of polypropylene

A two‐step investigation of polypropylene‐controlled degradation was performed. First the controlled degradation of polypropylene was investigated by assessing the effects of using dicumyl peroxide (DCP) and 2,5‐dimethyl‐2,5‐di(t‐butylperoxy) hexane (DHBP) in different suspensions (neat, calcium carbonate, and organically modified montmorillonite). The second part of this research was performed according to a factorial design at two levels (2² experimental design) with center point, in which peroxide concentration and reaction time were studied. Polypropylene degradation was assessed by melt flow rate (MFR) and parallel plate rheometry. Results showed that DCP presented higher molar efficiency in polypropylene degradation reactions in relation to DHBP; likely due to radical recombination reactions. The results also indicate that clay may catalyze the recombination reactions of polypropylene radicals. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

A factorial design applied to polypropylene functionalization with maleic anhydride

Maleic anhydride functionalized PP was prepared in a melt-mixer according to a factorial design. Two levels of maleic anhydride concentration (MA), dicumyl peroxide concentration (DCP), reaction time, and temperature were employed. The isolated and interaction effects of these variables on the degree of functionalization and molecular weights were analyzed. The products were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), titration, and torque measures. The reaction time showed no appreciable effect within the studied range (10 to 20 minutes); however, the other three factors showed significant main effects. MA and temperature presented an important interaction effect on the degree of functionalization and molecular weights. The highest degrees of functionalization were found to be related to the smallest molecular weights.     

PP熔融接枝AMPS的研究

以过氧化二异丙苯(DCP)为引发剂,采用反应挤出技术制备了聚丙烯接枝2-丙烯酰胺-2-甲基丙磺酸共聚物(PP-g-AMPS)。研究了引发剂、单体及第二单体丙烯酰胺(AM)用量、以及温度、螺杆转速等工艺条件对接枝共聚反应的影响,用红外光谱对制备的接枝物进行了表征。结果表明:PP熔融接枝AMPS反应的适宜温度范围及螺杆转速分别为190～200℃和25Hz;接枝共聚反应中DCP及AMPS的最佳用量分别为PP的0.3%和4.0%;添加一定量的AM有利于接枝产物接枝率的提高,AM的最佳用量为PP的0.5%;AM的加入在一定程度上抑制了PP的降解。     

磷酸三苯酯对丙烯酸熔融接枝等规聚丙烯的影响

利用磷酸三苯酯(TPP)预溶胀等规聚丙烯(i-PP),而后将单体丙烯酸(AA)及引发剂过氧化异丙苯(DCP)分散于聚丙烯(PP)树脂中,在190℃条件下熔融反应得到接枝产物。利用傅立叶红外光谱分析仪(FT-IR)、熔融流动速率测定仪、差示扫描量热仪(DSC)、热重分析仪(TGA)等对接枝产物的接枝率、熔融流动速率(MFR)、结晶度及热稳定性进行了分析和表征。实验结果表明,当w(TPP)=1%时,较未添加TPP的AA接枝PP,AA接枝率增幅高达130%;TPP的加入可以有效降低副反应的发生;随着接枝率的提高,接枝产物的熔点(Tm)及结晶度(Xc)下降,接枝物的热稳定性有显著提高。     

Melt grafting of maleic anhydride onto polypropylene with assistance of α‐methylstyrene

Melt grafting of maleic anhydride (MA) and α‐methylstyrene (AMS) onto polypropylene (PP) was performed by reactive extrusion. Effects of AMS on the graft degree of MA, crystallization behavior, and thermal properties of the graft copolymer were investigated. Results show that the addition of AMS as a comonomer can efficiently improve the MA graft degree. When the molar ratio of AMS to MA is 0.9:1, the maximum MA graft degree is attained, which increases about 56% compared with that using single monomer of MA. The results of the graft degree of MA obtained by chemical titration (CT) agree well with those obtained by Fourier transform infrared spectroscopy (FTIR). Melt flow rate (MFR) measurements indicate that the addition of AMS effectively reduces the degradation of PP molecules. The wide‐angle X‐ray diffraction (WAXD) results show that in comparison with the PP‐g‐MA sample, the PP‐g‐(MA‐AMS) sample shows no new crystalline form, but has a slight decrease in the average crystalline domain size. According to the results of thermogravimetry (TG) and differential scanning calorimetry (DSC), the graft PP in the presence of AMS exhibits a lower melting point and a higher crystallization temperature and thermal stability in comparison with that without AMS. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Effect of reactive group types on the properties of core-shell modifiers toughened PA6

Summary  Reactive monomers such as acrylic acid (AA), maleic anhydride (MA) and glycidyl methacrylate (GMA) were grafted onto acrylonitrile-butadiene-styrene core-shell copolymer (ABS) by emulsion polymerization method. These functionalized ABS were used to toughen PA6. FTIR and Molau tests showed that these monomers were introduced onto ABS copolymers and compatibilization reactions took place between PA6 and the AA, MA and GMA grafted ABS. TEM result showed that the modified ABS copolymer dispersed in PA6 matrix uniformly and no obvious difference could be found between the different PA6 blends. However, mechanical test showed that GMA and MA modified ABS achieved much better toughening effect than the AA grafted ABS copolymer due to the stronger interfacial reactions. Fracture characterization indicated that PA6 toughened with GMA and MA modified ABS showed higher G_ivalues according to the Vu-Khanh approach and much obvious shear yielding in the deformed zone could be found.     

Adhesion between ethylene-propylene-diene monomer and thermoplastics in two-component injection molding: Effect of dicumylperoxide as curing agent

Strong adhesion at the interface is an important aspect in two-component (2K) injection molding. It was therefore investigated whether dicumylperoxide (DCP) as curing agent in ethylene-propylene-diene monomer (EPDM) could stimulate interdiffusion and/or induce chemical bonding with thermoplastics. EPDM mixtures containing DCP concentrations between 2 to 8 parts per hundred rubber (phr) were combined with polar and non-polar thermoplastics. Changes in EPDM physico-mechanical bulk properties were analyzed, and the adhesion was evaluated by high temperature contact angle measurements and tensile testing. Results showed that DCP concentration did not influence EPDM-thermoplastic compatibility. However, EPDM adhesion with polyethylene (PE) did improve when using up to 6 phr DCP (57% adhesion) as crosslinking is promoted. While with polypropylene (PP), adhesion linearly decreased (from 55% to 35% adhesion) with higher DCP concentrations due to prevailing scission reactions. Adhesion through chemical bonding with acrylonitrile-butadiene-styrene (ABS) caused better adhesion at 4 phr (43% adhesion) compared to polycarbonate (PC) at 4 phr (13% adhesion) where only limited interdiffusion occurs. Thus, selecting the optimal DCP concentration is highly important to boost adhesion between EPDM and thermoplastics. Furthermore, at these optimal DCP concentrations, physico-mechanical properties require consideration as these properties were significantly affected.     

不同改性剂对ABS/CaCO_3复合材料性能的影响

首先采用不同改性剂对超细重质碳酸钙(CaCO_3)进行表面改性,然后作为无机填料填充丙烯腈–丁二烯–苯乙烯塑料(ABS),制备ABS/CaCO_3复合材料,研究了不同改性剂添加量和改性时间对CaCO_3吸油值、接触角和沉降体积的影响,测试了复合材料的力学性能、熔体流动速率(MFR)和热稳定性,并采用扫描电子显微镜观察了CaCO_3粒子在ABS基体中的分散性。结果表明:经不同改性剂表面处理后,CaCO_3的吸油值和沉降体积降低,接触角增大,其中以大分子活性硅烷(JST-3G)改性的CaCO_3的吸油值和沉降体积(60 min)最小,接触角最大,分别为16 m L/(100 g),0.2 m L/g和120°。经过表面改性的CaCO_3显著提高了复合材料的力学性能和加工流动性,改善了CaCO_3粒子在ABS基体中的分散性。采用大分子活性硅烷(JST-3G)改性的CaCO_3制备的复合材料的力学性能和加工流动性最佳,其拉伸强度、弯曲强度、简支梁缺口冲击强度和MFR分别达到了39.2 MPa,71.2 MPa,13.2 k J/m~2和37.6 g/(10 min)。经不同改性剂处理后,CaCO_3粒子在ABS基体中的分散性均有所提高,尤其以大分子活性硅烷(JST-3G)改性的CaCO_3在ABS基体中的分散性最优。     

Functionalization in solution of polypropylene with a maleinized hyperbranched polyol polyester: Structural,thermal, rheological,and mechanical properties

The functionalization of polypropylene (PP) with a maleinized hyperbranched polyester polyol (MHBP) was performed in solution to obtain PP-g-MHBPs. The degree of functionalization (FD) increased with MHBP and dicumyl peroxide (DCP) contents, but the contact angle followed an opposite behavior. The sample obtained with the proportion of 9.0 wt % MHBP and 2.0 wt % DCP and presented the highest FD value. An FD value of 2.4 wt %, produced a reduction of 19° on the contact angle. It was observed by differential scanning calorimetry (DSC) that the PP-g-MHBPs obtained by employing 3.0 wt % of MHBP, exhibited a slight reduction of the melting temperature (T_m) with the increase in the amounts of FD and DCP. Some FD values obtained in this study are higher than those obtained both commercial and noncommercial grades of PP functionalized with maleic anhydride. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46932.     

聚乙烯反应挤出接枝马来酸酐的研究

以过氧化二异丙苯(DCP)为引发剂,使用反应挤出机研究了不同种类聚乙烯及其共混物接枝马来酸酐的反应规律。实验结果表明:产物的接枝率和熔体流动速率(MFR)变化与聚乙烯的种类有直接关系,接枝性能从优到差的顺序为:LDPE>LLDPE>HDPE;引发剂DCP对LDPE接枝产物的MFR影响显著,对LLDPE次之,对HDPE的MFR几乎没有影响;聚乙烯共混物的接枝性能取决于组成共混物的聚乙烯种类和用量。接枝产物及纯化后样品的红外光谱分析表明,酐基是以化学键连接到聚乙烯分子链上,接枝产物几乎不含游离态的马来酸酐。     

马来酸酐接枝乙烯-丙烯酸丁酯共聚物的研究

以过氧化物为引发剂、马来酸酐（MAH）为单体,采用溶液法对乙烯-丙烯酸丁酯共聚物（EBA）进行接枝改性,并用傅立叶红外光谱技术对接枝物（EBA—g—MAH）进行了表征。系统考察了引发剂种类及用量、反应温度、反应时间、单体用量等因素对接枝率及熔体流动速率的影响。实验结果显示,EBA接枝MAH的优化反应条件是：原料配比为m（EBA）：m（MAH）：m（BPO）=100：2：0．28,反应时间为4h,反应温度为90℃,接枝率可达0．78％。随着反应温度的升高,接枝物的熔体流动速率急剧下降。不同的过氧化物引发剂对接枝反应的影响明显不同,与过氧化二异丙苯（DCP）相比,选择过氧化二苯甲酰（BPO）为引发剂,接枝效果较好,同时所得接枝物的MFR值适中。     

Styrene‐assisted grafting of maleic anhydride onto isotactic poly butene‐1

Grafting of maleic anhydride (MAH) onto isotactic poly butene‐1 (iPB‐1) was carried out by thermal decomposition of dicumyl peroxide (DCP) using electron‐donating monomer styrene (St), and were carried out in the molten state in a twin‐screw extruder according to an experimental design in which the content of MAH and St were varied. The calibration curve was constructed from FTIR measurements and titration which can obtain the absolute amounts of grafted MAH according to FTIR data. The proposed mechanism was that when St is added to the iPB‐1/MAH/peroxide grafting system, St reacted first with MAH to form a charge‐transfer complex (CTC). Then CTC react (or copolymerize) with macroradicals. The grafting of MAH onto iPB‐1 (iPB‐1‐MAH) accelerated crystalline transformation rate of form II to I. The contact angle decreased with the increase of grafting degree, which indicated that surface polarity increased. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Effect of dicumyl peroxide on biodegradable poly(lactic acid)/functionalized gum arabic based films

Blending of poly (lactic acid) (PLA)/functionalized gum arabic (FG) in presence of dicumyl peroxide (DCP) presents a simple process to produce film using melt extrusion (recycle time ~ 4 min, screw speed ~60 rpm) at 180°C with tailored characteristics. The FTIR investigation shows that the confirmation of grafting of PLA chains on FG through formation of new C─C linkage. Properties of fabricated films such as morphological, mechanical, UV barrier and contact angle are examined to develop film with improved interfacial interaction, increased toughness, UV–C blocking effect (~95%) and hydrophobicity (~14%). Polarized optical microscopy (POM) studies reveal that PLA/1FG with and without DCP has more crystal density as compared to PLA at 120°C. This melt extrusion permits straightforward, feasible bionanocomposite film and has great potential as a modification with DCP assists to overcome particular drawbacks of FG.     

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.     

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.