A study on melt grafting of maleic anhydride onto low‐density polyethylene and its blend with polyamide 6

Graft copolymerization of low‐density polyethylene (LDPE) with a maleic anhydride (MAH) was performed using intermeshing corotating twin‐screw extruder in the presence of benzoyl peroxide (BPO). The LDPE/polyamide 6 (PA6) and LDPE‐g‐MAH/PA6 blends were prepared in a corotating twin‐screw extruder. The melt viscosity of the grafted LDPE was measured by a capillary rheometer. The grafted copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microcopy (SEM). The influence of the variation in temperature, BPO and MAH concentration, and temperature on the grafting degree and on the melt viscosity was studied. The grafting degree increased appreciably up to about 0.45 phr and then decreased continuously with an increasing BPO concentration. According to the FTIR analysis, it was found that the amount of grafted MAH on the LDPE chains was ～5.1%. Thermal analysis showed that melting temperature of the graft copolymers decreases with increasing grafting degree. In addition to this, loss modulus (E″) of the copolymers first increased little with increasing grafting and then obviously decreased with increasing grafting degree. Furthermore, the results revealed that the tensile strength of the blends increased linearly with increasing PA6 content. The results of SEM and mechanical test showed that the blends have good interfacial adhesion and good stability of the phase structure, which is reflected in the mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 267–275, 2010     

Microwave-Assisted Synthesis and Characterization of Poly(itaconic acid) Grafted Gellan Gum

Poly(itaconic acid) was grafted on GG in aqueous medium under microwave irradiation using a catalytic amount of BPO. Grafted copolymers (GG-g-PIA) were characterized by FT-IR, TGA, and SEM techniques. The influence of microwave power, exposure time, and composition of the reaction mixture on extent of grafting was studied. Conditions for obtaining the highest extent of grafting were optimized. The rate of grafting was determined from weight measurements. The overall activation energy for grafting is found to be to be 28.3 kJ/mol, indicating the possibility of occurrence of the grafting process with absorption of low thermal energy.     

Analysis and Characterization of Microwave Irradiation–Induced Graft Copolymerization of Methyl Methacrylate onto Delignified Grewia Optiva Fiber

Grafting of methyl methacrylate (MMA) onto delignified Grewia optiva fiber using ascorbic acid/H₂O₂ as an initiator was carried out under microwave irradiation. The effects of varying the microwave power, exposure time, and concentration of initiator and monomer of graft polymerization were studied to obtain maximum grafting percentage (26.54%). The experimental results showed that the optimal conditions for grafting were: exposure time, 10min; microwave power, 110 W; ascorbic acid concentration, 3.74mol/L × 10^?2; H₂O₂ concentration, 0.97mol/L × 10^?1; monomer concentration, 1.87mol/L × 10^?1. The graft copolymers were characterized by Fourier transform-infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA).     

Self‐initiating performance of maleic anhydride on surface photografting polymerization

Maleic anhydride (MAH) was photografted onto low‐density polyethylene (LDPE) films with a grafting efficiency of about 70% in the absence of a photoinitiator. The self‐initiating performance was attributed to a mechanism of abstracting hydrogen atoms from LDPE chains by excited MAH dimers. The supporting experimental results were as follows: (1) the far‐UV radiation (200–300 nm) was indispensable for the graft polymerization and 2) the crosslinking reaction of LDPE inevitably accompanied the grafting of MAH. In addition, the initiation performance of MAH was further confirmed by surface photografting of acrylic acid in the presence of MAH, where MAH was used as the photoinitiator. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3246–3249, 2001     

Chemical initiation mechanism of maleic anhydride grafted onto styrene-butadiene-styrene block copolymer

The mechanism of grafting styrene-butadiene-styrene (SBS) tri-block copolymer with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2^′-azo-bis-isobutyronitrile (AIBN) was studied by FTIR and ¹H NMR spectroscopies. The variation of CC (double bond) content in SBS-g-MAH was used to verify the different graft mechanisms of BPO and AIBN, indicating that the chemical initiation mechanisms of MAH grafted onto SBS of AIBN is different from that of BPO. The graft reaction occurs by addition on CC for AIBN, while by removal of an allylic hydrogen atom from SBS and by addition on CC at the same time for BPO. The graft efficiency of AIBN is higher than that of BPO in this system.     

芴酮引发光接枝改性LDPE膜的研究

采用紫外光引发接枝表面改性的方法,以芴酮(FL)为引发剂,在低密度聚乙烯(LDPE)薄膜表面上接枝丙烯酸(AA)、甲基丙烯酸(MAA)、丙烯酸甲酯(MA)、甲基丙烯酸甲酯(MMA)、丙烯酰胺(AM)等单体,以赋予薄膜表面新的化学性质.考察了引发剂浓度、紫外光的辐照时间、辐照强度、单体种类对LDPE薄膜接枝程度的影响.结果表明,在一定范围内,增加芴酮浓度,可以提高单体的接枝率,但当芴酮浓度达到5%时,接枝率反而下降.延长辐照时间至4 min和提高紫外光的辐照强度达100 W/m2,均有利于接枝反应的进行.不同单体在LDPE膜上的接枝能力与单体的活性、单体与基材的相容性等因素有关.接枝后,LDPE与水的接触角下降程度不仅与单体在膜上的接枝量有关,还与接枝单体的亲水性能密切相关.     

不同引发剂引发SBS接枝马来酸酐的机理研究

采用FTIR和1 H NMR研究了引发剂过氧化二苯甲酰 (BPO)和偶氮二异丁腈 (AIBN)对聚苯乙烯 聚丁二烯 聚苯乙烯 (SBS)接枝马来酸酐 (MAH)的影响 ,讨论了相应的接枝机理 ,通过丁二烯 (PB)段碳碳双键(CC)随接枝率变化的规律进一步验证了机理 .结果表明 ,BPO与AIBN引发接枝的机理不同 ,BPO可引发PB的双键和烯丙位碳氢键 ,但引发烯丙位的速率比引发双键大 ;当BPO浓度达到一定量时 ,大量烯丙位的引发保护了碳碳双键 ,随BPO浓度的增大 ,碳碳双键的含量先减少后增加 .AIBN不能引发PB段烯丙位的碳氢键 ,只能引发双键接枝     

聚乙烯与丙烯酸的溶液接枝聚合

以过氧化苯甲酰为引发剂，二甲苯为溶剂，进行了丙烯酸与低密度聚乙烯的溶液接枝聚合，研究了ＢＰＯ用量、溶液浓度以及丙烯酸用量对接枝率的影响。聚乙烯接枝了丙烯酸后与铝的粘结强度显著增大，当接枝率为７．２％时，剥离强度由未接枝时的１９３Ｎ／ｍ，提高到９８４Ｎ／ｍ。     

Graft Copolymerization of Artemisia Seed Gum with Acrylic Acid under Microwave and its Water Absorbency

A super‐absorbent polymer was prepared by grafting copolymerization of acrylic acid onto Artemisia seed gum, using microwave irradiation and ammonium persulfate as an initiator. The effect of various preparation conditions on its water absorbency, such as the ratio of acrylic acid to Artemisia seed gum, degree of acrylic acid neutralization, amount of initiator and microwave irradiation time, was investigated by orthogonal tests. The optimal reaction conditions were 3 min (irradiation time), 70% neutralization degree of acrylic acid and 2% initiator on the basis of the mass of acrylic acid used. When the mass ratio of acrylic acid to Artemisia seed gum is 5:0.5, the product has a water absorbency close to 400 times at room temperature in distilled water, this indicated that is has a high water absorbency. The structure of the graft copolymer was confirmed by Fourier transform infrared spectrometer (FT‐IR) and thermogravimetric analysis (TGA). Further more, this microwave irradiation processing method to prepare water absorbent materials has no industrial cast off produced, that is to say, this method is environmentally friendly.     

Solvothermal process for grafting maleic anhydride onto poly(ethylene 1-octene)

Solvothermal process was developed to graft maleic anhydride (MAH) onto poly(ethylene 1-octene) (POE). Fourier transform infrared spectra (FT-IR) and ¹H NMR spectra confirmed that maleic anhydride was successfully grafted onto the POE. The influences of MAH content, initiator concentration, POE concentration, reaction temperature, reaction time and solvents on the graft copolymerization were investigated through both of the grafting degree (GD) and gel content (GC). The results demonstrated that high grafting degree (up to 10.85%) could be obtained while the gel content was still low. Further studies revealed that POE-g-MAH could also be achieved in poor solvents of POE through this method.     

Grafting copolymerization of styrene and maleic anhydride binary monomer systems induced by UV irradiation

Photografting copolymerization of maleic anhydride (MAH) and styrene (St) onto LDPE film was investigated by using a one-step method, and further thermally induced grafting copolymerization of them was carried out by using a two-step method. Regarding the photografting copolymerization of MAH/St binary monomer system, both conversion percentage (CP) and grafting efficiency (GE) increased with raising the content of MAH in the monomer feed. In addition, the content of MAH in the grafted copolymers also increased with increasing the fraction of MAH in the monomer feed. The formation of LDPE-g-P(MAH-co-St) grafted film was identified by FTIR and ESCA spectroscopy. In the case of grafting copolymerization of MAH/St by the two-step method, grafting copolymerization proceeded slowly compared with the non-grafting copolymerization. The apparent activation energy (E_a) for the non-grafting copolymerization in the solution and the grafting copolymerization on LDPE film was 24 and 82 kJ/mol, respectively, which were noticeably lower than those of MAH/vinyl acetate (MAH/VAC) binary monomer system under the similar grafting conditions. These data of E_a explained why the grafting copolymerization of styrene/MAH took place faster than that of MAH/VAC binary monomer system. The composition of the grafted copolymer chains was largely affected by the composition of the monomer feeds; however, the composition of the non-grafted copolymers nearly remained at 1/1 even in systems with largely different MAH/styrene ratios in monomer feeds. It is indicated that the non-grafting copolymerization proceeded predominantly following alternating copolymerization, but the grafting copolymerization performed random copolymerization.     

甲基丙烯酸缩水甘油酯/苯乙烯固相接枝聚丙烯

以苯乙烯(St)为共单体，过氧化苯甲酰(BPO)为引发剂，采用固相接枝反应将甲基丙烯酸缩水甘油酯(GMA)接枝到聚丙烯(PP)大分子链上。研究了反应时间、单体用量、引发剂用量等因素对接枝率的影响。采用凝胶渗透色谱(GPE)测定了PP和接枝物PP-g-(GMA-St)的分子量和分子量分布。结果 表明固相接枝PP反应条件为[GMA／[St]=2，反应3．5h，加入GMA 10份，BPO 5份。St的加入有助于GMA与PP的接枝，同时在一定程度上抑制了PP的降解。     

The effect of gamma irradiation on mechanical, and thermal properties of recycling polyethylene terephthalate and low density polyethylene (R-PET/LDPE) blend compatibilized by ethylene vinyl acetate (EVA)

A study has been made on the compatibility of recycled polyethylene terephthalate (R-PET) and low density polyethylene (LDPE) blend in the presence of ethylene vinyl acetate (EVA) as a compatibilizing agent prepared by extrusion hot stretching process. EVA content in the blend as a compatibilizing agent was an enhancement effect on radiation crosslinking of R-PET/EVA/LDPE blends and the highest radiation crosslinking was obtained when the EVA content was reached at 10 % EVA when irradiated by gamma irradiation. Blends containing different (EVA) ratios were irradiated to different doses of gamma irradiation 25, 50 and 100 kGy. The effect of the compatibilizer and radiation on mechanical, thermal properties of R-PET together with LDPE and morphology has been investigated. It was found that gamma irradiation together with the presence of compatibilizing agent (EVA) has positive effect on the mechanical and thermal properties of R-PET/LDPE blend. The structural properties of R-PET/LDPE modified by gamma irradiation and EVA as compatibilizing agent was examined by SEM. Also, it was found that the optimum concentration of EVA and gamma irradiation dose was found to be 10 % EVA and 100 kGy, respectively.     

Photoinitiated grafting of maleic anhydride onto polypropylene

The photoinitiated grafting of maleic anhydride (MAH) onto polypropylene with the use of benzophenone (BP) as the initiator has been investigated. In comparison with the process of thermally initiated grafting with peroxide as the initiator, photoinitiated grafting affords a higher grafting efficiency. The efficient photografting sensitized by BP can be explained by two possible mechanistic processes: the sensitization of the formation of the excited triplet state of MAH by BP and electron transfer followed by proton transfer between MAH and the benzopinacol radical, which may operate together. In the former case, the generated MAH excited triplet state abstracts a hydrogen from the polymer substrate to initiate grafting. A rate constant of 3.6 × 10⁹ M ^?1 s ^?1 has been determined by laser flash photolysis for the process of quenching the excited triplet state of BP with ground‐state MAH. In comparison, the rate constant for the quenching of the excited triplet state of BP by hydrogen abstraction has been determined to be 4.1 × 10⁵ M ^?1 s ^?1. In a study of photografting using a model compound, 2,4‐dimethylpentane, as a small‐molecule analogue of polypropylene, the loss of BP was significantly reduced upon the addition of MAH, and this is consistent with the proposed mechanistic processes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1953–1962, 2004     

超支化聚乙烯接枝马来酸酐及其过程中交联和降解反应的抑制

采用后过渡金属催化剂二-(2,6-二异丙基苯基)丁二亚胺溴化镍(IBNB),通过均相聚合法合成了高分子量和高支化度的超支化聚乙烯(HBPE).以二特戊基过氧化物(DTAP)为引发剂,研究了HBPE接枝马来酸酐(MAH)反应,并用N,N-二乙基肉桂酰胺(DECA)作为抑制剂,有效地抑制了接枝反应体系中的交联和降解副反应.接枝反应体系中分别加入相同摩尔量的DECA、N,N-二甲基乙酰胺、苯乙烯、3-(2-呋喃)丙烯酸、肉桂酸乙酯,通过比较接枝产物的凝胶含量和分子量,发现DECA抑制交联和降解副反应的效果最好,同时解释了DECA的作用机理.     

Barrier,Mechanical, Morphological and Thermal Properties of Compatibilized High Density Polyethylene and Polyamide 6 Blends

Effectiveness of the content of maleic anhydride (MAH) and polyamide 6 (PA6) on mechanical, thermal, barrier (moisture and oxygen) properties of HDPE/PA6 blends was investigated. Blends of HDPE with PA6 were prepared by in situ method. Molau test and FTIR spectroscopy results confirmed the reactive compatibilization through grafting of MAH on HDPE and PA6 chains in PA6/HDPE blends. Low concentration of benzoyl peroxide (BPO) and MAH reduced the particle size, improved phase morphology and mechanical properties of PA6/HDPE blends. Decrease in mechanical properties of PA6/HDPE blends was observed at high concentration of BPO and MAH.     

Thermal runaway reaction evaluation of benzoyl peroxide using calorimetric approaches

Benzoyl peroxide (BPO) has been used as initiator or medicine in the chemical industries. Several thermal runaway reactions, fires, and explosions have occurred in Taiwan due to its thermal reactivity and explosive properties. A serious accident was analyzed occurring at Fu-Kao Chemical Plant in Taiwan because of runaway reaction in a batch reactor including methyl acrylate (MA), acrylic acid (AA), and BPO. This accident resulted in one death and more than 100 injuries. Differential scanning calorimetry and thermogravimetry (TG) were used to investigate and calculate the thermal hazard and safety parameter of BPO. Finally, the effects of MA and AA mixed with BPO by DSC/TG were analyzed in this study. The T ₀ of BPO was 109 °C in this study. Therefore, the T ₀ of BPO/MA was calculated to be 105 °C by DSC. AA and MA were identified as catalyst for thermal decomposition of BPO.     

Fundamental studies of grafting reactions in free radical copolymerization. III. Grafting of styrene,acrylate, and methacrylate monomers onto cis-polybutadiene using benzoyl peroxide initiator in solution polymerization

Benzoyl peroxide (BPO), due to its higher radical reactivity as compared to AIBN, is known to promote grafting onto cis-polybutadiene. Switching from AIBN to BPO initiator made a dramatic difference in the extent of grafting for styrene and methacrylate monomers, but only a modest difference for acrylate monomer. For styrene and methacrylate monomers, graft site formation is due to BPO initiator radical attack onto the backbone via allylic hydrogen abstraction. Significant levels of grafting are achieved and depend upon the relative concentrations of monomer and backbone polymer but not upon the level of initiator. For acrylic monomer, graft site formation was found to be due to polymer radical attack at the double bond in the backbone. Abstraction of allylic hydrogen also occurs but results in retardation of the overall reaction rate. Graft level was dependent upon initiator and back-bone polymer concentrations but not upon monomer concentration. The effective role of the initiator is only to produce polymer radicals; the BPO has no direct role in the formation of effective graft sites. © 1995 John Wiley & Sons, Inc.     

Microwave-Assisted Synthesis and Characterization of Poly(2-(dimethylamino)ethyl methacrylate) Grafted Gellan Gum

Poly(2-(dimethylamino)ethylmethacrylate) was grafted on gellan gum (GG) in aqueous medium under microwave irradiation using ammonium persulfate and N,N,N′N′-tetramethylethylenediamine as the initiation system. Grafted copolymers were characterized by FT-IR, TGA, and SEM techniques. The influence of microwave power, exposure time, and composition of the reaction mixture on extent of grafting was studied. Conditions for obtaining the highest degree of grafting were optimized. The rate of grafting was determined from weight measurements. The overall activation energy for grafting is found to be 31.2 kJ/mol, indicating the occurrence of the grafting process with absorption of low thermal energy.     

Graft Copolymerization of 2‐Acrylamido‐2‐methyl Propane Sulfonic Acid on Dimethyl Sulfoxide Pretreated Poly(Ethylene Terephthalate) Films Using Cerium Ammonium Nitrate as Initiator

Abstract

In this study, graft polymerization of 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) on poly(ethylene terephthalate) (PET) films using cerium ammonium nitrate (CeAN) as an initiator was investigated. Before the polymerization reaction was carried out, films were swelled in dimethyl sulfoxide (DMSO) at 140°C for 1 h. The effect of polymerization temperature, time, initiator, and monomer concentrations on the graft yield were investigated. It was observed that the graft yield was initially increased with increasing temperature, monomer, and initiator concentrations; and then decreased. Graft yield was found to increase with increasing polymerization time up to 5 h, then remain constant. The effects of monomer and initiator inclusions on the grafting yield were also examined. Optimum conditions for grafting were found to be [AMPS] = 1.0 M, [Ce⁴⁺] = 1.5 × 10^?2 M, T = 85°C and t = 5 h. The rate of grafting was found to be proportional to the 0.1 and 0.4 powers of monomer and initiator concentrations, respectively. The overall activation energy for the grafting was calculated to be 11.4 kcal mol^?1. The effect of grafting on PET film properties such as intrinsic viscosity and water absorption capacity were determined. The grafted PET films were characterized with FTIR spectroscopy and scanning electron microscopy (SEM).