Rheology and thermal behavior of long branching polypropylene prepared by reactive extrusion

Su, Fenghua; Huang, Hanxiong

doi:10.1002/app.30061

Cited by 35 publications

(39 citation statements)

References 24 publications

(61 reference statements)

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“…Furthermore, as the concentration of LCBs increases, the shear‐thinning region becomes more appreciable, beginning at gradually lower frequencies. This behavior is typical of topological structures that get gradually more complex . An additionally interesting behavior can be also observed when the dynamic data are presented in this way.…”

Section: Resultssupporting

confidence: 88%

“…The melting process of all polymers is very similar, with T m and Δ H m of the modified materials slightly lower than those of PPg. This is in agreement with most of the works in the literature that deal with long‐chain branched PPs . The results suggest that the presence of branches in the molecules somewhat reduces the size and amount of the crystal domains.…”

Section: Resultsmentioning

confidence: 88%

“…Reactive extrusion involves the chemical attack of PP in the molten state in the presence of peroxide and a polyfunctional monomer. The peroxide decomposition induces the formation of macroradicals that react with the added monomer promoting the generation of branches and inhibiting the scission of the PP chains . The reactive extrusion process may also be applied to a functionalized PP, such as maleic anhydride grafted PP (PPg), which is melt blended with just the polyfunctional monomer or oligomer …”

Section: Introductionmentioning

confidence: 99%

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Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Guapacha

Failla

Vallés

et al. 2014

J of Applied Polymer Sci

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Long‐chain branched polypropylene was prepared using reaction in the molten state in the presence of glycerol and a linear polypropylene functionalized with maleic anhydride (PPg). The concentration of glycerol in the melt was varied in the range from 0.1 to 5 wt % to obtain different levels of branching. FTIR spectroscopy results indicate that the OH groups of glycerol react with the anhydrides on the PPg chains giving place to ester groups. The presence of long‐chain branches in the molecular structure of PPg was confirmed using multiple‐detection size‐exclusion chromatography and rheology. These techniques demonstrate that the level of branching increases with glycerol concentration and that the modification of PPg produces materials with a bimodal distribution of polymer species. Moreover, some of the highly modified materials display gel‐like behavior. The materials also display thermo‐rheological complexity and enhanced activation energy at low frequencies. The crystallization study shows that both the anhydride groups in PPg and the LCBs have opposite nucleating effects. PPg presents the largest activation energy of crystallization and its value decreases with the concentration of glycerol for a given level of crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40357.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Guapacha

Failla

Vallés

et al. 2014

J of Applied Polymer Sci

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“…For the pristine PP, the Cole‐Cole plot exhibits a shape of similar semicircle owing to its linear molecule structure. However, all the Cole‐Cole plots of PPs modified by the acrylate monomers deviate from semicircle and show an uptrend at high viscosity, indicating that a different relaxation mechanism and a long relaxation time . Besides, the curve of PP NPGDA is lower than that of pristine PP, which indicates that degradation reaction plays a main role in this free radical reaction due to the poor stabilization effect of NPGDA on the PP tertiary carbon radical .…”

Section: Resultsmentioning

confidence: 96%

“…These experiment results are consistent with those acquired from the torque curves. It is reported that Cole‐Cole plot ( η ′′‐ η ′), Figure C could be used to illustrate the long relaxation process . As shown in Figure C, the distinctions between pristine PP and modified PPs are obvious.…”

Section: Resultsmentioning

confidence: 96%

Influence of different functionality degree grafting monomers on polypropylene melt radical branching reaction and their structure

Zhang

Yang

et al. 2017

Polymers for Advanced Techs

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Long-chain-branched polypropylene (LCBPP) is one of polypropylenes (PPs) with high melt strength and good melt elasticity. Recently, due to its outstanding properties, LCBPP have been attracted increasingly attention in the field of development and characterization by the researchers all over the world. In this study, LCBPP was prepared by the melt radical branching reaction in a torque rheometer. The influences of various acrylate monomers with different functionality degrees on the structure and melt performance of PP products were investigated.The results indicated that grafting monomers with different functionality degrees made diverse influences on the branching density and branching chain length of branching PP products. With the increase of the functionality degree of grafting monomers, the branching level of PP products increased gradually and the "multiplicity" of branches became increasingly obvious. Besides, a higher reactivity of pentaerythritol triacrylate with hydroxyl than the similar molecular structured pentaerythritol tetraacrylate was confirmed. Furthermore, due to the high reactivity of dipentaerythritol penta(hexa)acrylate, branching and crosslinking reaction occurred simultaneously during the reaction process. As a result, the gel content increased and finally formed highly star branching structures with a shape of "dense and short." 1 However, the application of the ordinary commercial polypropylene in some processes, eg, thermoforming, extrusion foaming, and blow molding, is limited because of its linear structure and low melt strength (MS). Thus, lots of researches are focusing on improving its MS. 2-4Some researches proposed that a small quantity of long-chain branches (LCBs) in PP could reinforce the MS obviously, which is owing to the augment of entanglements among the macromolecule chains. [4][5][6] In addition, long-chain-branched polypropylene (LCBPP) exhibits obviously strain hardening behavior in the MS. 7,8 The LCB can be introduced via copolymerized reaction during the stage of propene polymerization or through the branching modification of linear commercial PP using a method of post-reactive process. Due to the inductive effect of methyl, the tertiary carbon atoms in PP own a great reactivity, which makes PP more vulnerable to be oxidized and thus then results in β-scission under the action of heat or high-energy rays. Therefore, the method of melt radical branching reaction, as a simple and effective way, is widely applied to prepare LCBPP. [5][6][7][8][9][10] Nonetheless, this reaction process must be controlled strictly because of the complexity of free radical reaction, which mainly included coupled reaction among PP chains and degradation caused by β-scission. 11Some grafting monomers are often added into the radical reaction system to stabilize the unstable tertiary carbon radicals. Those monomers are usually electron donors, such as styrene, acrylic amide, and acrylate. They can be combined with the PP tertiary carbon radicals and stabilize them via their conjugative ef...

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Reactive Extrusion of Polymers

Tzoganakis

Zhu

2012

Encyclopedia of Polymer Science and Technology

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Reactive extrusion (REX) is a process that combines the mass and heat transport operations with simultaneous chemical reactions taking place inside the extruder for the purpose of modifying the properties of existing polymers or for producing new ones. REX is increasingly becoming a powerful technique to develop and fabricate a variety of novel polymeric materials in a highly efficient and flexible way. This combination of chemical reactions and transport phenomena in an extruder provides a large opportunity window for fast prototyping a plethora of specialty polymers filling in the end‐use gaps among the existing commercial resins and natural products. A very large amount of literature on REX has been accumulated over the past few decades, and this review addresses some of the most recent publications while earlier references can be found in previous literature reviews.

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Rheology and thermal behavior of long branching polypropylene prepared by reactive extrusion

Cited by 35 publications

References 24 publications

Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Molecular, rheological, and thermal study of long‐chain branched polypropylene obtained by esterification of anhydride grafted polypropylene

Influence of different functionality degree grafting monomers on polypropylene melt radical branching reaction and their structure

Reactive Extrusion of Polymers

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