Preparation and Characterization of High-Melt-Strength Polylactide with Long-Chain Branched Structure through γ-Radiation-Induced Chemical Reactions

Xu, Huaimin; Fang, Huagao; Bai, Jing; Zhang, Yaqiong; Wang, Zhigang

doi:10.1021/ie403669a

Cited by 74 publications

(69 citation statements)

References 55 publications

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“…In accordance with Xu et al ., a higher elasticity of branched and/or crosslinked polymers can be illustrated by the angular frequency dependence of the loss tangent (tan δ = G ″/ G′ ), as shown in Figure (a 1 ,b 1 ,c 1 ). Tan δ is usually used as a characteristic of the material viscoelasticity, which is sensitive to the relaxation changes.…”

Section: Resultssupporting

confidence: 86%

Evaluation of electron beam‐induced crosslinking of poly(ε‐caprolactone)—Effect of elevated temperatures

Huang

Gohs²,

Müller

et al. 2019

J of Applied Polymer Sci

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The effect of elevated temperatures (40, 80, and 170 °C) on the electron beam (EB)‐induced crosslinking and degradation of poly(ε‐caprolactone) (PCL) in nitrogen atmosphere without adding crosslinking agents has been investigated. The increased mass average molecular mass of EB modified masticated PCL (mPCL) samples were measured by size exclusion chromatography. The sol–gel investigation showed that mPCL tended to dominating crosslinking at a temperature of 170 °C. At this temperature, the maximum gel content of 56% was observed for an EB treatment with a dose of 100 kGy. In addition, the ratio of chain scission density to density of crosslinked units amounted to 0.25. The dynamic rheological test demonstrated that EB treatment at 170 °C led to the most remarkable elasticity enhancement behavior with enhanced viscosity, modulus, and decreased loss factor (tan δ). The occurrence of branching structure was evidently detected by van Gurp–Palmen plot in combination with the Cole–Cole plot for dose values ≤50 kGy. Less δ and a broadened relaxation process can be observed due to the introduction of some branched structures into mPCL. The results of enhanced molar mass and gel content analysis were confirmed by the dynamic rheological measurements. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47866.

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Section: Resultssupporting

confidence: 86%

Evaluation of electron beam‐induced crosslinking of poly(ε‐caprolactone)—Effect of elevated temperatures

Huang

Gohs²,

Müller

et al. 2019

J of Applied Polymer Sci

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“…For film blowing processing, especially for ultrathin film, high enough melt strength is necessary to endure the stretching of melt and to stably produce films with smaller and more even thickness. Incorporating multifunctional monomers as a branching agent (BA) to synthesize long chain branching (LCB) polymers is a common way to modify chain topology so as to improve melt strength . For LCB structures, it means that the chain length between two branching points is long enough that one chain can entangle with others in the melt.…”

Section: Introductionmentioning

confidence: 99%

“…The branched chains introduced into the polymer materials can also alter integrity of the arrangements of segments and exhibit different rheological properties . Synthesis, thermo‐mechanical properties and rheology of some LCB polyesters have been reported, including LCB poly(ethylene terephthalage) (PET), LCB poly(lactide) (PLA), LCB poly(butylene succinate) (PBS) …”

Section: Introductionmentioning

confidence: 99%

Long chain branched poly(butylene succinate‐co‐terephthalate) copolyesters using pentaerythritol as branching agent: Synthesis, thermo‐mechanical, and rheological properties

Lü

2016

J of Applied Polymer Sci

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Incorporating long chain branching (LCB) structure into biodegradable copolyesters can effectively improve their melt strength and film blowing processability. However, branching also results in deterioration of crystallizability which is also important for copolyester properties and processing. In this study, pentaerythritol (PER) was used as branching agent (BA) instead of previous used in-situ BA, diglycidyl 1,2,3,6-tetrahydrophthalate (DGT), to synthesize LCB poly(butylene succinate-co-terephthalate) (PBST) copolyesters. The chain structure was characterized and the effects of branching on thermal transition, mechanical, and rheological properties were investigated. Similar to DGT, copolymerizing small amount of PER (0.1-0.4 mol %) generates LCB structure and, therefore, improves the melt elasticity or strength and tensile modulus but reduces the elongation at break. Differing from DGT, PER showed higher branching efficiency, and PER-branched PBSTs exhibited unchanged or even improved crystallization ability compared with linear PBST. The improved melt strength coupled with good crystallizability will endow PER-branched PBSTs with better film blowing processability.

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“…One way of doing so is the reactive modification of linear PLA. Free radical branching in the presence of peroxides [Sodergard et al (1995); Carlson et al (1998); Takamura et al (2008); Dean et al (2012); Takamura et al (2012)] or by beam irradiation [Shin et al (2010); Wang et al (2011); Xu et al (2014)] has been employed to induce branching points and increase PLA molecular weight. In the same spirit, the addition of polyfunctional chain extenders to PLA can also lead to branching.…”

Section: Introductionmentioning

confidence: 99%

Effect of chemical and physical branching on rheological behavior of polylactide

Nouri¹,

Dubois²,

Lafleur³

2015

Journal of Rheology

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This study was aimed at improving the process rheology of polylactide (PLA) melts by means of two strategies. First, PLAs of different branched structures, i.e., star shaped, comblike, and hyper branched, were synthesized and blended with a linear grade analog. Shear and extensional flow rheometry tests were performed on pure materials and their blends to evaluate their rheological properties. It was shown that the presence of branched poly(L-lactide) (PLLA) increased the shear thinning, shear and extensional viscosity, and elastic modulus of linear PLLA at the same time; the star shaped PLLA providing the most significant change. Second, poly(D-lactides) (PDLA) with similar molecular architectures were synthesized to have a double branching effect. In addition to the presence of branched architecture, physical cross-links due to the stereocomplex formation exist between PLLA and PDLA chains. Based on the rheological characterizations in shear and extensional mode, a greater improvement in PLA melt rheological properties was observed for blends containing stereocomplex structure as compared to linear/branched enantiopure blends. V C 2015 The Society of Rheology. [http://dx.

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Preparation and Characterization of High-Melt-Strength Polylactide with Long-Chain Branched Structure through γ-Radiation-Induced Chemical Reactions

Cited by 74 publications

References 55 publications

Evaluation of electron beam‐induced crosslinking of poly(ε‐caprolactone)—Effect of elevated temperatures

Evaluation of electron beam‐induced crosslinking of poly(ε‐caprolactone)—Effect of elevated temperatures

Long chain branched poly(butylene succinate‐co‐terephthalate) copolyesters using pentaerythritol as branching agent: Synthesis, thermo‐mechanical, and rheological properties

Effect of chemical and physical branching on rheological behavior of polylactide

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