Rheological properties of branched polystyrenes: linear viscoelastic behavior

Hepperle, Jens; Münstedt, Helmut; Haug, Peter K.; Eisenbach, Claus D.

doi:10.1007/s00397-005-0033-7

Cited by 39 publications

(22 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, while in the proximity of the glass transition temperature branches influence the thermorheological behavior only to a very slight degree (or not at all), because branching points have almost no effect on the free volume [67], for semicrystalline materials, such as PE, a significant influence of branches on the thermorheological behavior becomes obvious at least 100K above the glass transition temperature [68][69][70]. The activation energy of linear PE is found to be around 27-28 kJ/mol, while higher values are reported for linear mLLDPE, which scale with comonomer content and length (=short chain branch length) [34,[71][72][73][74][75][76][77][78][79].…”

Section: Introductionmentioning

confidence: 98%

Deriving comprehensive structural information on long-chain branched polyethylenes from analysis of thermo-rheological complexity

Stadler

Chun

Han

et al. 2016

Polymer

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 98%

Deriving comprehensive structural information on long-chain branched polyethylenes from analysis of thermo-rheological complexity

Stadler

Chun

Han

et al. 2016

Polymer

View full text Add to dashboard Cite

show abstract

“…We can anticipate that MM‐1000, whose chain rigidity and T g are higher than those of the polyols and tackifier, will increase η* and G ′; however, G ′ behavior at low shear rate cannot be explained this way. When short‐chain branches, whose molecular weight is smaller than the critical molecular weight for intermolecular chain entanglement, are introduced into a polymer chain, reduction of G ′ is generally observed at low shear rates because the molecular cross‐sectional area is increased and the intermolecular chain entanglement of main chain is restricted by the presence of short‐chain branches 19–22. So, this reduced intermolecular chain entanglement in the presence of short‐chain branches, resulting from modification with MM‐1000, seems to be the main cause of G ′ reduction at low shear rates (Fig.…”

Section: Resultsmentioning

confidence: 99%

Properties of reactive hot melt polyurethane adhesives with acrylic polymer or macromonomer modifications

Jung

Kim

et al. 2008

J of Applied Polymer Sci

View full text Add to dashboard Cite

The properties of reactive hot melt polyurethane adhesives (RHAs) modified by dihydroxyl-terminated reactive acrylic macromonomers were examined and compared with those of RHAs modified with a nonreactive commercial acrylic copolymer. The melt viscosity and initial bond strength was increased when a portion of the polyols and tackifier was replaced by macromonomers or acrylic copolymers, which have higher glass transition temperatures. When RHA was modified by macromonomer, the storage modulus at low shear rate was reduced and set time was increased, which suggests that the chain entanglement was diminished by short-chain branches created by the macromonomers.

show abstract

“…7a from ref. 48 Table 4 Rate coefficient data for the zero shear viscosity of the star polystyrene 3 and 4 obtained from fitting the experimental data in Fig. 6 via eqn (4).…”

Section: Resultsmentioning

confidence: 99%

Stability of star-shaped RAFT polystyrenes under mechanical and thermal stress

et al. 2014

View full text Add to dashboard Cite

Well-defined three-arm and four-arm star polymers designed via a Z-group approach carrying trithiocarbonate functionalities at the core are prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization featuring molecular weights of M n,SEC ¼ 156 kDa, Đ ¼ 1.16 (3-arm) and M n,SEC ¼ 162 kDa, Đ ¼ 1.15 (4-arm) based on multi-angle laser light scattering (MALLS) detection, respectively. The star-shaped polystyrenes are subjected (in bulk) to thermal stress in the temperature range between 140 and 200 C from 10 minutes up to 96 h. The thermally treated 3-arm and 4-arm star polymers are analyzed via size exclusion chromatography (SEC) to quantify the degradation process at variable temperatures as a function of time under an argon atmosphere. Cleavage rate coefficients of the star polymers are deduced as a function of temperature, resulting in activation parameters for the cleavage process, i.e. E a ¼ 131 kJ mol À1 ; A ¼ 3.93 Â 10 11 s À1 (M n,SEC ¼ 156 kDa, Đ ¼ 1.16, 3-arm star) and E a , ¼ 134 kJ mol À1 ; A ¼ 9.13 Â 10 11 s À1 (M n,SEC ¼ 162 kDa, Đ ¼ 1.15, 4-arm star), respectively. Processing of the star-shaped polymers is mimicked via a small scale counter rotating twin screw extrusion to achieve nonlinear shear and elongation flow under pressure. Furthermore, a rheological assessment via the linear shear deformation region (small amplitude oscillatory shear, SAOS) allows for a correlation of the processing conditions with the thermal degradation properties of the star polymers in the melt. Zero shear viscosity (h 0) as a criterion of the degradation process is measured in the rheometer and correlated to the weight-average molecular weight, M w .

show abstract

Rheological properties of branched polystyrenes: linear viscoelastic behavior

Cited by 39 publications

References 36 publications

Deriving comprehensive structural information on long-chain branched polyethylenes from analysis of thermo-rheological complexity

Deriving comprehensive structural information on long-chain branched polyethylenes from analysis of thermo-rheological complexity

Properties of reactive hot melt polyurethane adhesives with acrylic polymer or macromonomer modifications

Stability of star-shaped RAFT polystyrenes under mechanical and thermal stress

Contact Info

Product

Resources

About