Toughened Unsaturated Polyester Block Copolymers

Tong, S. N.; Chen, Chih‐Chien; Wu, Peter T. K.

doi:10.1021/ba-1989-0222.ch018

Cited by 3 publications

(2 citation statements)

References 1 publication

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“…Blending and composite preparation are most attractive and challenging methods among them. There are numerous publications concerned with blending of UPR based on elastomers, thermoplastics, block copolymers, IPNs, and so on 2‐4 …”

Section: Introductionmentioning

confidence: 99%

Itaconimide telechelics of polyethers, synthesis, and their impact on mechanical properties of unsaturated polyester resins

Jeemol

Mathew

Nair

2021

Polymers for Advanced Techs

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The present work focuses on the evolution in the mechanical properties of an unsaturated polyester resin (UPR) on blending with itaconimide‐end terminated polyethers, namely, polypropylene glycol (I‐PPG), polyethylene glycol (I‐PEG), and polytetra methylene oxide (I‐PTMO). Blends of an unsaturated polyester (UPR, based on propylene glycol, terephthalic, and maleic acids) resin with different loading of itaconimide end‐capped telechelics were investigated for their mechanical and thermal properties. Blending with these additives enhanced the mechanical and thermal properties of the crosslinked UPR. The impact strength and fracture toughness values were improved by more than 100% by small quantities of the additives. The improvement in fracture properties was correlatable primarily to a decrease in overall crosslink density. The distribution of the polyether chains in the cured matrix as dictated by the reactivity ratios of styrene and polyether macromer was found to have a role in deciding the properties. The properties were found to be the best for the blend toughened with I‐PPG with a molecular weight 2000 g/mole at a loading of 2.5 parts per hundred parts. On comparison with the resin blended with a maleimide‐encapped polyether of same molecular weight, the itaconimide end‐capped polyether was found to provide a better toughening of the UPR matrix. This could a priori be explained based on a difference in distribution of the end‐capped polyether as a consequence of the difference in the copolymerization behavior of itaconimide and maleimide functionalized telechelics toward UPR. The itaconimide enters into a random copolymerization with styrene and the probability for formation of the continuous sequences of the itaconic group is about 60%. This will permit polyether segments to come close enough to form micro or even sub‐micron clusters of the polyether which eventually forms the micro crystallites of poly ether that act as a crack stopper. This possibility cannot be envisaged in maleimides which forms invariably an alternating sequence with styrene. The morphological features as reflected in scanning electron microscopic analyses tallied with these observations. This work could help identify the ways for obviating the inherent brittleness of the UPR systems.

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Section: Introductionmentioning

confidence: 99%

Itaconimide telechelics of polyethers, synthesis, and their impact on mechanical properties of unsaturated polyester resins

Jeemol

Mathew

Nair

2021

Polymers for Advanced Techs

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“…The enhancement of fracture properties, namely the impact strength and resistance to crack propagation was investigated using rubber particles, thermoplastics, solid particles, or through interpenetrating network formation (IPN). [1,2,3,4] The most common method is blending. The blending of two or more polymers is an easy and profitable way of developing material with desirable properties.…”

Section: Introductionmentioning

confidence: 99%

On the toughening of unsaturated polyester resins using nadimide end‐functionalized polyether telechelics

Jeemol

Mathew

Nair

2021

Polymer Engineering & Sci

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Copoly-propylene glycol (terephthalate-maleate) based unsaturated polyester resin (UPER) was modified with nadimide end-capped polyether telechelics namely, polypropylene glycol (PPG with molecular weight 2000, 1000, 400 g/mol), polytetramethylene oxide (PTMO with molecular weight 2000 g/mol) and polyethylene glycol (PEG with molecular weight 2000 g/mol) (NPPG/NPTMO/NPEG). The telechelic NPPG/NPTMO/NPEG were synthesized from the corresponding polyols (hydroxy telechelics) by reaction with 4-nadimido benzoyl chloride. These derivatives were characterized by chemical and spectral methods. Blends of UPER with varying amounts of NPPG/NPTMO/NPEG were prepared. Blending boosted the cohesive energy through enhanced crosslinking as reflected in the gel content of the cured matrices done in separate studies. It increased the fracture characteristics tremendously. The addition of 2.5 phr of the nadimide end functional polyether gave the maximum toughness. The crosslink density showed an initial increase on blending, but further addition of the telechelics did not make any change. The properties of the prepared blends were compared with maleimide end-capped polyether toughened UPE resins. It was concluded that the toughening effect of the polyether additive depends not only on its concentration but also on its distribution in the matrix as dictated by its reactivity ratio with styrene. The high reactivity of the nadimide groups did not create an ambiance good enough to get an acceptable distribution of the polyether segments conducive for a tough matrix. Whereas the maleimide end-capped polyether provides better toughening efficiency.

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Toughening of vinylester–urethane hybrid resins through functionalized polymers

Gryshchuk

Jost

Karger‐Kocsis

2002

J of Applied Polymer Sci

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Liquid nitrile rubber, hyperbranched polyester, and core/shell rubber particles of various functionality, namely, vinyl, carboxyl, and epoxy, were added up to 20 wt % to a bisphenol-A-based vinylester-urethane hybrid (VEUH) resin to improve its toughness. The toughness was characterized by the fracture toughness (K c ) and energy (G c ) determined on compact tensile (CT) specimens at ambient temperature. Toughness improvement in VEUH was mostly achieved when the modifiers reacted with the secondary hydroxyl groups of the bismethacryloxy vinyl ester resin and with the isocyanate of the polyisocyanate compound, instead of participating in the free-radical crosslinking via styrene copolymerization. Thus, incorporation of carboxyl-terminated liquid nitrile rubber (CTBN) yielded the highest toughness upgrade with at least a 20 wt % modifier content. It was, however, accompanied by a reduction in both the stiffness and glass transition temperature (T g ) of the VEUH resin. Albeit functionalized (epoxy and vinyl, respectively) hyperbranched polymers were less efficient toughness modifiers than was CTBN, they showed no adverse effect on the stiffness and T g . Use of core/shell modifiers did not result in toughness improvement. The above changes in the toughness response were traced to the morphology assessed by dynamic mechanical thermal analysis (DMTA) and fractographic inspection of the fracture surface of broken CT specimens.

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Toughened Unsaturated Polyester Block Copolymers

Cited by 3 publications

References 1 publication

Itaconimide telechelics of polyethers, synthesis, and their impact on mechanical properties of unsaturated polyester resins

Itaconimide telechelics of polyethers, synthesis, and their impact on mechanical properties of unsaturated polyester resins

On the toughening of unsaturated polyester resins using nadimide end‐functionalized polyether telechelics

Toughening of vinylester–urethane hybrid resins through functionalized polymers

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