Kinetics of formation of polyurethane-poly(methyl methacrylate) interpenetrating polymer networks: 2. Synthesis of the rigid network in the presence of the elastomeric network

SYNOPSISIn a model polyurethane/poly(methyl methacrylate) (PU/PMMA) system, the partitioning of unreacted methyl methacrylate monomer (MMA) is studied in the late stages of its polymerization, simulated by incorporating controlled amounts of MMA in otherwise fully cured simultaneous interpenetrating networks (SIN) samples. Glass transitions temperatures (T,) were determined using dynamic mechanical spectroscopy and differential scanning calorimetry as a function of MMA content of the SINs. The lowering of T, in each phase due to the plasticization effect of MMA is used to calculate a plasticization coefficient for each phase, finally allowing calculation of the partition coefficient of MMA between the two phases. It is found that the MMA monomer distributes itself almost uniformly across the two phases of the current SIN system, leading to speculation as to the locus of late SIN polymerization.

Section: P Discussionmentioning

confidence: 87%

“…90% conversion of MMA, 13,20 subsequent polymerization of MMA is slowed considerably. However, complete conversion of MMA has been noted using Fourier transform infrared ( FTIR) spectroscopy in such SINS (even greater than the limiting conversion due to vitrification in pure PMMA samples) .…”

Section: P Discussionmentioning

confidence: 99%

Simultaneous interpenetrating networks of a polyurethane and poly(methyl methacrylate). II. Partitioning of MMA monomer in the last stages of polymerization

Mishra

Prez

Goethals

et al. 1995

“…The PU-PMMA system has been one of the focus of interpenetration poly-EXPERIMENTAL mer network (IPN) study. In 1970s, Kim et al 1 studied the structural morphology; and in 1980s, Raw Materials Jin et al 2 reported the polymerization kinetics. The raw materials used in the experiment were listed in Table I.…”

Section: Introductionmentioning

confidence: 99%

Morphological structure and mechanical properties of polyurethane modified with methyl methacrylate

Wang

Shi

Zhang

1998

Three kinds of polyurethane-poly(methyl methacrylate) (PU-PMMA), that is, linear polymer, block copolymer, and interpenetrating polymer network (IPN), were synthesized by a simultaneous polymerization process, respectively. The effects of several factors such as ultraviolet (UV) setting, heat setting, chemical composition, and physical structure on the morphological structure and mechanical properties of polymers were studied by scanning electron micrograph, dynamic mechanical loss spectrum, and mechanical tests. The results show that PU-PMMA is a partially compatible system with a two-phase structure; the linear polymer has the highest elongation at break, and IPN has the strongest tensile strength, while the block copolymer has poor mechanical properties. In addition, the UV setting block copolymer and IPN system, with regular microphase domain structures, have higher tensile strength and elongation at break than those of heat setting polymers. With MMA content and hard segment in PU increasing, the tensile strength increases, and the elongation decreases.

“…True simultaneity seldom occurs. For a better understanding of the development of morphology in IPN formation, we have prepared simultaneous IPNs, better named in situ IPNs, 2 by variation of the process: starting from the same initial homogeneous mixture of the component precursors, in situ seq (sequential) IPNs were obtained by forming a first network followed by the polymerization and the formation of the second network. In situ sim (simultaneous) IPNs 3 were made by performing both (noninterfering) reactions simultaneously, under kinetical control.…”

Section: Introductionmentioning

confidence: 99%

Influence of the process on phase separation induced by radical copolymerization of styrene and divinylbenzene in the presence of reactive polyurethane network precursors

Chenal

Colombini

Widmaier

2006

ABSTRACT:Interpenetrating polymer systems based on crosslinked polyurethane (PU) and polystyrene (PS) were prepared at room temperature by a one-shot (in situ) method, starting from an initial homogeneous mixture of reagents via noninterfering mechanisms. Both polymerizations were performed either simultaneously or one after the other. True simultaneity at every stages of the process is not possible. Despite the difference in refractive index of the components, hazy or optically clear films were obtained, thus indicating various levels of phase separation, also confirmed by glass transition temperature (T g ) measurements.The results suggest that controlling the chemistry and process (crosslink density, composition, and time sequence of events) of in situ interpenetrating network formation will give various morphologies, and hence properties, ranging from microphase separated materials to larger macrophase separated materials.