Expansion characteristics of expandable styrene/methyl methacrylate copolymer particles: The effects of copolymer molecular weight and particle size

2016 ◽  
Vol 54 (2) ◽  
pp. 283-308 ◽  
Author(s):  
Ehsan Mehravar ◽  
Farhang Abbasi ◽  
Kiyumars Jalili ◽  
Hadi Rostami ◽  
Mostafa Rezaei
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Methyl Methacrylate ◽  
Dimensional Stability ◽  
Suspension Polymerization ◽  
Average Molecular Weight ◽  
Blowing Agent ◽  
Expansion Behavior ◽  
The Matrix ◽  
Methacrylate Copolymer

Spherical foamable particles were synthesized by suspension polymerization of methyl methacrylate and styrene in the presence of a blowing agent. When the surrounding temperature was high enough to vaporize the blowing agent and soften the polymer shell, the particles were expanded due to pressure difference across the shell. The effects of initiator and crosslinker concentration on the particle size, average molecular weight, and molecular weight distribution of synthesized copolymer, pentane content and expansion properties (density, residual pentane, and dimensional stability of pre-expanded beads) of expandable particles were investigated. The results showed that the expansion behavior of the particles was dependent on molecular weight of the matrix polymer and size of the synthesized particles. In a constant copolymer molecular weight, the pre-expanded bead density decreased with increasing of particle size whereas it increased with molecular weight in a constant particle size. Moreover, the crosslinker improved dimensional stability of the pre-expanded beads.

scholarly journals Study of the features of suspension polymerization of methyl methacrylate in the presence of polymeric surfactants

2019 ◽  
pp. 23-25
Author(s):  
E. S. Kluzhin ◽  
A. A. Kholodova ◽  
O. A. Satkevich ◽  
I. A. Grizkova
Keyword(s):  
Molecular Weight ◽  
Methyl Methacrylate ◽  
Sulfonic Acid ◽  
Suspension Polymerization ◽  
Average Molecular Weight ◽  
Polymeric Surfactants ◽  
Molecular Weight Characteristics ◽  
Acid Sodium Salt ◽  
Methacrylate Copolymer ◽  
Sulfonic Acid Sodium Salt

The molecular weight characteristics of the polymer obtained by suspension polymerization of methyl methacrylate in the presence of polymeric surfactants - (co)polymers of 2-acrylamido-2-methylpropane sulfonic acid, sodium salt of methyl methacrylate copolymer with methacrylic acid and acrylamide copolymer with acrylonitrile and acrylic acid are studied. It was found that the highly dispersed fraction (0.5–2 μm) of polymethyl methacrylate has an increased molecular weight and even at a content less than 1% has a noticeable eff ect on the average molecular weight. It is shown that an eff ective way to reduce the content of polymer particles 0.5–2 μm is the use of a dispersant, in which the colloidal solubility of methyl methacrylate is minimal.

Polymerization of Methyl Methacrylate with a Novel Titanium Complex

2011 ◽  
Vol 179-180 ◽  
pp. 1203-1207
Author(s):  
Zheng Zai Cheng ◽  
Yu Jing Nie ◽  
Xiao Chao Yan ◽  
Rui Lei ◽  
Su Su Lin
Keyword(s):  
Molecular Weight ◽  
Methyl Methacrylate ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Ligand Complex ◽  
Dichloromethane Solution ◽  
Titanium Complex ◽  
Methyl Methacrylate Polymerization ◽  
Gel Permeation ◽  
Very High

Novel titanium complex [2-O-(5- NO2)C6H3CH=N[(C6H4) –2-O ]]2TiCl2 (1) has been prepared by treatment of the ligand complex 1a with TiCl4•2THF in dichloromethane solution. The complex 1a and 1 were characterized by 1H-NMR . Activated by MAO, Complex 1 displayed very high activity for methyl methacrylate polymerization and the viscosity-average molecular weight of PMMA is more than 35×104 at 60°C.The molecular-weight distribution of PMMA measured by gel permeation chromatography (GPC) is narrow.

scholarly journals Initiator Feeding Policies in Semi-Batch Free Radical Polymerization: A Monte Carlo Study

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1291 ◽  
Author(s):  
Ali Seyedi ◽  
Mohammad Najafi ◽  
Gregory T. Russell ◽  
Yousef Mohammadi ◽  
Eduardo Vivaldo-Lima ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Monte Carlo ◽  
Free Radical ◽  
Methyl Methacrylate ◽  
Radical Polymerization ◽  
Average Molecular Weight ◽  
Free Radical Polymerization ◽  
Monte Carlo Algorithm ◽  
Single Shot ◽  
The Impact

A Monte Carlo simulation algorithm is developed to visualize the impact of various initiator feeding policies on the kinetics of free radical polymerization. Three cases are studied: (1) general free radical polymerization using typical rate constants; (2) diffusion-controlled styrene free radical polymerization in a relatively small amount of solvent; and (3) methyl methacrylate free radical polymerization in solution. The number- and weight-average chain lengths, molecular weight distribution (MWD), and polymerization time were computed for each initiator feeding policy. The results show that a higher number of initiator shots throughout polymerization at a fixed amount of initiator significantly increases average molecular weight and broadens MWD. Similar results are also observed when most of the initiator is added at higher conversions. It is demonstrated that one can double the molecular weight of polystyrene and increase its dispersity by 50% through a four-shot instead of a single shot feeding policy. Similar behavior occurs in the case of methyl methacrylate, while the total time drops by about 5%. In addition, policies injecting initiator at high monomer conversions result in a higher unreacted initiator content in the final product. Lastly, simulation conversion-time profiles are in agreement with benchmark literature information for methyl methacrylate, which essentially validates the highly effective and flexible Monte Carlo algorithm developed in this work.

Synthesis of Ultra-High Molecular Weight Polyacrylonitrile (UHMWPAN) by Aqueous Suspension Polymerization

2015 ◽  
Vol 1120-1121 ◽  
pp. 615-619
Author(s):  
Hui Yu Jiang ◽  
Mei Hua Zhou ◽  
Ding Pan
Keyword(s):  
Molecular Weight ◽  
Suspension Polymerization ◽  
Aqueous Suspension ◽  
Average Molecular Weight ◽  
Monomer Concentration ◽  
Polymerization Process ◽  
Polymerization Temperature ◽  
Different Temperatures ◽  
Total Monomer Concentration ◽  
Ultra High Molecular Weight

Acrylonitrile (AN) and itaconic acid (IA) were used to synthesize UHMWPAN by aqueous suspension method with 2,2’-azobisisobutyronitrile (AIBN) as the initiator and polyvinylalcohol (PVA) as the disperser at different temperatures (55°C~75°C) for different timings (1.0h~3.0h). The usage amounts of AN, IA, AIBN and PVA were also technical polymerization parameters used to obtain the optimal polymerization process. We found that the conversion and the viscosity average molecular weight both achieved the optimum levels when the conditions were as follows: the total monomer concentration (21wt%), the monomer ratio (AN: IA=98:2), the usage amount of the initiator (AIBN, 0.01wt%), the usage amount of the disperser (PVA, 0.1wt%), the polymerization temperature (70°C) and the polymerization time (2h).

Relationships between synthesis parameters and properties of water expandable polystyrene

2012 ◽  
Vol 49 (1) ◽  
pp. 13-31 ◽  
Author(s):  
Sedigheh Mirhoseini Khosrowshahi ◽  
Farhang Abbasi ◽  
Naser Harasi ◽  
Behnaz Memar Maher
Keyword(s):  
Physical Properties ◽  
Water Content ◽  
Suspension Polymerization ◽  
Water Droplets ◽  
Blowing Agent ◽  
Synthesis Parameters ◽  
Expansion Behavior ◽  
Expandable Polystyrene ◽  
Negative Environmental Impact ◽  
Emulsified Water

Because of the negative environmental impact of volatile hydrocarbon-based blowing agents used in expandable polymers, water has been considered a suitable candidate. Water expandable polystyrene is a polystyrene containing water cells, which may be used as blowing agent. Because of different physical properties of water and volatile hydrocarbons, production conditions and physical properties of expandable polystyrene and water expandable polystyrene are completely different. In this work, water expandable polystyrene was prepared via suspension polymerization of the styrene/polystyrene mixture that contained water droplets as blowing agent. An inverse emulsion system was used to incorporate water into the organic phase. An experimental design was created to investigate the effects of variation of pre-polymerization time, surfactant concentration, suspension stabilizer/suspending agent ratio, suspension stabilizer addition time, and the amount of initial emulsified water on the particle size, distribution of water droplets, and the water content of the final beads. The relationships between the synthesis parameters and the properties of water expandable polystyrene were also studied. Regarding to the expansion behavior of water expandable polystyrene beads, the effect of water content and bead size on the expandability and the foam density were investigated.

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