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Reporter:Chen-Kun Lin
Adviser:Cheng-Chien Wang
2011.05.31
Introduction
• Natural rubber (NR) is almost 100% cis-polyisoprene
and has numerous advantages for a wide range of
applications because of its outstanding physical
properties including high resilience, strength, and fatigue
resistance .
• In addition, it is a renewable resource and the
applications of natural rubber latex (NRL) can be further
expanded by the grafting of a second polymer within
NRL particles .
Introduction
• Traditionally, polyacrylates have been established in
wide-ranging applications as adhesives, coatings, and
sealants.
• Principally, they have relatively low glass transition
temperatures, which make them apt to handle,
process,and purify .
• The chemical modification of NRL by grafting
polyacrylates should combine the properties of both NR
and the polymer of the grafted monomer.
Introduction
• The miniemulsion process is a versatile technique to
synthesize a range of different polymeric nanoparticles,
complex hybrid (polymer/inorganic) nanoparticles,
functionalized nanoparticles, polymeric nanocapsules for
controlled release applications, etc .
• Different parameters like, e.g., the monomer addition
sequence , the hydrophilicity of the monomers and
polymers , the initiating , the viscosity within the
monomer swollen seed latex particles, the reaction
temperature, the degree of cross-linking of the polymer
chains, etc., have influence on the morphology of these
modified NRL particles .
Introduction
• In this paper, we have used miniemulsion
polymerization as a technology platform to graft BA on
NRL.
• Different types of free radical initiators and different
amounts of monomers were used to investigate the
grafting efficiency of BA on NRL.
Materials
• Centrifuged NRL with 69% solid content
• Monomers:methyl, ethyl, butyl, hexyl, or lauryl
acrylates
• Sodium dodecyl sulfate (SDS), hexadecane
• 2,2′-azobis(2-methylbutyronitrile) (V59) and 2,2′azobis(4-methoxy-2,4-dimethyl valeronitrile) (V70)
• 2,4-Pentanedione, cumene hydroperoxide, horseradish
peroxidase(HRP)
Experimental
Synthesis of PBA, PHA, and PLA in miniemulsion
3 g butyl, hexyl, or lauryl acrylate
124 mg hexadecane, 60 mg initiator(i.e., V70)
124 mg SDS and
12 g deionized water
Stirred for 1 h for pre-emulsification
mixture was ultrasonicated forv120 s
The mixture was stirred at 35 °C for 1 day
Experimental
Grafting butyl/hexyl/lauryl acrylates with NRL using V59 as initiator
3 g methyl, ethyl, butyl, hexyl or lauryl acrylate,
124 mg hexadecane, 60 mg initiator(i.e., V59)
124 mg SDS and
12 g deionized water
14.5 g NRL for pre-emulsification
The miniemulsion was prepared by ultrasonicating the
mixture during 120 s
Then, this mixture was stirred at 72 °C for 24 h.
Experimental
Grafting butyl acrylate with NRL using cumene hydroperoxide
3 g butyl acrylate,124 mg hexadecane,
45 mg of cumene hydroperoxide
120 mg SDS and
12 g deionized water
14.5 g NRL for pre-emulsification
By ultrasonicating the mixture during 120 s
N2 gas and 50 °C
56 mg tetraethylenepentamine and stirred for 24 h
Experimental
Grafting butyl acrylate with NRL using HRP
3 g butyl acrylate,124 mg hexadecane
120 mg SDS and
10 g deionized water
were stirred with 14.5 g NRL
Mixture stirred under nitrogen in an ice bath for
pre-emulsification and
by ultrasonicating the mixture during 120 s
Experimental
Grafting butyl acrylate with NRL using HRP
9mg HRP was dissolved in 2 g deionized water
and purged with nitrogen for 10 min and injected into the
miniemulsion and stirred for 5 min, followed by adding 9
μL 2,4-pentanedione and 7 μL H2O2 simultaneously.
Experimental
Gel fraction
After forming films, the reaction products were submitted
to Soxhlet extraction to evaluate the gel content
The extraction
was performed with toluene for a period of 24 h
After each
extraction, the gel fractions were dried at 40 °C in vacuum
Results and discussion
Results and discussion
Results and discussion
Film-forming properties
Results and discussion
Film-forming properties
Fig. 1 Photograph of (a) opaque NRL and PBA (16.4 wt.%) blend and (b) transparent
BA (26.7 wt.%)- grafted NR films
Results and discussion
DSC analysis
NRL
BA
Fig. 2 DSC analysis of (a) blend of NRL
and PBA (16.4 wt.%) and (a) BA (26.7
wt.%)-grafted NRL. Arrows are indicating
the Tgs
Fig. 3 DSC analysis of (a) blend of
NRL and PLA (16.4 wt.%) and (b) LA
(16.4wt.%)/NRL. The arrows indicate
the Tm
Results and discussion
Morphology by TEM analysis
Fig. 4 TEM picture of double chemically fixed and ultramicrotome sections of pure NRL
Results and discussion
Morphology by TEM analysis
Fig. 5 TEM pictures of double chemically fixed and ultramicrotome sections of PBA
(26.7 wt.%) grafted NRL: (1) PBA particles, (2) PBA-grafted NRL
Conclusions
• That grafting efficiencies between 18% and 68% with
respect to the amount of employed BA are achieved
depending on the initiating system and the amount of
BA.
• The grafting efficiency of HA (41 wt.%) is observed to
be higher than LA (31 wt.%) on NRL.
• All the polyacrylate (16.4 wt.%)-grafted NRL produces
transparent films without cracks.
Conclusions
• Grafting reactions with a higher amount of BA
particularly with 26.7 wt.% lead to brittle films.
• Grafting of the acrylate polymers on NRL the Tg of the
polyacrylates vanish and probably merge with the Tg of
NRL.
• TEM analysis of the modified NRL with BA
demonstrates distinct core–shell structures.
回收NBR-BA微乳液聚合
• 使用回收的NBR橡膠，加入單體，使用微
乳化聚合，再將橡膠還原成NBR乳液。
攪碎過烘乾的橡膠 2克+Eac 30克溶
加入BA 18克 ，十八烷醇 0.8克，起始劑 0.18克
倒入
5克 SLS加入100毫升水 溶
均質機混合攪拌30分
未通氮氣
在75℃下反應2小時
提高至80 ℃反應5小時
最後升至85 ℃1小時
BA 18克 +十八烷醇 0.8克
加入攪碎過烘乾的橡膠 2克，起始劑 0.18克
倒入
5克 SLS加入100毫升水 溶
均質機混合攪拌30分
未通氮氣
在75℃下反應2小時
提高至80 ℃反應5小時
最後升至85 ℃1小時