α-Mangostin was extracted from the pericarp of the Malaysian local Garcinia mangostana linn., The structure was characterised by Infrared red, UV-Visible and Nuclear Magnetic Resonance spectroscopic data. The fluorescence peak at 500nm in ethanol was not observed in PNIPAM microgel solution. The increase of colloidal size of the gel in the presence of α-mangostin was studied by Dynamic Light Scattering and Transmission Electron Microscope. The size of the particle also increases with increasing temperature up to 45⁰C after which it began to shrink. The TEM micrograph at 45°C showed a uniformly structured pattern of the gel occurs in the range of the lowest solution critical temperature.
The purpose of this study was to produce a novel pH sensitive hydrogel with superior thermal stability, composed of
poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali
and bleaching treatments followed by acid hydrolysis. PAA was then subjected to chemical cross-linking using the crosslinking
agent (N,N-methylenebisacrylamide) in CNC suspension. The mixture was casted onto petri dish to obtain disc
shape hydrogel. PAA/cellulose hydrogel with the same composition ratio were also prepared as control. The effect of
reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH
was studied. The obtained hydrogel was further subjected to different tests such as thermogravimetric analysis (TGA) to
study the thermal behavior, Fourier transform infrared for functional group identification and swelling test for swelling
behavior at different pH. The cross-linking of PAA was verified with FTIR with the absence of C=C double bond. In TGA
test, PAA/CNC hydrogel showed significantly higher thermal stability compared with pure PAA hydrogel. The hydrogel
obtained showed excellent pH sensitivity and experienced maximum swelling at pH7. The PAA/CNC hydrogel can be
developed further as drug carrier
Kanji Dioscorea pentaphylla telah diubah suai dengan pensulfatan dan peneutralan bagi menghasilkan natrium
kanji sulfat. Tindak balas pensulfatan dilakukan dengan asid sulfurik dalam etanol dan air pada suhu 0o
C. Darjah
penukargantian dikira berdasarkan peratus karbon dan sulfur yang ditentukan menggunakan penganalisis unsur CHNS.
Natrium kanji sulfat yang mempunyai darjah penukargantian dan peratus nisbah berat hasil yang tinggi dipilih dan
dicirikan dengan spektrum transformasi Fourier inframerah (FT-IR) dan profil pembelauan sinar-X (XRD). Kehadiran
dua puncak getaran regangan C-O-S dan S=O dalam spektrum FT-IR dan puncak berbeza yang terhasil dalam corak
difraktogram XRD membuktikan tindak balas berlaku pada struktur kanji. Sifat termal juga ditentukan dengan kalorimeter
pengimbas pembezaan (DSC) dan analisis termogravimetri (TGA). Natrium kanji sulfat yang dihasilkan mempunyai
kestabilan termal yang baik kerana mempunyai suhu penguraian pada 265o
C. Natrium kanji sulfat ini sesuai dijadikan
bahan tambahan dalam penghasilan hidrogel, organogel dan filem dengan sifat anionik kerana degradasi tidak terjadi
di bawah suhu ini.
Kajian ini bertujuan menghasilkan hidrogel responsif berasaskan selulosa bakteria yang diperoleh daripada Nata de
Coco (NDC) dan asid akrilik (AA). Tiga jenis sampel telah disediakan berdasarkan nisbah NDC:AA iaitu sampel hidrogel
A [1:1], B [2:1] dan C [3:1]. Pencangkukan AA terhadap molekul NDC menggunakan kaedah pempolimeran radikal
Gamma (GRP) menghasilkan hidrogel NDC-AA (sumber: 60Co). Kaedah yang menggunakan tenaga yang tinggi ini akan
menghasilkan radikal bebas seperti OH•, H•, H2O2 dan H2. Kesemua radikal ini menyerang kumpulan berfungsi yang
terdapat pada NDC dan AA seterusnya menggalakkan proses pencangkukan AA terhadap NDC. Hidrogel B [2:1] dipilih dan
diuji sebagai penjerap metilena biru (MB) dan perubahan keamatannya telah dianalisis menggunakan spektrofotometer
UV-VIS. Keputusan yang diperoleh telah diselaraskan dengan dua model isoterma, Langmuir dan Freundlich. Perbandingan
pemalar bagi kedua-dua model isoterma ini mendapati hidrogel B [2:1] yang dihasilkan telah mematuhi kedua-dua
model isoterma. Keputusan yang diperoleh ini menyokong keupayaan hidrogel B [2:1] untuk digunakan sebagai penjerap
alternatif MB yang paling efisien.
Tujuan kajian ini adalah untuk mengkaji kebolehan hidrogel daripada selulosa bakteria (BC-g-PAA) sebagai pembawa bagi
menghasilkan nanozarah ferum oksida (FeNps). Hidrogel selulosa telah disintesis menggunakan kaedah pempolimeran
radikal bebas. Secara umum, kaedah pempolimeran radikal bebas ialah pempolimeran berantai (pempolimeran berion),
dengan monomer radikal bebas menyerang monomer lain yang ikatannya berganda sehingga membentuk rantai dan
akan melebarkannya. Nanozarah ferum oksida (FeNps) telah dihasilkan melalui gabungan antara 1 × 10-4 g/mL garam
ferosenium ke dalam sistem hidrogel, seterusnya agen penurun natrium oksida (NaOH) dengan kepekatan 1 M digunakan
untuk mendapatkan zarah. Hidrogel di dalam larutan penimbal pada pH10 ialah yang mempunyai nisbah pembengkakan
tertinggi. Keputusan FTIR menunjukkan bahawa asid akrilik (AA) berjaya dicangkukkan pada jaringan selulosa bakteria
(SB). Imej hidrogel telah dicirikan melalui analisis mikroskopi elektron imbasan (SEM), diikuti oleh spektroskopi tenaga
serakan X-ray (SEM-EDX) dalam penentuan peratusan elemen ferum (Fe). Nanozarah berhasil diperolah selepas hidrogel
dikalsinkan, seterusnya zarah tersebut diuji melalui mikroskopi transmisi elektron (TEM) dan pembelauan sinar-X
(XRD). Analisis TEM menunjukkan diameter zarah berukuran 5 - 20 nm. Keputusan XRD mengesahkan bahawa zarah
yang diperoleh ialah ferum oksida (Fe3
O4
) yang terletak pada puncak 2θ; 32°, 35°, 49° and 54°. Semua keputusan yang
diperoleh menunjukkan bahawa hidrogel berasaskan selulosa bakteria berjaya digunakan sebagai nanoreaktor untuk
menghasilkan nano zarah ferum oksida (FeNps)
Vinegar is a liquid product that undergoes both alcoholic and acetous fermentation of sugar (carbohydrate) sources. Soursop (Annona muricata) is easily available in Malaysia throughout the year. However, it is also highly perishable and has a short shelf-life. Therefore, in this research, soursop was used in the production of vinegar, to increase its utilisation and reduce wastage. The objectives of this research were to determine the effects of fermentation time and pH on soursop vinegar using a 3 × 5 factorial design and to determine its chemical compositions. It was found that pH and fermentation time showed significant (p<0.05) effects on the reduction of sugar content and the production of acetic acid, while only fermentation time showed a significant effect on the production of ethanol. The interaction between factors did not exhibit any statistical significance (p>0.05). It was evident that the sugar concentration reduces over time and it was inversely proportional to the ethanol and acetic acid concentrations, due to the conversion of sugar to ethanol and subsequently acetic acid. It was found that higher pH (pH5.5) gave significantly (p<0.05) higher acetic acid production in the vinegar, while pH has no significant (p>0.05) effect on ethanol production. There were no significant differences (p>0.05) in vitamin C content in all vinegar samples. Thus, it can be established that at fermentation time of 120 h and pH5.5, more sugar was used and more ethanol and acetic acid were produced.
In this study, Bacterial cellulose (BC) grafted with Acrylic acid (AA) was prepared using Co60 γ-rays source (30 KGy).
Although many samples were prepared, BC: AA with ratio of 1:1 labelled as A1 and 2:1 labelled as A2 gave the most
significant results. Hence these particular ratios have been selected and further investigated. AA was proven grafted onto
BC by using ATR-FTIR due to the absent of C-O stretching (1040 cm-1) in both hydrogels. The SEM image of both hydrogels
samples showed highly porosity networks structure have been produced. The physical properties of the hydrogels such
as equilibrium water content (%) and swelling ratio (%) in different pH buffer solution were measured. It was found
that the equilibrium water content (%) of A1 was 93.10% while A2 was 74.83%, respectively. The results indicated that
the equilibrium water content (%) increased by gaining the AA concentration. At pH10, the A2 swelling ratio (%) was
two folded with 3350% in comparison with the A1. For the removal of methylene blue (MB) from aqueous solution, the
results from the UV-VIS spectroscopy demonstrated that the A2 sample hydrogel was also an effective absorbent material